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.