Fast Estimation of Wireless Charging System in a Large Tissue

Wireless charging technology enables designers to miniaturize medical implants and eliminates the redundant surgical procedure to replace batteries. In this paper, we propose a precise and fast method of predicting mutual coupling inside a human body. A magnetic field at 6.78 MHz is generated with two different types of resonant coils - circumferential and Helmholtz coils. The circumferential coil generates a vertical magnetic field while the Helmholtz coil produces a horizontal field. They can operate individually or simultaneously. The combined field mitigates orientation mismatch and increases ability to charge the implant wirelessly within the volume of interest. To predict M precisely and rapidly, a theoretical derivation is presented and compared to a commercial full-wave solver. The results show that the theoretical value is well aligned with the simulated one. The time required to produce an estimation of the coupling within the entire constellation can be substantially reduced with this approach.