Design and Fabrication of a Thermal Conductivity Sensor with a Micro-Pillar Fin Structure to Enhance Hydrogen Response Speed and Minimize Flow Rate Interference

This paper presents a MEMS thermal conductivity sensor featuring an integrated micro-pillar fin structure, providing high stability and a rapid response for detecting hydrogen <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{H}_{2})$</tex> at ppm levels. The integrated microchannel-enhanced silicon cap effectively reduces flow rate disturbances, while the micro-pillar fin structure decreases the response time to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{H}_{2}$</tex> by 32%. The sensor has a wide detection range for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{H}_{2}$</tex>, spanning from 200 ppm to 1 %, with a limit of detection (LOD) estimated at 20 ppm. The new sensor boasts a fast response time of 0.21 seconds and a recovery time of 0.43 seconds, outperforming commercially available products in dynamic flow environments.