Development of a MEMS Thermal Flow Sensor With High Reliability and Universality for Various Gases

This paper presents an improved calorimetric MEMS flow sensor to meet the needs of large-scale industrial applications such as semiconductor and photovoltaics. Reliability and universality are considered the most critical factors for these fields, for which the porous silicon-based sensor was designed, fabricated and tested rigorously with eight gases. The results demonstrated that the sensor maintained nearly identical zero-flow outputs across various static gas environments (using N₂ as the baseline, with deviations ranging from 0.01%FS for CO to 0.69%FS for He). Moreover, well-defined conversion coefficients were established between any two gases. This characteristic enables the practical application of N₂-calibrated sensors to other gases through coefficient conversion, achieving an accuracy error within 2.0%FS. In addition, the sensor can survive and maintain its sensing capabilities even during continuous SiH₄ combustion reactions and under heavy pollution, whereas the suspended membrane-based sensor ruptures. This innovative work makes MEMS flow sensors more convenient and reliable in complex industrial applications, potentially replacing traditional flow sensors based on capillary structures.[2025-0009]