Fully gravure-printed NO2 gas sensor on a polyimide foil using WO3-PEDOT:PSS nanocomposites and Ag electrodes

With the emergence of printed electronics, the development of printed sensors on flexible substrates is on-going. Described herein is a flexible and lightweight chemiresistor made of a thin film composed of WO3 and poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonicacid) (PEDOT:PSS), which were printed onto a flexible polyamide substrate by using gravure technique. The optimized WO3-PEDOT:PSS sensor exhibits a low initial resistance(∼870 Ω) and good sensing response characteristics (∼1.2) towards 50 ppb NO2 gas at room temperature, with response and recovery time of 45.1 and 88.7 s, respectively. In comparison with a pure WO3 sensor, the enhanced sensing performance is attributed to the conducting channels provided by PEDOT:PSS, formation hetero-junctions at the WO3-PEDOT:PSS interfaces as well as the printed micro-scale striped structures. The printed WO3-PEDOT:PSS sensors show great potential for ultrasensitive detection of NO2 gas in a wide variety of fields where operation at room temperature, light weight and mechanical flexibility are important issues.