Quantitative analysis of CO-humidity gas mixtures with self-heated nanowires operated in pulsed mode

Abstract

Self-heating effect in individual metal oxide nanowires can be used to activate their response to gases with power consumptions below tenths of microwatts. The thermal response time of these devices is extremely fast (a few milliseconds) and it makes it possible to observe the kinetics of the interactions between the gas molecules and the metal oxide. In this work we demonstrate that such effects enable an experimental methodology to improve the selectivity of metal oxide-based sensors based on the analysis of their fast response dynamics. Specifically, this work jointly analyzes the magnitude and response time of SnO2 nanowire-based sensors to carbon monoxide (CO) and humidity (H2O) mixtures, proving that a quantitative analysis of CO–H2O gas blends can be achieved by modulating their work temperature through the self-heating effect.

Facile integration of ordered nanowires in functional devices

“…temperature) was in the order of tens of ms, both in the heating and cooling transients. These values are again comparable to the figures obtained with individual nanowires [43], sufficiently fast to study sudden surface-gas interactions [24], and clearly much faster than values reported for gas sensor based on thin films [44].…”

Self-heating effects in large arrangements of randomly oriented carbon nanofibers: Application to gas sensors

“…Finally, the low specificity is a known issue for carbon based gas sensors [41], self-heating could provide a low power method to improve the differentiation of different target gases through temperature modulation [22]. Therefore, the extension of this principle to other nanomaterials suitable for higher temperature operation (such as MOX or MOX-carbon compounds [70]) and the study of the microscopic temperature variations across randomly oriented films are worthinvestigating open questions.…”

“…This so-called self-heating effect has been already studied in nanosized gas sensor devices [16][17][18][19][20], achieving very low power figures. Specifically, self-heating was first proven in one single SnO 2 nanowire, obtaining reliable devices operated with less than 10 W [18][19][20][21][22]. To the best of our knowledge, self-heating has further been studied in sensor devices with highly ordered nanostructures, such as suspended nanowires [15,19,20], or catalytically activated materials [17].…”

Exploiting Water-Mediated Ethanol Sensing by Polycrystalline ZnO at Room Temperature

“…[3][4][5][6] Most investigations on the gas sensing performance of MOX materials have focused on analyte gas detection at relatively high operating temperatures (500-800 K), where optimal sensing responses are normally reached.…”

“…2 However, the presence of environmental H 2 O can effectively alter the reactivities of MOX surfaces, which leads to difficulties in obtaining reliable and selective sensing signals for different target gases in real-world environments. [3][4][5][6] Most investigations on the gas sensing performance of MOX materials have focused on analyte gas detection at relatively high operating temperatures (500-800 K), where optimal sensing responses are normally reached. 7 This is because the formation of surface hydroxyls from chemisorptive water dissociation tends to dominate at these high temperatures, and the net conductivity changes are determined by surface characteristics such as oxygen species density, surface defects and hydroxyl coverage.…”