Inductive Power Link for a Wireless Cortical Implant With Two-Body Packaging

This paper presents an inductive power link for remote powering of a wireless cortical implant. The link includes a Class-E power amplifier, a gate driver, an inductive link, and an integrated rectifier. The coils of the inductive link are designed and optimized for remote powering from a distance of 10 mm (scalp thickness). The power amplifier is designed in order to allow closed-loop control of the power delivered to the implant, by controlling the supply voltage. Moreover, a gate driver is added to the system to drive the power amplifier and to characterize the gate losses. A new packaging topology is proposed in order to position the implant inside a hole in the cranial bone, without occupying a large area, but still obtaining a short distance between the remote powering coils. The package is fabricated by using biocompatible materials such as PDMS and Parylene-C. The power efficiency of the remote powering link is characterized for a wide range of load power (1-20 mW) delivered from the rectifier and is measured to be 24.6% at nominal load of 10 mW.