Electrochemical blocking of sciatic nerve of a frog in-vivo using flexible electrode produced by microfabrication method

According to the statistics 5,6 million people in the current U.S. population (% 1.9) are suffered from paralysis. Functional Electrical Stimulation (FES) is a known method to restore the lost functions in nervous system. In this method, the nerves are stimulated by the electrodes to awake the muscles. But, it is hard to control the localization of the stimulation. Therefore, it causes non-targeted stimulation in adjacent nerves, causing pain. For this reason, blocking current should be applied to terminate the unwanted stimulations. Since the applied DC blocking current in large quantities damages the nerves permanently, the blocking current is desired to be as low as possible. We used the electrochemical method using microfabrication techniques to reduce the blocking current. We aimed to decrease the blocking current with planar and flexible electrodes, produced by using microfabrication method, compared to classical method (blocking with cables). In addition, we intend to electrochemically reduce the blocking current using ISM (ion selective membrane). In our research, we compared the minimum required blocking currents. For applying the blocking currents; we used flexible electrodes, planar electrodes and cables. Required experiments were done in in-situ and in in-vivo along the sciatic nerve of a frog. Because planar electrodes have larger contact area with sciatic nerve, they are more suitable than cables for blocking. From these results, it can be seen that the blocking current obtained by the planar electrodes is % 50-70 lower compared to the blocking current obtained by the conventional method. Furthermore, we compared the blocking current values obtained from the flexible electrodes with the blocking current values obtained from the planar electrodes and the cables. Since the flexible electrodes surround the nerve better, it has more contact area with the sciatic nerve compared to others. The blocking current obtained from the flexible electrodes is % 80-95 lower than the blocking current obtained from the cables. In the nervous system, internal and external ion concentrations and their role in the action potential formation are known. The most active ions are Na+, K+ and Cl- and indirectly Ca2+ ions. But since the Ca2+ ion is the most effective one in terms of activity, we lowered the blocking current using ISM (ion selective membrane) for the Ca2+ ion. We achieved a reduction of % 40-50 in the blocking current compared to the bare electrode using ISM. In conclusion, we have observed that flexible electrodes are more effective at reducing blocking current compared to the planar electrodes and conventional methods. In addition, by using Ca2+-ISM (Calcium-ion selective membrane) for the electrochemical method, we achieved a decrease in blocking current compared to the bare electrodes. Thus, it is possible to get rid of the permanent damage caused by the DC blocking current applied at high values on the nerve. In addition, in the future, the technology we have developed can be produced in smaller sizes and can be implanted and used in other applications for use in tissues with small nerves, such as paralyzed facial muscles. Keywords: Functional electrical stimulation (FES), Ion-selective membrane (ISM), Nervous sysyem, Implant, Flexible electronics.