Open AccessMulti‐coil approach to reduce electromagnetic energy absorption for wirelessly powered implants
Author(s) -
RamRakhyani Anil Kumar,
Lazzi Gianluca
Publication year - 2014
Publication title -
healthcare technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.45
H-Index - 19
ISSN - 2053-3713
DOI - 10.1049/htl.2013.0035
Subject(s) - electromagnetic coil , specific absorption rate , wireless power transfer , electrical engineering , materials science , voltage , maximum power transfer theorem , bandwidth (computing) , coil tap , computer science , power (physics) , acoustics , biomedical engineering , physics , engineering , telecommunications , rogowski coil , quantum mechanics , antenna (radio)
Near‐field inductive coupling is a commonly used technique for wireless power transfer (WPT) in biomedical implants. Owing to the close proximity of the implant coil(s) with the tissue (∼1 mm) and high current (∼100–300 mA) in the magnetic coil(s), a significant induced electric field can be generated for the operating frequency (1–20 MHz). In this Letter, a multi‐coil‐based WPT technique is proposed to selectively control the currents in the external and implant coils to reduce the specific absorption rate (SAR). A three‐coil WPT system, that can achieve 26% reduction in peak 1‐g SAR and 15% reduction in peak 10‐g SAR, as compared to a two‐coil WPT system with the same dimensions, is implemented and used to demonstrate the effectiveness of the proposed approach. To achieve the seamless design for the external and implant electronics, the multi‐coil system achieves the same voltage gain and bandwidth as the two‐coil design with 46% improvement in the power transfer efficiency.