Silicon chip changes color when it detects a particular pollutant

Credit: Sailor Lab/UCSD

For city dwellers, the ability to know the quality of the air around us is important. Is it a high pollution day? Should asthma sufferers stay indoors? Is asthma getting more common because of the air quality? Surrounded by vehicles spewing noxious fumes, buildings aspirating toxins, the urban landscape keeping air from circulating and other issues that keep the air from being fresh, it's no wonder weather channels keep us updated. But what if we could keep ourselves updated, or even contribute to a better understanding of what areas of a city are worst during which times?

The concept of personal air quality sensors isn't new. Sensaris is a company that already developed a pollution-sensing wristband and is testing it in pilot projects. The collection of people wearing the wristband gathers data about the air around them and uploads it to a database where a map of the air quality of the area can then be created. But many scientists want to be more embedded into people's lives than a clunky wristband. Cell phones have been singled out for years as the perfect device in which to embed air quality sensors. And one team from University California, San Diego has invented a chip that could be the solution.

Sensitive Silicon Chips in Cell Phones Could Save Lives

Researchers have developed a tiny silicon chip that can be embedded in cell phones and detect dangerous airborne chemicals, alerting emergency responders through the cell phone network. It can be used for everything from detecting gas leaks, the release of a toxin, or high levels of pollutants in a given place, like carbon monoxide.

"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."

Pollution-Sniffing Silicon Chips Act Like Noses

With funding coming from the Department of Homeland Security, Sailor's team is already developing a prototype device using the silicon chip, which is a porous flake of silicon that changes color when it interacts with specific chemicals. Specific parts of the chip can be tuned to react to specific chemicals by manipulating the shape of the pores. The chips can potentially detect hundreds of different chemicals.

"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."

Cell Phone Network Providers Getting Onboard

It won't be too difficult getting cell phone network providers to get on board. DOCOMO is already working on packaging up data on air quality, including pollen, carbon dioxide (CO2), ultraviolet (UV) sunlight and other atmospheric conditions that affect humans in the area, and selling it to companies who want the information for their products and services, such as pharmaceutical companies, health care providers, and local government agencies.

The information from pollution-sensing cell phones could be used not just for companies and organizations, but to provide real time information to the public and help re-route traffic flow, or even save lives by alerting the cell phone owner of dangerous toxins in the room.

With cell phone companies already beginning to see the benefits of this nascent technology, researchers will have few limitations seeing their work implemented once it's ready to be tested out in public spaces. So one day in the not-too-distant future, your cell phone may be notifying you to breathe shallowly while you read your text messages.