Fabrication and Characterization of a Hydrogen Sensor Based on Palladium Nanowires

A hydrogen sensor based on an array of palladium nanowires has been realized starting from a silicon substrate coated with a Si₃N₄ where an interdigitated electrode pattern has been fabricated using photolithography. Saturated palladium solution has been prepared and array of palladium nanowires has been formed applying at the electrodes a voltage signal. As grown Pd nanowires are conductive and do not exhibit any response to hydrogen. Their response can be activated after a treatment which modifies physical properties of Pd nanowires, improving their response. The array has been tested towards 4% H₂ in nitrogen carrier. We have observed that the device response, at room temperature, is quite strong and reversible so that the sensor device seems to be useful for those applications where the Lower Explosive Limit needs to be controlled.