Co-Axial Glass-to-Metal Seal Feedthrough for Miniaturized Cell Lids
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Solution Overview
Problem
Modern electrochemical cell designs for implantable medical devices face challenges in accommodating a case-neutral configuration with two glass-to-metal seals, which requires a larger casing lid, making it difficult to miniaturize while maintaining hermeticity and functionality.
Innovation Solution
A co-axial glass-to-metal seal design featuring a terminal pin electrically isolated from an inner ferrule by insulating glass, which is itself supported by an outer ferrule, allowing for a single terminal pin connection to either the anode or cathode, with both ferrules being electrically isolated from the terminal pin and each other, enabling a compact case-neutral design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a case-neutral cell design with two glass-to-metal seals is used, then hermeticity and electrical isolation are maintained, but the casing lid size increases, preventing miniaturization
Solution Approach 1:
The patent applies nesting by placing one glass-to-metal seal inside another, creating a co-axial configuration where an inner GTMS is nested within an outer GTMS. This allows both seals to occupy the same spatial footprint on the casing lid, enabling hermetic sealing and electrical isolation without increasing the overall lid area, thus resolving the contradiction between maintaining reliability and enabling miniaturization.
Solution Approach 2:
The invention transitions from a planar arrangement of two separate GTMSs to a three-dimensional co-axial configuration. By utilizing the vertical dimension and nesting one seal within another, the design achieves the required electrical isolation and hermeticity while reducing the horizontal footprint on the casing lid, thereby enabling device miniaturization without compromising sealing reliability.
2Volume of moving object
If a co-axial glass-to-metal seal design is used, then miniaturization is enabled, but manufacturing complexity increases
Solution Approach 1:
The patent divides the sealing system into two distinct but integrated segments: an inner glass-to-metal seal and an outer glass-to-metal seal. Each segment can be manufactured and prepared separately, then assembled together in a co-axial configuration. This segmentation allows for standardized manufacturing processes for each seal while achieving the compact co-axial structure, thus enabling miniaturization without excessively increasing manufacturing complexity.
3Reliability
If two separate glass-to-metal seals are used in case-neutral design, then electrical isolation is achieved, but the casing lid must be larger to accommodate both seals
Solution Approach 1:
The patent implements nesting by positioning one glass-to-metal seal concentrically within the other, creating a co-axial arrangement. This allows both seals to maintain their electrical isolation function while occupying the same radial footprint on the casing lid. The nested configuration ensures that the inner and outer seals remain electrically isolated while minimizing the overall area required on the lid, thus resolving the contradiction between maintaining electrical isolation and reducing lid size for miniaturization.
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 co-axial design achieves hermetic sealing, sufficient electrical isolation, and thermal durability, allowing for the miniaturization of electrochemical cells without compromising functionality, while meeting the requirements of corrosion resistance and weldability for the materials used.
Implementation Method 1
The outer ferrule is welded into an opening in the cell casing
Implementation Method 2
The insulating glass seals around the perimeter of a terminal pin and the ferrule supports the insulating glass in a surrounding relationship
Implementation Method 3
A glass-to-metal seal is considered critical because it hermetically isolates the internal environment of a component from the external environment to which the component is exposed
Data Source
AI summary
A case-neutral electrochemical cell has an electrode assembly comprising a separator positioned between an anode and a cathode housed inside a casing. The casing supports a co-axial glass-to-metal seal comprising an inner insulating glass hermetically sealed to a terminal pin and to the inner surface of a first or inner ferrule. An outer insulating glass is hermetically sealed to the outer surface of the inner ferrule and the inner surface of a second or outer ferrule, and the outer ferrule is secured to an opening in the casing. Then, one of the anode and the cathode is connected to the terminal pin and the other of the anode and the cathole is connected to the first or inner ferrule. An electrolyte is provided in the casing to activate the electrode assembly.