Ahydrogen sensor is a gas detector that detects the presence of hydrogen. They contain micro-fabricated point-contact hydrogen sensors and are used to locate hydrogen leaks. They are considered low-cost, compact, durable, and easy to maintain as compared to conventional gas detecting instruments.[1]
There are five key issues with hydrogen detectors:[2]
There are various types of hydrogen microsensors, which use different mechanisms to detect the gas.[4] Palladium is used in many of these, because it selectively absorbs hydrogen gas and forms the compound palladium hydride.[5] Palladium-based sensors have a strong temperature dependence which makes their response time too large at very low temperatures.[6] Palladium sensors have to be protected against carbon monoxide, sulfur dioxide and hydrogen sulfide.
Several types of optical fibre surface plasmon resonance (SPR) sensor are used for the point-contact detection of hydrogen:
Sensors are typically calibrated at the manufacturing factory and are valid for the service life of the unit.
Siloxane enhances the sensitivity and reaction time of hydrogen sensors.[5] Detection of hydrogen levels as low as 25 ppm can be achieved; far below hydrogen's lower explosive limit of around 40,000 ppm.