Impact of bending deformation on a capacitive power transfer system.

Wireless power transfer enables reliable energy delivery to fully embedded devices, eliminating the need for physical connectors while supporting device miniaturization. Flexible wireless power transfer systems extend this potential to applications requiring mechanical compliance, such as powering implantable medical devices in anatomically challenging locations with reduced foreign-body sensation. Capacitive power transfer is a near-field wireless power transfer method that is often cited as tolerant to bending deformations. However, this claim is based on limited evidence derived from studies on non-resonant systems or systems operating over larger distances, leaving the bending tolerance of resonant systems at small transfer distances largely unexplored. This work presents a systematic evaluation of bending on resonant capacitive power transfer at small distances, quantifying the impact of bending deformation on both the capacitive link and overall system performance. The results reveal that while concentric bending has negligible impact, outward receiver and inward transmitter bending significantly affect the system performance. AC-analysis measurements show that outward receiver bending shifts the optimal resonance frequency and reduces the power transfer efficiency by 54.5%. With inward transmitter bending, frequency splitting occurs which enhances the maximum power transfer efficiency with 8.5%. The findings redefine the bending robustness of capacitive power transfer systems and provide insight into their suitability for powering flexible applications.