@ARTICLE{ iet:/content/journals/10.1049/htl.2013.0035, author = {Anil Kumar RamRakhyani}, affiliation = {Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT 84112, USA}, author = {Gianluca Lazzi}, affiliation = {Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT 84112, USA}, keywords = {multicoil-based WPT technique;biomedical implant coils;implant electronics;wireless power transfer;magnetic coil;specific absorption rate;electromagnetic energy absorption reduction;induced electric field;tissue;near-held inductive coupling;multicoil approach;SAR;two-coil WPT system;three-coil WPT system;power transfer efhciency;wirelessly powered implant;}, language = {English}, abstract = {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.}, title = {Multi-coil approach to reduce electromagnetic energy absorption for wirelessly powered implants}, journal = {Healthcare Technology Letters}, issue = {1}, volume = {1}, year = {2014}, month = {March}, pages = {21-25(4)}, publisher ={Institution of Engineering and Technology}, copyright = {© The Institution of Engineering and Technology}, url = {https://digital-library.theiet.org/;jsessionid=9g2tn1gn89sgj.x-iet-live-01content/journals/10.1049/htl.2013.0035} }