Bipolar Spiral Midfield Wireless Power Transfer for Cardiac Implants Application

This letter proposes a midfield wireless power transfer system using a bipolar spiral-shape transmitter (BPSP-Tx) for cardiac implants application. Optimal current distribution is built on BPSP-Tx surface following spiral structure to generate a focused field inside human tissue and adapt the implantable receiver (Rx) misalignments. Source performance has been verified by implantable hooked-shape Rx (HKSD-Rx) that separated at a distance of 45 mm from Tx. Measurements are conducted in minced pork for validation. Experimental results show that the transmission coefficient can achieve -20.48 dB at a distance of 45 mm and -22.15 at 60 mm. Furthermore, the Rx misalignment is verified by output power level, which shows that the proposed system can maintain high performance on a rotation range of Rx from -90°to 90°. Finally, the human safety regulations are verified to present a low specific absorption rate, which demonstrates the potential for cardiac implants.