05-12-2016 | | By Paul Whytock
The world's first gas sensor that can take advantage of the technical characteristics of graphene has been developed by Fujitsu Laboratories in Japan. The sensor operates on a new principle in which the gate element of a silicon transistor is replaced by graphene.
Graphene is a two-dimensional sheet of carbon one atom thick and has electrical properties that can push the developmental boundaries of future electronic components. Current usage of silicon as the base technology for the manufacture of chips is now seen as having reached its limits relative to future VLSI (very large scale integration) requirements.
When a gas molecule adheres to the graphene in the sensor the graphene's operational function changes. The result is a major change in the switching characteristics of the silicon transistor. This allows the sensor to detect concentrations lower than tens of parts per billion of nitrogen dioxide and ammonia. With nitrogen dioxide in particular the sensitivity has improved more than tenfold to less than one part per billion.
The sensor is tiny with a detection area of only a few hundred micrometers but could be made even smaller and because its mechanism does not rely on chemical reactions the sensor returns to its original state through methods such as the application of heat to the device.
Detecting disease and pollution
This sensor could be used to measure nitrogen dioxide in real-time at the environmental benchmark level of sensitivity of 40-60 parts per billion which is an index of air pollution. It will also simplify detection of gas components in breath which can be used to quickly discover some diseases.
There are conventional semiconductor gas sensors that are compact and work in real-time but these generally operate at a sensitivity on the order of parts per million so their performance is not sufficient for detecting certain gas components.
Fujitsu Laboratories has said it will put the graphene gate sensor into practical applications as an environmental sensor after verifying its characteristics and studying its durability. The company also plans to find ways to detect gases other than nitrogen dioxide and ammonia by combining graphene with other molecules.