A 6.78-MHz Wireless, Mode-Convertible Single-Stage Resonant CC/CV Battery Charger for Implantable Biomedical Devices.

Area of Science:

• Biomedical Engineering
• Electrical Engineering
• Wireless Power Transfer

Background:

• Implantable biomedical devices require reliable wireless charging solutions.
• Extended charging range and battery health are critical challenges in current systems.

Purpose of the Study:

• To develop a mode-convertible single-stage resonant charger (SSRC) for implantable devices.
• To enhance wireless charging distance and ensure battery longevity.

Main Methods:

• A 6.78-MHz SSRC was designed with automatic mode switching (Normal Mode/Resonant Mode) based on current variation.
• The charger was fabricated using a 180 nm Bipolar/CMOS/DMOS process.
• Performance was validated through benchtop and ex vivo testing.

Main Results:

• Achieved an extended charging distance of up to 104.34% (from 23 mm to 47 mm).
• Successfully limited maximum current to prevent battery degradation.
• Measured peak power conversion efficiencies of 89.42% (NM) and 76.6% (RM).

Conclusions:

• The proposed SSRC effectively extends wireless charging range for biomedical implants.
• The charger provides safe and efficient power delivery, preserving battery health.