Project Summary: Next Generation Mechanically Adaptable Microelectrode Implantable microelectrodes are essential tools for understanding basic electrophysiology. Although considerable progress has been made in the past several decades in terms of electrode design, the current devices are still unable to retain their functionalities in a physiological environment over long periods, due to failure is related to the staggering mismatch between the mechanical properties of the electrodes and tissue. There have been significant research efforts in the development of flexible implantable electrodes. However, the flexible electrode will buckle during insertion and require rigid shuttle/coating to penetrate the targeted issue The complications of tissue insertion has significantly hindered the practical usage of the flexible implantable electrodes. In this project, we will take an innovative material approach to develop a new class of thermo-responsive and mechanically adaptable microelectrode between room temperature and physiological temperature. We will harness the unique thermal/mechanical/electrical properties of gallium to design a mechanically adaptable electrode array. Gallium has a unique melting point of 29.36 C at 1 atm pressure. This indicates gallium will be a rigid solid at room temperature (Young's modulus of 10 GPa) and a liquid (no mechanical strength) at body temperature. We aim to develop a thermal drawing process to create gallium/polymer core-shell structure and assemble the structures into microelectrode array. We will assess the mechanical properties, electrochemical performance, in vivo signal recording ability, and biocompatibility of the gallium-based microelectrode arrays.