A Dual-Band HF and UHF Antenna System for Implanted Neural Recording and Stimulation Devices

We present a dual-band high-frequency (HF) and ultrahigh-frequency (UHF) (13.56 and 902-928 MHz) antenna system for implanted neural recording and/or stimulation devices. This system consists of implant-side and external antennas. These antennas are intended for dual-band systems, where power is supplied to the implant via inductive coupling in the HF band, while data are transferred via UHF near-field coupling. The antenna system consists of an implant-side antenna of 25 mm diameter and 3 mm thickness, as well as an external antenna of 85 mm diameter and 3 mm thickness. We present both timeand frequency-domain simulation results for antenna performance and specific absorption rate in a layered tissue model, as well as experimental confirmation of antenna performance in a saline tissue proxy. With an implant depth of 11 mm and an air gap of 5 mm, the power link has a 17% measured power transfer efficiency in the HF band, inclusive of matching component losses, and the UHF communication link has 38-dB insertion loss over the 902-928-MHz band.