Fig. 1

(A) Schematic depiction of a bipolar stimulation (adapted from Sijgers et al.²⁰). (B) Schematic depiction of a CI electrode placed in a saline filled epoxy cylinder. (C) Proposed bipolar EEC of two SEs (a and b) of a CI. The equivalent electrical circuit consists of the connecting wires inside the silicone carrier (green, wire inductances \(L_{{{\text{wa}}}}\), \(L_{{{\text{wb}}}}\), wire resistances \(R_{{{\text{wa}}}}\), \(R_{{{\text{wb}}}}\) and capacitance between wires \(C_{{{\text{ab}}}}\)), the SE-electrolyte interfaces (red, frequency-dependent polarization capacitances \(C_{{{\text{pa}}}}\), \(C_{{{\text{pb}}}}\), polarization resistances \(R_{{{\text{pa}}}}\), \(R_{{{\text{pb}}}}\) and faradaic resistances \(R_{{{\text{fa}}}}\), \(R_{{{\text{fb}}}}\)), the electrolyte between the SEs (blue, resistance \(R_{{{\text{el}}}}\) parallel to capacitance \(C_{{{\text{el}}}}\) and resistance \(R_{{{\text{elep}}}}\)) and the surrounding epoxy cylinder (grey, resistance \(R_{{{\text{ep}}}}\) parallel to capacitance \(C_{{{\text{ep}}}}\)).