An RF-Ultrasound Relay for Powering Deep Implants Across Air-Tissue Interfaces with a Multi-Output Regulating Rectifier and Ultrasound Beamforming

Single modality wireless power has limited depth for mm-sized implants across air-tissue (e.g. retina implants) or skull-tissue interfaces because of high loss in tissue (RF, optical) or high reflection at the medium interface (ultrasound). The proposed RF-ultrasound (US) relay uses an RF link across the interface to a relay chip which rectifies the RF power and transmits focused ultrasound to the implant using a 6-channel phased array with 251% efficiency improvement at 2.5 cm over fixed focusing.