Hydrogen microsensor
A hydrogen microsensor is a sensor that detects the presence of hydrogen . It is used to find leaks.
main features
There are four main characteristics that a hydrogen sensor should meet:
- Reliability : functionality that is easy to verify
- Resolving power : Detection of 0.5% or less hydrogen in the air, reaction time <1 second
- Lifetime : At least the time until scheduled maintenance
- Cost : Target is $ 5 per sensor and $ 30 per controller
Types
There are several types of hydrogen sensors that differ in the way they detect the gas:
- Palladium is used in many sensors because it has a high adsorption capacity for hydrogen and palladium hydride is formed. However, palladium-based sensors are highly temperature-dependent, which leads to a long response time if the temperature is too low. They also need to be protected from carbon monoxide , sulfur dioxide and hydrogen sulfide .
- Optical fiber sensors use surface plasmon resonance and can detect hydrogen at a contact point
- The combination of nanotechnology with MEMS allows the production of sensors that function flawlessly at room temperature. The sensor is covered with a film of indium (III) oxide (In 2 O 3 ) and tin (IV) oxide (SnO 2 ). On contact with hydrogen, this film swells and creates new electrical connections.
- Some sensors consist of a Schottky diode , the activation energy of which is available when hydrogen is adsorbed by palladium. A Schottky diode with a Pd / In Ga P semiconductor can detect a concentration of 15 ppm hydrogen in the air.