Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
741803 | Sensors and Actuators B: Chemical | 2006 | 7 Pages |
The widespread use of hydrogen as both an industrial process gas and an energy storage medium requires fast, selective detection of hydrogen gas. This paper reports the development of a new type of solid-state hydrogen gas sensor that couples novel metal hydride thin films with a micro-electro-mechanical system (MEMS) structure known as a micro-hotplate. Micro-hotplate structures are fabricated via surface silicon micro-machining, resulting in a suspended platform with an embedded heater and thermally isolated from the substrate. A rare earth metal thin film, overcoated with a palladium capping layer, is deposited on this structure and serves as the active hydrogen-sensing layer. The change in electrical resistance of this bilayer when exposed to hydrogen gas is the sensor output. Sub-second response times to 0.25% hydrogen in air and sensitivity to hydrogen concentrations below 200 ppm are measured. Rise and decay times of the response depend on the effective temperature of the micro-hotplate and decrease with increasing heater power. These results suggest that this device has the potential to meet the sensing requirements of advanced hydrogen applications.