Resonant Charging System for Implantable Medical Devices
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Solution Overview
Problem
The inefficiency of transcutaneous energy transmission to implantable medical devices (IMDs) due to factors like misalignment and distance variations, leading to reduced charging efficiency and potential tissue damage from heat dissipation in non-rechargeable battery-powered IMDs, necessitates improved methods for charging rechargeable batteries in IMDs.
Innovation Solution
The system optimizes energy transfer by measuring and adjusting the resonant frequency of the charging system, using techniques such as driving electrical pulses and sweep signals to match the resonant frequency of the IMD and external charging device, thereby enhancing charging efficiency and reducing heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If transcutaneous energy transmission is used to charge the battery in the IMD, then the operational life of the IMD is extended, but charging efficiency is reduced and heat dissipation occurs in the IMD housing
Solution Approach 1:
The patent applies resonant frequency excitation to the charging system, causing the IMD housing and external charger to vibrate at their natural resonant frequency. This mechanical vibration enhances the coupling between the magnetic field and the charging coil, significantly improving energy transfer efficiency during transcutaneous charging.
Solution Approach 2:
The system dynamically adjusts the frequency of the external charger to match the resonant frequency of the charging system. By changing the operating frequency parameter to align with the natural resonant frequency, the system maximizes energy transfer efficiency and reduces losses during charging.
2Ease of operation
If the distance between the IMD and the external charger is increased, then patient comfort is improved, but charging efficiency is reduced
Solution Approach 1:
By exciting the charging system at its resonant frequency, the patent creates a stronger magnetic field coupling that maintains efficient energy transfer even when the distance between the IMD and external charger is increased, thereby improving patient comfort without sacrificing charging efficiency.
Solution Approach 2:
The patent employs a resonant charging system that creates a composite electromagnetic field environment, enhancing the magnetic coupling between the external charger and IMD. This composite field approach allows for more efficient energy transfer at greater distances compared to conventional non-resonant systems.
3Ease of operation
If the IMD is not properly aligned with the external charger, then ease of operation is improved, but charging efficiency is reduced
Solution Approach 1:
The resonant frequency excitation creates a robust magnetic field coupling that is less sensitive to misalignment between the IMD and external charger. The vibrational resonance enhances the magnetic field penetration and coupling, maintaining charging efficiency even when perfect alignment is not achieved.
Solution Approach 2:
The system dynamically adapts to misalignment conditions by maintaining resonant frequency operation. The resonant charging mechanism provides dynamic compensation for alignment variations, allowing the system to maintain efficient energy transfer across a range of positions and orientations.
4Adaptability or versatility
If additional therapy features are added to the IMD, then patient benefit is increased, but battery life is reduced
Solution Approach 1:
The resonant charging system enables the IMD to recharge its battery autonomously through transcutaneous energy transmission. This self-service charging capability allows the device to sustain additional high-power therapy features without requiring larger batteries, as the battery can be recharged repeatedly through the efficient resonant charging process.
Solution Approach 2:
By changing the charging mode from conventional to resonant frequency charging, the system dramatically improves charging speed and efficiency. This parameter change enables the battery to be recharged quickly and efficiently, supporting the addition of more demanding therapy features while maintaining or extending overall operational life.
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
This approach improves charging efficiency, reduces charging time, and minimizes heat dissipation, extending the operational life of IMDs and ensuring safer tissue conditions.
Implementation Method 1
generation of a magnetic field external to the patient's body which induces current flow in a charging circuit of the implanted IMD
Implementation Method 2
measuring and adjusting the resonant frequency of the charging system, using techniques such as driving electrical pulses and sweep signals to match the resonant frequency of the IMD and external charging device
Implementation Method 3
the magnetic field may induce current flow not only in the charging circuit of the IMD, but also in the metallic housing of the IMD. Current flow in the IMD housing is dissipated as heat.
Data Source
AI summary
Apparatus and methods for charging a power cell in an implantable medical device (“IMD”) are disclosed herein. In one embodiment, a method includes providing an electrical pulse to an inductor external to the IMD. A frequency of an oscillation signal induced in the inductor by the current pulse is measured. The inductor is driven with an oscillating signal having a frequency based on the measured frequency of the oscillation signal. The power cell is charged using current induced in the IMD by the driving of the inductor.