Solid-state Hydrogen sensors for measurement the small concentrations in the range 1-1000; 1-300; 1-100 ppm.
Solid-state Hydrogen gas sensors are dedicated for gas leak detectors, analyzers, transmitters in FCEV, fuel cells, storage, DGA applications transportation, refueling and perform the long-term life span and stability of operation. Their technology is based on the multilayer “Metal-Insulator-Semicondictor” (MIS) H2 sensitive structure, which changes it’s electrical properties according to the H2 gas concentration in the monitored media. Main features of the Xmetra H2 gas sensing elements: Life span 10+ years; low cross-sensitivity; operational ambient temperature -40°C_+120°C ; relative humidity up to 98%; vibration/shock resistant. It operates regardless of the gas flow. Small dimensions. No moving parts. The solid-state H2 sensors are also used in Dissolved Gas Analysis (DGA) in Power Transformers Monitors, because they are able to contact directly the monitored transformer oil.
1 – Pd film; 2 – dielectric film; 3 – SiO2 layer; 4 – silicon plate; 5 – metal electrode; 6 – insulating plate; 7 – film heater; 8 – electrical contacts of the heater; 9 and 11 – electrical contacts of the MIS capacitor; 10 – thermistor
A silicon wafer coated with a SiO2 dielectric film is used as a base. An additional layer of Ta2O5 is deposited on the SiO2 layer using solid-state frequency laser radiation. Then a film of catalytic metal (Pd) is deposited onto Ta2O5. The temperature of the MIS structure is maintained in the range of 80-200 °C, measured by a thermistor and stabilized by an electronic circuit.