Transcutaneous energy and information transfer for biomedical implants

Summary form only received as follows. Systems delivering energy and information to implanted devices via magnetic induction provide an alternative to the use of percutaneous wire leads for long-term medical implants. Design tradeoffs are governed by the conflicting demands of energy transfer efficiency, communication bandwidth, insensitivity to changes in coil coupling variation, and concerns about patient quality-of-life. Systems range in size from that of the waist-encircling transformer developed for energizing ventricular assist devices, to miniature encapsulated systems intended for intramuscular implantation via hypodermic. Information transfer bandwidth may be considerable, as in the case of the cochlear prosthesis. In high-energy transfer applications, selection of operating frequency involves tradeoffs between tissue thermal and electronic switching losses which tend to increase with frequency and losses in the tuned-circuits driving a coil which are inversely related to frequency. These systems have been in regular use since at least the time of the transcutaneously recharged pacemaker, and new applications continue to be developed