Wireless Power Delivery to Flexible Subcutaneous Implants Using Capacitive Coupling

Implantable devices need sustainable wireless powering for safe long-term operations. In this paper, we present a near-field capacitive coupling (NCC)-based wireless powering scheme to transfer power to implants efficiently. By modeling the power link, we identify that the optimal operating frequency of the NCC scheme for subcutaneous power delivery is in the subGHz frequency range. The proposed scheme has desirable features, such as flexible and conformal power receiver realizations, and complies well with IEEE C95.1 specific absorption rate safety standards. The NCC link was designed and tested in a nonhuman primate cadaver, and the experimental results showed that it could safely deliver up to 100 mW of power to an implant with a peak operating efficiency of over 50%. A bending deformation study of the transmitter-receiver patches was also performed to demonstrate the reliability of the NCC powering scheme, in realistic postimplantation scenarios. Our studies validate the NCC method as a safe wireless powering scheme, which can be used as an alternative to the near-field resonant inductive coupling method, for chronic use in subcutaneous implants.