Flexible Numerical Evaluation of Human Head Exposure to a Transmitter Coil for Wireless Power Transfer at 13.56MHz

Wireless power transfer (WPT) systems are widely applied for brain implants. In this context, the electromagnetic safety of brain tissue exposed to the magnetic and induced electric fields is important. In this contribution, the field exposure levels related to the transmitter (TX) coil of a 13.56 MHz WPT system inside a human head model are investigated. In order to surmount the computation challenges in field detection of WPT structures in human head models, a Huygens' source replacement approach in combination with method of moment (MoM) is utilized. The flexibility of this approach facilitates the simulation in terms of various parameter sweeps such as distance and angle variations. To implement the simulation setup, the TX coil is first stimulated with a 1 V voltage generator in a full-wave simulation and then replaced by a Huygen's source for MoM simulations at 13.56 MHz. Fast and efficient investigations in comparison to other full-wave simulations are achieved. The simulation results show the human head exposure level of the electric field up to 9 dBV/m and the magnetic field up to −36 dBA/m.