Differential Structure With Graphene Oxide for Both Humidity and Temperature Sensing

A graphene oxide (GO)-based sensor with differential structure was designed to detect both humidity and temperature. Two identical units have been fabricated with patterned gold electrodes on which a layer of GO was deposited by the drop-casting or spraying coating method. One unit was then covered by a layer of polydimethylsiloxane to modify its response to the temperature and humidity. Using this differential structure, the sensor shows great linearity in a temperature range from 20 °C to 60 °C and a humidity range from RH25% to RH95%. The humidity response of the two units varied for three orders of magnitude under the same temperature, which indicates a good sensitivity of the device. We have also found that the spray-coated sensor has a relatively short response and recovery times than the drop-casted one.