Fabrication and testing of low-cost and flexible smart sensors based on conductive PEDOT-PSS nanocomposite films for the detection of liquefied petroleum gas (LPG) at room temperature

Abstract

Owing to their high potential applications, the organic conductive layers and devices on flexible substrates as gas sensors at room temperature have been receiving increasing attention. Hence, there is a continued need to develop novel gas sensing materials with excellent mechanical, electrical and sensing stability along with mechanical flexibility in comparison to conventional metal oxide based materials. In this work, we present fabrication of a novel nano-heterojunction between poly (3, 4-ethylenedioxythiophene: poly (styrene sulfonic acid)) (p-PEDOT-PSS) and Tin oxide (n-SnO2) treated with Dimethyl sulfoxide (DMSO) and poly (vinyl alcohol) using a simple spin coating technique. The surface morphology and distribution of SnO2 nanoparticles in the composite was investigated through SEM, whereas the structural features of the composite and bare PEDOT-PSS were compared through XRD. The post treatment of the composite film with strong acid (H2SO4) enhances the conductivity by several orders of magnitude. Presence of DMSO and PVA substantially improves the Young's modulus and Tensile strength of composite films. This ultra-sensitive, highly flexible thin layer of PEDOT-PSS: DMSO: PVA SnO2 composite film post-treated with H2SO4 was employed as a chemiresistive sensor towards detection of LPG (10–100 ppm) at room temperature. The composite sensor shows excellent sensitivity of 79% @ 100 ppm of LPG with long term stability, short response and recovery time of 25s and 30s respectively. This work reports for the first time, LPG gas sensor at room temperature with highly stable sensitivity at various bending angles and exposure to different humidity conditions (0–100% RH). Due to excellent conductivity, sensitivity, short response/recovery time, stability under mechanical deformations and humidity conditions, these composites can be ideal materials to be used as flexible sensors towards detecting LPG at room temperature.