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Revolution in the air

If you've ever questioned the worth of scientific research, its utility to mankind, and the justification for spending vast amounts of the government's money on something that just may result in nothing - sometimes you might have a case.

Occasionally, however, there exist a few rare gems likely to revolutionize life in the millennium, and the University harbors one such secret: aerogels.

Aerogel is the world's lightest material, the best thermal insulator and the best electrical insulator - and it is a unique material.

Prof. Pamela Norris, director of the University's Aerogel Research Laboratory and recipient of over $1 million in research grants, said Fortune magazine described aerogels as the "material that will have as large an impact on society as plastics have had in the past."

Norris began developing aerogels at the University to support her Microheat Transfer Laboratory.

She said she receives "requests from people all over world wanting aerogels - as many as one per week." But, in spite of the large market that exists to sell them commercially, she only responds to those involved in collaborative research, high school projects or museums.

The University's Aerogel Research Laboratory is the only institution of higher education in the United States to manufacture aerogels.

What are Aerogels?

Aerogels are not new. They've been around since the 1930s, but it is only recently that fabrication techniques have improved enough to make the possible applications realistic.

If you take a wet, gel-like substance, then extract the liquid part of it and replace it with air while still retaining the solid structure, you've created an aerogel.

Dr. Stephen Kistler, who produced the first aerogel in 1931 and coined the term, said the key to producing aerogels was in replacing "the liquid with air by some means in which the surface of the liquid is never permitted to recede into the gel."

Norris said the first step in creating an aerogel is to make the wet gel substance known as an alcogel - a combination of alcohol, silica, de-ionized water and ammonia. Adjustment of the quantities of these substances controls the physical properties of the aerogel. The mixture is poured into a mold, and the silica precipitates until all that remains is "a fragile solid skeleton of silica with excess water and alcohol," Norris said.

To remove the liquid part it must be converted into a supercritical fluid (see information box), possible only at high pressures and temperatures, in a vessel known as an autoclave. This is highly explosive for alcohol, and, in fact, the first aerogel manufacturing plant in Sjobo, Sweden, erupted in 1984 when the methanol ignited after reaching the supercritical temperature of 240 degrees Celsius.

To avoid this outcome, Norris removes the excess water from the wet gel by soaking it in alcohol and then exchanging the alcohol with liquid carbon dioxide prior to positioning in the autoclave. The supercritical temperature is reduced to 31 degrees Celsius. The gel dries for one week in the autoclave, and the supercritical fluid is vented out.

Norris said she can produce up to 40 petri dishes per month. The Lawrence Berkeley National Lab sells the equivalent amount of aerogels for $40,000.

Geometric analysis reveals that aerogels possess a fractal-like structure (see information box) with dimension 2.1 rendering them open and accessible so that "a sugar-cube [sized] piece of silica aerogel has the internal surface area equivalent to a basketball arena," Norris said.

The research

One of Norris' research projects is the development of a biological warfare detector. In conjunction with a Department of Defense contract, Norris can coat the aerogels' large internal surface with smart drugs - substances that are highly receptive to specific toxins, viruses and bacteria.

These doped aerogels could be placed on little airplanes or even bumble bees and sent into areas possibly contaminated by biological weapons. Once returned, the aerogels could be analyzed, and any foreign chemicals identified.

The technology also can be used in hospitals as an influenza detector.

The Department of Defense also sponsors the growth of cells in aerogels. One can "buy a cube of cultivated cells" in an aerogel and thus "revolutionize experiments with cells" and avoid the tediousness of growing your own cells, Norris said.

IBM also has developed an interest in Norris' lab. Since aerogels are a better electrical insulator than air, placing an aerogel composite between microchips may serve to increase the speed of computers.

Norris' Microheat Transfer Lab already makes use of the insulating property of aerogels. Lab workers mount thin gold films on aerogels and then accurately can monitor the transfer of energy across metals on a short (micro) time scale and length scale.

An aerogel future?

Silica aerogels also have been utilized by NASA on the Mars Rover to study micrometeoroid space. Their porous nature enables the dust on the Martian surface to become embedded within the aerogel - thus taking a miniature Mars soil sample.

Alternatively, carbon aerogels have a super capacity to store an enormous amount of electric charge - and store it in the size of an AA battery. Four of these battery-sized aerogels could be sufficient to start a car.

Could this be a future for everyone? Think of everything you use in everyday life and then imagine it made with an aerogel.

When you wake up in the morning you'll stare out of your super-insulating window, made with aerogel frames, and you'll turn on your aerogel-embedded radio that eliminates interference and improves reception. Breakfast: As you grab the milk from your refrigerator it will be a thinner, lighter refrigerator that operates more efficiently, and your Greenberry's coffee mug will be a super-insulating flask which actually keeps your coffee hot all the way to class. Finally, when you return home in the evening you may opt for the more diffuse and ambient lighting, in which case the window panes will be made from aerogels

Graduate College student Matthew Guise, responsible for creating an aerogel filter for the biological warfare detector, said "once all the bugs in manufacturing have been taken out [aerogels] would benefit society very well in the future."


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