Screen-Printed Three Electrode-Type Sticker Device with Long-Term Stable Liquid Junction-Type Reference Electrode

Abstract

A three electrode system is widely used to evaluate the corrosiveness of metal. However, three electrode system normally requires various instruments such as a salt bridge, reference electrode, counter electrode and flask. Thus, the three-electrode-type corrosion test is often applied to lab tests rather than field work. To solve the problem, in this study, we developed a new concept of a three electrode system using a sticker device that enables the simple and accurate measurement just only stick the device on a test metal.The three-electrode-type sticker device was fabricated by screen printing. Figure 1 (a) shows the model of the sticker device. A reference electrode with a liquid junction developed previously in our group1) used for the reference electrode part. A silver layer, a silver-silver chloride layer, a liquid junction layer, and a saturated KCl layer were also forms on the PET substrate by screen printing. A working electrode part of the sticker device has a 2 mm diameter hole. Electrochemical measurements can be performed by attaching this device to the measurement target. In this study, tin-plated copper and copper was used as a substrate.At the reference electrode of the sticker device, a solution is penetrated from the liquid junction layer, and the saturated KCl layer absorbs the solution to form a saturated KCl aqueous solution, and functions as a reference electrode.Figure 1 (b) shows the results of the open circuit potential measurement at the reference electrode of the sticker device. The open-circuit potential was stable at a solution concentration in the range of 10 ppm to 300 ppm after 60 seconds. Also, it was found that open-circuit potential was within ± 15 mV vs. SSE. It was confirmed that the potential after 300 seconds of immersion were almost constant in that each solution concentration, and that the device reference electrode had a stable with potential independent of the solution concentration.Figure 1 (c) shows polarization curve of the tin-plated copper measured using the sticker device. When the working electrode potential was scanned to the noble side, the current drastically increase due to the occurrence of pitting corrosion between -0.2 V and 0.1 V, depending on the solution concentration. The pitting potential was confirmed to have a positive correlation with the chloride ion concentration. Reference 1) M. Komoda, I. Shitanda, Y. Hoshi, and M. Itagaki, Electrochemistry, 87, 65 (2018). Figure 1