Corrosion-Resistant Feedthrough Assembly for Implantable Devices
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Solution Overview
Problem
Implantable medical devices (IMDs) face challenges with corrosion due to interactions with electrolyte solutions like body fluids, which compromise the integrity of feedthrough assemblies and shorten their operational lifespan.
Innovation Solution
A feedthrough assembly for IMDs is designed with a housing, solid insert, conductive elements, metal filler, and a non-corrosive sealant, where the non-corrosive sealant, such as alumina or parylene, coats the metal filler to inhibit corrosion, and optionally covers the conductive elements and housing surfaces, enhancing corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the feedthrough assembly is miniaturized to reduce device size, then the device dimensions are improved, but the corrosion resistance deteriorates due to increased exposure to electrolyte solutions
Solution Approach 1:
A non-corrosive metal filler (such as tungsten or platinum) is introduced as an intermediary material between the conductive elements and the housing. This filler serves as a barrier that prevents direct contact between corrosive body fluids and the metal components, thereby maintaining corrosion resistance while allowing miniaturization of the overall device structure.
Solution Approach 2:
The feedthrough assembly employs composite construction by combining dissimilar materials (metal housing, ceramic or polymer solid insert, non-corrosive metal filler) with complementary properties. This multi-material approach allows each component to contribute its strengths: structural integrity from metal, electrical insulation from ceramic/polymer, and corrosion resistance from the non-corrosive filler, enabling miniaturization without sacrificing reliability.
2Reliability
If the feedthrough assembly uses traditional metal components to ensure electrical conductivity, then the electrical functionality is improved, but the operational lifespan deteriorates due to electrochemical reactions with body fluids
Solution Approach 1:
The non-corrosive metal filler acts as a mediator that maintains electrical continuity while protecting against corrosion. Materials like tungsten or platinum are selected for their exceptional corrosion resistance and electrical conductivity, allowing them to replace more susceptible metals in critical areas exposed to body fluids.
Solution Approach 2:
Different regions of the feedthrough assembly are assigned different material properties tailored to local requirements. The solid insert uses ceramic or polymer for insulation where needed, while the metal filler provides corrosion-resistant conductivity in areas exposed to electrolytes. This localized optimization extends operational lifespan without compromising overall electrical functionality.
3Ease of manufacture
If the feedthrough assembly uses a simple structure to reduce manufacturing complexity, then the manufacturing ease is improved, but the corrosion protection deteriorates
Solution Approach 1:
The feedthrough assembly is divided into discrete, functionally optimized segments: a housing component, a solid insert component, and a metal filler component. Each segment can be manufactured separately using appropriate processes for that material type, then assembled together. This segmentation allows specialized manufacturing techniques for each material while maintaining overall manufacturing feasibility.
Solution Approach 2:
The composite structure, while multi-component, follows a straightforward assembly sequence: placing the solid insert into the housing, positioning the metal filler in the central cavity, and sealing the assembly. This modular composite approach balances manufacturing ease with enhanced corrosion protection, as each material is optimized for its specific function rather than requiring complex processing of a single homogeneous material.
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 solution significantly enhances the corrosion resistance of IMD feedthrough assemblies, maintaining hermeticity and extending the operational lifespan of IMDs by protecting against electrochemical reactions with body fluids.
Implementation Method 1
The non-corrosive sealant, such as alumina or parylene, coats the metal filler to inhibit corrosion
Data Source
AI summary
A feedthrough assembly for an implantable medical device includes a housing, a solid insert, one or more conductive elements, a metal filler, and a non-corrosive sealant. The housing defines a central cavity through a height of the housing. The solid insert is disposed within the central cavity of the housing. The one or more conductive elements extend through one or more apertures defined within the solid insert and extend through the central cavity of the housing. The metal filler is disposed within a joint defined by an outer surface of the solid insert and an inner surface of the housing that defines the central cavity. The non-corrosive sealant coats a top surface of the metal filler to inhibit corrosion of the metal filler.