Micro-machined Thin Film Hydrogen Gas Sensors

The ability to detect gaseous hydrogen is of critical importance to acceptance and utilization of hydrogen as an energy carrier. Micro-machined gas sensors are a new generation of sensor technology combining existing integrated circuit fabrication technology with novel deposition and etching processing. This results in a new device structure, known as a "micro-hotplate", which consists of an integrated hotplate on a suspended thermal isolation structure. This structure allows the sensor to operate at elevated temperatures, and provides a platform where the operating temperature can be rapidly changed to achieve desired response characteristics. ATMI has been developing novel thin film materials to function as hydrogen-selective active layers on top of micro-hotplate devices. This combination of micro-hotplate and novel active thin film materials has led to hydrogen sensors that demonstrate an array of highly desirable features, such as fast response speeds, low-level sensitivity, and amenability to mass production. These sensors are adaptable to a wide variety of sensing applications for a hydrogen-based energy economy, spanning from hydrogen based process monitoring to life safety protection.; This paper describes recent efforts and progress made in developing micro-hotplate based hydrogen gas sensors at ATMI. This progress includes designing the sensor geometry to reduce power consumption and investigating the cross sensitivity to several contaminant gases - carbon monoxide, hydrogen sulfide, and isopropyl alcohol. Portable signal conditioning hardware was developed to help study long-term operation stability. Future work will be directed towards continuous improvement of the fabrication process and the development of new application specific operational models.