Implantable Wireless Charger Magnetic Coil Alignment
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Solution Overview
Problem
Current wireless charging systems for implantable medical devices (IMDs) face inefficiencies due to misalignment of transmit and receive coils, leading to prolonged charging times and increased heating risks, which are exacerbated by the need for oversized transmit coils to accommodate misalignment.
Innovation Solution
The integration of magnets, specifically electromagnets, to align the transmit and receive coils automatically, ensuring precise alignment and reducing heating effects by allowing the coils to be similarly dimensioned, thus increasing the coupling coefficient and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If transmit coils are oversized to accommodate misalignment, then alignment tolerance is improved, but coupling efficiency deteriorates
Solution Approach 1:
The patent replaces manual alignment mechanisms with a magnetic field-based alignment system. Magnets embedded in both the IMD and charger automatically attract and align the transmit and receive coils when the charger is placed on the patient's skin, eliminating the need for oversized coils to compensate for misalignment.
Solution Approach 2:
The patent changes the physical state by introducing magnetic fields to control coil alignment. By using magnets with specific magnetic field strengths and polarities, the system achieves precise alignment dynamically, allowing transmit coils to be sized optimally rather than oversized for tolerance.
2Device complexity
If manual alignment by feeling the bump is used, then device simplicity is improved, but alignment precision deteriorates
Solution Approach 1:
The patent replaces tactile manual alignment with magnetic field-based automatic alignment. Magnets in the IMD and charger create an attractive force that automatically positions the coils in alignment when the charger is placed on the skin, providing both simplicity and precision.
Solution Approach 2:
The alignment system is self-aligning through magnetic attraction between the IMD magnet and charger magnet. The system automatically finds its optimal position without requiring patient intervention or complex mechanical adjustment mechanisms.
3Productivity
If charging rate is increased to reduce charging time, then productivity is improved, but temperature rises causing tissue damage risk
Solution Approach 1:
The patent incorporates temperature sensing and control mechanisms that monitor tissue temperature during charging. The system adjusts charging parameters in real-time based on temperature feedback, allowing high charging rates when temperatures are safe and reducing rates when temperature thresholds are approached, thus preventing tissue damage.
Solution Approach 2:
The patent dynamically changes charging parameters including power level, pulse duration, and duty cycle based on real-time temperature measurements. This allows the system to optimize charging speed while maintaining tissue temperature within safe limits through continuous parameter adjustment.
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 solution reduces charging time and heating risks by ensuring optimal coil alignment, improving charging efficiency and compliance with thermal safety limits, while allowing for intuitive alignment feedback and compatibility with MRI environments.
Implementation Method 1
a magnet configured to provide a magnetic field to couple with a corresponding magnet of an external charger when placed adjacent the IMD
Implementation Method 2
receive coils connectable by the electronics unit to charge the rechargeable battery and arranged to receive an electromagnetic field to provide electrical energy for wirelessly charging the rechargeable battery
Data Source
Figure 1
Figure 2A
Figure 2B~2C
AI summary
A wireless charger (20) and implantable medical device, IMD (1) that are paired to allow the charger to wirelessly charge a rechargeable battery (17) of the IMD (1) when the latter is subcutaneously implanted in a patient in tissue (72) under the skin (70). For wireless charging, power is transferred inductively from transmit coils (23) in the charger (20) to receive coils (13) in the IMD (1). To align the transmit and receive coils (23, 13), the charger (20) and IMD (1) are provided with respective magnets (21, 7) arranged centrally within their associated coils (23, 13). Magnetic attraction between the magnets when the charger is positioned over the IMD (1) site provides tactile feedback when alignment is achieved. Moreover, once the coils are aligned, the continued magnetic attraction between the magnets holds the alignment position during subsequent charging.