Dual-Array Mixed Magnetic Metamaterials via Strong Magnetic Coupling Based Wireless Power Transfer System for Cardiac Pacemakers

To address the issue of coil misalignment in wireless power transfer (WPT) systems for cardiac pacemakers, which leads to fluctuations in power transmission efficiency (PTE) and reduce system stability, this paper proposes a WPT system operating at 150 kHz based on dual-array mixed magnetic metamaterials (Mix-MNG). First, three types of resonant units with different magnetic permeability were designed based on the quality factor theory of metamaterials. The arithmetic variation method was employed to reduce the ohmic losses of hexagonal resonant units, optimizing their quality factor. Second, a dual-array structure of Mix-MNG was constructed based on the varying magnetic field refraction capabilities of units with different magnetic permeability. The system's transmission performance and misalignment tolerance were analyzed through simulations and experiments. Third, a human body model was created in COMSOL to evaluate the system's safety. Experimental results show that at a transmission distance of 20 mm, the PTE of the system incorporating the dual-array Mix-MNG increased from 30.7% to 73.2%. Furthermore, within a 30 mm misalignment range of the single array Mix-MNG and the receiving coil, the system maintained transmission efficiencies of 41.2%-58.1% and 30.3%-56.6%. During a 30-min charging test, the tissue SAR values and temperature rise remained within safe thresholds.