Feedthrough Glass Seal Composition for Implantable Devices
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Solution Overview
Problem
Existing feedthrough assemblies for implantable medical devices face challenges such as the need for forming weights in construction, limited minimum size, and susceptibility to erosion by body fluids, which affect performance over time.
Innovation Solution
The development of glass insulating members and preforms with specific compositions, including 30% B2O3, 30-40% of CaO, MgO, or SrO, 5% La2O3, 10% SiO2, and 15% Al2O3, used in feedthrough assemblies to create a ferrule, insulating structure, and glass seal, which reduces tensile stress and enhances durability and compatibility with body fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional insulating members (e.g., Ta-23 glass, Cabal-12 glass) are used in feedthrough assemblies, then the feedthrough can be constructed, but the insulating member is susceptible to reaction with body fluids causing erosion and performance degradation over time
Solution Approach 1:
The patent modifies the chemical composition parameters of the glass insulating member by specifying precise ranges of oxides (B2O3: 30-40%, SiO2: 5-15%, Al2O3: 10-20%, CaO: 5-20%, MgO: 5-20%, SrO: 5-20%, BaO: 5-20%, La2O3: 2-10%) to create a glass formulation that is chemically resistant to body fluids while maintaining mechanical properties and hermetic sealing capabilities
Solution Approach 2:
The patent creates a composite glass material combining multiple oxide components in specific proportions to achieve both chemical inertness against body fluids and mechanical durability, resulting in a hermetic seal that resists erosion and maintains performance over time in implantable medical devices
2Ease of manufacture
If forming weights are used in feedthrough construction, then the assembly can be manufactured, but the production process is complicated and the minimum feedthrough size is limited
Solution Approach 1:
The patent eliminates the need for forming weights by modifying the glass composition to achieve proper filling and sealing through chemical and physical properties of the glass material itself, thereby simplifying the manufacturing process and removing the constraint on minimum feedthrough size
Solution Approach 2:
By adjusting the glass composition parameters (particularly adding lower melting point oxides and modifying viscosity characteristics), the patent enables the glass to self-fill and self-seal the feedthrough assembly without requiring external forming weights, simplifying manufacturing
Data Source
AI summary
A feedthrough assembly includes a ferrule, an insulating structure, at least one terminal pin and a glass seal that fixedly secures the insulating structure within the ferrule. The insulating structure has a top portion, a bottom portion, and an inner diameter portion. The inner diameter portion defines at least one aperture extending from the top portion to the bottom portion of the insulating structure. The at least one terminal pin extends through the at least one aperture. The glass seal comprises about 30% B2O3, about 30% to about 40% of a member selected from the group consisting of CaO, MgO, SrO, and combinations thereof, with the proviso that the individual amounts of CaO and MgO are each not greater than about 20%, about 5% La2O3, about 10% SiO2, and about 15% Al2O3, wherein all percentages are mole percentages.