Ultra-high response ethanol sensors from fully-printed co-continuous and mesoporous tin oxide thin films

Printed vapor and moisture sensors are essential components of the multi-sensor platforms that the pharmaceutical and food safety industries require in large quantities; however, fully-printed gas or volatile organic compounds (VOCs) sensors have rarely been reported in the literature. In this regard, we demonstrate the fabrication of high surface-to-volume ratio co-continuous mesoporous tin oxide based fullyprinted chemiresistive-type ethanol gas sensors. Herein, a soft templating method that mimic evaporation induced self-assembly (EISA) process has been utilized with amphiphilic triblock co-polymer pluronic F127 (PEO106-PPO70-PEO106) as the templating agent and a low-cost swelling agent 'xylene' as the micelle expander to obtain pore diameter in the range of 10-25 nm. The tuned pore size at this range is found optimal for high surface area and high pore volumes, at the same time. The fully-printed ethanol sensors fabricated with such mesoporous SnO2 active elements show highly selective sensitivity towards ethanol with an average response of 1050 for 100 ppm and a very short response and recovery time of 9 and 129 s, respectively. The observed high response can be attributed to the high density and easily accessible active sites and simultaneous high mobility electron transport through the well-crystalline and co-connected tin oxide ligaments. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

High surface-to-volume ratio fully-printed chemiresistive-type ethanol gas sensors based on mesoporous tin oxide were fabricated using a soft templating method. The sensors exhibited highly selective sensitivity towards ethanol with short response and recovery times. The optimal pore size range contributed to the high surface area and volume of the sensors.