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

Abstract

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.

A review on efficient self-heating in nanowire sensors: Prospects for very-low power devices

“…More recent works also show that the self-heating effect can be observed in devices based on large random networks of 1D nanostructures with relatively good efficiencies [78,81], considering the simplicity of the approach. These systems are extremely easy to produce (e.g.…”

“…From then on, a number of papers reported significant energy savings in gas sensing applications, by using this efficient self-heating approach in a great variety of materials, like metal oxides, carbon-based materials and metal catalysts [12,53,61,62,[65][66][67]69,71,[73][74][75][76][77][78][79][80][81].…”

“…These systems are extremely easy to produce (e.g. by drop casting of nanostructures dispersed in a solvent [78], or just by the direct growth of the 1D-nanomaterials [81]) and exhibit good reproducibility (i.e. in contrast with small arrangements of a few nanowires, these networks contain thousands of wires and they are large enough to offer a macroscopic average of the distribution and properties of the individual nanowires) [77].…”

“…According to further investigations, the reason why the temperature of large networks of nanowires can be elevated with a few milliwatts (ESH  10 -3 ) [80,81] is that heat dissipation concentrates in certain regions of the network: the so-called hot spots (see Figure 10.a). In fact, the most effective regions for heat dissipation seem to be the most resistive segments.…”

“…Apparently, a network of 1D wires forms a thermal insulating scaffold structure that prevents the direct contact between the substrate and most of the material. This way, the spots in the network that combining sufficient insulation with proper electrical connectivity concentrate most of the heating (Figure 10.a) [65,71,75,[77][78][79][80][81]. To illustrate this phenomenon, a structure made of multiple nanowires randomly interconnected has been simulated ( Figure 10.b).…”