Hermetically Sealed Wet Electrolytic Capacitor for Implantable Devices
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Solution Overview
Problem
Existing capacitors for implantable devices, such as cardioverter defibrillators, face challenges in being compact, reliable, and capable of rapid electrical charging and efficient energy delivery.
Innovation Solution
A hermetically sealed wet electrolytic capacitor with a cathode made from a metal substrate having a noble metal alloy layer and an electrolytic solution with specific conductivity, designed for efficient energy storage and delivery, is developed. The capacitor includes a hermetically sealed case with terminals connected to the anode and cathode, and an insulator between them, allowing for high performance and reliability in a small size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the capacitor size is reduced to fit within limited ICD volume, then the volume is reduced, but the energy delivery capability and reliability may deteriorate
Solution Approach 1:
The patent implements a nested structure where the cathode is positioned inside the anode, creating a concentric cylindrical arrangement. This nesting allows both electrodes to occupy the same radial space, significantly reducing the overall capacitor volume while maintaining sufficient electrode surface area for reliable energy storage and delivery in implantable cardioverter defibrillators
Solution Approach 2:
The patent transitions from a planar electrode arrangement to a three-dimensional concentric cylindrical structure. By utilizing the radial dimension and creating nested cylinders, the design maximizes electrode surface area within a compact volume, enabling high energy density and reliable performance in a small form factor suitable for ICD implantation
2Power
If the capacitor is designed for rapid electrical charging and high energy delivery, then the power and energy capability are improved, but the size and complexity increase
Solution Approach 1:
The patent employs porous nickel as the cathode material and porous tantalum as the anode material. These porous structures provide extremely high surface area to volume ratios, enabling rapid charge acceptance and efficient energy delivery. The porous morphology increases the effective electrode surface area by orders of magnitude, allowing high power capability in a compact volume suitable for implantable devices
Solution Approach 2:
The patent utilizes composite electrode structures combining porous nickel with conductive coatings, and porous tantalum with oxide layers. These composite materials provide both high surface area for energy storage and excellent electrical conductivity for rapid charging. The combination of porous substrate materials with conductive surface treatments optimizes both power density and volumetric 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
The capacitor effectively delivers at least 80% of stored energy, ensuring reliable operation in implantable devices by providing rapid charging and sufficient energy pulses to restore heart function, while being compact enough to fit within limited device volumes.
Implementation Method 1
an electrolytic solution having a conductivity between 10 and 60 mS/cm
Implementation Method 2
a cathode, an anode, an electrical insulator between the anode and the cathode and an electrolytic solution
Data Source
AI summary
Methods of manufacturing a hermetically sealed wet electrolytic capacitor and a hermetically sealed wet electrolytic capacitor are described. A method of manufacturing a wet electrolytic capacitor includes forming a cathode of the capacitor by forming a case comprising a metal substrate, the metal substrate having an alloyed surface, depositing a smooth film comprising palladium and copper as a tacking layer on the alloyed surface of the metal substrate, and depositing a rough, high surface area layer on the tacking layer to achieve a high capacitance cathode. A first terminal is electrically connected to the cathode. An anode is formed. A second terminal is electrically connected to the anode. An electrolytic solution is disposed within the case, and the case is hermetically sealed.