A Bidirectional CMOS MEMS Thermal Wall Shear Stress Sensor with Improved Sensitivity and Low Power Consumption

For the first time, we reported a highly sensitive, low power consumption and bidirectional thermal wall shear stress sensor using 0.18 μm 1P6M CMOS MEMS technology. To fulfill the bidirectional sensing, a sensor design of a calorimetric structure is adopted. Benefited from the 0.18 μm 1P6M CMOS technology, to enhance the sensitivity and reduce the power consumption, the sensor film thickness is reduced from 8.56 μm to 2.7 μm utilizing a novel film thinning method (metal 2 layer as the hard mask). Furthermore, the p+ silicide polysilicon is adopted as the sensing material due to its highest temperature coefficient of resistance (TCR) of 3360 ppm/°C. Finally, the fabricated device is tested with high sensitivity of 1.759 V/Pa and bidirectional measurement range of -12 Pa to 20 Pa, even under the low power consumption of ~1 mW, demonstrating its promising application as a wall shear stress sensing node and a potential candidate for the Internet of Things.