Abstract
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.
Highlights
Ethanol sensors can be applied in environmental and industrial monitoring
A spectrum analyzer, a test chamber, a power supply, a LCR meter and an infrared thermometer were employed to measure the characteristics of the ethanol sensor
Tin dioxide was adopted as the sensitive material of the ethanol sensor, and it was prepared by a sol-gel method
Summary
Ethanol sensors can be applied in environmental and industrial monitoring. Humans can inhale over 1000 ppm ethanol vapor that can cause headaches, nausea, balance disorders, dizziness and confusion [1]. The sensitive film of the ethanol sensor was ZnO nanowire, and the material needed a working temperature of 300 °C to sense ethanol gas. The power consumption of the gas sensor depended on the working temperature of the sensitive film. In this work we prepare tin dioxide nanostructure as the sensitive ethanol material to enhance the sensitivity of ethanol sensor. These sensors [7,8,9] were not integrated with circuitry on-a-chip. We utilize the same process to develop a capacitive ethanol microsensor with a readout circuit on-a-chip. The capacitive ethanol sensor has potential as a wireless communication ethanol sensor if combined with a micro-antenna
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