Near-infrared light transcutaneous telemetry system having an implantable transmitter driven by external laser irradiation

We present an optical telemetry system using a small implantable transmitter which is both powered and given a carrier wave by transcutaneous near-infrared laser irradiation. The transmitter transcutaneously sends a phase-modulated signal to the receiver by the use of a near-infrared light-emitting diode. The received signal is demodulated with a lock-in amplifier. The operation of the transmitter is stable as long as it is irradiated with enough power. In the irradiation intensity range of 3.2–19 mW/cm2, the variation in the receiver output was only 3% for a baseband signal of 3.0 V, in peak-to-peak amplitude. Using the present system, we have succeeded in optical transmission through chicken several millimeters thick.