High‐throughput screening is important in various fields, and electrochemical approaches are effective because of advantages such as fast response time and electrode array. Hence, we developed a two‐dimensional electrochemical array sensor. However, its signal intensities for lower concentrations of the redox pair (100 μM–100 pM [Fe[CN]6]3−/4−) were unstable; Therefore, in this study, we investigated and demonstrated a method for improving the signal stability at lower concentrations. Two types of counter electrodes were prepared to assess their influence; the material of the first electrode was the same as that of the working electrode (same material condition), and the other was prepared from a different material (different material condition). First, the differences in the electric potentials between different materials were investigated at lower concentrations. Furthermore, the concentration dependence was investigated using our newly developed light‐addressable amperometric sensor for the two conditions. In the different condition, it was observed that differences in the electric potentials between the electrodes at lower concentrations. It was also observed that the signal intensity was more stable for the same material condition than the different material condition. Limit of detection(LOD) for the same material condition was lower than that under the different material condition. The proposed method using the same materials is thus an effective means to measure low concentrations of redox ions and expected to contribute to a fabrication of a smaller and more stable device without reference electrode. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

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We have studied the Light Addressable Amperometric Sensor (LAAS) which is a two dimensional electrochemical sensor. In this study we report the LAAS that enables multiples samples measurement based on planer structure made by photolithography. We deposited SU-8 and platinum films on the LAAS device to form well array in order to keep individual sample solutions. The LAAS performs individual measurements by selecting each well using addressing light beam. The results showed that the observed current value depends on concentration of redox species from 10pM to 1 mM in 1 well. Therefore, we found that the proposed structure functions correctly, and expect efficiency improvement of processes such as drug discovery screening