An Investigation of Implantable Capacitive Coupling Intra-body Power Transfer based on Full-band Loss Compensation

Capacitive coupling intra-body power transfer (CCIBPT) is a promising technique for powering implantable medical devices (IMDs) due to its flexible transmitter (TX) placement. However, several frequency-dependent capacitive impedances increase the path loss. Traditional methods have only compensated for partial path loss at the initially measured optimal frequency, which limits power transfer efficiency (PTE) enhancement. To address this issue, this paper investigates the effect of full-band loss compensation (FBLC) on the transmission characteristics, both through theoretical analysis and implantation experiments to achieve maximum PTE at a system level. In the vector network analyzer (VNA)-based simulation and measurement, FBLC achieves a higher path gain of 6.6 dB than conventional methods. Furthermore, we establish an implantable CC-IBPT prototype system to demonstrate the effects of FBLC on endto-end power gain and PTE enhancement. The measured results indicate that with a 1 mm2 square electrode implanted 4.6 cm deep in the pork tissue and positioned 15 cm away from the TX electrode, FBLC enhances PTE to 2.06%, an improvement of 3.55 times compared to 0.58% using conventional methods. This work demonstrates that FBLC achieves a higher PTE than traditional methods and validates the capability of CC-IBPT to achieve a relatively elevated PTE in long-distance wireless power supplies for IMDs