Ultralow-power hydrogen sensing with single palladium nanowires

Palladium nanowires were fabricated on silicon substrates using conventional microfabrication techniques. Sensors based on such nanowires show a reversible response to hydrogen concentrations as low as 27 ppm with response times varying from 5 s (H(2) concentrations >20%) to 30 s (H(2) concentrations < 100 ppm) at room temperature. The response times can be reduced by increasing the applied bias due to resistive heating. The noise spectrum of the nanowires shows a 1/f behavior, sufficiently low to enables the detection of hydrogen with an ultralow-power consumption. The influence of oxygen on the nanowire response was also investigated.