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.”
“The beauty of this technology is that the number of sensors contained in one of our arrays is determined by the pixel resolution of the cell phone camera. With the megapixel resolution found in cell phone cameras today, we can easily probe a million different spots on our silicon sensor simultaneously. So we don’t need to wire up a million individual sensors,” Sailor said. “We only need one. This greatly simplifies the manufacturing process because it allows us to piggyback on all the technology development that has gone into making cell phone cameras lighter, smaller, and cheaper.”
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.
Sensitivity to additional chemicals is on the way. One of the top priorities for emergency responders is carbon monoxide, which firefighters can’t smell in the midst of a sooty fire though it’s deadly. Sensors on their masks could let them know when to switch to self-contained breathing devices, Sailor said. Similar sensors might warn miners of the buildup of explosive gases
Another detection system that was recently in the news is a Lawrence Livermore system for identifying the genetic sequence of any virus, bacteria or other previously sequenced organism.
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