Study of the Brain Tissue Ohmic Losses and Specific Absorption Rate in an Inductive Wireless Power Transfer System

Wireless power transfer (WPT) is increasingly used to energize implanted biomedical devices and sensors, offering a convenient alternative to traditional battery-powered systems. By eliminating the need for frequent surgical procedures to replace batteries, WPT significantly enhances patient safety and comfort. Inductive coupling is a widely adopted method for short-range power transfer due to its simplicity and effectiveness in medical implant applications. However, safety concerns must be addressed, particularly regarding the specific absorption rate (SAR), which measures the electromagnetic energy absorbed by human tissue. Regulatory compliance with SAR limits is critical to avoid potential tissue heating or adverse biological effects. Another cause of temperature rise in the tissue could be the ohmic losses due to the Eddy current. This paper investigates the influence of coil misalignment on SAR and ohmic loss levels using ANSYS simulation software. Simulations are conducted using a realistic anatomical head model to evaluate how deviations in coil positioning impact SAR and ohmic losses. Results indicate that SAR and ohmic losses are not directly correlated.