Manipulation of palladium nanoparticles in a 20 nm gap between electrodes for hydrogen sensor application

This study reports a promising, cost-effective nanoscale hydrogen sensor fabricated using the dielectrophoresis (DEP) process. Palladium nanoparticles (NPs) of diameter in the range 2-4 nm were assembled in a 20 nm gap between electrodes under optimized DEP parameters of frequency, voltage and assembling time of 1M Hz, 1.5V and 90 s, respectively. The fabricated nanoscale device was powered by applying a dc voltage of 10 mV across nanogap electrodes and temporal change in resistance at an operating temperature of 160 degrees C was recorded in the presence of 3000 ppm of hydrogen gas. A rise and recovery times of 100 s and 300 s, respectively, in the temporal hydrogen gas response characteristic were observed which could be attributed to the hydride formation due to the strong affinity of assembled palladium NPs towards hydrogen. The nanoscale device was sensitive enough to respond to hydrogen presence even at 30 degrees C. Preliminary results show the potential of DEP in fabricating cost-effective nanoscale hydrogen sensor.