Investigation of MEMS Thermal Wind Sensors in Martian Environment

This article explores the performance of micro-electromechanical systems (MEMSs) thermal wind sensors in the Martian environment for the first time. Theoretical analysis, as well as finite element method (FEM) simulation, was given to show the influence of environmental parameters on the heating power and the temperature gradient for the sensors. Above all, the special wind tunnel system was chosen as the experimental platform due to its ability to change pressure, gas composition, and sand concentration. After three MEMS wind sensors were tested, the experimental results demonstrated that the control voltage and output voltage both decreased when the air was replaced by CO2 in hot-film mode and calorimetric mode. Among them, in hot-film mode, the saturation phenomenon was suppressed at higher overheated temperatures within the pressure range of 200–1500 Pa. However, in the calorimetric mode, the output voltage together with the wind-induced temperature gradient decreases with the pressure for the same speed. Furthermore, the tunnel was filled with sand and the results indicated a degraded sensitivity in calorimetric mode, while the influence is not obvious in hot-film mode. Finally, the MEMS wind sensor was tested twice with a direction interval of 120°.