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.