基于微热板技术的氢气传感器

MICRO-HOTPLATE-BASED HYDROGEN GAS SENSORS

新型固态氢气传感器将新颖的氢化金属薄膜与带微热板的微机电(MEMS)系统结构相结合。微热板结构通过硅表面微加工制作,产生带有嵌入式加热器并与衬底绝热的悬置平台。涂覆钯保护层的稀土金属薄膜淀积在这个结构上,用作主动氢气敏感层。当敏感元件暴露在氢气中时,这两层的电阻变化就是传感器的输出。对空气中0.25%氢气的响应时间为亚秒(低于1s)。可测量低于200ppm的氢气浓度。传感器的上升时间和下降时间取决于微热板的有效温度,且随加热器功率的增加而变短。上述结果表明,该器件满足微量氢气测量的敏感需求。

In this paper, a new type of solid-state hydrogen gas sensor that couples novel metal hydride thin films with a microelectro-machined mechanical system （MEMS） structure known as a micro-hotplate is described. Micro-hotplate structures are fabricated via surface silicon micromachining, resulting in a suspended platform with an embedded heater and thermally isolated from the substrate. A rare earth metal thin film, coated 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 to 0.25% hydrogen in air and sensitivity to hydrogen concentration below 200ppm 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 the device has the potential to meet the sensing requirements of trace hydrogen gas application.