Cell phone sensors for toxins developed at UC San Diego

If embedded in many cell phones, its developers say, the new type of sensor could map the location and extent of hazards like gas leaks or the deliberate release of a toxin.

A tiny flake of silicon can be engineered to respond to a wide range of chemical hazards. Credit: Sailor Lab/UCSD

''Cell phones are everywhere people are,'' said Michael Sailor, professor of chemistry and biochemistry at the University of California, San Diego who heads the research effort. ''This technology could map a chemical accident as it unfolds.''

In collaboration with Rhevision, Inc., a small startup company located in San Diego, Sailor's research group at UCSD has successfully finished the first phase of development of the sensor and have begun to work on a prototype that will link to a cell phone.

The sensor, a porous flake of silicon, changes color when it interacts with specific chemicals. By manipulating the shape of the pores, the researchers can tune individual spots on the silicon flake to respond to specific chemical traits.

''It works a little like our nose,'' Sailor said. ''We have a set of sensory cells that detect specific chemical properties. It's the pattern of activation across the array of sensors that the brain recognizes as a particular smell. In the same way, the pattern of color changes across the surface of the chip will reveal the identity of the chemical.''

Already their chips can distinguish between methyl salicylate, a compound used to simulate the chemical warfare agent mustard gas, and toluene, a common additive in gasoline. Potentially, they could discriminate among hundreds of different compounds and recognize which might be harmful.
 A megapixel camera smaller than the head of a pencil eraser captures the image from the array of nanopores in Sailor's chip.