The Role of Impedance Matching for Depth Adjustment of Inductive Charger for Medical Implants

The paper describes the power supply method of implantable devices using inductive wireless power transfer for the built-in battery charge. Spiral transmitting PCB inductor 100$\times$100 mm and toroidal receiving PCB inductor 30$\times$20 mm are used. The charging current distribution at various relative positions of the transmitting and receiving inductors is explored. Analytically calculated values are compared to the bench test results in the air and imitation environments. The maximum charging current was achieved in the receiving inductor location area, which is determined by the equipotential value zone of the inductor coupling coefficient, which ensures the load matching in a system. With a coaxial arrangement of the inductors, the maximum was reached at a distance of 35 mm between them.