Measurement of Patient Leakage Current from Air-core Transcutaneous Energy Transmission System with High-frequency Isolation Transformer

Usage of the air-core transcutaneous energy transmission system (TETS) is a method that shows potential with respect to the supply of energy to ventricular assist devices. The TETS is composed of two coils of the transformer with spirally wound conductive wires; the external coil is fitted outside the body and the internal coil is embedded in the subcutaneous tissue of a patient. Here, it should be noted that patient leakage current (PLC) from the TETS can flow between the external and internal coils into the ground because of the capacitive coupling of the coils and human tissue. In this study, we analyzed the PLC of a TETS using a circuit simulator and designed a circuit model of a TETS with considering the equivalent circuit of biological tissue using circuit analysis tools. The respective circuit parameters were used as the measurement value of LCR meter at the transmitting frequency of 207 kHz, the PLC was analyzed using transmitting powers of 10 – 30 W. The results showed that the simulated value of the PLC was 9.37 μ A, and the measured value was 8.86 ±0.08 μ A at 15 W of output power. These results are seen to be in good agreement.