A Study on Micropillar Fin-Integrated Thermal Conductivity Sensor for Hydrogen Response Speed Enhancement and Flow Rate Interference Suppression

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Abstract
In this brief, an MEMS hydrogen thermal conductivity sensor (TCS) with high stability and fast-response performance is innovatively proposed. TCS has been widely applied in many crucial fields for hydrogen (H ${}_{{2}}\text {)}$ detection such as new energy vehicles. However, the change in gas flow rate can interfere with the TCS, significantly affecting the performance of the sensors. By using an integrated microchannel-enhanced silicon cap, the disturbance caused by the gas flow rate can be effectively suppressed. Compared to the sensor chip without a cap, when the gas flow rate changes from 20 to 200 sccm, the response change is reduced by 92.2%. In addition, by integrating a micropillar fin array structure on the sensor, the response time ${T} _{{90}}$ of the sensor is shortened to 200 ms, with an improvement of 32%. The sensor exhibits good linear response characteristics to H2 with concentrations ranging from 10 to 10 000 ppm, and the lowest detection limit (LOD) can reach 10 ppm. The TCS sensing chip in this brief is fabricated on a (111) silicon wafer by MEMS technology, and it is packaged with the microchannel cap wafer using a wafer-level bonding process, successfully achieving the fabrication of the sensor on a 4-in wafer.
Funding Information
  • National Key Research and Development Program of China (2023YFF0721900)
  • National Natural Science Foundation of China (U21A20500, 62227815, 62271473, 62104241)

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