Abstract
Microsensors have many advantages, including small size, low power consumption, high measurement precision, and high sensitivity, etc. A micro thermal sensor is usually the key component of many microsensors, such as flow sensors, IR sensors, and vacuum gauges, etc. The design and fabrication of micro thermal sensors are presented in this work. The working principle of the micro thermal sensor is thermistor, using platinum as the sensing material. A new mesh membrane structure is also presented in this research. This special structure has lots of advantages. Compared to a closed membrane, the backside etching is not necessary; therefore, it is timesaving and less material consuming. In addition, double-side polished wafers and double-side alignment are not necessary. Compared to a floating membrane, the mesh membrane is strong enough to avoid cracking and provides more available area. The sensitivity of the micro thermal sensor is 3.263℃/mW, with a response time is less than 5ms. In addition, flow sensors based on these kind of micro thermal sensors were designed and fabricated. For the flow velocity higher than 1.5m/s, the sensitivity of the flow sensor operating in constant voltage mode is above 0.01433 mA(m/s)-1/2; in constant current mode is above 7.98 mV(m/s)-1/2.