Source: ACS SensorsResearchers from Saudi Arabia’s King Abdullah University of Science and Technology (KAUST) have developed an electronic sensor that issues an alarm when toxic industrial and vehicle-exhaust gases reach levels considered unsafe.

The device, which is considered just one piece of an air quality sensor distributed network, detects nitrogen oxide (NO₂), a hazardous group of gases associated with air pollution.

At the heart of the compact KAUST sensor is an NO₂-sensing thin-film transistor. The indium gallium zinc oxide (IGZO) film serves as both an electronic component of the device and also as the NO₂-detecting layer.

The NO₂ molecule is attracted to the electrons located on the transistor's surface. Consequently, as the number of NO₂ molecules that adhere to the IGZO film increases, the more electrons are eliminated from the film’s surface, transforming the electronic output and prompting an NO₂ detection notification.

Following notification, the IGZO layer is subsequently revived with light from an integrated blue light emitting diode (LED), which produces negatively charged electrons and positively charged holes in the IGZO film that neutralizes absorbed NO₂, thereby releasing it from the film’s surface and resetting the sensors.

With the hope of improving air quality with the placement of the compact sensors throughout metropolitan areas, the KAUST team intends to turn their research into a prototype and have detailed their findings in the journal ACS Sensors.