Transformer Charging Circuits for Implantable Medical Devices
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Solution Overview
Problem
Subcutaneous implantable cardioverter defibrillators (ICDs) face challenges in generating sufficient energy levels to deliver appropriate therapy due to the placement of leads and electrodes outside the heart, requiring circuitry and techniques to enhance electrical stimulation therapy output.
Innovation Solution
The implementation of a multi-cell power source system with a transformer configuration, including primary and secondary windings magnetically coupled around a core, and a capacitor array coupled to the secondary windings, to generate higher voltage or current for electrical stimulation therapy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If leads and electrodes are placed subcutaneously outside the heart, then the device structure is simplified and implantation is easier, but the energy levels required for effective defibrillation therapy cannot be achieved
Solution Approach 1:
The patent divides the power delivery system into multiple independent capacitor banks (first capacitor bank, second capacitor bank, third capacitor bank) that can be charged and discharged separately. This segmentation allows the device to accumulate sufficient energy through multiple capacitor units while maintaining the simplified subcutaneous implantation structure.
Solution Approach 2:
The patent combines multiple capacitor banks with a transformer to create a unified energy amplification system. The capacitors are charged in parallel from the battery, then the transformer steps up the voltage to deliver high-energy defibrillation shocks, merging the advantages of simple capacitor charging with high-voltage output capability.
2Device complexity
If a single battery is used to power the device, then the power source structure is simple, but the battery cannot directly provide sufficient voltage for defibrillation therapy
Solution Approach 1:
The patent introduces a transformer as an intermediary device between the battery and the output electrodes. The transformer receives low-voltage input from the battery (through the capacitor banks) and converts it to high-voltage output suitable for defibrillation therapy, acting as a mediator that bridges the voltage gap without requiring a complex multi-cell battery system.
Solution Approach 2:
The patent charges multiple capacitor banks in advance from the battery before defibrillation is needed. This preliminary charging action stores energy in the capacitors at manageable voltage levels, allowing the system to quickly deliver high-voltage shocks when required without needing the battery to directly provide defibrillation-level voltage.
3Power
If multiple capacitor banks are used to store energy, then sufficient energy levels can be achieved, but the circuit complexity increases
Solution Approach 1:
The patent designs the capacitor banks and transformer to serve multiple functions: the capacitor banks both store energy and provide voltage multiplication through the transformer, the transformer both steps up voltage and isolates the battery from high-voltage output, and the system can deliver both defibrillation shocks and cardioversion therapy. This multi-functionality reduces the need for separate dedicated components for each function.
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 configuration enables the delivery of effective electrical stimulation therapy with higher voltage or current than directly available from the battery, addressing the energy generation challenges in SubQ ICD systems.
Implementation Method 1
a transformer, including primary and secondary windings magnetically coupled around a core
Data Source
AI summary
An implantable medical device includes a low-power circuit, a high-power circuit, and a dual-cell power source. The power source is coupled to a transformer having first and second primary windings, each of which is selectively coupled to the power source and a plurality of secondary windings that are magnetically coupled to the first and second primary windings. The plurality of secondary windings are interlaced along a length of each of the secondary windings. Each of the plurality of secondary transformer windings is coupled to a capacitor, and the capacitors are all connected in a series configuration. The low power circuit is coupled to the power source and issues a control signal to control the delivery of charge from the power source to the plurality of capacitors through the first and second transformers.