Crosstalk current measurements using multi-electrode arrays in saline

This paper investigates how the configuration of return electrodes in an electrode array affects the amount of current crosstalk when electrodes are driven simultaneously in saline. Two pairs of electrodes in different return configurations were stimulated with different-amplitude biphasic currents. Stimulating electrodes were controlled by current sinks and current sources while return electrodes were connected to supply voltage or ground. Measurement results show that no matter what return configuration was used, the return current was almost equally distributed amongst the return electrodes, which is problematic in bipolar concurrent stimulation, at least in saline. This result is due to the fact that the spreading impedance of saline solution is small compared to the electrode-electrolyte impedance, which makes the saline solution have almost the same potential. This result suggests that monopolar stimulation using a common remote return electrode be used in simultaneous stimulation to avoid crosstalk.