Hybrid Rectification for Implantable Medical Device Recharging
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Solution Overview
Problem
Implantable medical devices (IMDs) face inefficiencies in energy transfer during recharging, leading to prolonged recharge times and potential tissue heating, which can be detrimental and inconvenient for patients, especially when using primary cell batteries that do not provide lasting power for energy-intensive functions.
Innovation Solution
A system that dynamically switches between half-wave voltage-doubling and full-wave rectification based on monitored conditions such as coupling efficiency, current flow, voltage levels, and temperature to optimize energy transfer efficiency, using a charging module within the IMD to control which rectification method is used during a recharge session.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If inductive coupling is used for transcutaneous energy transfer, then the IMD can be recharged without external wires, but tissue heating occurs and recharge time is prolonged
Solution Approach 1:
The system dynamically switches between half-wave and full-wave rectification modes based on real-time monitoring of coupling efficiency and temperature conditions. When coupling is strong, full-wave rectification maximizes power transfer; when coupling deteriorates or temperature rises, the system transitions to half-wave rectification to reduce power density and minimize tissue heating while maintaining wireless recharging capability.
Solution Approach 2:
The patent changes the operational parameters of the rectification circuit by switching between two distinct modes (half-wave and full-wave) depending on the coupling conditions. This parameter change allows the system to adapt to varying tissue properties, coil positions, and temperature conditions, optimizing the balance between recharging efficiency and thermal safety.
2Object-affected harmful factors
If inductive coupling efficiency is low, then tissue heating is reduced, but recharge time increases significantly
Solution Approach 1:
The system continuously monitors coupling efficiency and dynamically adjusts the rectification mode accordingly. When coupling efficiency is high, full-wave rectification is used to maximize power transfer speed. When coupling efficiency drops, the system switches to half-wave rectification, which requires less power and can maintain operation with weaker coupling, thus adapting to changing conditions to optimize both safety and recharge time.
Solution Approach 2:
The patent implements a feedback mechanism where the system monitors coupling conditions and temperature in real-time, then adjusts the rectification mode based on this feedback. This closed-loop control allows the system to respond to deteriorating coupling conditions by switching to a more tolerant rectification mode, preventing excessive heating while minimizing recharge time extension.
3Device complexity
If a single rectification mode is used, then device complexity is reduced, but recharge efficiency cannot be optimized under varying conditions
Solution Approach 1:
The patent implements a multi-functional rectification system that can operate in both half-wave and full-wave modes using a unified circuit architecture. The same rectification circuitry serves multiple purposes: full-wave mode for high-efficiency recharging when coupling is strong, and half-wave mode for thermal management and compatibility with weaker coupling conditions. This universal design achieves high productivity across varying conditions without proportionally increasing device complexity.
Solution Approach 2:
The system employs dynamic switching between rectification modes to optimize recharge efficiency under varying coupling conditions. The ability to transition between half-wave and full-wave rectification allows the system to maintain high productivity whether the coupling is strong or weak, adapting to the instantaneous operating conditions to maximize power transfer 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 approach enhances recharge efficiency, reducing the time required for recharging and minimizing tissue heating, thereby extending the operating time of IMDs and increasing the interval between recharge sessions while providing more power for therapeutic applications.
Implementation Method 1
An internal, or 'secondary' coil may be part of or otherwise electrically associated with the IMD. An external, or 'primary' coil is associated with the external power source or recharging device. According to one method, the recharging device drives the primary coil with an alternating current. This induces a current in the secondary coil through inductive coupling.
Implementation Method 2
A charging module within the implantable medical device may be used to control how this recharge occurs. According to one aspect, the charging module of the implantable medical device may utilize either a full-wave rectifier or a half-wave voltage-doubling (HWVD) rectifier to supply current to the rechargeable power source.
Data Source
AI summary
A charging system is disclosed. In one embodiment, the system includes a charging unit having a primary coil, and an implantable medical device comprising a secondary coil to receive charge from the primary coil. The implantable medical device further includes a half-wave voltage-doubling rectifier coupled to the secondary coil, a full-wave rectifier coupled to the secondary coil, and a rechargeable power source. Control logic is provided to periodically configure the rechargeable power source to receive charge from a selected one of the voltage-doubling circuit and the full-wave rectifier in a manner that increases rate at which charge is transferred from the secondary coil to the rechargeable power source. The control logic may configure the rechargeable power source to receive charge based on one or more monitored conditions which may include, for example, an indication of a current, a voltage, a coupling coefficient, back-scatter, and temperature.