Design And Test Of Multi-channel Flexible Microelectrode Array With Dual-layer Metallization For Epiretinal Prosthesis

Epiretinal prosthesis consists of external device and internal one, which includes neural-interface module, the microelectrode array (MEA) to stimulate retinal nerve cells. Since the implanted MEA is the direct interface between the external electronic circuit system and the nerve tissue, it plays an important role in the system of vision restoration, deciding the accuracy and efficiency of the vision perception. With the rapid development of MEMS technology in recent years, the R&D of flexible thin-film MEA has tackled tons of obstacles regarding the capability and safety of the electrode. This paper presents the research on the flexible thin-film MEA and the design of multi-channel dual-layer electrode, as well as the electrochemical test of the electrical properties.The main research contents include:I. By studying the development of retinal MEA of the frontier research groups in the world, we designed a 64-channel flexible thin-film MEA with dual-layer metallization, which was produced by SIMIT afterwards. We also optimized the design in light of the pre-test feedback of the Pt electrode and proposed to use gold material for electrode. II. In order to overcome the inefficiency of the traditional three-electrode measurement, we proposed an automatic test system based on multi-path selection, with an electrode connecting set, which greatly enhanced the test efficiency and safety.III. We studied the basic electrochemical theory of the electrode-electrolyte interface and discussed the equivalent circuit model as the theoretical base for electrode test. After setting up the bionic experimental environment, we tested the electrical properties (impedance and phase) of the packaged electrode and analyzed the result.IV. We summarized the key issues and challenges of the design and production of the multi-channel flexible MEA.