Wearable Toxic Gas Sensors Based on Hybrid Integration of Multifunctional Nanomaterials

Description

In the past decade, the advent of wireless devices, cloud data and printable electronics hasrevolutionized our daily lives and substantially enhanced our life quality. For instance, simply byintegrating with different sensors into our smartphones, we can easily collect lots of externalinformation, such as our temperature, fitness data and others, in which all these examples presentopportunities for the development of next-generation mechanically flexible and wearable sensorsto even monitor chemical processes. It would be convenient to turn our phones into tools or torealize sensor tapes attaching onto any surface detecting dangerous chemicals in the real time,which are important for environmental monitoring, food safety, personal security and etc. At thesame time, due to the rapid development of nanotechnology, multifunctional nanomaterials suchas one-dimensional (1D) nanowires (NWs) and two-dimensional (2D) thin films have beenconsidered as promising building blocks for future sensor technologies owing to theirintrinsically large surface-to-volume ratio, excellent mechanical elasticity, well-established cost-effectivesynthesis approaches and the easy modulation of their material properties. Thus far,extensive works have been focused on many nanomaterials-based chemical sensors, especiallydedicated for the toxic gas detection (e.g. NOx, CO, NH3and etc) at room temperature; however,all these sensors are not appropriate for the emerging mobile, flexible and wearable sensorplatforms owing to operating voltages and powers far beyond the supply capability of batterysystems. Another issue with these ordinary sensors is the short lifetime because of materialdegradation brought by the chemical fatigue associated with the close contact between metalelectrodes and analytes as well as the electrical stress after extended operation. As a result, thereare still many challenges in the development and performance assessment of cost-effective, high-performance,flexible and robust toxic gas sensors for wearable applications. In this proposal, wewill concentrate on the heterogeneous integration of high-mobility 1D semiconductor NWs forthe current conduction channel and 2D metal-oxide thin films deposited on top of the NWs forthe toxic-gas-sensitive media on flexible plastics. This unique hybrid device configuration,engaging p-type GaSb and n-type InAs NW channels dedicated for the oxidizing and reducinggas sensing, respectively, is employed to decouple chemically sensitive regions from conductingchannels in order to significantly reduce the operating voltage and to enhance the sensorreliability, without sacrificing any sensing performance operated at room temperature. In the end,we plan to build the large-scale sensor arrays as well as to assess their performance limits withthe goal to establish a versatile, low-cost and powerful platform to achieve the fully flexible,high-performance and ultra-low power sensor arrays based on multifunctional nanomaterials forthe practical utilization in wearable environments.