New types of chemical sensors for environmental monitoring, food safety or security applications could be based on nanotechnology, according to Frank Osterloh, an assistant professor of chemistry at UC Davis.

"Nanomaterials are very well suited for chemical sensor applications, because their physical properties often vary considerably in response to changes of the chemical environment," Osterloh said. Because nanomaterials can be made up of structures just a few atoms across, just a few molecules of chemical can trigger a response, he said.

Osterloh, with graduate student Xiubin Qi and former student Jason Martino, discovered that nanowires made of lithium, molybdenum and selenium atoms show changes in electrical resistance of up to 200 percent when exposed to vapors of organic solvents. By depositing the nanowires between two conductors, they made a simple chemical sensor.

By attaching chemical groups to the nanowires, the researchers could modify the sensor to measure the acidity of a solution. The team is now investigating if this "programming" property can be extended to make sensors for the detection of explosives or environmental contaminants such as lead in drinking water, Osterloh said.

The work will be presented at the 228th national meeting of the American Chemical Society in Philadelphia, Aug. 22-26.

Osterloh's laboratory is also experimenting with nanoscale chemical sensors based on materials that change color; nanomaterials that can be manipulated in magnetic fields; and luminescent materials.