Omnidirectional Wireless Power Transfer for Millimetric Magnetoelectric Biomedical Implants.

Area of Science:

• Bioelectronic Engineering
• Implantable Medical Devices
• Wireless Power Transfer

Background:

• Miniature bioelectronic implants offer advanced therapies for cardiovascular and neurological conditions.
• Wireless power transfer (WPT) is crucial for miniaturization, but its efficiency degrades with misalignment.
• Existing WPT systems struggle with implant orientation and body movements, limiting practical application.

Purpose of the Study:

• To develop an omnidirectional WPT platform for millimetric bioelectronic implants.
• To enhance the robustness, efficiency, and charging range of WPT systems.
• To address the challenges posed by misalignment and limited orientation control in bioelectronic implants.

Main Methods:

• Employed magnetoelectric (ME) WPT modality with magnetic field steering using 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 14.2 mm³ implantable stimulator with a low-power SoC, ME film, and a custom AE receiver (RX) chip.

Main Results:

• The AE RX achieved -161 dBm/Hz input-referred noise and a 64 dB gain tuning range for reliable signal sensing.
• Omnidirectional WPT demonstrated 6.8x higher power transfer efficiency (PTE) compared to a single-coil baseline under 90-degree rotation.
• AE tracking error negligibly impacted PTE (<2% degradation) compared to ideal control.

Conclusions:

• The developed omnidirectional WPT platform significantly enhances the reliability and efficiency of powering miniature bioelectronic implants.
• The active echo scheme effectively compensates for misalignment and orientation issues, enabling robust wireless power delivery.
• This technology paves the way for more advanced and practical implantable bioelectronic devices for various medical applications.