Implantable active telemetry system using microcoils

The use of microcoils in an active telemetry system that is intended to be implanted in the body for biomonitoring applications is presented in this paper. To achieve a moderate transmission range, active telemetry was realized instead of passive telemetry by load modulation, which is often used in systems incorporating microcoils. Sample microcoils with a diameter of 1 cm and 16 windings were fabricated and used for tests. A telemetry system operating at the 27 MHz ISM band was constructed using a small number of circuit components. The performance of the constructed system was evaluated in a laboratory condition. The transmission range of the realized system was measured up to 20 cm when a biological tissue in a thickness of 1 cm was applied between the transmitter and the receiver.