Omnidirectional Wireless Power Transfer for Millimetric Magnetoelectric Biomedical Implants

Area of Science:

• Bioelectronic Engineering
• Medical Device Technology
• Wireless Power Transfer

Background:

• Miniature bioelectronic implants offer advanced therapies for cardiovascular and neurological conditions.
• Wireless power transfer (WPT) is crucial for battery-free implants, but efficiency drops with misalignment.
• Existing WPT systems struggle with body movements and implant orientation, limiting reliability.

Purpose of the Study:

• To develop an omnidirectional WPT platform for millimetric bioelectronic implants.
• To enhance the robustness and efficiency of WPT despite misalignment.
• To enable reliable power delivery for implantable medical devices.

Main Methods:

• Utilized magnetoelectric (ME) WPT modality with magnetic field steering via multiple transmitter (TX) coils.
• Developed an Active Echo (AE) scheme with a miniature implant coil for closed-loop control of the TX array.
• Integrated a 14.2mm³ implantable stimulator with a custom SoC and an ME film, alongside a multi-coil TX array.

Main Results:

• The Active Echo (AE) receiver achieved -161dBm/Hz input-referred noise and 64dB gain tuning.
• The omnidirectional WPT system demonstrated 6.8x higher power transfer efficiency (PTE) at 90° misalignment compared to a single-coil system.
• AE scheme minimally impacted PTE (<2%) even with tracking errors.

Conclusions:

• The proposed omnidirectional ME WPT system with AE significantly improves power transfer robustness and efficiency for millimetric bioelectronic implants.
• This technology addresses key challenges in powering implantable devices, paving the way for more reliable therapies.
• The Active Echo scheme offers a robust solution for adaptive control in WPT systems, enhancing medical implant functionality.