Fabrication of a HCHO gas sensor based on a MEMS heater and inkjet printing

We have developed In2O3 particle ink that can be applied in inkjet printing on a microelectromechanical systems (MEMS) heater and have fabricated semiconductor-type gas sensor based on that heater. The formaldehyde (HCHO) sensor prepared by inkjet printing showed comparable or even higher sensitivity compared to that of the sensor prepared from conventional screen printing when increasing the number of printings was increased. By virtue of its non-contact printing nature, this In2O3 ink as a sensing material could be deposited on the MEMS heater without damage to the heater membrane. We found that the sensor prepared on the MEMS heater by using the inkjet deposition technique showed response/recovery times of 7s/17s with a sensitivity of 0.63 at an 18 mW power and 60 ppb HCHO.