Wireless Power Supply Based on MNG-MNZ Metamaterial for Cardiac Pacemakers

To solve the low power transfer efficiency and magnetic field leakage problems of cardiac pacemaker wireless powering, we proposed a wireless power supply system suitable for implanted cardiac pacemaker based on mu-negative (MNG) and mu-near-zero (MNZ) metamaterials. First, a hybrid metamaterial consisted of central MNG unit for magnetic field concentration and surrounding MNZ units for magnetic leakage shielding was established by theoretical calculation. Afterwards, the magnetic field distribution of wireless power supply system with MNG-MNZ metamaterial slab was acquired via finite element simulation and verified to be better than the distribution with conventional MNG slab deployed. Finally, an experimental platform of wireless power supply system was established with which power transfer experiment and system temperature rise experiment were conducted. Simulation and experimental results showed that the power transfer efficiency was improved from 44.44%, 19.42%, 8.63% and 6.19% to 55.77%, 62.39%, 20.81% and 14.52% at 9.6 mm, 20 mm, 30 mm and 50 mm, respectively. The maximum SAR acquired by SAR simulation under human body environment was -7.14 dbm and maximum reduction of the magnetic field strength around the receiving coil was 2.82 A/m. The maximum temperature rise during 30min charging test was 3.85°C, and the safety requirements of human bodies were met.