Selective laser-induced etching process-enabled double-cavity glass MEMS hydrogen sensor at room-temperature sensitivity

This paper introduces a glass-based MEMS hydrogen sensor that leverages single glass wafer cavity engineering along with a melamine-formaldehyde-derived nitrogen-doped carbon sphere (NCS) support bearing a Pt catalyst. A Laser induced selective wet etch process monolithically forms high-aspect-ratio vias and double cavities in a single glass wafer. The suspended sensing membrane integrates Pt interdigital electrodes and patterned Pt/NCS catalyst islands, where pyridinic/pyrrolic nitrogen sites promote H₂ dissociation and spillover, enabling chemiresistive transduction at room temperature. Finite-element simulations and infrared thermography show that under identical electrical drive, the low-thermal-conductivity glass and double-cavity architecture suppress heat loss and maintain the sensing region ~10 °C higher than planar counterparts. This thermal advantage translates directly into an order-of-magnitude (~10 times) increase in sensitivity at room temperature. By integrating a simplified, bonding-free single glass wafer process with a Pt/NCS-functionalized suspended membrane, this work establishes a scalable, economical, and reliable platform for high-performance, room-temperature hydrogen sensing in microsystem applications.