Novel Systematic Design of Asymmetric Flexible Transceiver Coils with Optimal Wireless Power Transfer for Biomedical Implants

This paper introduces a novel systematic design methodology to implement highly efficient flexible asymmetric transceiver (TRX) coils optimized for wireless power transfer (WPT) with area controllability. The system comprises of dual planar spiral coils and L-section impedance matching networks (IMN). A comprehensive theoretical analysis, based on power transmission efficiency (PTE) vs frequency characteristics is developed, which led to new sets of precise design equations, including PTE’s dependency on coil size. Moreover, the performance of one of the TRX coils placed in the air (TRX-1) exhibits an excellent PTE of 41.98% ensuring > 20 dB return loss (RL) at both input and output side, whereas another prototype, TRX-2 with RX coil inserted inside the pork meat, stands out with 2.01% PTE and > 15 dB RL maintaining a 10 mm vertical distance and within a < 5x5 mm² RX area constraint for both the cases. Therefore, the fabricated prototypes working at 20 MHz for both air and tissue mediums substantiate perfect correlation with the proposed theory and simulation, highlighting this technique’s potential in diverse biomedical WPT applications.