Modeling and Design of a Transcutaneous Resonant Capacitive Power Transfer Link for Biomedical Implants

This article proposes a transcutaneous resonant capacitive power transfer link for biomedical implants using parallel thin-film electrodes as coupling plates. First, the practical multilayer tissue circuit model is obtained by tissue dielectric properties and current path. Analysis is presented to identify the influencing factors of loss mechanisms on power transfer efficiency (PTE) and power delivered to the load (PDL). Then, an asymmetric insulation layer coupler is proposed to reduce losses. The parameters of this design are obtained from the finite-element method for maximum PTE and high PDL. Moreover, the safety assessment and power transfer strategies are performed according to the IEEE C95.1 guideline; 90.73 mW of PDL is safely received at 47.02% PTE. Finally, two sets of comparative experiments are conducted at 6.78-MHz operating frequency using pork as the medium, evaluating the performance of symmetric insulation layer (t₂ = 0.015 mm) and asymmetric insulation layer coupler (t₂ = 0.15 mm). The experimental results show good agreement with the analytical and simulation results; the asymmetric insulation layer compared with the symmetry insulation layer improves efficiency by 8.9%.