In this paper, we study size effects on the reference electrode performance of flexible inkjet printed electrochemical (EC) sensors and present a scheme to print a reliable miniaturized Ag/AgCl(s) electrode for biomedical device applications. The newly printed electrode only with a size of 6900 μm², i.e., equivalent to 83 × 83 μm² can perform as well as the commercial one. Experimental results show the electrode impedance is effectively reduced via the incorporation of graphene flakes into the ionic liquid-based PVC film coated on the electrode to accelerate the ion-transferring rate of the chloride ions, thereby facilitating rapid chloride ion redistribution for the film to reach a quick potential balance with the reference electrode for open circuit potential (OCP) measurement. The EC sensors using the reference electrode can exhibit a fixed OCP output with a low potential variation, quick response time and potential drift, which are ±2.1 mV variant, 50 s, and 23.5 μV/h, respectively regardless of the concentration of chloride ions in the tested environment.

在本文中，我们研究了尺寸对柔性喷墨印刷电化学 (EC) 传感器参比电极性能的影响，并提出了一种为生物医学设备应用打印可靠的小型化 Ag/AgCl(s) 电极的方案。新印刷的电极尺寸仅为6900 μm ²，即相当于83×83 μm ²可以和商业的一样好。实验结果表明，通过将石墨烯薄片掺入到涂在电极上的离子液体基PVC薄膜中，可以有效降低电极阻抗，从而加快氯离子的离子转移速率，从而促进氯离子快速重新分布，使薄膜达到与参比电极的快速电位平衡，用于开路电位 (OCP) 测量。使用参比电极的 EC 传感器可以表现出固定的 OCP 输出，具有低电位变化、快速响应时间和电位漂移，无论氯离子浓度如何，分别为 ±2.1 mV 变化、50 s 和 23.5 μV/h在测试环境中。