Ultra-low-power hydrogen sensing with palladium nanowires

Palladium nanowires (50 nm diameter, ~5 mum length) have been fabricated on silicon substrates using conventional techniques. The room temperature hydrogen sensing behavior of individual nanowires was investigated. The nanowires show a reversible response to hydrogen concentrations as low as 2.5 ppm with an ultra low power consumption of less than 10 nW. The electrical resistance increases nonlinearly with the hydrogen concentration. Response times (t90) vary from 5 seconds (H₂ concentrations > 20%) to 30 seconds (H₂ concentrations < 100 ppm). The response times can be decreased by increasing the applied bias at the cost of sensitivity.