Inductive Charging Control for Implantable Medical Devices
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Solution Overview
Problem
Current inductive charging methods for implantable medical devices (IMDs) are inefficient due to energy conversion into heat, require patients to remain still, and are not flexible enough to accommodate varying user movements, leading to prolonged charging times and inconvenience.
Innovation Solution
A hybrid closed-loop control system that adjusts inductive power based on real-time feedback from the IMD, combining fast-loop and slow-loop approaches to maintain optimal power delivery and alignment tolerance, allowing for charging during patient activity while minimizing heat generation and misalignment issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If inductive charging is performed while the patient is mobile, then user convenience and flexibility are improved, but alignment between transmitting and receiving coils deteriorates causing charging interruptions
Solution Approach 1:
The patent implements dynamic adjustment of charging parameters based on real-time detection of alignment quality. The system continuously monitors coupling conditions and adapts the charging process accordingly, allowing the patient to move while maintaining effective charging through parameter optimization rather than requiring fixed positioning
Solution Approach 2:
The system incorporates feedback mechanisms that detect alignment quality during inductive charging and use this information to adjust charging parameters. This closed-loop control enables the system to compensate for misalignment caused by patient movement, maintaining charging reliability while allowing mobility
2Productivity
If inductive charging power is increased to reduce charging time, then productivity is improved, but heat generation increases causing safety concerns
Solution Approach 1:
The patent dynamically adjusts charging parameters including power level, frequency, and pulse duration based on real-time conditions such as tissue temperature and coupling efficiency. This allows the system to optimize charging speed while preventing excessive heat generation through continuous parameter adaptation
Solution Approach 2:
The system employs periodic charging pulses with variable duty cycles rather than continuous high-power delivery. This intermittent charging approach allows heat dissipation between pulses while maintaining effective charging over time, reducing peak temperature generation
3Reliability
If traditional recharging methods require the user to sit still, then alignment between coils is maintained, but user convenience and flexibility deteriorate
Solution Approach 1:
The system automatically detects and compensates for alignment changes caused by patient movement without requiring user intervention. The charging device self-adjusts parameters to maintain effective charging, eliminating the need for the user to consciously maintain positioning while preserving charging reliability
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, reduces waste heat, and allows for more flexible and convenient charging of IMDs, ensuring reliable and timely power replenishment even during patient mobility, thereby improving user experience and device performance.
Implementation Method 1
recharging of the power supplies of electrically powered implantable medical devices (IMDs)... using inductive charging techniques
Implementation Method 2
the inductive signal is transmitted by the external charger and received through the patients skin by the IMD via an implant coil. The recharging circuitry converts the inductive signal into electricity for charging the IMD battery
Implementation Method 3
During charging, some of the energy that is inductively transferred to the IMD is converted into heat instead of being converted into electricity for charging. Eddy currents form on the housing of the IMD during charging and these currents dissipate as heat
Implementation Method 4
The recharging circuitry converts the inductive signal into electricity for charging the IMD battery
Data Source
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AI summary
A system and method of controlling the charging of the battery of a medical device using a remote inductive charger, with the method utilizing both a relatively fast closed-loop charging control based on a proxy for a target power transmission value in conjunction, and a slower closed-loop control based on an actual measured transmission value to control a charging power level for charging the medical device.