Reform and characterization of concentric-circle electrode tip for neural stimulating or recording

The purpose of this paper is to obtain non-directional electrodes for neural stimulating or recording by reforming the wedge-shape tip of concentric circle electrodes which applied to electromyography (EMG) detection. The electrode tips were ground by sand paper. The electrodes before and after ground were characterized by photomicrography and Electrochemical Impedance Spectroscopy (EIS). Animal test was taken to test the electrical performance. The photomicrographs showed that the tip of the electrode before ground was wedge-shape while the exposed surface of the inner electrode tip after reformed was cone shape and almost evenly in all directions. The impedance-frequency curve and the phase-frequency curve obtained from EIS showed that the electrical performance of the reformed electrode was steadier than before. The impendence of the electrode before reformed was 38.5 ± 7.2 kΩ and that of reformed one was 20.8-53.3 kΩ at 1 kHz, and the standard deviation is only 1.5-4.1 kΩ. Animal test showed that the amplitude recorded by the electrode before reformed changed during rotated the electrode along its longitudinal axis a certain angle and the difference between maximum and minimum is 200 mV. While the amplitude recorded by the reformed electrode is much steadier, the difference between maximum and minimum is 60 mV.