Scientists build smartphone sensors that can detect pollution

Scientists build smartphone sensors that can detect pollution

A new method to identify unhealthy levels of nitrogen dioxide could let those at risk take control of their health with cheap, personalized sensors, according to new research by Australian and Chinese scientists.

Australian scientist Kourosh Kalantar-zadeh had a personal interest in finding a way to detect the gas after his pregnant wife was diagnosed with preeclampsia, a dangerous condition for mother and child associated with high blood pressure. Kalantar-zadeh realized nitrogen dioxide is considered by some scientists to be a risk factor in developing the illness.

Around 80% of the nitrogen dioxide in our cities comes from vehicle exhaust, according to Australia’s Department of Environment. Unhappy with the sensors available on the market, he began looking at different materials that could detect nitrogen dioxide, but came up short until his colleague from the Chinese Academy of Sciences brought tin disulphide to his attention.
“This was a magic material,” he said about the pigment, which is generally used in varnishes. “The surface of this material has a nice energy that attracts nitrogen dioxide gas molecules selectively onto the surface.”

To his knowledge, no one has used tin disulphide for this purpose before — and he hopes that one day we will see it built into our personal smartphones as a sensor, allowing people to monitor the gas in the air around them. Importantly for the working of the sensor, no other gas can be attracted to the surface of the material. This makes it much better than any other available nitrogen dioxide sensors that have difficulty distinguishing different gases, Kalantar-zadeh claimed.

Most importantly the material is cheap. “The process of making this sensor is very low cost,” Kalantar-zadeh said. “It costs less than one A$1 to make.” He believes it could act as a personal alert system when nitrogen dioxide levels are too high, and could also be useful as a monitor at home or in a car.