WEST LAFAYETTE, Ind. Purdue University researchers have discovered how to harness the light-emitting properties of porous silicon to stabilize the material's surface and direct it to respond to specific chemical environments or cues.

The development may allow scientists to tap the unique photoemissive qualities of porous silicon to create new types of drug-delivery systems, or biological and chemical sensors capable of performing real-time measurements in medicine and manufacturing, says Jillian Buriak, associate professor in Purdue's Department of Chemistry.

"We've shown, for example, that we can tailor the surface of a porous silicon wafer to survive within simulated in-vivo conditions, such as those found in blood plasma," Buriak says. "Untreated porous silicon dissolves too quickly to be useful in such environments. By functionalizing the surface, we may be able to develop sensors for use in diagnosing and treating disease."

The procedure also can be used for applications in opto-electronics or integrating light-emitting devices with silicon chips.

The study, published in the 32nd issue of the Journal of the American Chemical Society, details how Buriak, working with doctoral student Michael P. Stewart, used the light emitting properties of porous silicon to carry out an unprecedented chemical reaction on material's surface.

The study also is the first to illustrate how nanocrystalline silicon a form of porous silicon made up of crystals measuring just billionths of a meter in diameter works to emit light. Nanocrystalline silicon gets its name from nanometer, which is one-billionth of a meter, or about 100,000 times smaller than the width of a human hair.

"This reaction only works on nanocrystalline silicon," Buriak says. "It belongs to this whole field of nanotechnology where properties, such as color and reactivity, can depend on size. If you keep cutting a material down to the nanoscale, you may reach a po
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Contact: Susan Gaidos
sgaidos@purdue.edu
765-494-2081
Purdue University
25-Sep-2001