Using light to "spy" on materials.

• Position: Molecular optical probes

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...