From Ceramic Tube to Microcantilever: A New Strategy for Low Power, Fast Heating and High Integrated Metal Oxide Semiconductor Gas Sensor

A microcantilever-type metal oxide semiconductor (MOS) gas sensor was successfully designed and fabricated via typical micro-electro-mechanical system (MEMS) technique. The active region is on a narrow and long single cantilever, to achieve very low static power consumption and very fast heating response. The complicated meandering microheater and interdigital electrode structure are removed to make the sensor the most simplified, which greatly reduces the total size of the sensor and improves the integration. Microcantilever heaters were fabricated on a four inch Si wafer using MEMS process, and SnO
₂
was loaded as the sensing material to form the complete sensor. Static testing of ethanol indicates that the sensor can detect and distinguish 0-10 ppm (1 ppm step) and 10-100 ppm (10 ppm step) ethanol with a static power consumption of 4.32 mW, while dynamic testing of hydrogen indicates that 0-10 ppm (2 ppm step) and 10-100 ppm (10 ppm step) hydrogen can be detected with a static power consumption of 7.16 mW. The sensor shows a good linear characteristic and quadratic characteristic to low concentration range (0-10 ppm) and high concentration range (0-100 ppm) of ethanol and hydrogen, respectively.