Controlled transcutaneous powering of a chronically implanted telemetry device.

Radiofrequency (RF) powered subcutaneous transmitter devices offer the unique possibility of very long-term measurements from sites within the body under a variety of normal living conditions without percutaneous connections and concomitant dangers such as local tissue infection. Disturbances in the energy transport across the cutaneous barrier may, however, give rise to output data signal fluctuations, which are perceived as transients or drift. A RF-powered implanted biotelemetry device is proposed where the energy transport is controlled by continually optimizing the emission frequency and the duration of energy transfer.