Self-aligned precise upload of Pd-modified mesoporous In2O3 on suspended MEMS heating-plate for ultra-sensitive H2 gas sensing

This paper reports a novel top-down and bottom-up compatible technique for sensing materials self-aligned upload onto the specific area of sensor. Using a lift-off-like fabrication process, hydrophobic self-assembly monolayer (SAM) is patterned on the non-sensing area of suspended heating-plate while the surface of sensing area is kept hydrophilic by chrome layer. Constrained by hydrophobic surface, droplets of sensing material can be manually uploaded precisely, easily and repeatedly. Interference signal and noise coming from sensing material disperse can be obviously reduced. With palladium modified mesoporous-In₂O₃ uploaded, the sensor shows ultra-high sensitivity to 0.5-100ppm hydrogen and capable for H₂ leak detection [1]. This technique offers promise of batch fabrication and application in plenty kinds of chemical sensors.