Characterization of embedded Micro-heater and Temperature Sensor in a CMOS-MEMS Resonator for gas sensing

摘要

In this paper, a CMOS-MEMS resonator is fabricated with embedded micro-heater and temperature sensor for application in the detection of ammonia in exhaled breath. The resonator is fabricated using commercial 0.35 μm CMOS technology. An aluminium micro-heater and temperature sensor is used to control the temperature of the sensing layer for the detection of ammonia. The measured value of the temperature sensor resistance is determined at room temperature (24.3℃) and is found to be 184.8 Ω compared to the calculated value of 189.85 Ω, thereby showing good agreement within an error of 0.57%. The temperature coefficient of resistance (TCR) of the sensor is determined by measuring its resistance variation as a function of temperature from 25℃ to 100℃ in 5℃ increments. It is found to be 3.68×10~(-3)/℃ and 3.79×10~(-3)/℃ for the increasing and decreasing temperature measurements, respectively, with a percentage error of 5.6% and 2.8%, respectively, compared to the standard value of 3.9×10~(-3)/℃ available in the literature. The effect of the humidity on the TCR is examined in the humidity range of 30% RH to 90% RH for the same temperature range of 25℃ to -40℃ and the humidity is found to have a negligible effect on the TCR of the temperature sensor.