A Miniaturized, Low-Frequency Magnetoelectric Wireless Power Transfer System for Powering Biomedical Implants

Area of Science:

• Materials Science
• Biomedical Engineering
• Electrical Engineering

Background:

• Implantable medical devices (IMDs) require wireless power solutions.
• Existing wireless power transfer (WPT) systems face challenges with miniaturization, power efficiency, and safety (specific absorption rate - SAR).
• Magnetoelectric (ME) transducers offer potential for miniaturized WPT systems.

Purpose of the Study:

• To demonstrate a miniaturized ME wireless power transfer (WPT) system for powering implantable medical devices (IMDs).
• To address the trade-offs between device miniaturization, power attenuation, and SAR.
• To ensure biocompatibility for potential clinical applications.

Main Methods:

• Fabrication of a micromachined ME heterostructure (3.5 × 5 mm²) operating at 50 kHz.
• Characterization of the ME device under low-intensity AC magnetic fields without DC bias.
• Integration of a self-powered power management circuit (PMC) for regulated DC output.
• In vitro cytotoxicity analysis using human hepatic cell line (WRL-68).

Main Results:

• Achieved 0.4 V output voltage and 6.6 μW power across an 8 kΩ load.
• Reduced SAR to < 1 μW/kg by operating at 50 kHz.
• Developed a PMC providing 3.5 V regulated DC from 0.7–3.3 V AC input with >85% efficiency and <550 nA current consumption.
• Confirmed biocompatibility of the Parylene-C encapsulated ME device over 7 days.

Conclusions:

• A miniaturized ME-WPT system suitable for IMDs has been successfully demonstrated.
• The system achieves significant size reduction and operates safely with low SAR.
• The integrated PMC enhances power management, and the device exhibits excellent biocompatibility.