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Micro hotplate gas sensors were fabricated and utilized for ethanol detection.The micro hotplates,with an effective area of 100x100um2,were fabricated by CMOS technique and post-CMOS technique.In the CMOS process,membrane and heating resistors were fabricated.Tungsten was chosen for the heating resistors,which has better long-term thermal stability than silicon and is CMOS compatible.In the post-CMOS process,the membrane was released by front-side bulk silicon etching to achieve excellent adiabatic performance.Then Pt/Ti electrode and SnO2 sensitive layer were sputtered on the device.Measurements showed that at room temperature in atmosphere,the device had a low power consumption of 19 mW and a rapid thermal response of 8 ms for heating up to 300℃.The tungsten heater exhibited good high temperature stabilitv when working at 300℃ for 336 h.The micro hotplate gas sensors possessed good sensitivity to ethanol when operating at the optimum working temperature of 380℃.The sensors response showed a nearly linear relationship with ethanol concentration over the range of 8-80ppm.Besides,the micro hotplate gas sensors can also be used for detecting other flammable and toxic gases if proper sensitive layers are deposited on the device.