Operating Principle of EIM and Results of Stimulation Experiments with Ca2+ Ion Enhancement
(A) Operating principle of EIM with Ca2+ ion enhancement. Schematic drawing of the flexible stimulating electrode and the operating principle of the device (left); cross section of sciatic nerve and flexible stimulating electrode to demonstrate the operating principle of ion selective membrane (ISM) (right).
(B) Stimulation experiment results for bare electrode and ISM-coated electrode. Stimulation threshold is increased from 110 to 145 mV by using ISM-coated electrode.
(C) Comparison of stimulation threshold values for bare electrode, PVC-coated electrode, and ISM-coated electrode (n = 3). The values are normalized with respect to bare electrode. The stimulation thresholds are nearly the same for PVC-coated and bare electrodes; however, there is 45% increase for ISM-coated electrode. Vs = 30 mV→230 mV in 5-mV step (stimulus), tp = 1 ms (pulse width), f = 1 Hz (pulse frequency), n.s., not significant, ***p < 0.001, error bars represent 2 SD.
(D) Comparison of stimulation threshold values for bare electrode, ISM-coated electrode with Ca2+ ion depletion, and ISM-coated electrode with Ca2+ ion enhancement (n = 3). The values are normalized with respect to bare electrode. There is 22% decrease in stimulation threshold using ISM-coated electrode with Ca2+ ion depletion and 45% increase using ISM-coated electrode with Ca2+ ion enhancement. By depleting or enhancing Ca2+ ions around the nerve, we can either decrease or increase stimulation threshold. Vs = 60 mV→170 mV in 2-mV step (stimulus), tp = 1 ms (pulse width), f = 1 Hz (pulse frequency), n.s., not significant, ***p < 0.001, error bars represent 2 SD.