Groups of researchers in Japan and the U.S. have jointly developed a material — a coated carbon nanotube — that could realize a low-cost, easy-to-carry toxic gas sensor that works with smartphones. The researchers at the National Institute for Material Science (NIMS) in Ibaraki Prefecture and the Massachusetts Institute of Technology announced that the material is a carbon nanotube coated with insulating polymer. Carbon nanotube is normally highly conductive, but the insulating polymer serves to significantly lower the tube’s conductivity. But the coated polymer breaks apart when it is exposed to toxic gases, in which case the conductivity of the tube drastically increases.
NIMS says it can make a sensor by loading this material in a chip that can exchange data wirelessly with smartphones in close proximity just like the Suica cards used for shopping or paying for train rides. When toxic gas is present in the atmosphere, the material in the sensor becomes conductive, so if people hold their smartphones over the sensor, the handsets will react.
Shinsuke Ishihara, a senior researcher at NIMS, said the Japanese team explained that the toxic gas detectors currently used are heavy and expensive. But with 1 gram of the new polymer, it is possible to make 4 million sensors, he said. The researchers hope to put the material to practical use before 2020, and hope to install the sensors at public facilities and subway station to prepare for possible terrorist attacks such as one perpetrated by the Aum Shinrikyo religious cult in the Tokyo subway system in 1995 using sarin nerve gas.
The researchers are thinking of establishing advanced systems, such as one that can automatically send signals to smartphones whenever toxic gases are detected, Ishihara said. The sensors can be also attached directly to smartphones, Ishihara added. If there is a smartphone app that can automatically check sensors once every few seconds, it can be used to monitor toxic gases in real time. MIT researchers in the meantime are hoping to use the sensors to design lightweight radio-frequency identification badges that could be worn by soldiers on the battlefield, according to the MIT website.
