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

Self-heating operation, or the use of the resistance-probing signal to warm up and control the temperature of nanowire devices, has been the subject of research for more than a decade. In this review, we summarize the most relevant achievements reported to date in the specialized literature. The state-of-the-art shows that this approach is serving to lower the power demand in temperature-activated devices, especially in conductometric gas sensors, but the simplicity of eliminating the heating element comes with the complexity of integrating 1-dimensional nanomaterials in electronic devices. Results show however that this is feasible, and in some cases, even cost-effective. To contribute to the further development and optimization of the self-heating approach, we compile here a set of recommendations on how to increase the efficiency of the future devices. These suggestions aim at clarifying the impact on the power efficiency of factors like the nanowire cross-section, the electrical and thermal conductivities of the material, the thermal insulation characteristics, and the operating conditions. To facilitate the comparison of the performances obtained in past and future works, we also propose a figure of merit: the efficient self-heating coefficient (ESH), which accounts for the maximum temperature increase (in Kelvin) per microwatt of Joule power dissipated in the material. In this way, ESH values about 1 or above are indicative of highly efficient technologies, capable of raising the temperature over hundreds of degrees with less than a milliwatt of dissipated power. (C) 2017 Elsevier B.V. All rights reserved.