Enhancing Wireless Power Transfer Efficiency for Implantable Medical Devices Using Metamaterial

Increasing the wireless power transfer efficiency (PTE) is crucial for implementing implantable medical devices (IMDs). The challenge in powering such implants stems from the human brain tissue's elevated permittivity, conductivity, and mass density, which pose difficulties across high frequencies. This study introduces a metamaterial-based near-field wireless power transfer (WPT) system. It evaluates its performance against traditional WPT systems with a 36×36 mm transmitter and 900×485 um receiver coil. The size of the metamaterial unit cell is 12×12 mm. Numerical analysis reveals that the S21 parameter of the metamaterial-based WPT system shows a 4.21 dB enhancement over the conventional WPT system at 200 MHz, specifically for an ultra-small receiver coil. From the specific absorption rate simulation, it can be found that maximum transmitted power improved by more than 2.4 times due to the distance between the transmitter coil and tissue stack. Additionally, a comparative analysis involving magnetic fields has been conducted to deepen the understanding of the power transfer mechanism. Moreover, a comparative study has been provided with a recent metamaterial-based WPT system for IMDs. The proposed system demonstrates the potential for use in neural implants, offering an improved PTE.