Sensors (Jan 2015)

Ethanol Microsensors with a Readout Circuit Manufactured Using the CMOS-MEMS Technique

  • Ming-Zhi Yang,
  • Ching-Liang Dai

DOI
https://doi.org/10.3390/s150101623
Journal volume & issue
Vol. 15, no. 1
pp. 1623 – 1634

Abstract

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The design and fabrication of an ethanol microsensor integrated with a readout circuit on-a-chip using the complementary metal oxide semiconductor (CMOS)-microelectro -mechanical system (MEMS) technique are investigated. The ethanol sensor is made up of a heater, a sensitive film and interdigitated electrodes. The sensitive film is tin dioxide that is prepared by the sol-gel method. The heater is located under the interdigitated electrodes, and the sensitive film is coated on the interdigitated electrodes. The sensitive film needs a working temperature of 220 °C. The heater is employed to provide the working temperature of sensitive film. The sensor generates a change in capacitance when the sensitive film senses ethanol gas. A readout circuit is used to convert the capacitance variation of the sensor into the output frequency. Experiments show that the sensitivity of the ethanol sensor is 0.9 MHz/ppm.

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