Figure 9.
(A) The circuit diagram of the dual-electrode setup. The catheter has two electrodes. The tip is in contact with the tissue and is similar to Fig. 6, whereas the ring is in contact with the bath and can be turned on and off using switch S. (B) The bootstrapped version of the lumped-element model of the electrode-tissue interface is shown. The output of the unity gain amplifier forms a positive feedback loop and boosts the ground connection of the voltage divider. We assume Rs′Rs. The faradaic resistor Rf and the half cell (B) apply to nonpolarizing electrodes (Rf = ∞ for polarizing electrodes).