PMC

Results of Stimulation Experiments with Ca²⁺ Ion Depletion
(A) Stimulation experiment results for bare electrode and ISM-coated electrode. The stimulation threshold decreases from 84 to 68 mV on the ISM-coated electrode.
(B) 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 threshold values for the bare electrode and the PVC-coated electrode are very similar, whereas there is 22% decrement with ISM-coated electrode. V_s = 10 mV→110 mV in 2-mV step (stimulus), t_p = 1 ms (pulse width), f = 1 Hz (pulse frequency), n.s., not significant, ***p < 0.001, error bars represent 2 SD.
(C) Contractile force (mN) obtained for varying stimulus pulse amplitude (mV) for the bare electrode (left) and ISM-coated electrode (right). Higher dynamic range (higher maximum contractile force) is attained with ISM-coated electrode.
(D) Average and standard deviation of contractile force (mN) measured for varying stimulus pulse amplitude (mV) for the bare electrode and ISM-coated electrode obtained from the results in (C). Better resolution is acquired with ISM-coated electrode.
(E) Average and standard deviation of contractile force twitch width (ms) measured for varying stimulus pulse amplitude (mV) for bare electrode and ISM-coated electrode obtained from the results in (C). First large and then small axons are stimulated with ISM-coated electrode.

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. V_s = 30 mV→230 mV in 5-mV step (stimulus), t_p = 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. V_s = 60 mV→170 mV in 2-mV step (stimulus), t_p = 1 ms (pulse width), f = 1 Hz (pulse frequency), n.s., not significant, ***p < 0.001, error bars represent 2 SD.

Results of Blocking Experiments with Ca²⁺ Ion Depletion
(A) Blocking experiment results for bare electrode and ISM-coated electrode. The blocking current is applied after the third stimulation pulse for four or five pulse duration. The current needed for full blocking decreases from 9 to 5 μA using ISM-coated electrode.
(B) Comparison of blocking current values for bare electrode, PVC-coated electrode, and ISM-coated electrode (n = 3). The values are normalized with respect to bare electrode. The currents needed to obtain full blocking are very similar for the PVC-coated and the bare electrodes, whereas there is 38% decrease for the ISM-coated electrode. V_s = 90 mV (stimulus), I_b = 1 μA → 100 μA in 1-μA step (DC blocking), t_p = 1 ms (pulse width), f = 1 Hz (pulse frequency), n.s., not significant, ***p < 0.001, error bars represent 2 SD.
(C) Average and standard deviation of contractile force (mN) measured for varying blocking current (μA) in log scale for bare electrode and ISM-coated electrode obtained from the results in (A).
(D) Average and standard deviation of contractile force twitch width (ms) measured for varying blocking current (μA) for the bare electrode and ISM-coated electrode obtained from the results in (A). First large and then small axons are blocked with ISM-coated electrode.

Structural characterization of the sensor in 5.0 mmol/L [K₃Fe(CN₆)] solution in 0.1 mol/L KCl. (A) Cyclic voltammogram (CV): A bare electrode CV (bare SPCE), B electrode after deposition of HAuCl₄ solution, C electrode after polymerizing cyromazine molecular polymer, D electrode after elution, E electrode (CK) after elution of non-imprinted sensor. (B) Electrochemical impedance spectroscopy (EIS): A bare electrode, B electrode after deposition of HAuCl₄ solution, C electrode after polymerizing cyromazine molecular polymer, D electrode after elution.