Low power consumption micro C2H5OH gas sensor based on micro-heater and screen printing technique

Micro C2H5OH gas sensor based on micro-heater and tin oxide thick film was fabricated by using complementary metal-oxide semiconductor (CMOS) compatible micro electro mechanical systems (MEMS) process, which showed low power consumption and high response. Semiconducting SnO2 nano-powders were synthesized via co-precipitation method, and to increase the sensitivity for alcohol gas rare metal dopants were added. Bridge type micro-heater based on Si substrate was fabricated by surface micromachining technique and in the structure of micro-heater, the resistances of two semi-circled Pt heaters are connected to the spreader for thermal uniformity. The response of the micro gas sensor was 0.78 for 2 ppm alcohol with lower power consumption (35 mW) than that of the commercial alcohol gas sensor. The mechanical stability of the sensor was tested under the higher direct current (DC) power than that of the normal operation power and the variation rate of the micro-heater resistance was below 2% after 105 times repetitive 35 mW pulse operations.