Blue Penguin Report

By Red Sox Steve
VagabondGuru.com

I spent October and November 2010 in China - I've seen the largest green energy project in the world (Three Gorges Dam), rode high-speed trains all around the country, and took the Middle Kingdom's impressive public transportation system in every city I visited. I didn't take pleasure cruises or use high-end travel services; I walked the streets and rode the subways and busses.

I see, I learn, I process and think. I do it all for my edification and yours - those willing to ponder the 22nd and 23rd centuries, at least.

How we produce renewable energy is essential to that future, and it's why I write about it today.

China and the United States are the two largest greenhouse gas producers in the world, together responsible for around 40% of global greenhouse gas production. This is the direct result of converting nonrenewable resources like coal, oil and natural gas into electricity. China and the US are also among the top four nations (Russia and India are the other two) holding 60% of global coal reserves. 70% of China's energy comes from burning coal, and in the US, 46%.¹

In absolute terms, we see more distinctions: Each year, the sum of human activity puts 37 billion tons of CO₂ in the earth's atmosphere; two decades ago, it was less than 25. On average, an American puts 25 tons of CO₂ into the atmosphere each year, and a Chinese person puts 8. America's per capita electricity use is 13.6 megawatt hours/year, while China's is less than 3.² China's total energy consumption as of 2009 is 2,234 Mtoe (Million "Tonnes of Oil Equivalent", energy produced from burning one ton of oil), while the United States consumed 2,201 Mtoe. The next closest was India with a distant 655.³

In both nations, non-renewable resources make up a huge percentage of energy production, and renewable resources, such as solar panels, make a small contribution - In each of China and the United States, solar panels make up less than 10% of energy production.

China's economy has been growing for about 3 decades, and this growth can be traced back to market reforms initiated by Deng Xiaopeng in 1978. Thereafter, China's economic output grew quickly, steering millions away from the agrarian lifestyle they had known for generations. China started to become heavily dependent on the burning of minerals and fossil fuels; its yearly energy consumption has more than quadrupled since the 1980s. By the early 1990s, construction on the Three Gorges Dam had begun (oil prices were at a then record high), and China's commitment to renewable energy hasn't wavered since.

Today, China's fast growing economy is accompanied by some sobering public health statistics - 16 of the top 20 most polluted cities in the world are in China⁴, and cancer is one of the nation's leading causes of death.⁵ During my visits to cities as far north as Harbin and as far south as Guangzhou, it became typical to see a hazy skyline when viewing the cityscape - as if the sun wasn't shining brightly on even the clearest days.

By the start of the 21st century, construction on the Three Gorges Dam was proceeding apace, but was still more than a half decade from completion. The 18,200 MW it was forecast to produce would make a sizable dent in China's fossil fuel consumption, but more renewable sources were needed. Around that time, the Chinese turned to solar production in a big way.

The largest producer of solar panels anywhere in the world today is a company called Suntech, headquartered in Wuxi, Jiangsu Province, China, just an hour's train ride from Shanghai. Let's have a glance at highlights taken from an article about the company⁶:

- Zhengrong Shi, CEO of Suntech, earned a Ph.D in solar power technology in the mid 1990s from Australia's University of New South Wales, and after working in Australia for a few years, returned to China in 2000, founding Suntech in 2001.
- Suntech's first factory opened in 2002, and has since cut solar panel production time significantly.
- In 2007, only 2% of global solar panel production came from China. In 2010, that number was 42%.
- Per Watt production costs have dropped from $3.20 in 2004 to $1.28 in 2010 for Chinese manufacturers.

According to the article and a related video⁷, the main component behind Suntech's solar panels is a molecule called "multicrystalline silicon". Multicrystalline silicon is a silver metal with an irregular crystal structure. In other words, the locations of, and distances between, silicon atoms is not uniform throughout the molecule; the irregularity lends itself to an unpredictable path for electron travel. Carrying this one step further, the unpredictability of an electron's path has ramifications in the efficiency of a solar panel's ability to convert incoming light to electric current. The movement of electrons through an irregular crystal structure is similar to telling a blindfolded person to navigate a maze without hitting a wall - very few make it all the way through.

Suntech's multicrystalline silicon technology has broken its own record for solar cell efficiency and is currently more than 17% efficient, the highest in the world. However, there is a technology being investigated at UNSW, which is discussed in the video interview: solar panels that use the PERL method. PERL stands for "Passivated Emitter and Rear Locally diffused". In an upgrade from widely used solar-cells that use doped silicon, and reflect light back out of the solar cell, PERL technology captures more of those escaping photons.

Here is a link to the white paper that contains the above schematic: PERL technology. The front edge of the solar panel is coated (industry term: "passivated") with an anti-reflective surface, preventing photons from bouncing back out of the solar panel once inside. The coating is a metal-oxide substance that can be one of two types: "SLAR" or "DLAR" - "Single-layer anti-reflective" or "Double-layer anti-reflective". According to Suntech's CEO, PERL technology has achieved 25% efficiency for about 20 years.

Until the last couple of years, when UNSW started collaboration with Suntech to commercialize PERL-based solar cells, PERL had no economic viability. One of the main obstacles was found in the panel production process. As stated in the video - the front (sun-facing side) of solar cells are coated with narrow metal lines that collect electrical charge. According to Dr. Stuart Wenham, Suntech's CTO, these narrow lines are actually too wide, reducing the amount of light retained, and thus reducing efficiency of the solar cell. Dr. Wenham concludes that the metal lines placed on solar cells must be one-sixth (from 120 microns wide to 20 microns wide) as wide as they currently are to effectively use the highly efficient PERL technology and make it commercially viable.

According to a 2009 whitepaper released by Suntech ⁸, they have successfully changed some of the processes and materials associated with PERL production and have "whittled" the width of the metal lines down to 25 microns, as compared to 20 microns in PERL solar cells; these lines are spaced less than 1mm apart, which is exactly the spacing found in PERL solar cells. As a result, Suntech has achieved greater than 18% efficiency⁹ (verified by an outside source) and has been marketing the new solar cells under the trademark "Pluto".

China and America continue to be - far and away - the largest energy consumers on earth, and are consequently its biggest polluters as well. Over the last couple of decades as the Chinese economy has grown rapidly, the Chinese have evidenced a commitment to renewable energy through massive projects like the Three Gorges Dam. Companies like Suntech fit perfectly under this umbrella - they mass produce solar cells and continue to add layers of understanding and improvement to solar cell technology, pulling in well-understood research and attempting to commercialize it. The concepts I've discussed above are merely the beginning of the renewable energy revolution mankind needs to meet the energy requirements of the future.

Sources:
1, 2. "Dirty Coal, Clean Future", Atlantic Monthly, December 2010
3. http://yearbook.enerdata.net/
4. China's View of Climate Change by Ying Ma, Policy Review, June & July 2010
5. http://www.earth-policy.org/data_center/C21
6. "Solar's Great Leap Forward", Technology Review, July/August 2010
7. http://technologyreview.com/video/?vid=581
8, 9. http://am.suntech-power.com/images/stories/pdf/other/pluto_whitepaper.pdf

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By Red Sox Steve

Last time, we talked about carbon nanotubes - they are strong and conductive, yet unless we get them to adhere to a surface, we will have trouble getting the full potential out of them. Scientists have used a process called electrophoretic deposition to layer a thin film of CNTs onto a substrate surface; additional procedures make the entire film (which we cannot see with our naked eye) stronger and more stable.

Now though, especially after my trip to Brazil where nearly every car on the road there would be considered a "compact" car in the US and nearly every light bulb was an energy saving bulb, I've got my mind on that very topic - how can we generate more energy using new science? Is it possible, within the field of nanotechnology, to develop systems that can generate electricity? How is this all accomplished?

Scientists are investigating the use of a compound called Gallium (III) Nitride ("GaN") made into nifty objects called "nanorods", combined with an atomic force microscope with a PtIr (Platinum Iridium) tip to generate current.

Before we get into all that, let's talk about GaN and nanotechnology. From prior discussions about nanotech, we know that by using the nano-properties of molecules, we are deviating from "traditional" science which incorporates a molecule's bulk properties into any experimentation and analysis. Please read some of my prior articles for a more extensive discussion of the differences between bulk and nano properties.

Here though, we are going to revisit a topic very familiar to our nanotech journey - crystal structure. In studying ZnO ("Zinc Oxide") previously, we are aware of one of its predominating crystal structures, known as the wurzite structure. The wurzite crystal structure appears in a number of semiconducting materials, like GaN and ZnO. It is what is known as a "hexagonal" crystal structure and each atom within this "binary" (because there are only two unique atoms) structure is tetrahedrally coordinated - in other words, each atom is connected to four neighboring atoms. Without going into specific properties of bonding, the atoms work together to share electrons with each other (recall that the sharing of electrons is the fundamental characteristic of a chemical bond).

Scientists who study crystals understand a couple of critical things about the wurzite structure: 1) it is non-centrosymmetric (in other words, when inverted, it displays no axis of symmetry) and 2) the surface of wurzite crystals is polar which means that electrons will be able to move around the crystal easily. These two properties are very useful when discussing materials that "semi-conduct" electrons because the electrons can be absorbed or given up with relative ease and without changing the structure. Furthermore, because of the electronic structure of Gallium and Nitrogen and their combined form of Gallium Nitride, the bandgap between the valence band and the conductance band is ~3.4 eV (electronVolts).

These principles lead us to the idea behind using GaN to generate current in the first place and something we've discussed here before in our writings about ZnO... piezoelectricity! Piezoelectric compounds generate an electric potential when mechanical stress is applied, which is what is going on in this experiment.

That's the science behind GaN, but how were the nanorods assembled?

The process used to make the nanorod sample is called "Molecular Beam Epitaxy" ("MBE" for short). The idea behind epitaxy is depositing a substance that is one crystal thick onto a substrate. Like much of what we've previously discussed in nanotechnology, a non-reactive substrate was used - in this case, a silicon wafer. An ultrapure sample of Gallium in solid form was heated in an effusion cell and sublimated (going directly from solid to gaseous form without becoming a liquid). The purpose of the effusion cell is to get the Gallium sample hot enough to where it becomes a gas then releasing it over the substrate. Nitrogen, which exists in nature just like hydrogen and oxygen, in a diatomic gaseous form, was fed into a plasma generator, turning it into an ionic gas. Both gases were passed over the substrate, and at 720 deg. C, a layer of GaN started to form. The GaN self-assembled into nanorods, and their presence was confirmed via Scanning Electron Microscopy (SEM).

Nanorods cannot be seen with the naked eye, however, to prove that the samples exist in the configuration scientists believe them to be, their presence must be confirmed. This is where SEM comes in - a beam of electrons is shot at a sample, and through specialized detectors which record electron scattering and electromagnetic radiation, a topographic image of the sample can be created.

Caption: An image of GaN nanorods as a result of SEM analysis. The photo is similar to a topographic map - the SEM electrons detect and deflect, giving the observer a sense of what has been created. Without SEM, scientists would have no idea what is happening at the nanoscale.

Understanding the principles behind Gallium (III) Nitride and how it works in the world of nanotechnology is another weapon in our arsenal. Continuing to make diatomic semiconductors from transition metals and gases will continue to expand the possibilities of nanotechnology. In this case, we can see that wurzite crystal structure, just like in both ZnO and ZnS, is a critical part of conductivity of electrons and can incorporate the piezoelectric effect. If we are going to use nanotechnology to solve the energy problems of the world we inhabit, we need to meet these nanoparticles where they are - in other words, on a very small scale, we need to understand how current can be generated from the manipulation of substances like GaN. Next time, we will discuss the mechanical force that is applied to the nanorods and how the nanorod responds to give us the piezoelectric effect we are looking for!

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By Red Sox Steve

So last time we were here, we took a look at our setup: The GaN nanorod comes into contact with the AFM tip and the substrate. Because different layers have been inserted within this array, any current formed when the nanorod bends will flow through the voltmeter. It's also important to keep in mind that no other voltage or current has been introduced into the system - the only current/voltage source is the nanorod. Furthermore, the AFM tip-nanorod interface forms a metal-semiconductor diode, more commonly known as a "Schottky diode".

Diodes are used in circuits in order to allow electric current to flow in one direction, preventing it from flowing in the opposite direction. The direction in which current flows is known as its "forward biased" orientation, while the opposite direction is called the "reverse biased" orientation. For our GaN nanorod, we only want current to flow away from the rod and towards the voltmeter.

Photo: AFM Tip Bending the Nanorod

Caption: We saw this photo last time, to get an idea of how our experiment is setup. Here, the AFM tip is beginning to come into contact with the GaN nanorod, bending it and creating a potential difference (aka voltage) across the rod.

On the side of the nanorod being stretched (here, the left side), the current's direction as indicated by the arrow is forming a "forward-biased" diode. As the nanorod is bent and the tip grazes across the stretched side, current increases sharply relative to voltage (i.e. NOT in a linear fashion). As the tip comes into contact with the compressed side of the nanorod, the amount of current generated DROPS very quickly. The "reverse bias" of the Schottky diode ensures that no current flows back into the nanorod.

So, for the purposes of generating a current, the tip is run across the nanorod; as the rod is bent, the stretched side generates a current (in the "forward biased" direction of the Schottky diode) while the compressed side produces no current (corresponding to the Schottky diode's "reverse bias"). The idea here is that the kinetic energy of the AFM tip deforms the nanorod via elastic energy to generate a current.

What scientists further investigated was whether scanning speed had any relationship to current - setting the tip across the nanorod at various speeds produced higher and higher currents. By gathering experimental information and understanding kinetic energy transfer to elastic energy in the nanorod, Dr. Su's team was able to determine the influence of a number of variables on current output. The displacement of the nanorod is linearly proportional to scanning speed (rate at which the AFM tip moves... measured in microns per second), while it has previously been determined that voltage is linearly proportional to nanorod displacement. Therefore, scanning speed and voltage output also have a linear relationship. Because scientists are able to factor in scanning speed, voltage and even displacement distance of the nanorod, they can determine the amount of current that a Schottky diode will generate.

Converting mechanical energy into electrical energy in the GaN nanorods involves piezoelectricity, semiconducting properties (ohmic contacts) and Schottky diodes. The idea behind generating current less than an ampere is that this "lost" energy can be used to power other nanomaterials. As the rod is bent, a potential difference is formed and current is generated. The Gallium Nitride nanorod is specifically oriented in order to generate potential in a specific direction, and the ohmic contact it makes with the substrate prevents the "leaking" of any electrons away from the circuit.

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By Red Sox Steve

A few weeks ago, before my trip to South America and while the weather gods of the Northeastern US were still unaware that it was summer, providing rain and thunder around the region, we were discussing Nanotube adsorption onto substrates. In the study I cite here below, scientists were "functionalizing" nanotubes with carboxylic acid groups, adsorbing them onto a substrate, and then bombarding the entire array with protons. All this was done in the name of strength and stability - adding carboxylic acid groups was thought to help the nanotubes stick more strongly to the substrate, and adding protons to the system was thought to create a more stable system of cross linkages between nanotubes.

So, the experiment was conducted, the nanotubes were functionalized, adsorbed, and then bombarded with protons, but what happened?

Three different samples were examined using a device called a "profilometer". A profilometer's job is to measure the characteristics of a surface in order to determine how rough it is. Think of a needle on a record player - grooves in a record's surface are manifested as sound because of the needle's interaction with the record. In our case, the profilometer's job is to measure the change in thickness as a result of coating the substrate with nanotubes.

Prior to running the surfaces through the profilometer, however, samples were subject to the following conditions:

1) An electrochemically deposited CNT sample which was not exposed to proton bombardment was rinsed in a hexane solution, then in a deionized water solution.

2) An electrochemically deposited CNT sample which was exposed to proton bombardment had been rinsed in a hexane solution, and then a deionized water solution.

3) An electrophoretically deposited CNT sample exposed to an acid solution was rinsed in a hexane solution, then a deionized water solution

- The CNT sample (1) that had not been exposed to proton bombardment was able to remain adhered to the substrate surface after being put in a hexane solution and placed in a centrifuge for 5 minutes (the "hexane rinsing"). However, the same sample was completely removed during the deionized water rinsing process.

- The CNT sample (2) that was bombarded by protons was also able to resist the hexane rinsing process; it suffered only a 33% loss in thickness when rinsed with deionized water.

- The CNT sample (3) produced by electrophoretic deposition then exposed to acid was unable to survive the profilometry process. It was "scratched" off the substrate's surface when placed in the profilometer, indicating an extremely weak adsorption to the surface.

There are a number of pieces of evidence in this study which tell us how effective things like functionalization and proton bombardment can be to controlling the adsorption strength of nanotubes. First of all - as it relates to EPD - the electrophoretic deposition of nanotubes onto a substrate surface has proven to be too weak. If the samples can't survive being put through a profilometer, then little analysis can be done.

Next, with respect to ECD - both the proton bombarded and non-proton bombarded samples survived the hexane rinsing process intact. Before and after being put in a hexane solution and then a centrifuge, there was no change in the surface thickness according to the profilometer. This means that functionalized CNT samples can remain adhered to their substrate when being exposed to a nonpolar hydrocarbon solvent (in this case, hexane).

However, it was the deionized water rinsing process that produced much more interesting results. The idea behind bombarding functionalized CNTs with protons is that the excess H+ ions will increase the reactivity of the H atoms already in the system. In our case, the carboxylic acid groups that exist on the surfaces of the nanotubes provide existing H atoms, ripe for reactivity. The theory is that when such a system is bombarded with protons, the Hydrogen bonds of the COOH group break producing COO- ions which are ripe for reactivity. The nearest positively charged ion is the iron-based substrate surface, thus the carboxylic acid group reacts with the substrate, more strongly adhering the CNT to its surface.

Furthermore, proton bombardment also weakens the C=C double bond (recall from previous discussions that this is also known as a "pi" bond) enough where freed carbon radicals migrate along the graphite surface and are able to react with other carbon radicals. When carbon radicals on adjacent CNTs meet, a new pi bond is formed, therefore strengthening the cross linkages between neighboring CNTs. The process of proton bombardment is delicate enough, however, that these samples were all given a relatively low dose of excited protons in order to ensure that reactions only took place on the outer layers of our multi-walled CNTs.

So, the deionized water rinsing process produced interesting results because neither the electrophoretically deposited CNT NOR the electrochemically deposited CNT prior to proton bombardment were able to remain adsorbed to the substrate. Only the CNT sample that was exposed to proton bombardment was able to remain adhered to the substrate after both the hexane rinsing and deionized water rinsing.

Carbon nanotubes were pretty neat already - they are super conductors and have more strength per unit mass than steel. The problem scientists have now taken on is how to effectively adhere them to a substrate. Electrochemical deposition is a step up from electrophoretic deposition of nanotubes onto substrates, and functionalizing the nanotubes provides another level of flexibility and control over the entire process. Furthermore, proton bombardment can control the inter-nanotube cross linkages that are needed for additional system stability. At nearly the tiniest level known to man, scientists can manipulate atomic interactions to produce more appealing and more useful substances. In this case, adding organic functional groups and energized protons into the mix gives the nano-world something further that it can work with to miniaturize everything around us. We are undoubtedly witnesses to something that cannot be identified by the naked eye: the growing powers of nanotechnology!

Fabrication of cross-linked multi-walled carbon nanotube coatings with improved adhesion and intrinsic strength by a two-step synthesis: electrochemical deposition and hyperthermal proton bombardment
Appl. Phys. A 91, 403–406 (2008)
DOI: 10.1007/s00339-008-4459-5

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By Red Sox Steve

So last time, we discussed various methods of synthesizing Carbon Nanotubes (CNTs) - using either electrical current, lasers or gaseous deposition, CNTs of differing characteristics can be synthesized with various yields - the process of Chemical Vapor Deposition (CVD) seems to be the most popular in this regard. The next challenge for scientists is adhesion of CNTs onto substrates, which brings us to a process called electrophoretic deposition (EPD).

The current problem scientists are having with nanotubes is in their arrangement and assembly, especially their combination with other molecules, all of which ultimately influence their function and utility. As a result, scientists out of Hong Kong, Xuchang, and Canada (citation below) are developing a new method of adhering CNTs onto a substrate in order to increase the utility of the CNT.

They are attempting to use EPD to deposit "functionalized" MWCNTs (Multi-walled carbon nanotubes a/k/a CNTs) onto a substrate, then bombard the functional groups with protons thereby creating a very strong multi-layered structure of interwoven CNTs. That's a mouthful! Here's the idea - by taking CNTs and adding functional groups onto their surface, they can change the relationship that the CNTs have with each other and with the substrate. After functionalizing the CNTs, they are then using EPD to adhere CNTs onto an iron-based substrate. In this case, the functional group they are adding is a carboxylic acid group (below).

In addition to adding carboxylic acid into the mix, they are using a process called hyperthermal proton bombardment (HPB). Using HPB in the process allows the nanotube array (which has now been functionalized with carboxylic acid) to undergo greater cross-linking of adsorbed molecules; CNTs are adsorbed (also known as "stuck") to the substrate surface we are attempting to cross-link.

The point in all this is strength. Scientists need to be able to prod, push and pull these nanotubes without them detaching from the substrate. By putting an acid group on the surface and then bombarding the entire sample with protons, they are working on strengthening the inter-tube linkages so the nanotubes can withstand more force.

So what about the experiment?

Let me preface this by saying that there are many ways of explaining what is going on in the process we are talking about called "electrochemical deposition". In electrochemical deposition, an electrical charge sent from a negative to a positive electrode does two things: 1) it removes electrons from metals at the anode creating a positively charged ion which allows negatively charged ions from the solution to "deposit" on the surface of the anode and 2) it sends electrons over a wire, to reduce positively charged metal ions at the cathode creating neutral metal ions there, which then dissolve in the solution. In our case, our CNTs will collect on the surface of the anode due to the loss of electrons there, while our graphite rod cathode deposits electrons into the solution, producing hydrogen gas. Have a look at the schematic below:

The CNTs were functionalized with a carboxylic acid group and suspended in a non-reactive hydrocarbon solution. By putting together a structure similar to the galvanic cell above, scientists were able to achieve CNT deposition onto the iron anode. At the other electrode, electrons combined with free hydrogen ions to form hydrogen gas which was released into the air.

When nanotechnology was first contemplated by Dr. Feynman in 1959, there were no such things as nanotubes; By 1996, nanotubes were able to be developed on a massive scale. Many properties of nanotubes are well known, however numerous aspects still challenge scientists. For example, being able to control subatomic particles and nanotube orientation via molecule-molecule interactions is a critical part of the next phase of nanotechnology. Scientists are still working on ways to gain further control over this miniature world by customizing nanotube assembly methods like the one we're talking about here. On Saturday, we'll look at how successful the procedure was and, in the process, continue to develop an understanding of the world in terms of these very tiny objects.

Fabrication of cross-linked multi-walled carbon nanotube coatings with improved adhesion and intrinsic strength by a two-step synthesis: electrochemical deposition and hyperthermal proton bombardment
Appl. Phys. A 91, 403–406 (2008)
DOI: 10.1007/s00339-008-4459-5

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By Red Sox Steve

Over the course of exploring nanotechnology, as opposed to when I first began writing months ago, I'm finding that there is nearly universal agreement among scientists and other interested parties on a couple of things: first, where the nano world begins, the macro (or, bulk) world stops. In other words, as soon as principles related to bond length, electron transfer and molecular or crystal dimensions start to become important, we are in the nano world. When a material is present in bulk, however, such a small percentage of molecules exists on a surface that it is difficult to ascertain the characteristics of a single molecule. When a material is present on a larger scale, the average of each molecule's properties is taken to represent the whole; At the nano level, a molecule's particular characteristics may be completely different.

Second, because of the scale of nano-science, this particular field of study changes our relationship with nature, especially in areas related to medicine and electronics. DNA and cellular pores have dimensions on the order of nanometers; scientists have worked on semiconductors that generate less heat and more electricity (electron flow!) based on molecular interactions. Nanotechnological discoveries will miniaturize much of the world around us, and, ultimately provide more specific solutions for the very acute problems of our world.

I've been doing some digging trying to find out the latest and greatest in nanotechnology (within my chemistry-based understanding), and I came upon a 2006 study done out of Columbia that talks about carbon nanotube (CNT) positioning. Part of the problem, after CNTs are created (synthesized), is determining and controlling their orientation.

Before we get into that though, let's try to understand some of the methods associated with synthesis, and the characteristics and background of carbon nanotubes...

Nanotechnology was first discussed as its own branch of science in 1959 by Richard Feynman in a speech given at the annual meeting of the American Physical Society at the California Institute of Technology (Caltech). In the speech, Feynman talks about how it would be possible to get all the volumes of the Encyclopedia Brittanica written on the head of a pin. By 1991, the first carbon nanotubes were inadvertantly created in a process intended to produce fullerenes (a/k/a Bucky Balls) from graphite. In 1992, the same technique was used to intentionally produce CNTs, and by 1996, large-scale production of CNTs was first reported.

Before continuing, have a look at what I had to say about nanotubes in this article.

Carbon nanotubes can be synthesized in a number of ways:

1) Arc Discharge - an electric arc is created between two electrodes, one positive and the other negative. Nanotubes are formed from the carbon existing on the negative electrode. The relationship in this system between current and voltage (think of circuits and Ohm's Law) is very difficult to control in this process relative to an electrical circuit. Further, the temperature is so high that carbon sublimates - it goes directly from solid to gas, without liquefying! It's expensive and typically yields less than 30% CNT.

2) Laser Ablation - a laser, in a pulsing fashion intended to pump high energies in a short amount of time, vaporizes graphite (carbon) while an unreactive gas permeates the reaction chamber. The vaporized carbon will then condense on a cooled surface, where nanotubes will collect. This method is expensive relative to #1 above and #3 below, but has a higher yield and is better controlled.

3) Chemical Vapor Deposition - To start the process, a substrate is layered with metal catalyst particles such as Nickel or Cobalt. The intended diameter of the nanotube is related to the size of the metal catalyst deposited or etched onto the substrate. The substrate is heated to 700°C, and gases are then slowly delivered into the substrate's chamber. Two gases are used - one is called a "process gas", which would be ammonia, nitrogen or hydrogen, while the other is a carbon-based gas (acetylene, ethanol, methane). The nanotubes grow on the catalyst because the carbon-based gas breaks apart at the catalyst surface.

4) The fourth method, which is in the process of being improved, is called "electrophoretic deposition" (EPD). Electrophoresis is the movement of particles within a fluid after the application of an electric field. EPD involves a suspension solution of particles - the solution contains the insoluble particles of interest in ion form. A current is applied to the solution, and depending on the charge, the ions will deposit on their oppositely charged electrode. Although this process involves CNT adhesion to substrates, it doesn't synthesize CNTs. Rather, CNTs are turned into CNT ions first, then these ions are electrically deposited on the surface of a cathode.

Subsequent to EPD, the carbon nanotubes are used in field emission. In other words, electrons were emitted from CNTs via the application of external electromagnetic fields. Field emission can take place from solids and liquids and can also promote electrons from valence bands to conduction bands within an atom (think semiconductors!).

Part of the problem with these methods is the adhesion of the CNT to the substrate - the adhesion force isn't strong enough, mostly because the CNT and the substrate are not chemically bound to each other. Specifically, as the study of CNTs is related to a field called "microfluidics", scientists understand that a principle called "flow stress" predominates over the stability of the CNT.

What does this all mean in english?

Microfluidics - this is the study of the behavior of fluids on the microscale (as opposed to the easily observable macroscale). Surface tension, energy dissipation and fluid resistance dominate a "micro" system. Studying the microfluidic properties of a fluid means examining how the behaviors change and can be worked with. Very similar to nanotechnology, the physical and chemical phenomena observed on a large scale may completely change on a very small scale. For example on a micro level, fluids may not actually mix and molecules may only move between fluids as a result of diffusion.

Flow stress - the amount of stress required to sustain deformation of a substance at a particular strain. Chemical composition, crystal structure, and grain size all affect the flow stress of a substance.

In the case of CNTs adhered to a substrate, it has been difficult to get the CNT to stick to the surface, especially when placed under a deforming tension or other type of stress. Therefore, only a CNT very strongly adhered to its substrate's surface can withstand additional pressure. As a result, scientists are developing ways to adhere CNTs to a substrate much more strongly. One of the most important factors in more solidly attaching the CNT to the substrate is the way the CNT is assembled, which we will talk about next time...

Posted by Red Sox Steve at 11:27 AM | Permalink | Comments (1) | TrackBacks (0)

By Red Sox Steve

Thusfar, we've gone all the way from a general understanding of Zinc Oxide, to a cutting-edge, practical application of nano-level science. Using Zinc Oxide (an inorganic molecule) together with an organic molecule (something with carbon in it) allows us to make a nanostructure with a variety of uses. As long as the molecules used are not toxic, they can have medical applications. Furthermore, using a lamellar structure allows a further "customization" of the nano-properties of the structure, such as electron conductivity and self-assembly. Because it can be broadly applied in fields ranging from medicine to computing, nanotechnology clearly has a role to play in the future of our world.

Pardon the pun, but that's the "bigger" picture as it applies to our tiny world. On a much smaller scale, let's flesh out one of the most critical concepts in science as it applies to nanotechnology. Without this concept, much of the benefit of examining molecule-molecule or atom-atom interactions and the characteristics of crystal structures would be lost. That's right, I'm talking about electrons and conductivity. Without the ability to understand and manipulate electron behavior, it would be difficult to justify doing all this nanoscience!

Same goes for the nanostructure we've been looking at of late - the lamellar organic/inorganic photoconductor hybrid. Dr. Sofas and her team have been studying organic/inorganic nanolayers of Zinc Oxide and organic compounds to try to develop an optimally performing nanostructure for use in optoelectronics. Sans the scientific jargon, they are working on developing something very small that will manipulate the flow of electricity in very specific ways.

Can our Zinc Oxide organic/inorganic photolayer move electrons, and serve as a useful semiconductor? First, they had to confirm that electrons can be conducted in the presence of Zinc Oxide but not in the presence of Zinc Hydroxide. It was found that below 150 deg. C (the annealing temperature of Zinc Oxide), the Zinc Hydroxide's resistivity (resistance to the flow of electrons) was very high - higher than 10^12 ohm • cm (read as "ohm centimeters").

A voltage was applied to the system between two terminals to produce a given current. This is done because of a scientific law related to electrical circuits, Ohm's Law. Ohm's law defines the relationship among current, voltage and resistance by stating that the current between two points is directly proportional to the voltage between them and inversely proportional to the resistance between them. In mathematical terms, this is written as V = IR, where V is Voltage, I is Current, and R is resistance.

In the case of a Zinc-Hydroxide organic/inorganic nanostructure, the resistance was extremely high, both before and after UV light was introduced into the system. Because Zinc Hydroxide is widely known to be an insulator and not a conductor, these results are not surprising. However, after annealing the nanostructure to 150 deg. C, the system's resistance dropped considerably - to nine orders of magnitude lower! In other words, ZnO is an excellent conductor, as compared to Zinc Hydroxide. Although the resistivity value is about 8 x 10^3 ohm • cm, what's even more interesting is that it is very similar to that of polycrystalline ZnO by itself! Furthermore, when UV light was shined onto the structure, the resistance dropped even further! This information is leading nanoscience down the "road of tunability"; in other words, scientists are developing ways to understand and control electron flow in molecules and nanostructures! Awesome!

How, though, does the organic component affect the conductivity of the nanostructure?

When a molecule gets excited, just like a person, it has higher energy - it moves faster, it heats up, and some molecules even emit light. In our case, one excited phase of the organic/inorganic structure is called an "excimer". An excimer is an excited dimeric (two molecules) structure in an intermediary energy state - in other words, an excimer is not fully excited, however, at least one of the molecules of the dimer is in an excited state.

In the nanostructure we are talking about, scientists have also examined the fluorescence of the organic/inorganic hybrid. First, what is notable is that at room temperature (the key being that this is below the annealing temperature of ZnO), the excimer gives off light; however, after annealing, the emitted light is much much less intense.

Whenever molecules are exposed to heat and subsequently fail to have the same characteristics as before being heated, many scientists are correct in surmising that the structure of the molecule must have changed - after all, the heat disrupted the molecular configuration, and by doing so, changed the molecule's function, right? In this instance, however, it has been confirmed that the structure of the energetically excited organic compound hasn't changed. By using another tool of scientific analysis called NMR (NMR = Nuclear Magnetic Resonance), scientists were able to determine that the organic was still present... after 12 hours of heating at 150 deg. C, it was still the same molecule.

What happened? All the organic molecule's excited electrons, instead of contributing to luminescence, were transferred to the newly formed Zinc Oxide! Yep, after annealing to 150 deg. C, the Zinc Hydroxide compound converted to Zinc Oxide, and because of its conductive properties, ZnO was able to participate in electron transfer from the organic absorbing all the electrons that would have been emitted as light. Pretty goddamn neat!

These are only the very early stages in terms of the impact that nanotechnology will make on our world. Although the study we've been reviewing is one of many that is seeking to understand and develop nano-level science, it is useful for our purposes - It lets us explore, on a granular level (I do enjoy my "nano-puns", thank you very much!), the process of how nanotechnology is evolving. It may not be that the particular device we are talking about someday keeps a heart beating or a brain functional, or puts man on the moon; however, it is the journey of exploration that man has undertaken which will continue to develop humanity's understanding of our subatomic world that is critical to the well-being of all. The micro-verse being explored here is a critical part of the 21st century world mankind is inevitably striving to build.

Study:
A synergistic assembly of nanoscale lamellar photoconductor hybrids
Nature Materials Vol. 8 January 2009
DOI: 10.1038/NMAT2336

Posted by Red Sox Steve at 09:57 AM | Permalink | Comments (1) | TrackBacks (0)

By Red Sox Steve

Last time, we talked about the structure of our organic surfactant, which is part of a larger organic/inorganic nano-sized semiconductor. The "bigger" picture (hee hee) here is that this is an example of the cutting edge research taking place where scientists around the world try to understand and master molecular interactions at the subatomic level. In other words, when two molecules are bonded to one another, how do the electrons involved in the bonds behave? This is just one of the many questions that scientists studying crystal structure, ionization energies, and single atom to single atom interactions attempt to answer.

What we know thusfar about Dr. Sofas' investigation into an organic/inorganic nanostructure is that ZnO has certain characteristics which make it favorable for use in nanotechnology, and that organic molecules with certain properties provide another layer of versatility which scientists can use to "tune" the sensitivity of the nanostructure. In other words, by using the same inorganic compound (ZnO) with different organic compounds, scientists are able to examine how the nanostructure changes, especially with respect to electron conductivity and self-assembly.

Now, what more can we discover about the structure? How does it respond to different temperatures? What happens to the inorganic phase, and what happens to the organic phase?

One of the focal points of the investigation is into temperature sensitivity of the ZnO crystal structure within the nanostructure. At 150 deg. Celsius, the structure of the inorganic changes from Zn(OH)2 to ZnO. In other words, the Zinc-based inorganic crystal structure is sensitive to temperature and ZnO is formed in systems where the temperature is at or above 150 deg. C. Furthermore, through Transmission Electron Microscopy, scientists were able to determine that above 150 deg C, the ZnO crystals in our nanostructure take their wurtzite form, which is the most common. For further discussion of the crystal structures and other characteristics of ZnO, click here.

The properties of ZnO are well understood - crystal structure, conductivity, resistance to temperature; however, the properties of our organic molecule and thus the entire nanostructure are not. How does the organic compound respond to changes in temperature and what does that do to our nanostructure?

We know our surfactant binds to the Zn cation because the surfactant has a negatively charged head, and the ionized Zinc is positively charged. Furthermore, we know that conjugation (the "single-double-single" configuration) allows electrons to be delocalized (spread out) throughout the organic molecule we have studied. Dr. Sofas' team wanted to study a couple of things:

1) Does the conjugated characteristic of the surfactant influence the strength and stability of the nanostructure?

2) Does the head group influence the strength and stability of the nanostructure?

In order to investigate the effect of conjugation, an organic (but non-conjugated) amphiphilic (polar head, non-polar tail) surfactant called Sodium Dodecyl Sulfate (SDS) was bonded to the inorganic.

It is already evident that at temperatures below 150 deg. C, the inorganic molecule that predominates is Zinc hydroxide, not Zinc oxide. Therefore, after the nanostructure was created at room temperature, it was heated to 150 deg. C in order to form the inorganic ZnO through a process called "annealing".

Let's diverge and just talk annealing really quickly - annealing is used in mettalurgy (work with metals) to change the strength and hardness of a crystal structure or the properties of a molecule. At room temperature, our zinc/oxygen molecule is not ZnO, but rather Zn(OH)2 ("Zinc HYDRoxide"). The melting point of Zinc Hydroxide is 125 deg C, while the melting point of ZnO is nearly 2000 deg. C. In order to change from Zinc Hydroxide into Zinc Oxide, the sample is heated to 150 deg. C. Therefore, at 150 deg. C., scientists can rely on the fact that no Zinc Hydroxide is present, and the material is entirely Zinc Oxide.

When the lamellar nanostructure of an inorganic & SDS was heated to 150 deg. C, the sample decomposed, the results of which we will discuss just after we explore our next finding.

To investigate the impact of the head group on the nanostructure, decanoic acid was bonded to the inorganic phase.

Here's the thing - SDS has a very strongly negative polar head group which will easily attach to a Zinc cation. It also has a long hydrocarbon chain, but no conjugation. Decanoic Acid has a carboxylic acid head group, which is similar to the other surfactants examined by Dr. Sofas' team. However, Decanoic Acid, like SDS, has a long non-conjugated hydrocarbon chain. Setting up studies with these conditions is based on the desire to answer one question: does the electronegativity of the head group influence the stability of the nanostructure?

After annealing to 150 deg. C, the outcome was simple: the lamellar nanostructure again decomposed.

As discussed above, by examining the lamellar nanostructure formed between Zn and SDS, scientists were able to determine the role that conjugation and the polar head group each play within the nanostructure. The result in all this? The head group's binding strength to the inorganic layer does not contribute to the thermal stability of the nanostructure as it converts from a zinc hydroxide structure to a zinc oxide structure. This is evidenced by the fact that neither the SDS-based nanostructure nor the Decanoic acid-based nanostructure were able to maintain stability during the transformation of Zinc Hydroxide to Zinc Oxide (the annealing process).

What about conjugation? Dr. Sofas' team is already aware of the fact that the conjugated 1-Pyrene Butyric Acid (1-PyBA) forms a stable lamellar nanostructure with Zinc Oxide that exists above 150 deg. C. Notice that 1-PyBA (below) is conjugated and contains a carboxylic acid head group.

Because 1-PyBA forms a stable nanostructure with ZnO above 150 deg C. and SDS doesn't, we know that it is NOT the head group that influences the stability of the nanostructure. Furthermore, because 1-PyBA forms a stable thermal-resistive nanostructure and Decanoic Acid doesn't, this tells us that something about the surfactant contributes to the lamellar stability of the nanostructure. That contributing factor is conjugation, the difference between the two molecules. Conjugation contributes to stability by what are called "pi-pi stacking" interactions. This brings us back to a prior discussion on quantum theory, whereby a single bond between two atoms is between the atom's S orbitals, and a double bond incorporates each atom's P orbitals. Bonding between P orbitals is called "pi" bonding (via our trusty Greek alphabet).

The theory behind pi-pi stacking is that inter-molecular pi-pi interactions allow molecules to create a system of further electron sharing between molecules which is thought to be what is happening when our conjugated surfactants line up on the surface of the inorganic. Although not as strong as a covalent bond (a more conventional and stable sharing of electrons), pi-pi interactions are able to contribute to a molecule's stability. Therefore, by introducing a molecule with NO conjugation, Dr. Sofas' team discovered that conjugation plays an important role in the nanostructure's thermal stability.

On a very small scale, the organic/inorganic nanostructure shows a variety of characteristics when altered. Building a nanostructure, and then testing its atomic makeup, thermal stability and organic/inorganic bonding strength provides more insight into how the structure can be influenced. By looking at the interactions between electrons and molecules, the synthesis and investigation taking place remains well within the confines of nanotechnology. This type of organic/inorganic semiconductor helps us understand that nanotechnology and certain types of molecules will play a role in our new and tiny world. Ultimately, nanotechnology will play a role in our 21st and 22nd century life, and by looking at the science involved today, we are merely glimpsing the possibilities of the future.

Study:
A synergistic assembly of nanoscale lamellar photoconductor hybrids
Nature Materials Vol. 8 January 2009
DOI: 10.1038/NMAT2336

Posted by Red Sox Steve at 09:34 AM | Permalink | Comments (0) | TrackBacks (0)

By Red Sox Steve

So, here we are again! Optoelectronics and nanotechnology, Zinc Oxide and inorganic/organic semiconductors, electron holes and excitons... there are so many exciting topics, relatively new scientific concepts which we will use to modernize our world.

In the case of our semiconductors, Dr. Sofas (citation below) and her team are using ZnO, which we already know a great deal about, and an organic molecule, also referred to here as a "surfactant". A surfactant is a shortened form of "surface acting agent" and it is a substance known to reduce surface tension between two types of substances - for example, between a liquid and a gas or between a liquid and a liquid. Furthermore, surfactants are known to be "amphiphilic"; in other words, their molecular structure has both a hydrophobic portion ("water fearing", thus soluble in organic solvents) and a hydrophilic portion ("water loving", thus soluble in water). In semiconductors, where we need to bind an organic molecule with an inorganic molecule, a substance that dissolves in water and other solvents AND can adhere to different surfaces will be very useful!

In this case, scientists are using organic surfactants, some of which are thiophene-based. Recall from last time that thiophenes are a class of molecule containing a sulfur-based 5 member conjugated ring. Thiophenes have been found to be a good organic conductor of electrons - based on trap state lifetimes and conjugated bond structure ("single-double-single").

So, what's happening? Scientists have used the method popular in "microelectronics" called electrodeposition to adhere a single crystal thick layer of the inorganic ZnO molecule onto a negatively charged surface. The surfactant, which has been dissolved in the solution, binds to the positively charged Zinc ions, and the product of this reaction is observed via high-powered microscopy - a "Scanning Electron Microscope" and a "Transmission Electron Microscope" as well as X-Ray scattering were used to determine the appearance, orientation and structure of the resulting object.

A quick note about microscopy: Early in the 20th century, a French physicist named Louis de Broglie suggested that if beams of electrons have certain characteristics, they might be used in microscopes. Furthermore, it was important that magnetic fields be used as lenses to detect the electrons. In 1931, a so-called "electron microscope" was invented which produced images based on its electron source. Optical microscopes (based on visible light) can magnify objects up to 2000 times while today's electron microscopes can magnify an object 2 million times - a clear winner for observing nano-scale science.

So, after subjecting the product to different types of electron-based microscopy, scientists were able to observe a couple of things:

- by viewing the surface of the product, it was observed that the surfactant was spread evenly across the layer of zinc; by viewing a cross-section at even greater magnification, scientists could observe that the resulting nanostructures were randomly oriented, AND that the largest structures grew nearly vertically off the surface.

- neither of those observations are as cool as this: under even greater magnification, the team could see that the structures previously observed were actually very tiny layers (recall, this is a "lamellar" structure we are talking about) of alternating Zinc crystals and surfactant crystals.

Most importantly, by knowing the size of both the Zinc ion and the surfactant molecule (both on the order of about 1 nanometer) scientists could determine the relative amounts of each and how they self-assembled. It was determined that the structure was actually "zinc-surfactant-surfactant-zinc".

Why? Recall a couple of things - first when Zinc is ionized as it is here, it forms a cation, another way of saying it is a positively charged ion. Our surfactant has a polar end and a non-polar end, and when it is ionized (as it is when it's dissolved), the surfactant forms an anion (at the polar end), a negatively charged ion. Thus, the cation bonds with the negatively-charged/polar end of the surfactant anion. It is energetically favorable that the two non-polar ends of the surfactant face each other, surrounded by layers of zinc. Think of a peanut butter sandwich. Take two pieces of bread, put peanut butter on one side of each piece, then put the pieces of bread on top of one another, with the peanut butter sides facing each other - in our case, the zinc is the bread (on either side) and the peanut butter is the surfactant (in the middle)!

Observed interactions between the surfactant and the zinc layer aren't that surprising when we take into account the amphiphilic structure of the surfactant. Furthermore, scientists, after knowing the lengths of the crystals, can examine the nanostructure via high-resolution microscopy to confirm its configuration. Next time, we are going to look at the various surfactants used, and how they influence our nanostructure. Properties like crystal structure, molecule length, conductivity, and trap states are the nano-level characteristics that are critical to further development of optoelectronic devices.

Study:
A synergistic assembly of nanoscale lamellar photoconductor hybrids
Nature Materials Vol. 8 January 2009
DOI: 10.1038/NMAT2336

Posted by Red Sox Steve at 07:45 AM | Permalink | Comments (1) | TrackBacks (0)

By Red Sox Steve

Last time, we discussed Zinc Oxide, and the process of forming nanowires on a silicon-based substrate. Scientists electrodeposited zinc crystals onto electrodes, heated the substrate and ran oxygen gas over it for a number of hours, and voila! Zinc oxide crystals form, which are the basis of nanowires. In our quest to understand and control molecular activity at the sub-atomic level, while constructing objects that are energy efficient and environmentally sound, Zinc Oxide based photoconductors (a subset of optoelectronics) are a good start.

Much of the benefit of constructing efficient optoelectronic devices (devices that create, detect or control light) comes from combining both an organic and an inorganic molecule within the nanostructure. The key to all of conductance is the movement of electrons throughout a molecule or a junction between two molecules. Since this is the case, what is critical to understand is a molecule's ability to literally "trap" an electron. How long a molecule can maintain this "trap-state" is related to its ability to conduct electrons. Electrons that can move from molecule to molecule do so by moving into the electron holes that are created when a molecule is in its trap state.

That's a mouthful - here's the point: when molecules act as conductors, they are moving electrons from one place to another. A molecule's ability to move electrons is related to its ability to either free electrons or accept them - scientific evidence of electron holes in molecules and the lifetime of a given molecule's trap state are a good start to understanding semiconductors and optoelectronics.

Ah wait, there's more! We understand lots about ZnO at this point - if not refer to the previous Tuesday and Saturday articles for further discussion. ZnO has a useful crystal structure, can be synthesized on a substrate, and works great as a semiconductor. Here's the thing - scientists are now trying to determine how to tune the sensitivity of trap state lifetimes and trap state densities by using organic compounds which can be bound to a nanometer thick layer of ZnO crystals. In other words, not only are scientists on their way to understanding how ZnO works at the nano-level, but they are in the process of determining how to adjust the sensitivity of a ZnO-based semiconductor by adding organic compounds into the mix! Way cool!

The group of organic compounds discovered to work well with ZnO are known as thiophenes - Thiophenes are a classification of molecules that have a 5 member ring containing one Sulfur atom. Scientists have found that thiophenes are ideal for conduction based their ability to maintain an electron hole. How is this possible?

Thiophenes use a principle organic chemists call "conjugation" to spread electrons throughout its structure. In the examples you see above, note that there are sections of each molecule which contain successive single-double-single carbon-carbon bond units, or what are known as conjugated units. Remember, these illustrations are merely schematic diagrams of what each molecule looks like. In reality, whenever conjugation occurs along a carbon chain, this means that electrons are uniformly spread along the chain - in other words, the electrons are "delocalized" throughout the conjugated chain. Scientists have been able to confirm through experimentation that thiophenes are good candidates for organic semiconductors, partly because of the presence of the 5-member ring.

It is critical for a semiconductor to be able to move electrons across its structure, however, there are actually two types of semiconductors - "p-types" and "n-types". The "P" stands for positive. A P-type molecule can accept additional electrons within its structure; in other words, what are known as "electron holes" are found in the molecule's structure. The molecule's ability to accept electrons depends on the lifetime of the electron hole, which ultimately will determine the ability of the molecule to be a p-type semiconductor. "N-type" (Negative) semiconductors are just the opposite - there is an abundance of electrons and a lack of available electron holes in the molecule's crystal structure. As a result, the electrons are easily conducted out of the crystal structure. In our case, ZnO is the P-type semiconductor, while the organic molecule thiophene is the N-type - both work together to transport electrons.

What is also important in an organic/inorganic hybrid nanostructure is the interaction between electrons and the electron holes throughout the nanostructure. That's a mouthful - the point is that when an electron finds an electron hole, the resulting structure is called an exciton. Because of the interaction between ZnO and the thiopene, exciton lifetime is relatively long AND the p-type charges remain well separated from the n-type charges. Thus, the ZnO/thiopene relationship is conducive for inorganic/organic hybrid nanostructures.

We're going to leave this topic here and revisit it next time when we discuss more about the lamellar (lamellar means nothing more than a thin plate or layer for our purposes) structure of our semiconductor. Nanostructures using inorganic and organic molecules together are merely the starting point of optoelectronics. As nanotechnology continues to claim more territory in the digital world, scientists are finding ways to self-assemble nanostructure and transfer electrons efficiently. Optoelectronics, dealing with the transmission, transformation and generation of light, will continue to become smaller and more capable. Understanding how organic compounds work with ZnO in the world of semiconductors is an early step in the process of controlling our subatomic world.

Study:
A synergistic assembly of nanoscale lamellar photoconductor hybrids
Nature Materials Vol. 8 January 2009
DOI: 10.1038/NMAT2336

Posted by Red Sox Steve at 11:29 AM | Permalink | Comments (0) | TrackBacks (0)

By Red Sox Steve

Last time, we examined some of the nanoproperties of Zinc Oxide (ZnO), a fundamental component in nanowires. Because of its useful crystal structures, electron conductivity, and other molecular properties, scientists have found ZnO to be a very useful conductor of electrons on a very small scale. Thusfar, according to the study cited below, scientists have created substrates (non-reactive surfaces), in order to assemble the ZnO nanowire on one surface before moving it to another. An electrical field had to be created on the substrate in order to align the nanowires correctly. Apparently, both using an electric field and being unable to determine the alignment of the nanowires greatly hindered nanowire production.

So what's new? Well, scientists have now figured out how to use an electric field layered on a silicon-based substrate to build ZnO nanowires that can be quickly examined and understood.

Here's the story: On the foundation layer of the substrate, made of silicon nitride (silicon and nitrogen), Dr. Law's team has placed two gold electrodes, with a gap between the electrodes mere micrometers in distance. On top of the substrate layer, they've added a monocrystalline layer of silicon nitride. In the silicon nitride layer, a space for the zinc electrodes was etched out at the junction between the gold electrodes. The etching has also left a distance of 3 micrometers between the zinc electrodes. Then, a layer one crystal thick of zinc has been deposited onto the substrate via a process called "thermal evaporation". Finally, to get a functional substrate (similar to how microchips are made) scientists literally peel off the monocrystalline substrate layer, leaving behind zinc deposits at the only place they were ever needed - forming a junction at the electrodes, with a tiny gap between them.

Now, we have our zinc-based substrate, with a critical, but very small distance between the electrodes. The substrate is placed in an oven (700 degrees C), with oxygen gas flowing towards the substrate's surface for 3 hours. During this time, the ZnO nanowires were formed according to the principles we discussed on Saturday, at the gap between the zinc electrodes. By using what is called "high-resolution transmission electron microscopy", scientists were able to observe nanowires of about 30 nanometers in diameter, a single crystal thick.

The key to this entire process was not only to grow ZnO nanowires on the substrate, but to analyze how they were able to grow. Observing the Zinc grains on the electrodes before the substrate went into the oven, scientists saw randomly oriented grains of metal - not much use as a solid. However, Zinc melts at about 419 degrees Celsius... therefore, when put into the oven, the grains formed tiny droplets. The droplets were able to react with the oxygen flowing over the substrate, to form the nanowires.

The coolest part of the whole thing? Scientists consider the process to be "self-catalytic". Some chemical reactions require a non-reactive element or molecule, which essentially makes a given reaction more favorable (in other words, more likely to occur). This molecule, which participates in the reaction, but is neither a reactant nor a product, is called a catalyst. It "pushes" the reaction along. In the case of our nanowire, here's what scientists think is happening:

ZnO clusters at the tips of the solid grains are where Zinc atoms bind with Oxygen atoms. There is a scientific concept called "wettability" which basically describes whether or not a solid surface can maintain contact with a liquid. Liquid materials with high wettability tend to flatten out on a solid surface whereas materials with lower wettability tend to form more round shapes, therefore avoiding contact with a solid surface (see photo below).

In our case, the wettability of ZnO with Zn is poor. That means that ZnO resists its Zinc surface, and does not collect on it. Therefore, ZnO nanowires grow outward, and each new ZnO molecule would prefer to attach to another ZnO molecule, and not on the Zn surface. Because Zn is the reactive surface in this case, and because ZnO molecules would rather avoid it than collect on it, scientists consider Zinc a catalyst and the reaction to be "self-catalyzing".

Remember our discussion on band gap last time? This is the gap between valence electron energy and conductance electron energy, as indicated by the amount of energy it takes to get from one to the other. Dr. Law's team used a process called photoluminescence to study this property in the ZnO nanowire. Basically, after shining a HeCd (Helium-Cadmium) laser into the sample, they observed two things: 1) as expected, there was an emission of light with 390 nanometers of wavelength which corresponded with 3.37 eV of energy (which we discussed last time), and 2) there was also an emission of light at 500 nanometers of wavelength, which was not expected.

There is a concept in semiconductor technology called a "deep-level defect" which is when an energy level of an atom or molecule is found at the center of the band gap - between the valence and the conductance bands. It is considered a "defect" because it doesn't contribute to either the donation or acceptance of electrons. In this case, the 500 nanometer emission of ZnO is an indication of a deep-level defect.

The nanowire described above was fabricated with the intention that it be used as a photodetector (used in things like solar panels). Further examination was done on the ZnO product to determine its response to UV light. By understanding the fabrication process, scientists were able to gain some insight into the process of formation of ZnO. By analyzing the product, scientists were able to understand more about ZnO's structure and energy properties. Nanowires have the ability to be inserted anywhere in the body and threaded through blood vessels up to the brain. Without actually coming into contact with neurons, scientists believe nanowires will be able to detect neuronal activity. Substrate-based nanowire growth is an early step on an infinitely long journey to integrate nanotechnology into our 21st century world.

Study: Simple fabrication of a ZnO nanowire photodetector with a fast photoresponse time
J. B. K. Law and J. T. L. Thonga

Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering
Drive 3, Singapore 117576, Singapore
APPLIED PHYSICS LETTERS 88, 133114
2006

Posted by Red Sox Steve at 11:53 AM | Permalink | Comments (0) | TrackBacks (0)

By Red Sox Steve

We've recently been discussing different components of the brain. Starting when vertebrates first inhabited earth half a billion years ago, the brain has evolved into a complex network of neurons, fluids, and other cells protected by a hard shell and a blood-brain-barrier. Pharmacological treatments and surgeries have to pay particular attention to all these factors in order to effectively treat neurological problems.

Scientists are figuring out a way to use what are called "nanowires" to understand neuron to neuron interaction in the brain. Nanowires (on the order of a nanometer) are being created which are thinner than even the most narrow blood vessels (micrometers wide). In one experiment, nanowires made of platinum were inserted into a circulatory system and used to detect activity in neurons lying adjacent to blood vessels. Scientists feel that nanowires will be able to pinpoint damage from injury and stroke, localize the cause of seizures, and detect the presence of tumors and other brain abnormalities.

First, however, nanowires must be effectively constructed. In the process of constructing them, scientists learn about some of their properties - dimensions, crystal structure, conductivity, reactivity. The process of constructing nanowires thus far has been relatively tedious. Scientists have been using ZnO ("Zinc Oxide") as the substance of choice - the overall process has been to bind Zinc with Oxygen on an unreactive substrate (surface), before dispersing it onto a surface containing electrodes (poles with an electric charge) or using lithography (think of literally carving a substrate with light) to create electrical contacts. By using these methods, it was difficult for scientists to determine the orientation and position of the nanowire in advance - critical information for determining many of its properties. Furthermore, according to the study I read (cited below), it was difficult to do something that challenges scientists and chefs alike: "scale up" the reaction (in other words, make more in a single batch!). The point in all this is that now scientists have developed a better way of making nanowires - quicker, more efficient, more effective. Since they are making nanowires out of a substance called Zinc Oxide (ZnO), let's talk about some of the properties of Zinc, Oxygen, and the Zinc Oxide molecule first.

Zinc has an atomic number of 30, which means it has 30 protons (positive charge) and 30 electrons (negative charge). It's outer shell has 2 electrons (4s^2) in an "S" orbital and 10 electrons in a "D" orbital (3d^10), and with this electron configuration exists as a stable atom. Oxygen's electron configuration is 1s2 2s2 2p4. Let's keep a couple of things in mind: when it bonds with another atom, Zinc would love to be able to share the 2 electrons in its 4s orbital while Oxygen would love to find 2 electrons to fill its 2p orbital.

Bonding 1 Zinc atom to 1 Oxygen atom, requires Zinc to share its electrons with Oxygen. This works because of a concept called "oxidation" which basically means a loss of electrons - Zinc becomes oxidized when it bonds. It is energetically favorable for Zinc to lose its 2 outermost electrons, those in the 4th orbital. Therefore, its most common ionic form is Zn^(+2). In addition, it is energetically favorable for Oxygen to accept 2 electrons, so its most common ionic form is O^(-2). Zinc wants to give up 2 electrons to make the Zn^(+2) ion, also known as a Zinc cation; Oxygen wants to accept 2 electrons, forming an O^(-2) ion, known as an Oxygen anion... "Louis, I think this is the beginning of a beautiful friendship."

What happens, though, when you get Zinc Oxide? What are its properties?

There are two different worlds when we discuss molecules - the "bulk" world and the "nano" world.

When bulk properties of any molecule predominate we are concerning ourselves with things like color, density, and melting point. Zinc oxide is a white solid that, because of its hardness and resistance to heat, is widely used as an additive in objects like plastics, ceramics, cement and paints.

In the nano world, properties like conductivity, crystal structure, electron mobility, and bandgap (don't worry, I discuss it below) are reasons Zinc Oxide is the molecule used in our aforementioned nanowire. Based on its nano-properties, ZnO is used in energy-saving windows and light-emitting diodes (LEDs).

Zinc oxide has three distinct crystal structures, with unique electronic properties (of course!):

Hexagonal wurtzite is the most stable structure of the three, and therefore the most common. Note a couple of things about this structure - first, each atom is tetrahedral (connected to four other atoms) in the crystal structure, linked by weak electronic interactions, and there is no inversion symmetry. This means that when you flip it, the structure will change before your eyes! Why does this matter? There are two scientific concepts critical to the nanoworld:

- Piezoelectricity: Piezoelectric compounds generate an electric potential when mechanical stress is applied. Cool! The same compounds generate a mechanical response when an electric potential is applied. Double cool!

- Pyroelectricity: Hexagonal wurtzite Zinc Oxide is pyroelectric as well (pyro... think fire... think heat). This means that when heated or cooled, pyroelectric molecules generate a temporary electric potential due to a reconfiguration of their atoms. How cool is that?

So, only asymmetric molecules can be piezoelectric or pyroelectric. Symmetric compounds do not exhibit piezoelectricity or pyroelectricity.

2) "cubic zincblende"

Zincblende ZnO also has no inversion symmetry, giving rise to piezoelectricity (but not pyroelectricity), similar to wurzite. It can exist in stable form by synthesizing ZnO on a substrate and is tetrahedral.

3) "cubic rocksalt"

The cubic rocksalt structure is the least stable of the three crystal structures. Looking at its tightly packed crystal structure, it's no surprise that it only forms and exists at high pressures. It is not useful in nanotechnology as a result.

Let's talk about ZnO electrons - ZnO has band gap of ~3.3 eV ("electron volts"). A band gap is the difference between the highest energies of the valence band and the lowest energies of the conductance band. What does this all mean in plain english?

Remember from previous discussions that valence electrons are the outermost electrons of an atom (in this case a molecule). Conductance electrons are the electrons that are able to break free from the pull of the nucleus. When a substance is a conductor, this means it can easily share electrons with its neighbors. All a conductance band energy tells us is all we need to know - it is the minimum amount of energy that needs to be applied to free electrons from a given molecule. The highest valence band energy is the energy contained in the outermost electrons of an atom or molecule. Thus, the band gap is the energy difference between the two - the amount of energy that can be absorbed by an atom or molecule in order to free an electron. :)

Caption: Valence electrons that exist in the outermost shell of a molecule have a certain amount of energy. If you apply an electric potential to the atom that is high enough, you can free electrons from the atom. Therefore, the difference in energy between the valence band and the conductance band is the maximum amount of energy an atom or molecule can absorb and remain stable. Any energy applied equal to or greater than the band gap energy will free the electron from the molecule.

Now, back to band gaps and zinc oxide. In general, a material with a smaller band gap (of 3-4 eV) is called a "semiconductor" because electrons move off the molecule relatively easily. A material with band gap larger than 4eV is called an "insulator" because it doesn't transfer electrons so easily (because more energy is required to traverse the band gap!). By these designations, ZnO is well within the range to be considered a semiconductor. Furthermore, it can hold an electric potential and heat without breaking down, critical to its use as a nanowire.

Conductivity, resistance to heat, piezoelectricity, crystal structure, etc... these are all critical concepts in the world of nanotechnology. Scientists take them into consideration when seeking to understand the nano-properties of an atom or molecule. When we return here on Tuesday, we are going to analyze a ZnO fabrication method to get into the "nitty gritty" (as my mother likes to say) of nanowire technology. What is important at this point is to understand the characteristics of Zinc Oxide - the nano-level properties of this molecule are critical both to the process that is undertaken to synthesize it and its uses once it exists.

Sources:

1) Wikipedia
2) Simple fabrication of a ZnO nanowire photodetector with a fast photoresponse time
J. B. K. Law and J. T. L. Thonga

Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering
Drive 3, Singapore 117576, Singapore
APPLIED PHYSICS LETTERS 88, 133114
2006

Posted by Red Sox Steve at 10:42 AM | Permalink | Comments (0) | TrackBacks (0)

By Red Sox Steve

Last time, we discussed some principles of the chirality of molecules, why chirality is important, how we find out which enantiomer a reaction has produced, and in what amount. Previously, you've also read about what types of advantages nano-scale research and development can introduce into already existing technologies.

What happens when these concepts are combined? At an engineering level, is it possible to use the properties of a chiral molecule to create better switching mechanisms (for a number of uses, semiconductors being one)? At a scientific level, what types of molecules will we need to work with to accomplish this?

This is where the field of "chiral nanoscience" comes in (nothing original in the name, just a combination of different fields of investigation). In chiral nanoscience, switches called "chiroptical molecular switches" are constructed from molecules that are able to either change from one enantiomer into another or to use other physical properties related to only one enantiomer of a pair to produce a biological result. Recall that enantiomers have the same chemical composition, but different and complementary physical structures.

Molecular switches are used in two main areas: computing and biology. Since the early 1990s, scientists have been investigating the use of DNA molecules in computing, mainly because such molecules are faster and smaller than the semiconductors currently in use. In biology, switching mechanisms are used in our cells all the time, especially in response to changes in acidity or the presence of light. Enzyme or protein activity is regulated by its binding to an effector molecule, potentially changing the protein's structure and function. In both biological and computational fields, these types of changes can be used to store and recall information more efficiently.

Now, getting back to how chirality plays a role in the world of switching, what scientists are trying to determine is what effects things like light and temperature have on the structure of a molecule. Part of the change a molecule can undergo is related to its ability to form a helical coil around a central axis, similar to DNA. When exposed to heat, polymers (the same molecule connected to itself multiple times, forming a chain) will twist and bend into different formations. When they undergo this structural change, their function changes as well. It is up to scientists to study these changes and figure out how they can be put to use.

The twisting (known as coiling) of a molecule around itself plays a role in the DNA in every single cell in our body. DNA is made of two parallel helices, hence why it is known as a "double helix" or a "double strand". DNA's main function is to store the genetic code required by the cell to replicate. It does this by creating a chain of nucleotides (recall that only 4 nucleotides are used in various sequences and billions of combinations), binding them to their complementary strands, winding them around each other, and therefore safely storing the genetic message that cells need to later replicate. Under the proper cellular conditions, step by step, this process takes place billions of times over the course of one's lifetime.

Scientists are trying to construct new molecules that exhibit the same properties, subjecting them to various chemical and temperature changes, in order to determine how their structure changes. In a study published in 2007, Zhao, et. al. (citation at bottom) have synthesized two Serine based polymers, one with a hydroxy side chain (a/k/a an "OH" group), and another with a "trimethylsilane" side chain (SiMe3).

Taken from the paper's introduction, one of the main reasons that scientists are using Serine is that one of its enantiomers (the "L" isomer) is a naturally occuring amino acid. What they are trying to do is modify its structure so that the new molecule will mimic some of its biological properties, while assuming new characteristics as well. One of the properties they are examining is its propensity to form a helix at different temperatures and in different solvents. Ultimately, in certain types of solvents, where the Serine based polymer is completely dissolved, there is evidence of a stable helical (helix) structure. When a solution with the hydroxypolymer is heated, there is evidence that it starts to unwind, which is expected because heat breaks the bonds that initially formed the helix. As it relates to the trimethylsilane polymer in a particular solution, heating actually caused the helix to wrap around itself further, which the scientists were unable to explain.

Scientists are discovering how polymers made from biologically occurring substances can be altered at the atomic level - structure and function change as a result of these atomic manipulations. They are discovering how resistant these polymers are to different temperatures and environments, and in the case discussed above, are using a single enantiomer of a chiral pair to synthesize needed molecules. Chirality is a critical part of the function of many substances, especially molecules that are found in nature. In this case, scientists are studying and changing these molecules at the nano-level, with the possibility of using their properties for various applications at some point in the future.

Zhao paper:
Journal of Macromolecular Science w, Part A: Pure and Applied Chemistry (2007) 44, 389–394
Synthesis and Chiroptical Properties of L-Serine-Based Poly(phenylacetylenes)
HAICHAO ZHAO, FUMIO SANDA, and TOSHIO MASUDA
Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura Campus, Kyoto, Japan

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By Red Sox Steve

Last time we talked science, we talked about orbital theory - how electrons are shared between atoms to create different types of chemical bonds, and what those bonds mean for the overall structure of the molecule.

We've got to discuss something else that is specific to molecules, and is critical to molecular function on a nano-scale level: chirality.

In any introductory text that discusses organic chemistry (the term "organic" simply means carbon is involved), the example that is used to illustrate chirality is a pair of human hands. When you face your palms together, you can see that each hand is "chiral" to the other. What this means is that each hand is an exact mirror image of the other, however, when placed on top of one another, they are not identical. OK - now you're thinking, "Red Sox Steve has fallen off the wagon! When I put my hands together they match up exactly... how else am I supposed to clap when my team scores?" Not true. When you put your hands together so that the palms touch, one is facing right, and one is facing left. They are NOT superimposed on each other. If the palms were facing in the SAME direction, one set of fingers and thumbs goes one way, and the other set goes the other way. Your hands are chiral with respect to each other. So, two objects are chiral when their mirror images cannot be superimposed on each other.

Now, let's talk about plane-polarized light. When we look into the sky without any type of lenses on our eyes, we see light in all directions. With an increase in sunlight, things around us also become brighter. What is happening is that the sunlight is being absorbed, reflected and refracted by the particles in the earth's atmosphere, and scattered all around us. Part of the reason for this is that the atmospheric particles are, on a molecular level, physically facing any one of an infinite number of directions, causing the light to diffuse across the sky. In fact, the importance of the ozone layer is that it absorbs some of the sun's harmful rays before they reach earth.

Why is plane-polarized light so important to molecules? Alright, first, plane-polarized light is the result of light that passes through a filter. What the filter does is allow only light that is traveling in a certain direction, and ONLY that direction to pass through. In other words, if particles in the atmosphere scatter the sun's light rays, and a polarizing filter is applied to that light, then only certain light waves, traveling in a certain direction, make it through the filter. This is how sunglasses work - they protect your eyes by preventing most, but not all, of the light from getting through. Things appear darker because less light reaches your eyes, protecting them from the harmful effects of bright light.

Now, how do chirality and plane-polarized light work together? First, here is an example of two molecules that are chiral. Each have the same component pieces ("R" is not an element, it is just a variable, or "side chain" off the molecule). Note that there are two different configurations - they are mirror images of each other, and they are NOT superimposable:

If a chemical reaction produces the molecule you see above, and the resulting mixture is made up of 50% of the one on the left and 50% of the one on the right, the mixture is said to be "racemic". In a racemic mixture, there are equal amounts of both kinds of "enantiomers". The molecule on the left is one enantiomer, and the molecule on the right is the other enantiomer.

The most infamous example of how serious chirality and racemic mixtures are is found in the drug thalidomide. From the late 1950s to the early 1960s, pregnant women took thalidomide to prevent morning sickness. Here's the thing - one enantiomer cured morning sickness while the other enantiomer produced birth defects. It gets worse - it is possible to separate enantiomers from one another, however, although both enantiomers in a racemic mixture have the same chemical makeup, they have entirely different physical structures (like your hands!). So, scientists devised a way to separate what is known as R-thalidomide from S-thalidomide ("R" was the drug, while "S" was the harmful version). Because, however, of the structure of the thalidomide molecule, "S" and "R" were easily able to convert (without a catalyst) into their complementary enantiomer. In other words, there was no way to separate the good compound from the bad compound, so pregnant mothers were always ingesting both.

The two enantiomers of thalidomide.

"S" and "R" are added to the name so we know which of the two enantiomers we are talking about. The "R" and the "S" are labels derived from IUPAC nomenclature (IUPAC = International Union of Pure and Applied Chemistry). One of the major challenges that organic chemists and pharmaceutical companies face is related to chirality - how to create chemical reactions that produce a single enantiomer for use in the synthesis of a drug.

Let's talk about different mixtures of enantiomers and plane-polarized light for a second. When you shine plane-polarized light into a solution that is a mixture of enantiomers, what you are looking for is how the mixture rotates the light. There is terminology that scientists use to understand what is happening. If the light is rotated clockwise, as it travels towards the observer, this is called (+) or "dextrorotatory" rotation. If the light is rotated counterclockwise, this is called (-) or "levororotatory" rotation. Note that the rotation of a light wave is not observed with the naked eye, rather it is done with a device called a polarimeter. In a racemic mixture, (remember 50:50), each enantiomer rotates light in a different direction, however because this is done in equal proportions due to the equal mixture of enantiomers, the net effect is that the observed light is not rotated. Therefore, in a mixture that is predominantly one enantiomer over another, the observer sees a net rotation of the light wave, in one direction or the other. This is how scientists are able to figure out the relative proportions of each enantiomer in their mixture.

Even though a scientist may perform a chemical reaction to make a single product, there are some instances where the product contains a single (or multiple) chiral center. In this case, we may have a racemic mixture, or a mixture where one enantiomer is produced in greater proportion to the other. We can only discover what is going on when we shine plane-polarized light into a mixture to determine how much of each enantiomer is present. Next time, we are going to discuss the implications of chiral chemistry (aka "stereochemistry" because the chiral center is sometimes also called a "stereocenter") on nanotechnology.

Posted by Red Sox Steve at 02:47 PM | Permalink | Comments (3) | TrackBacks (0)

By Red Sox Steve

Yankee Stadium and Citi Field are open for business. New York is still hurting, just like the rest of America, from the financial crisis, but good weather has NEVER been a mood dampener, and that's what's going on outside right now. Here, though, we're sticking with nano. This stuff gets us all into the 21st century world that I am talking about.

The key to all of nanotechnology is that a given chemical's surface properties begin to take precedence over its bulk properties. We've spoken about this before, albeit indirectly, but here's what I mean. When a Japanese scientist discussed nanotechnology in a 1974 paper, he wrote: "'Nano-technology' mainly consists of the processing of, separation, consolidation, and deformation of materials by one atom or by one molecule." Atom by atom and molecule by molecule deconstruction is influenced by bonding properties and electron transfer, as well as a number of other molecular forces - surface properties. Bulk properties, however, are things like density (mass per volume) and viscosity (the extent to which a fluid flows or resists flowing). When scientists get down to the nano level (one one billionth of a meter), they are more concerned with how electrons move around and what holds one molecule to another and less concerned with a compound's odor or appearance. We need to understand the surface properties of atoms and molecules to be able to explore nanotechnology.

I want to talk about chemical detection systems and how our understanding of the nanotechnological world will allow us to construct such systems with increasing effectiveness. Biological agents have been used in both warfare and terrorist attacks: recall the Germans using 1,5-dichloro-3-thiapentane (a/k/a Mustard Gas) against its enemies in World War I, or the Japanese subway attacks of 1995 where a terrorist group released 2-(Fluoro-methylphosphoryl)oxypropane (a/k/a Sarin). Science and technology are necessary to continue to assist us and keep us safe, not to mention the fact that the principles we are working with here can be applied to solve a number of different problems (oops, I just did!).

One of the ways we can detect harmful agents (since we can't see or smell them) is to use metals and sugars. Recall our discussion of the properties of a carbon atom - 6 protons, 6 neutrons and 6 electrons. The metals we are talking about here are a little more complex. First, they are generally larger - palladium, platinum, silver, gold, osmium all have higher atomic numbers than carbon (check your own periodic table if you don't believe me! :) ). What this means is that each of their nuclei contains more protons and neutrons, and those nuclei are surrounded by more electrons. Carbon and Hydrogen are some of the simplest atoms in the periodic table - the model we can come up with to describe the relationship between Carbon and Hydrogen's electrons and their respective nuclei is similar to planets revolving around the sun. The electrons remain in an "orbit" due to the gravitational force of the protons and neutrons.

Larger atoms are not so simple - our "solar system" conception breaks down pretty quickly. What happens - especially in the presence of OTHER molecules or atoms - is that these metals share their electrons in ways the typical Carbon or Hydrogen atom could not; electrons that are not in the outer-most shell, or that may or may not bond in predictable ways can be absorbed or given up by these atoms, creating new chemical bonds that are much more complex than the Carbon-Carbon bond that we talked about last time. From these properties, we get a chemical term that you have certainly heard HERE before: semi-conductors. Many of the atoms from Groups 3-12 (also known as the "Transition Metals") in the periodic table are semi-conductors of electrons. In other words, they don't always absorb electrons, and they don't always give up electrons.

In order to create one type of detection system, first, specific carbohydrates are attached to metal atoms, creating the nanomolecule we need to detect the poisonous substance. Carbohydrates (of which sugars are a subset) are various combinations of Carbon, Hydgrogen, and Oxygen and all living things are made of carbon, hydrogen and oxygen. Because biological warfare agents are created specifically to either bind with human tissue, or to be absorbed through mucous membranes (eyes, nose, throat) to do damage, science must create molecules that will successfully bind with the harmful biomolecule by using the carbon, hydrogen and oxygen found throughout the human body.

When the harmful substance is introduced, either in the form of liquid or gas, the harmful substance will bind with the carbohydrate. When this happens, the solution changes color. That is only the beginning of the story. The metal that is in the solution, as we discussed above, has a complex makeup of electrons, neutrons and protons. When the carbohydrate and the harmful substance bind, this creates an opportunity for the metal to change its electronic structure. When it does, it is able to absorb light. This is where a new field of study in science is introduced that works in the realm of subatomic particles: plasmonics.

A plasmon is a type of particle, and the behavior of this particle is based on the behavior of electrons in ionic gases. All we need to know is that the study of light and wavelength is related to the electronic structure of the metal, and, as it relates to the metals I mentioned above, electron behavior is quite complicated. Furthermore, in the case of our detection system, we are only concerned with surface plasmons - the electrons that exist on the outer surface of the molecule we are looking at. (You just got served... an introduction to chemistry and particle physics!)

Let's wrap this up - the basic makeup of this system, used to detect the presence of harmful substances in small concentrations is this: When the carbohydrate (the "good guy" which is bound to our metal) binds to the poisonous substance, the metal is released and all the released metals aggregate in the solution. Based on the type of metal we are dealing with, they absorb light at a certain wavelength, which appears as a color to the naked eye. This is how we know there is something harmful in the air or water that we can't readily observe. In the scientific literature I've read where gold is the metal used, in the presence of a harmful material, the gold turns red in the solution when the carbohydrate releases it. As the concentration of our gold-carbohydrate nanomolecule increases, the solution becomes red-purple in the presence of the harmful material.

It is the nano-characteristics of the metal we are working with that determine how effective our detection system will be. Harmful substances need to be detected in even the smallest concentrations (parts per billion or parts per trillion) for this to be an improvement over existing technology. Furthermore, when these types of systems are put in transportable devices, they can be used by security, law-enforcement, and even medical personnel to gain more knowledge about the possible presence of previously unnoticeable materials. In the case described above, nanotech is used to detect harmful substances, mostly in adversarial situations involving either criminals or security systems; However, it is no stretch to consider that this type of science can be modified and used to know when a foreign substance is introduced into ANY system (the human body, a space shuttle, a gallon of water). Nanotechnological applications continue to grow, especially as nanotechnology continues to be applied to fields in biology, chemistry, and now physics. By solving the problems we have today using the latest scientific discoveries available, we are pushing the frontier of the possible further and further.

Posted by Red Sox Steve at 08:02 AM | Permalink | Comments (0) | TrackBacks (0)

By Red Sox Steve

We've got a pretty good sense of how desalination works, and, based on our previous discussions about the lack of water, understand that governments all around the world are going to have to spend money on getting drinking water from the ocean if they are to meet the demands of the 21st century. What we need to understand is what kinds of new technologies are going to help us get there.

“I think the biggest mistake we can make in the field of water treatment is to assume that reverse osmosis technology is mature and that there is nothing more to be gained from fundamental research,”; “We still have a long way to go to fully explore and develop this technology, especially with the exciting new materials that can be created through nanotechnology."

- Eric Hoek, UCLA professor, 2006

The most popular form of filtration of sea water is reverse osmosis (RO). Pressure is applied to salt water - the water is literally "squeezed" through a filter, and because of the characteristics of the filter, only pure water ends up on the other side - the filter prevents salt and other harmful particles from crossing.

There are a couple of problems created by this process. First, according to some sources, at least 800 psi must be applied to accomplish the "squeezing" needed to obtain pure water. For reference, a car tire usually handles around 30 psi, while a scuba tank compresses air with around 3000 psi. Imagine applying 800 psi to create millions of gallons of water every day - it requires a great deal of mechanical energy and becomes so energy-consumptive that it isn't worth trying, when compared against other methods. Part of the reason that desalination failed to take off although the tech and understanding has been available for years is the prohibitively high cost of energy. Add to that the fact that the high pressures require frequent repair of the filters, and we've got a problem only scientists and engineers can solve.

What is it about the filter that only allows water molecules through? How long do filters last, and can they be damaged in their normal course of function? First, H2O molecules are among the smallest molecules on earth - as the atomic numbers of atoms on the periodic table increase, they generally increase in diameter and mass; since we're dealing with 2 Hydrogen atoms attached to one Oxygen atom, a quick glance at a periodic table tells you these filters are allowing only the smallest molecules on earth to pass through. Furthermore, the "salt" in salt water can come in many different forms, and the Potassiums, Sulfates and Magnesiums generally found in ocean water are much much larger than water. In other words, water is small enough to make it through and anything larger and more complex (such as salts, bacteria and protozoa) are caught by the filter. (Phew!)

The earliest RO technology is based on a compound called cellulose acetate - it's a fancy way of saying lots of carbons, hydrogens and oxygens are put together in a pattern-like fashion, creating the filter we need. This was patented at UCLA in the 1960s, according to various sources, and comes in a thin-film form. In other words, various acetate compounds are layered on top of one another to produce an optimally performing membrane. In the 1970s, this technology was improved upon by creating a FILMTEC(TM) FT30 filter. The FT30 is made up of a polyamide barrier layer on top of a polysulfone layer. The polyamides are smaller than acetates, making the filtration process more effective, and the polysulfone layer provides a rigidity that withstands high pressures (recall 800 psi!), has greater resistance to waters of various pH (acids and bases), and is able to withstand a wide variation in temperature.

I want to quickly cover one characteristic of the aforementioned filters before proceeding - fouling. Fouling is the degradation of the membrane in its normal course of function. Basically, as the pH, temperature and solid content of the pre-filtered water varies, less capable membranes will foul faster. In other words, as the membranes work under more difficult conditions, they will function less and less effectively - this contributes to overall system cost and energy-consumption... more pressure is required to squeeze seawater through a fouled membrane, therefore system output and efficiency decreases. In terms of membrane technology, durability under varying conditions combined with efficiency and an ability to resist fouling will produce superior membrane technology. This is why the FT30 is an improvement upon the cellulose acetate membrane, and why nanofiltration will improve upon both of them.

Part of the problem is that water-borne microorganisms adhere to the membrane's surface, contributing to fouling. Dr. Hoek and other scientists examined the performance of a variety of membranes, and according to a study published in Separation Science and Technology (41: 1475–1487, 2006) in 2006, membranes that were hydrophilic, more negatively charged, and had smoother surfaces, would be more effective in reducing the initial adhesion of microorganisms.

A company called Nano H2O in partnership with Dr. Hoek has moved the technology forward by constructing a membrane that filters particles based on their nano-level properties. Thus far in trial runs, it is almost twice as productive as existing membranes - you can get almost double the water with the same energy OR the same amount of water for half the energy. Furthermore, these nano-based membranes have an increased resistance to fouling, according to Nano H2O CEO Jeff Green (Water & Environmental Technology, Sept. 2008).

Producing potable water from sea water has a few main concepts that are easily understood: man-made pressure pushes salt water through a filter, and clean water ends up on the other side. Whatever gets caught is diluted and sent back into the ocean. The filters that do the work need to be cleaned, replaced, studied, and improved upon if the systems are to produce ever more clean water (necessary!) and consume less and less energy (necessary!). Companies like Nano H2O have secured venture capital funding and are ready to improve on the technology that has been developed by the likes of GE, Sumitomo, Filmtec, TriSep and Saehan as we continue to create better systems for desalinating water. Scientists and engineers like Dr. Hoek are leading the way. They have been able to examine and improve upon membrane technology, which produces systems that use less energy, are more cost-effective, and therefore more reliable so we can continue to meet the water demands of the 21st century.

2 more items to check out related to desalination technology:

1) When you get a chance, check out the Solar Cube, the result of collaboration between Spectra WaterMakers, of San Rafael, CA and Trunz (Switzerland). According to its makers, it can be erected in less than one hour. It is an RO desalination device powered by either the sun or the wind - it generates more power than it needs and can be a power source for small villages, or devastated areas. It's been used in Pakistan, requires no tools, and only needs a pickup truck to be transported! Kewl!

2) Where there is lots of ocean water, there is usually lots of wind, so a German engineering firm has decided to produce a wind turbine that simultaneously desalinates ocean water. Aerodyn Energiesysteme of Rendsburg, Germany is working on a turbine that mechanically draws water up its column where it is compressed. It can then be vaporized, removing the solute, and recondensed as pure water, OR it can go through the RO process, filtering out any harmful materials. Wind energy to desalinated water without having to convert mechanical energy to electrical energy. Wow.

Posted by Red Sox Steve at 05:43 PM | Permalink | Comments (0) | TrackBacks (0)

By Red Sox Steve

I've compiled a number of reports on nanotechnology, and what you'll read below is what I've found to be the most easily understood application of what has been discovered in the nanoworld thusfar - nano-fabrics can protect and assist us in ways that regular textiles just can't. Prior to today, we've discussed semiconductors and various other high-tech applications of nanotechnology. Carbon-based nanotubes are stronger and lighter than steel, more conductive than copper wire, and billions of times smaller than either of them. Semiconductors that incorporate nanotechnology can be faster, more powerful, and consume less energy - these concepts are the seedlings of a nano based world; they are merely some of the most fundamental applications of nanotechnology that exist today.

Nano discoveries can also be used in clothing - imagine wearing something that protects you from the wind, rain and even snow, but still allows air to pass through so a person's skin can breathe; you can sweat, but you won't get wet. Fact is, this is already a wildly popular fabric called Gore-Tex (tm). Gore-Tex fabric works as a nano-scale filter - in a Gore-Tex protected piece of fabric, the Gore-Tex layer is surrounded by protective layers on both sides - a soft inner layer, protecting the Gore-Tex layer from the body's oils, and a tough outer layer, protecting the fabric from abrasion or damage.

The key ingredient is Polytetrafluoroethylene (PTFE), which was first discovered in 1938. Its use was adapted for fabrics by being converted into a porous form of PTFE, inter-connected by fibers that have a diameter of - you guessed it - 1 nanometer. This porous PTFE was patented by Robert Gore in 1976. It allows water vapor to pass through, however does not allow water in liquid form to penetrate the PTFE (Gore-Tex layer). Thus, a person can sweat without heating up, and rain in an outer layer won't make it through the fabric.

Gore-Tex has essentially invented a new type of fabric, but it is also possible to layer an element over a textile to produce a new type of functional outerwear. Silver has been used in jewelry, as a chemical catalyst, as well as in various antibacterial functions. Now a company out of Scranton, PA (no, not Dunder Mifflin, it's actually called Noble Materials) has figured out a way to create a fabric called "X-Static" by layering silver molecules onto nylon. There are already a number of known uses for silver (it has been used to preserve foods and bacteria) - what was discovered was that it can be applied to various fabrics to accomplish some of the same goals. X-Static can also be used in bedding, towels and freshly dried linens. Silver is great at conducting energy, so having a silver layer on a textile means that a person's body heat can be steadily maintained under both warm and cold conditions. According to Plunkett's research, this technology is being used in a number of brand-name products: Adidas, Brooks Sports, Polartec, and even Victoria’s Secret!

What about health, wellness, and safety - say you have a heart condition which isn't yet severe enough to warrant surgery or a pacemaker, but needs to be constantly monitored; or say you are a fire chief - how would you want to monitor the health of your first-responders as they rush into a burning building? Textronics, from Wilmington, DE is working on these types of technologies, incorporating micro-electronics into clothing in order to monitor the body's function. From their website, we can see that they are working in 6 main areas: 1) Sports & Fitness, 2) Health & Wellness, 3) Military & Public Safety, 4) Home Textiles, 5) Personal Electronics, and 6) Industrial.

Haven't heard of Demron? It is a new form of radiation shield manufactured by a company called Radiation Shield Technologies (Coral Gables, FL) - Demron is a "radiopaque nanopolymeric compound" (a fancy way of saying it's a substance that stops radioactive molecules from getting through) surrounded by protective layers on both sides. When Demron fabric becomes multi-layered, it can protect against biological and chemical attacks, as well as stronger and stronger sources of radiation.

From Nanotechwire.com:

"Demron has proved to block gamma rays, X-rays and other nuclear emissions by the Lawrence Livermore National Laboratory, part of the National Nuclear Security Administration within the U.S. Department of Energy, the Georgia Institute of Technology and the Columbia University College of Physicians and Surgeons. Demron is currently deployed worldwide by NATO, NASA, the National Guard, US Navy, UAE and the governments of South Korea, China, Saudi Arabia and Australia, among others. Scientists have selected it for thermo-mechanical suits for future space travel."

What's cool about these applications? The list is long, but it is also what I would call "near-term practical". Gore-Tex already exists, and anything that can shield radiation like Demron (and be as light weight) would make Marie Curie proud. Furthermore, X-static, which already has a number of proven uses, is trying to expand into areas related to household pets. Textronics, trying to match the needs of today's world with the capabilities of micro-electronics and nanotechnology, is meeting the demand created in a wide variety of areas from exercise to civil services. I've read a ton about nanotechnology, but there is still so much more to learn - the capabilities of the nano world continue to astound, and most of the applications are forward-looking, as smart fabrics surely are. These types of businesses and applications are signs that technology is creeping into the larger, consumer-driven world. From nano-based semiconductors to smart clothing, we will continue to expand the uses of nanotechnology as the 21st century marches forward.

Posted by Steve at 09:11 AM | Permalink | Comments (2) | TrackBacks (0)

By Red Sox Steve

Whenever I start writing, I always want to say something generic like, "nanotechnology has many uses" or "we are discovering new ways to use nanotechnology every day". It sounds so silly to keep introducing the topic like that, but I'll be damned if it's NOT true!

We've talked in this space about the types of things we can expect in the nano-world, why it is relatively new (you could say it was "born" in 1981, when it was first observed (via the scanning tunneling microscope), and how science has incorporated it into our understanding of the world. We've also discussed its practical uses - cell phones, semiconductors, bullet-proof vests.

The list keeps getting bigger - the more I explore nano sciences, the more I learn, and the more I am in awe of the ways in which science will continue to expand our world, in a never-ending effort to make it smaller...

We know from previous writings here about the scientific virtues of carbon nanotubes - they are super strong, super light, super small, super conductive and extremely energy efficient. Their applications vary from construction to plastics to wires. If they can be used in memory chips, the chips will be faster and more powerful than conventional silicon & metal based chips. In Denver, Colorado a company called Zettacore is exploring the possibility of a carbon nanotube based semiconductor, which we've talked about here previously. Using carbon nanotubes on its chips will enable the storage of trillions of bits of data per square centimeter. The concept here is that because the nanotubes are so small, the chips can be ultra-dense: information can travel faster and use less energy in the process. We know that memory chips are used in everything from cell phones to MP3 players, but the latest application of this technology will be in computers that boot up instantly!

Nantero, a company based in Woburn, MA is doing similar work in this field (known as "molecular electronics", a subset of nanotechnology). The idea is to supplant SRAM (static random access memory) and DRAM (dynamic) with a nanotube-based product called NRAM (non-volatile). The idea behind one of Nantero's nanotube-based prototype devices is to suspend ten billion nanotube junctions, each one representing a memory bit, on a single silicon wafer in either an up or down position. The bits are then switched by applying an electrical field. They are also producing these wafers using industry standard semiconductor production processes, so that any future adaptation can maximize compatibility while using nanotubes in a wafer's manufacture. Nantero is the first company to actively develop semiconductor products using carbon nanotubes in a CMOS (Complementary metal–oxide–semiconductor - a class of semiconductors) circuit, and the first company to develop microelectronic-grade carbon nanotube material, compatible with CMOS circuit production processes.

Solar cells are silicon-based flat, inflexible sheets covered with a non-reflective coating - they catch the sun's light in the form of photons and create a current by freeing electrons and pushing them onto metal plates; this flow of electrons is then used to power a variety of objects. The sun's rays are used to power things like homes, calculators and even satellites. The production of silicon-based cells runs into a few problems: 1) the supply of silicon is finite, 2) producing solar cells is very expensive, and 3) these solar cells are hard, heavy, and inflexible, limiting their uses.

Scientists at Massachusetts company Konarka Technologies are exploring the use of titanium and organic molecules to generate a current from the photons in sun light. In what is known as "Third Generation" solar technology, Konarka has been able to manufacture organically based photovoltaic cells ("photovoltaic" is a fancy way of saying "solar power") which they are able to overlay onto a number of flexible, lightweight surfaces to make cells that come in a variety of shapes and sizes. One of the main innovative advantages of their business is the ability to synthesize molecules that maximize absorbtion of the sun's rays and convert them into electric current.

Another company that produces third generation solar cells is Nanosolar out of Palo Alto, California. They use a printing process where they apply what are known as nanodots onto thin-film solar cells. The nanodots are called "CIGS" (a substance made of Copper Indium Gallium diSelenide), and are applied onto a film in the form of ink; the film is then heated, creating a semiconductor. This report gives you a sense of how the business is doing: although the panels, when coated with glass to protect the ink, are expensive, they are sold out for the next 3 years. One of their main customers, Google, expects that within 7 years, these panels will pay for themselves in the form of cost savings.

The application of nanotechnology in a number of different areas gives us an idea of the future that is to come. In a group discussion with a number of engineers last night (thanks Chuck, Doug and Jason), they brought up the point that one of the major impediments to widespread implementation is that these technologies haven't yet become cost-effective. There is no doubt about that - Nantero has sold off a division to Lockheed Martin and Zettacore has used up millions of dollars in multiple rounds of venture funding, and we still don't have panels on every roof of every house while folks still dread the electric bill and the next trip to the gas station. But, in my view, we're getting there. These companies are on the right track and they are asking the right questions, and, most importantly, we are in the process of learning - scientists are using that trusty ol' scientific method to create a useful body of knowledge on which we can base future developments and innovations. From a business standpoint, there can be NO GUARANTEE of cost certainty with respect to the economically sound implementation of these technologies. That being said, the idea that mankind will NOT benefit from the continuous study of all the applications of nanotechnology is ABSURD - through investigation and rigorous attention to scientific detail we will continue to expand our world... by making it smaller.

Posted by Steve at 08:18 AM | Permalink | Comments (1) | TrackBacks (0)

We discussed the nano-world here on Tuesday. Basically, in my reading of the scientific literature, I'm seeing that there are a few different points of view on when the conventional biological and molecular world stops and when the nano world begins:

1) some scientists set up a clear demarcation line: anything where the atoms or molecules discussed are from 1 to 100 nanometers in size means we are talking about nanotechnology.

2) others say that it is where conventional physical laws (theorized by Isaac Newton and others) break down and quantum physics (Einstein calculated the width of a sugar molecule as being 1 nanometer in 1905) takes over.

3) others say it is where behavior changes of a particular molecule are observed: from what is expected in the conventional scientific world to a nano-level type of behavior, especially as it relates to strength or electronic resistance.

Nanotechnology can be used in so many different fields that it must incorporate principles of physics, chemistry, biology and engineering in order to be fully understood and utilized.

MEMS (Micro-Electro Mechanical System) are central to the miniaturization of electronic devices - they convert electronic signals to mechanical signals and vice versa. These devices can be used in areas ranging from drug delivery in humans to airbag release in an automobile. In other words, microchips on the order of one one millionth of a meter (a micrometer) can be created and then inserted into the body - these chips, which are biodegradable and will contain tailor-made drug combinations, will detect and analyze what is going on inside a person's body and deliver drugs to treat illnesses accordingly. In automobiles, miniature sensors and switches can detect when to release the airbag - at what level and force of impact should the bag release, or not? The structure of the MEMS will give us our answer.

Carbon Nanotubes - These were discovered in 1991 in Japan. Carbon (found commonly in graphite sheets - yes, the stuff on the tip of a lead pencil), when combined with other carbon atoms produces a structure that is tens or even hundreds of times stronger than steel, and can also function as a very energy efficient conductor of electricity, more conductive than a copper wire. In practice so far, scientists have only been able to construct them to be a few centimeters in length, however, in theory, their length should extend much further. Recently, on the Science Channel (channel 111 for Time Warner subscribers in the NYC area), there was discussion of the construction of a pyramid city on Tokyo bay. The backbone of the pyramid city could be made of carbon nanotubing, which would be light enough to keep the structure from sinking into the ocean floor, and strong enough to support the weight of 10 city blocks and withstand the force of the occasional tsunami.

Within the carbon nanotube world are SWNTs and MWNTs, Single-walled nanotubes and Multi-walled nanotubes. Low grade carbon nanotubes are irregular in structure, and can be significantly improved on if they can be deliberately constructed to contain a single layer or multiple layers. SWNTs are expensive to manufacture, but are highly useful - they can be used in smaller and smaller electronic devices, and MWNTs can be mixed into plastics to improve their strength.

Incorporating Moore's Law (the number of transistors that can be placed on an integrated circuit will increase exponentially, doubling every 18 months or so) means that there will be more electricity moving around over a smaller and smaller area. This being the case it is hard NOT to conclude that carbon nanotubing, in some form, will replace the transistor, simply because it conducts electrons more efficiently, emitting less heat in the process.

"Once nanotubes are used in electronics, devices will be able to operate at much higher speeds and applications that we cannot even conceive at the moment will become possible.'

- Dr. Mirco Cantoro, Cambridge University for an article in The Engineer, vol 293 Aug 21, 2006

Let's take a look at the larger world for a moment to get a sense of how we got where we are today. In 1981, the scanning electron microscope was discovered, giving scientists the ability to observe atomic-sized objects for the first time. In 1991, carbon nanotubes were discovered in Japan. In 2000, the Clinton administration launched the National Nanotechnology Initiative, increasing government spending on nanotech to $497 million for 2001, from about half that amount. In 2004, U.S. Congress approves $961 million to fund nanotechnology and the Bush administration enacts the 21st Century Nanotechnology Research and Development Act, providing a total of $3.7 billion to nanotech between 2005 and 2008; similar funding efforts are simultaneously made in China, Singapore and South Korea.

Nanotechnology is a term that is used broadly within the worlds of biology, chemistry, physics and engineering to understand phenomena that are not readily observable at a macro level. These three components - MEMS technology (creating a nano-based outcome in different systems), carbon nanotubes (essentially a super strong, super conductive material, observed on a nano-scale), and the larger, political world in which these technologies will be developed all help to form the foundation for future discovery. Already, there are things in the average person's life (cell phones, digital cameras) that use nanotech or MEMS to function efficiently and effectively. Not only is there broad political support in the United States for nanotechnology research funding, but there also seems to be a "limitless" aspect to the potential applications of nanotechnology. With scientists and government working from a public-private platform, making a wide variety of objects and devices smaller, more energy efficient, and more powerful will be one of science's greatest contributions to moving humanity forward into the 21st century and beyond.

Posted by Steve at 05:32 PM | Permalink | Comments (0) | TrackBacks (0)

By Red Sox Steve

Major market indices all down, across the board. The government is keeping the lights on at AIG, and with the auto sales data out Tuesday, we should have another bloodbath on our hands. As of today, we have now erased all the gains of the last 10 years. This is pretty depressing.

We have to learn from this crisis - corporate, governmental and personal profligacy are all to blame. On the left, there are cries of not enough spending, on the right, cries of not enough tax cuts. America, and many other rich countries are s...l...o...w...i...n...g d...o...w...n or stopping - the Japanese are exporting next to nothing, Citigroup stock can be had for the cost of a Happy Meal (DO NOT call your broker with a hot stock tip from vg.com on this one!), and Warren Buffett's annual letter eulogizes the credit bubble.

We need perspective; we need to think about the future. When last we met, we spoke about the highest of high-tech devices... the semiconductor. How is all that computing power in there? If chips are smaller now than they were 10 years ago, why do they keep getting faster and more powerful?

The answer: NANOTECHNOLOGY!

To the casual observer, there is nothing to be seen or even felt. Nanotechnology doesn't work like that. "Nano" is the Greek prefix for dwarf, and, for a modern scientist's purposes, means 10, raised to the minus 9 power. In other words, a nanometer is one one-billionth of a meter.

Let's try to give ourselves a frame of reference: 1) The molecule that creates everything in the living world, DNA, is just over 2 nanometers wide, and less than 1 millimeter long, 2) 10 Hydrogen atoms fit in a nanometer, and 3) Human hair grows faster than 1 nanometer/second. Got that?

In the physical world that IS easily observable, we have things like automobile engines, electrical appliances, health food... we turn the key, there is a spark in the engine, the engine starts burning fuel and the car has the power to move; we plug in a lamp, turn a switch to connect a circuit and a light goes on; we eat oatmeal and fruits, and, next thing we know, our doctor is telling us that the cholesterol levels in our blood have decreased. These are all observable scientific events, cause is related to effect, and we are all better off because science has converted the unknown into the known for all humanity.

Nanotechnology is a little like that, just on a much smaller scale. What is observed on the small scale that is NOT observed on the large scale is that, as the surface area of a given molecule increases, the strength and energy of the molecule increase as well. That is one way for a scientist to know she has crossed into a nanoscale world.

Carbon nanotubes are a great example of this. Picture a tube, made entirely of bonded carbon atoms. Because of the nature of the bonds between the atoms, this structure is the strongest ever discovered in the natural world, over 300 times stronger than steel. Furthermore, the conductivity (rate at which it can transport electricity) is 1,000 times greater than a copper wire, and its ability to withstand the heat generated is also much greater than copper. In other words, these types of structures are extremely strong, and very energy efficient.

Efficiency and speed on a nano-scale govern the evolution of semiconductors. The smaller a circuit is, the faster an electron can travel; the smaller the circuit is, the less power the circuit uses... a semiconductor's uses become more versatile (i.e. the product sells!). Changes in the distances on the scale of nanometers affect the power and efficiency of the transistors found in semiconductors. When an electronic signal hits one of the transistor's logic gates, that signal needs to go somewhere based on its voltage, frequency and the makeup of the transistor. Currently, in iPods, transistors function on the scale of 32 nanometers; and efforts are being made to reduce that distance by almost 50%! Smaller, faster, stronger.

In conventional memory chip manufacturing, there were two ways to get more power out of a chip, insulate the wires with better material, or send more electrons through the system. In the production of copper wires around a microchip, manufacturers would overlay the insulation onto the copper wires, create patterns, and then remove any excess insulation. Voila - you have a circuit (with insulation around the copper wires)!

Based on a September 2008 article I read in Manufacturing Engineering, IBM scientists have discovered a way to overlay a silicate-based glass compound onto the same network of copper wires, skipping the process of insulation altogether. Then, during a baking process, nanoscale holes are formed around the copper wires. The chip is taken out of the oven, the glass is removed and vacuums are left behind to surround the wires - greater efficiency and more power can be generated within a given circuit by using vacuum-based insulation, and this process is observed and completed entirely on a nano-level scale.

A company called QuantumSphere operating out of Santa Ana, CA is taking molecules produced at the micron level (that's only one one millionth of a meter - not small enough...!), melting them and condensing them down to a nano-scale size based on a patented process - again, based on the idea that for a given surface area, the potential energy of the substance increases. Ultimately, the effect is to get more energy out of a given metal, like cobalt for example. Other than getting more energy out of a given mass of material, replacing platinum with cobalt or aluminum is also cost effective, due to the high cost of platinum.

We need this stuff - as the world gets more populated and humanity gets more hip to the idea that NEW tech is GOOD tech, and we look for solutions to energy problems, computing and data storage problems, and health-related problems, using smaller and smaller materials and discovery methods will be to everyone's benefit.

Posted by Steve at 07:52 PM | Permalink | Comments (0) | TrackBacks (0)

On Tuesday, we started talking about the technologies that are going to help bring humanity fully into the digital world.

First, though, I've got to rip on an Investor's Business Daily article:

"Investing in broadband sounds cutting-edge. Promoting the Internet and knowledge economy appeals to the public — especially the latte-sipping Web surfers who are big supporters of President Obama."

This wasn't a quote by someone for the article, it was a statement made in the article! Clearly, an underlying agenda is being put forth which has NOTHING TO DO with technology or its function. Is this any way to treat a reader? I don't think so!

These technologies are going to change our way of life, for the better. Once they are implemented, businesses will run more cost effectively, information will travel faster, and folks near and far will all have access to - and contribute to - the knowledge base that we need to fully integrate the digital world and our lives. Once again, most of the information here is courtesy of Plunkett's Research, Ltd.

Cellphones - Cellphones are an ideal way for a developing nation to get connected, and with the development of 3G (& 4G!) technology, the capabilities of these handsets are increasing to text, picture, video, internet, money transfers, bill payment. Let's talk progress: cell phones now run on standard cell phone circuits (those towers you see everywhere are part of the system), but now leading companies are developing phones that, in the presence of a Wi-Fi network (used mainly for computers with WLAN cards), will switch to VOIP (Voice Over Internet Protocol) in order to transfer information. That's not the end of it. If you've ever used wireless internet, you know the range is limited to a matter of feet - don't worry, though, because leading technology companies of all varieties (Intel, Google and Comcast) are working on a more powerful alternative. It's called WiMAX (stands for Worldwide Interoperability for Microwave Access) - apparently, WiMAX networks can work over a matter of MILES!

WiMAX - So, WiMAX can deliver information to all manner of wireless devices (including computers), if the device is within a 30 mile radius of a WiMAX antenna. WiMAX antennae are being developed in over 20 countries around the world from the Ukraine to Mexico to India. Sprint Nextel has combined its wireless broadband business with Clearwire into one entity, retaining the name Clearwire. Clearwire has put together $3.2 billion in combined financing from Intel, Google, Comcast, Time Warner Cable and Bright House Networks, combining the interests of the WIMAX industry leaders. Intel will work with manufacturers to embed WiMAX chips into Intel Centrino 2 processor technology-based laptops and other Intel-based mobile Internet devices and will market Clearwire’s service along with Intel’s performance notebook PC brand. Google will partner with Clearwire to develop Internet services, advertising services and applications for mobile WiMAX devices. Sprint, Comcast, Time Warner Cable and Bright House Networks will enter into agreements to provide 4G technology as part of the mobile WiMAX service. The focus of the new company will be to develop and deploy the first U.S. nationwide mobile WiMAX network.

3G technology - 3G technology makes it possible to surf the internet and send video data over mobile handsets. 3G superceded 2.5G and 2G. Without going back any further, 2G was the standard that allowed cell phones to send SMS (Short Message Service) messages between phones, while 2.5G (more a term used for marketing purposes) is actually a mix of 2G and 3G technologies. As of early 2008, only 12% of cell phone users have made the transition from 2G to 3G, but with India and China rapidly adding millions of cell phone users every month, we can be sure this number will change. Intel is incorporating 3G technology into its MIDs (Mobile Internet Device) and UMPCs (Ultra Mobile Personal Computer), via its new Silverthorne silicon chip, AND for cellular use, Intel plans a ground-breaking new system called Moorestown which will combine a variety of PC elements (increasing processing power and decreasing energy consumption) onto a single tiny chip that’s small enough to use in cellphones.

RFID, Generation 2 ("Gen2 RFID"): We discussed RFID tags previously... the basics are that it can store information about a product and the accompanying product/item can therefore be tracked and scanned - this can work for everything from cuts of beef in a supermarket to luggage on an airplane. There are limitations, however, such as the amount of data that is currently stored on (1st generation or "Gen1") RFID tags, and how quickly a reader can read the tags (Gen1 RFID tags are read at about 100 per second). There is discussion of tripling the memory in Gen2 tags, which will apparently increase the accuracy and decrease the duplicity of tags read by certain UHF readers. Further, the rate at which Gen2 tags can be read will increase to 1500 per second! Intel developed an R1000 chip for UHF readers in 2007, which combines numerous functions from previous versions, bringing down the cost of the readers. This is what technology is all about!

I have to give a "shout out" to 2 strong performers in the technology sector:

Apple - clearly the standard bearer when it comes to consumer electronics. Apple, Inc.'s recent financial performance is a reflection of that. In spite of the fact that we are clearly experiencing a global recession, Apple sold a record number of iPods in 1Q2009 (ending Dec. 27, 2008). Unfortunately, Steve Jobs' health issues remove him from the picture, but as long as Apple continues to remain committed to developing a quality product that is easy to use, it will remain one of the few healthy global technology companies.

Intel - how's this for "stimulus": when company after company announces loss after loss (Friday, both ThyssenKrupp (steel) and Abercrombie & Fitch (retail) announced quarterly drops in revenue of over 60%!) Intel recently announced that it would invest $7bn in the US economy over the next 2 years! Intel is in all the hot technology areas, from RFID to WiMAX to MIDs and UMPCs. Intel will continue to develop its product from a position of strength, so it can continue to compete with its main rival in the semiconductor industry, AMD.

On this site, we've got a lot to handle - politics, business, sports and culture keeps us all pretty busy. We're going to keep an eye on these companies and technologies and look for performance from the ones mentioned above as well as any newcomers with new ideas. If you find any, don't hesitate to let me know - steve@vagabondguru.com.

Posted by Red Sox Steve at 09:47 AM | Permalink | Comments (0) | TrackBacks (0)

The biggest news item of the day is Obama's "stumping" for the stimulus package in Elkhart, Indiana (over 10% unemployment). Unfortunately, until the stimulus package is passed, we can only guess how the US economy will be impacted. Government spending is necessary, and, although it was hard to listen to the whole thing (a Q&A with the folks of Elkhart would normally be an immediate "turn off the TV", but it's Obama who is calling the tune on the stimulus, all he's doing is answering their questions anyway...) I was happy to hear that efforts will be made to pursue alternative/clean energy, as well as energy conservation.

The discussion here on vagabondguru.com has to move on. The stimulus will be what it is, the money will be spent when it will be spent, and we all now know that the economy will severely contract (less money for everything) in the short term and stay that way. For a while.

I've been looking at technology - we're going to need it to get out of the quagmire. We're going to have to spend public and private money on it; no worries because all of us are going to benefit from its many uses. Wireless. RFID. Broadband. Municipal Wi-Fi. This is just the beginning, and it's all going to be in demand as we wire up the US of A going forward. Because there is so much information, we're going to look at this in 2 parts - this is an intro to some areas of interest, and then we'll explore the topic further here on Saturday.

RFID (Radio Frequency Identification) - I love this stuff! RFID tags can go on everything from automobiles (EZPass AND SpeedPass!) to cargo to electronics to food. Wal-Mart uses it, Marks & Spencer uses it, and Wal-Mart (& Sam's Club) is strong-arming all their suppliers to get on board with it. There is a ton of cost-savings that will take place after RFID tags are effectively implemented. Wal-Mart has already seen a reduction in the number of times a product is out of stock at a given store by using this strategy. This can make inventory management quicker and cheaper, and of course better service will build customer loyalty. The discussion I see on Plunkett's (an industry research service that should take MUCH of the credit for the info presented here) is that the Japanese are already employing this technology in supermarkets. Get this: a Japanese consumer can use their cell phone to scan an RFID tag on a meat package. The consumer gets a link to a web site that shows pictures of the ranch from which the meat came and medical and feed records pertaining to the specific cow! Awesome! The Germans are using it in grocery stores, the US Dept. of Defense is using it for inventory management, and many other major retailers like Best Buy and Albertson's are getting in on the game. Airlines are using it to reduce incidences of lost luggage, and hotels are using it for speedy check-in. Check this website out for further info.

Broadband & Municipal Wi-Fi - high speed internet. Amy Klobuchar, Senator from Minnesota and a member of the Senate Commerce Committee was on CSPAN on January 30th talking mainly about the recent bill she sponsored trying to move the DTV transition from February to June. Turns out that over 3 million people were waiting for coupons and never got them. No big deal right? Minnesota and West Virginia (John Rockefeller, Chairman of the Commerce Committee) take this very seriously. With so many rural communities affected by the transition, their thinking is that it'd be better off if the transition was done in June. Folks out there aren't just watching Lost and 24 like yours truly... rural communities are highly dependent on accurate weather information, especially during the winter! Sen. Klobuchar's rhetorical remark to the moderator: "have you ever tried to adjust a rooftop antenna in Minnesota in February?" But I digress...

In 2000, the US was 4th in the world in terms of broadband penetration. By 2008, we were - gasp! - 15th! Part of this stimulus package will put funds towards further broadband integration into underserved communities. Libraries, police stations, hospitals. It's very simple - with high speed internet, these folks are wired too. Their jobs are easier and more efficient. This is the perfect example of effective stimulus spending: wiring up America for the 21st century AND creating jobs in the process.

In 2007 and 2008, efforts to supply municipalities with wi-fi technology stumbled a bit in Chicago, Houston, Miami and San Francisco. In Minneapolis in 2006, the city government agreed to subscribe for a minimum number of users, guaranteeing the service provider a minimum amount of revenue. St. Cloud, FL had provided internet service to about 5,400 households as of 2006 at a cost of $3 million. This trajectory is similar to any number of historical precedents from the telephone, to rural electricity to the interstate highway system - government efforts to cover our landscape with such things have been nothing but a benefit to all of us.

Wireless - Let's get with some trends in the wireless phone industry (got this from Plunkett's):

1) 16% of all households in America have NO landline. As my own aside, you can be sure that percentage is much much higher in cities with 2 things: a) renters, and b) young people.
2) There were 3 billion global cellular telephone subscribers by mid 2008, including more than 260 million in the U.S. alone.
3) 1.2 billion cell phones are sold every year, the fastest selling consumer electronics item by far.
4) More MP3-capable cellphones are sold each year than stand-alone MP3 players. More digital camera-equipped cellphones are sold than stand-alone digital cameras.
5) The US has 213,300 cellular telephone towers (up from 195,600 at yearend 2006). The American cellphone industry provides direct employment for 254,000 people, as of the end of 2006.
6) Approximately 84% of Americans have a cellphone subscription (up from 79% at the end of 2006), and they spend an average of $49.79 monthly on their cellphone bills according to the CTIA.

3G technology (3G = Third Generation)
3G technology gives cellphone users the ability to surf the internet, send videos, shop, watch TV and play games on their device, which neither 2G or 2.5G offered. 3G technology was offered in Japan (through NTT DoCoMo in 2001) and Europe (Vodafone in 2004) earlier than it was offered in the United States. Finally, in 2005, Verizon started selling 3G technology in major metropolitan areas in the United States. Exploration of 4G services are already underway. Samsung hopes to offer 4G service by 2010, as does DoCoMo.

There you have it, a brief overview of technology and some of the related applications and trends that we'll be paying attention to as we go forward. Have a great week, and I'll see you back here on Saturday.

Posted by Steve at 06:30 PM | Permalink | Comments (1) | TrackBacks (1)