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Using light to "spy" on materials.

Researchers at Purdue University have developed new tools that use light and tiny molecules as "spies" to measure the properties of materials smaller than the thickness of a human hair. The technique is based on gauging changes in light emitted by molecules. Now utilized to monitor the properties of lubricating oil between ball bearings, the process could be used in the future to examine many materials on a microscopic scale, from tiny circuit elements in super-small computers to activity inside living cells.

"These devices, known as molecular optical probes, use molecules as microscopic |spies' that relay information about their environment through the light that they emit," explains Dor Ben-Amotz, professor of chemistry. "Some of the ideas we're applying are not new, but we're developing them into tools engineers can use in manufacturing, medicine, and nanotechnology."

These tools can monitor variables engineers want to know about on a microscopic level, such as temperature, pressure, viscosity, film thickness, and composition. Because the technique relies on using light, measurements ca i be made remotely using fiber optics.

Using this new technology, Kimberley Schrum, a doctoral student in chemistry, developed and built a thermometer that can measure the temperature of an area 100 times smaller than the thickness of a human hair. Being able to measure the temperature of these microscopic samples will benefit engineers and manufacturers, such as those who design and build very small computers.

"Heat transfer is one of the biggest problems with making computers small," she explains. "Engineers are very interested in knowing where the heat comes from in a microscopic circuit element. The nice thing about this device is that it's so simple. The light we shine interacts with the dye molecule in the sample, which fluoresces in different wavelengths, or colors, of light. The light is then collected and focused onto a monochrometer, which measures the intensity of the light one wavelength at a time. As temperature increases, the amount of blue light emitted increases relative to the amount of greenlight. By measuring this intensity increase, the temperature of the fluid can be determined within about one degree."

In another project, the Purdue group measures the temperature pressure, and film thickness of oil between moving ball bearings and hard surfaces, using the lubricant's molecules as "spies," instead of using dye molecules. Ben-Amotz says these studies may lead to the development of lubricants that last longer and more effectively reduce wear. "There are two big advantages to using light, One is that, in principle, you can measure these properties remotely using fiber optics. That means you can have all the sensing equipment off in another room, away from the factory where everything is happening, where it might be noisy or hostile tile some way. And doctors already use fiber optics to probe the human body, The second advantage is that you can look at things on a very small scale. The technique has many applications, because any sample you can get under a lens, you can get light into and out of."
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Title Annotation:molecular optical probes
Publication:USA Today (Magazine)
Date:Jun 1, 1994
Words:503
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