Toxin Sensing Mobile Phones

Researchers at the University of California San Diego have just finished the first phase of an initiative to develop a mobile sensor capable of detecting toxic chemicals in our environment. With a small startup called Rhevision Inc., the chief researcher on the project, Michael Sailor, has devised the sensor, a porous flake of silicon which 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.

According to Sailor, the sensor "works a lot like a nose. 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.” At this point in the development phase, the sensors can be used to identify methyl salicylate and a handful of other chemical agents used in chemical weapons. However, it's Sailor's hope that the sensors could be used to distinguish between hundreds of different compounds.

Using a fine-scale detail in the optical array, the team uses a new kind of supermacro lens that works more like an animal’s eye than a camera lens, allowing a them to achieve much more detailed readings.

“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.”

Eventually the research team will push to develop a new network of toxin-sensing mobile phones with their innovative sensors. Much in the way the quake quake-catcher network works, individual mobile phone users equipped with these sensors would form a coordinated network of sensors; and, in the event of a chemical leak or toxic exposure, scientists could use the coordinated network to map toxic exposure as it unfolded.