Novel Self-Heated Gas Sensors Using on-Chip Networked Nanowires with Ultralow Power Consumption.

The length of single crystalline nanowires (NWs) offers a perfect pathway for electron transfer, while the small diameter of the NWs hampers thermal losses to tje environment, substrate, and metal electrodes. Therefore, Joule self-heating effect is nearly ideal for operating NW gas sensors at ultralow power consumption, without additional heaters. The realization of the self-heated NW sensors using the "pick and place" approach is complex, hardly reproducible, low yield, and not applicable for mass production. Here, we present the sensing capability of the self-heated networked SnO NWs effectively prepared by on-chip growth. Our developed self-heated sensors exhibit a good response of 25.6 to 2.5 ppm NO gas, while the response to 500 ppm H, 100 ppm NH, 100 ppm HS, and 500 ppm CHOH is very low, indicating the good selectivity of the sensors to NO gas. Furthermore, the detection limit is very low, down to 82 parts-per-trillion. As-obtained sensing performance under self-heating mode is nearly identical to that under external heating mode. While the power consumption under self-heating mode is extremely low, around hundreds of microwatts, as scaled-down the size of the electrode is below 10 μm. The selectivity of the sensors can be controlled simply by tuning the loading power that enables simple detection of NO in mixed gases. Remarkable performance together with a significantly facile fabrication process of the present sensors enhances the potential application of NW sensors in next generation technologies such as electronic noses, the Internet of Things, and smartphone sensing.