Nanoparticle SnO2 Gas Sensor with Circuit and Micro Heater on Chip Fabricated Using CMOS-MEMS Technique

The fabrication of a carbon monoxide (CO) micro gas sensor integrated with an inverting amplifier circuit and a micro heater on chip using the commercial 0.35mum complementary metal oxide semiconductor (CMOS) process and a post-process have been implemented. The gas sensor is composed of a polysilicon resistor and a CO gas sensing film. Tin dioxide prepared by the sol-gel method is adopted as the CO gas sensing film. The micro heater is used to provide the working temperature of the gas sensor. The gas sensor, which is a resistive type sensor, changes the resistance when the sensing film adsorbs CO gas. The inverting amplifier circuit is utilized to convert the resistance of the gas sensor into the voltage output. Experimental results show that the sensitivity of the CO gas sensor is about 1 mV/ppm.