Optimization method of implantable receiver for magnetic resonant wireless power transfer between wearable on-body and implantable in-body

In this paper, optimization methods of implantable receiver for wireless power transfer are studied in order to increase transfer efficiency between resonators positioned on and in the human body. The spiral coil-resonators of magnetic resonant wireless power transfer (MR-WPT) are designed and fabricated on a wearable textile substrate, which covers the human body (on-body) as the transmitter (Tx) and on the acrylic substrate inside the human body (in-body) as the receiver (Rx). The experiment showed that when the Rx resonator was inserted into a muscle-mimicking liquid (MML), the transfer efficiency of on/in-body system decreased significantly. This decrease attributed to the mismatch of the resonant frequency between the Tx resonator in the air and the Rx resonator in the MML. To mitigate this effect, three approaches, which demonstrated the recovery of the transfer efficiency, were investigated using either a selected optimal capacitor or an air-pocket, and additional approach using pattern designed in the MML.