Shielded Relay Coil design to Optimize WPT and SAR for Distributed Wireless Brain Implants

Area of Science:

• Biomedical Engineering
• Electromagnetics
• Wireless Communication

Background:

• Wireless Power Transfer (WPT) is crucial for powering implanted medical devices.
• Specific Absorption Rate (SAR) is a key safety metric limiting power levels for biomedical implants.
• Optimizing WPT and minimizing SAR simultaneously presents a significant challenge for implantable systems.

Purpose of the Study:

• To present a novel shielded relay antenna design.
• To enhance Wireless Power Transfer (WPT) efficiency.
• To reduce Specific Absorption Rate (SAR) for distributed brain microimplants.

Main Methods:

• The proposed antenna utilizes strategically placed conductive features.
• Eddy currents are generated to counteract high magnetic fields.
• High-Frequency Structure Simulator (HFSS) was used for electromagnetic simulations.

Main Results:

• The design equalizes and increases magnetic field strength across the cortical surface.
• Simulations demonstrate a 1.2 dB enhancement in WPT for a 2x2 cm2 wireless brain-machine interface (BMI) system.
• A significant 29% reduction in SAR was achieved at 915 MHz.

Conclusions:

• The shielded relay antenna effectively addresses the WPT and SAR co-optimization challenge.
• This technology holds potential for improving the safety and efficacy of various biomedical implants.
• The design offers a promising solution for future wireless-powered neural interfaces.