Graphene oxide/doped polyindole/hydroxypropyl cellulose coated on interdigitated electrode as methanol sensor

Abstract

GO/dPIn are coated on an interdigitated electrode for the methanol vapor detection. Initially, the composite sensors are laboratory tested for the material selection. Various effects are investigated namely: solvent types for preparing the composites; mixing with hydroxypropyl cellulose (HPC) to improve the methanol response and surface adhesion; number of coating layers; and also sensor performances. The GO/dPIn prepared in acetone provides the highest relative current response towards methanol. The GO/dPIn/HPC achieves not only a good adhesion but also an increase in methanol response, especially 0.5 g of GO/dPIn mixed with 0.75 g of HPC. One coating layer, the relative current response reaches the highest value under N2. However, it decreases in ambient air due to the effects of humidity and interfering gases. Besides, the high applied voltage leads to the increase in methanol response but the sensing layer is damaged by heat generation. Finally, the sensor is integrated with a portable sensor platform, connected by NFC to a mobile phone. The sensitivity is 0.0123 ppm−1 in the dynamic range 97–1041 ppm at the applied voltage of 0.8 V under ambient air, whereas the response and recovery times are within 12–50 s depending on methanol concentration.