Transmitter Array for Misaligned Biomedical Implants
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Solution Overview
Problem
Conventional wireless power transfer systems for biomedical implants face challenges in maintaining high power transfer efficiency due to misalignment between transmitter and receiver coils, especially in tissue environments with distinct dielectric properties, which degrades performance and increases implant size requirements.
Innovation Solution
A transmitter array topology with a central excitation coil surrounded by resonant coils is used, allowing for efficient power transfer to an on-chip receiver coil, even with up to 150% misalignment, by optimizing the coupling coefficient and load impedance to enhance power transfer efficiency and mitigate misalignment issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-coil wireless power transfer system is used, then the system structure is simple, but power transfer efficiency degrades significantly with misalignment between transmitter and receiver coils
Solution Approach 1:
The transmitter is divided into multiple resonant coils arranged in an array configuration. Each coil operates at the resonant frequency and contributes to the overall magnetic field, providing redundant coupling paths that maintain power transfer efficiency even when misalignment occurs between the transmitter array and receiver coil.
Solution Approach 2:
Multiple resonant coils are combined to form a unified transmitter array that operates cooperatively. The coils are coupled together and driven by a common RF source, creating a distributed magnetic field that enhances coupling with the receiver coil and mitigates the effects of misalignment through constructive interference of magnetic fields.
2Reliability
If the transmitter coil area is increased to improve coupling with the receiver, then power transfer efficiency improves, but the implant size requirement increases
Solution Approach 1:
The problem is solved by transitioning from a single large coil in one dimension to multiple smaller coils arranged in a two-dimensional array. This spatial distribution allows the system to achieve the necessary total coupling area while keeping individual coil sizes small, enabling compact implant design without sacrificing power transfer efficiency.
Solution Approach 2:
Different regions of the transmitter array provide different contributions to the overall coupling. Coils closer to the receiver provide stronger local coupling, while distant coils provide supplementary coupling. This distributed approach allows the system to achieve high overall efficiency without requiring any single coil to be large.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves a variation in power transfer efficiency of less than 2.6 dB with 150% misalignment, improving performance compared to conventional single-coil systems and enabling smaller implant sizes while maintaining efficient power delivery.
Implementation Method 1
a transmitter (TX) array comprising an excitation coil and a plurality of resonant coils distributed about the excitation coil. The RF power source can excite the excitation coil via an RF power amplifier.
Implementation Method 2
a plurality of resonant coils distributed about the excitation coil. The excitation coil and individual resonant coils of the plurality of resonant coils can have a substantially square shape.
Data Source
AI summary
Various examples are provided for wireless power transfer to implants. In one example, a system includes a radio frequency (RF) power source and a transmitter (TX) array comprising an excitation coil and resonant coils distributed about the excitation coil. The TX array can transfer power from the RF power source to a biomedical implant inserted below a skin surface of a subject when the TX array is positioned on the skin surface adjacent to the biomedical implant. A receiver (RX) coil of the biomedical implant can inductively couple with the TX array for the power transfer. The resonant coils can allow power transfer when the RX coil is not aligned with the excitation coil.