Flexible Printed Reference Electrodes for Electrochemical Applications

This work presents screen-printed thick film reference electrodes (REs) on a polyethylene terephthalate substrate. The ion-conducting channel of presented screen-printed thick film Ag|AgCl|KCl electrodes are made from a composite of glass–KCl powder. With this new formulation the REs exhibit negligible variation in the potential (±4 mV), when evaluated under different bending states (radius 3, 5, and 7 mm). With a stable electrode potential and in-depth electrochemical studies, the utility of the presented REs for pH-sensing and flexible supercapacitor (SC) applications is demonstrated. With amperometric studies, we have shown that for pH-sensing applications, the presented REs can exhibit a sensitivity of 9 µA pH−1. At 1 mHz, the electrochemical investigations involving presented thick film REs and graphene-based SCs demonstrate a capacitance of 75 µF cm−2. With a flexible form factor, high endurance, and a miniature size, the presented RE has distinct advantages over conventional glass-based REs, particularly for emerging applications such as flexible sensing and for characterization of materials for energy storage devices