DRIE trenches and full-bridges design for sensitivity improvement of MEMS silicon thermal wind sensor

In this paper, a micromachined silicon thermal wind sensor with improved sensitivity is demonstrated. Deep reactive ion etching (DRIE) trenches are fabricated to suppress the lateral heat conduction between the heater and the thermistors. Moreover, two Wheatstone full-bridges consisting of eight thermistors are designed to increase the output voltage by 50%. Based on these two methods, the sensitivity of the micromachined wind sensor can be improved remarkably, which is verified by the experiments. The results show that the measurement wind speed range can be up to 33m/s in constant voltage (CV) mode with the initial heating power of 256mW. The sensitivity is measured to be 29.37mV/ms−1 at the wind speed of 3.3m/s, achieving an improvement of about 226%, compared with the traditional wind sensor. The results also show that wind direction in a full range of 360° can be determined with an accuracy of ±5°.