External Charger Sense-Coil Alignment for IMD Charging Efficiency
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Solution Overview
Problem
Existing wireless external chargers for implantable medical devices face challenges in efficiently charging devices due to poor coupling between the charging coil and the implantable device, which can result in slow charging times and increased power consumption in the external charger.
Innovation Solution
The improved charging system incorporates a charging coil assembly with one or more sense coils that detect alignment and centering with the implantable device, allowing for real-time adjustments to the magnetic field power and frequency to optimize charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless charging is implemented without alignment detection, then charging simplicity is maintained, but charging efficiency deteriorates due to poor coupling
Solution Approach 1:
The patent implements a feedback mechanism where sense coils continuously detect the position and alignment of the implantable device relative to the external charger. The system uses this feedback information to dynamically adjust the magnetic field generation, optimizing coupling efficiency in real-time while maintaining ease of wireless operation.
Solution Approach 2:
The patent replaces manual alignment procedures with an automated electromagnetic detection system. Instead of requiring users to mechanically align devices, the sense coils automatically detect position and guide the charging process through electromagnetic field adjustments, substituting mechanical alignment with field-based optimization.
2Speed
If charging power is increased to compensate for poor coupling, then charging speed is improved, but power consumption in the external charger increases
Solution Approach 1:
The patent employs dynamic power adjustment where the external charger continuously adapts its output power based on real-time coupling conditions detected by the sense coils. When coupling is poor, the system dynamically increases power temporarily, then reduces it when optimal coupling is achieved, avoiding sustained high power consumption while maintaining fast charging capability.
Solution Approach 2:
The system changes operating parameters including magnetic field strength, frequency, and power levels based on detected coupling conditions. By dynamically adjusting these parameters rather than maintaining constant high power, the system achieves fast charging speeds only when necessary while minimizing overall power consumption during the charging process.
3Productivity
If sense coils are added to detect alignment, then charging efficiency is improved, but device complexity increases
Solution Approach 1:
The sense coils serve multiple functions: they detect alignment, determine depth of implantation, guide positioning, and monitor charging progress. By making these components multi-functional, the patent achieves improved charging efficiency without proportionally increasing system complexity, as the same hardware performs several critical tasks.
Solution Approach 2:
The sense coils act as intermediary sensors that mediate between the user and the implantable device during charging. Rather than requiring complex user interactions or sophisticated control algorithms, the sense coils provide simple positional information that guides the charging process, reducing overall system complexity while improving efficiency.
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 enhances charging efficiency by ensuring optimal alignment and centering of the charging coil with the implantable device, reducing charging time and minimizing power consumption in the external charger.
Implementation Method 1
one or more sense coils that detect alignment and centering with the implantable device
Implementation Method 2
external charger 50 used to wirelessly convey power to the IMD 10... Primary charging coil 52 in the external charger 50 is energized via charging circuit 64 with an AC current, Icharge, to create an AC magnetic charging field 66
Implementation Method 3
Power transmission from the external charger 50 to the IMD 10 occurs wirelessly and transcutaneously through a patient's tissue 25, via inductive coupling
Data Source
AI summary
A charging system for an Implantable Medical Device (IMD) is disclosed having a charging coil and one or more sense coils preferably housed in a charging coil assembly coupled to an electronics module by a cable. The charging coil is preferably a wire winding, while the sense coils are preferably formed in one or more traces of a circuit board. One or more voltages induced on the one or more sense coils can be used to determine one or more parameters (magnitude, phase angle, resonant frequency) indicative of the position between the charging coil and the IMD, which position may include the radial offset and possibly also the depth of the charging coil relative to the IMD. Knowing the position, the power of the magnetic field produced by the charging coil can be adjusted to compensate for the position.