MEMS calorimetric gas flow sensor based on vanadium dioxide

Abstract

Traditional platinum-based thermal Micro-Electro-Mechanical Systems (MEMS) gas flow sensors exhibit low sensitivity and poor performance in high-precision microflow detection. To address this bottleneck, this work utilizes tungstendoped vanadium dioxide (W-VO2), which exhibits a metal-insulator phase transition near room temperature, as the core sensing material to develop a MEMS thermal gas flow sensor with a suspended membrane Wheatstone bridge structure. The device structure was optimized via COMSOL simulations, followed by film preparation, chip fabrication, and packaging. Experimental results show that the output voltage of the W-VO2 sensor has excellent linearity with gas flow. Notably, its sensitivity is 49 times higher than that of a counterpart platinum sensor. The sensor exhibits prominent dynamic performance with an response time under 0.3 s. While the effective full range reaches 60 standard cubic centimeter per minute (sccm), the sensor achieves stable flow resolution in the microflow range of 3.8–4.7 sccm. Furthermore, a 200-minute cyclic test yields a coefficient of variation below 1%, proving good repeatability. This work demonstrates the great potential of W-VO2 in micro-flow detection and provides a promising strategy for highperformance MEMS flow sensors, which can be further optimized via temperature compensation in the future.