Flexible pH sensors based on OECTs with a BTB dye-embedded ion-gel gate dielectric

Abstract

With the advantages of miniaturization, simple device structure, and fast response, organic electrochemical transistors (OECTs) have become an emerging platform for developing wearable pH sensors for real-time human health monitoring. However, the application of devices is limited because they use water electrolytes. This paper proposed a feasible pH-sensitive OECT with a flexible BTB dye-embedded ion-gel dielectric layer. The real-time H⁺ detection performances of the devices, the effects of the BTB content in the ion-gel layer and gate voltages on the pH sensing capability, as well as the property–microstructure relationship of the ion-gel were investigated. The experimental results showed that the pH-sensitive OECT integrated with a 15 wt% BTB ion-gel layer exhibited outstanding H⁺ ion sensitivity and linear response properties at a gate voltage of −0.4 V. The pH-sensitive ion-gel modified OECT presented here provides a novel strategy for developing wearable pH sensors with high real-time monitoring characteristics.