Study on the acoustic impedance matching of human tissue for power transmitting/charging system of implanted biochip

This paper presents an acoustic impedance matching model for the power transmission in human tissue. Utilizing the piezoelectric effect, the acoustic wave provides a feasible way to wirelessly charge the battery of the implanted biochip. A modified matching method from Desilets microwave transmission theory is derived to match the acoustic impedance between the piezo-transmitter/receiver and the human tissue. The lead-zirconate-titanate (PZT, 39.71MRayl) is used to be the material of transmitter/receiver. Based on the results of the modified matching model, the double impedance matching layers are constructed by the aluminum alloy 6061T6 with impedance 17.1MRayl and polymethylmethacrylate (PMMA) with 3.33MRayl. The maximum power gain is 5.55 dB in simulation and 3.13 dB in experiment result.