Ultrasonic Implant Localization for Wireless Power Transfer: Active Uplink and Harmonic Backscatter

Area of Science:

• Biomedical Engineering
• Ultrasound Technology
• Implantable Devices

Background:

• Efficient power transfer to implantable devices relies on precise ultrasonic beamforming.
• Implant location shifts can rapidly degrade power transfer efficiency.
• Ultrasound localization offers a method for tracking implants to maintain optimal energy transmission.

Purpose of the Study:

• To present a framework for calculating ultrasound localization accuracy for implantable devices.
• To compare harmonic backscatter and active uplink methods for implant localization.
• To demonstrate improved ultrasonic power transfer using accurate localization.

Main Methods:

• Developed a framework to assess localization accuracy using a linear array probe.
• Investigated harmonic backscatter and active uplink approaches for implant communication.
• Characterized localization accuracy with a minimal three-channel receiver setup.

Main Results:

• Achieved sub-millimeter localization accuracy, with standard deviation two orders of magnitude smaller than the beamwidth.
• Harmonic backscatter demonstrated comparable localization performance to active uplink.
• Beamforming based on measured implant location increased power transfer efficiency over 20-fold.

Conclusions:

• Sub-millimeter ultrasound localization of implants is feasible with minimal receive channels.
• Accurate localization significantly enhances ultrasonic power transfer efficiency.
• The proposed framework and methods pave the way for robust wireless power for medical implants.