Hydrogen Detection Using Carbon Nanotubes Microsensor

摘要

Initial resistance in air of interdigitated Pd electrodes microsensor with linear CNT to 1% H2 was 8-fold higher than that of entangled CNT. This was the reason why the G/D ratio of liner CNT (0.93) was higher than that of entangled CNT (0.76). The sensor responses (%) of linear CNT and entangled CNT microsensors were 7.9 and 3.2 at 300 oC, respectively. The repeatability of linear CNT microsensor to 1% H2 at 250 oC indicated stable response-recovery characteristics. The sensor response and 90% recovery time were ca. 5.5 % and 3 min, respectively. On the other hand, the linear CNT microsensor with interdigitated Au electrodes did not respond to 1% CO2 but respond to 1% H2 and 5 ppm H2S. The selectivity to 1% H2 and 5 ppm H2S, i.e., the ratios of sensor response to 1% H2 and 5 ppm H2S to that to 1% CO2 were 63 and 114, respectively. The selectivity of linear CNT microsensor to 5 ppm H2S depended on the amount of released electron. The interface effect between CNT and Pd or Au electrodes, i.e., the sensor responses per adsorption area (%/mm2) of Pd or Au electrodes to 1% H2 are 86.4 and 0.176, respectively. From above results, it was found that linear CNT microsensor with interdigitated Pd electrodes was suitable for H2 detection.