Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published March 2012 | public
Book Section - Chapter

Reduction of AC Resistance in MEMS Intraocular Foil Coils Using Microfabricated Planar Litz Structure


The next-generation implantable high-power prosthetic devices, such as retinal prostheses, will be powered by inductively coupled coils of high efficiency. However, the use of high-frequency power carriers almost always induces significant AC resistance due to skin and proximity effects, which limits the overall coupling efficiency. Inspired by the widely used round Litz wire, planar coils with planar Litz structures were investigated on the printed circuit board (PCB) and showed the reduced AC resistances in some specific frequency ranges. Herein, various planar Litz structures were introduced into previous MEMS foil coils, which have been proved to be superior over the conventional planar counterparts. The experimental results provided by the aforementioned prototypes showed a reduction of AC resistance up to 13.3% compared to a solid foil coil. A microfabrication process, which combines a single layer metal deposition and patterning with a post folding step, was developed to construct the planar Litz structure.

Additional Information

© 2012 IEEE. The funding is provided by the NSF BMES ERC Center under Award Number H31068. The authors would like to sincerely thank Mr. Trevor Roper and other members of the Caltech Micromachining laboratory for their assistance with fabrication.

Additional details

August 22, 2023
October 23, 2023