Hermetic Feedthrough Insulator with Rounded Corners

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Solution Overview

Problem

Hermetic feedthroughs for implantable medical devices face challenges in maintaining long-term biostability and hermeticity due to issues with fluid penetration and electrical conductivity, particularly when exposed to bodily fluids and varying temperatures.

Innovation Solution

A hermetic feedthrough design featuring a ceramic insulator with co-fired conductive conduits, where the insulator and conduits form a strong bond, and the corners are rounded to reduce stress concentrations, integrated with a ferrule for enhanced sealing and biocompatibility, using materials like alumina and platinum for durability and biostability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If sharp corners are present on the insulator, then manufacturing is easier, but stress concentrations occur leading to reduced reliability

Engineering Contradiction:

Improveinsulator fabricationVSAvoidhermetic seal integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The insulator is designed with rounded corners instead of sharp edges. This curvature eliminates stress concentration points that would otherwise form during thermal cycling and mechanical loading, preventing crack initiation and maintaining hermetic seal integrity over the long term while having minimal impact on the manufacturing process

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Reliability

If conventional sealing methods are used, then device complexity is reduced, but hermeticity cannot be maintained over long durations

Engineering Contradiction:

Improvelong-term hermeticityVSAvoidsealing structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The sealing function is merged into the insulator body itself through an integrated sealing structure that forms a hermetic seal between the insulator and the ferrule. This integrated approach eliminates the need for separate sealing components while achieving superior long-term hermeticity through the co-firing process that creates a monolithic structure

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The feedthrough utilizes a composite structure combining ceramic insulator material with metallic ferrule components. This composite design enables the formation of a hermetic seal through co-firing, where the ceramic and metal materials are bonded together to create a durable, long-term hermetic barrier against fluid penetration

Inventive Principle:

Principle #40Composite materials

3Adaptability or versatility

If biocompatible materials are selected, then implantability is improved, but biostability over long duration becomes challenging

Engineering Contradiction:

ImproveimplantabilityVSAvoidbiostability duration

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of stationary object

Solution Approach 1:

The feedthrough employs a composite construction using biocompatible ceramic materials for the insulator and biocompatible metallic materials for the ferrule and conduits. This composite material selection ensures both immediate biocompatibility for implantability and long-term biostability by resisting degradation, corrosion, and fluid penetration throughout the device's operational lifetime

Inventive Principle:

Principle #40Composite materials

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 ensures long-term biostability and hermeticity, preventing fluid ingress while maintaining high electrical conductivity, as demonstrated by successful immersion testing and thermal shock resistance, with improved durability and reduced risk of dye penetration and helium leak.

Implementation Method 1

The conduit and insulator have a co-fired bond therebetween, which hermetically seals the conduit with the insulator

Methodology Applied

Scientific EffectCo-firing:

Implementation Method 2

A rounded corner extends between adjacent edges of any two adjacent substantially flat surfaces. Each rounded corner between any two adjacent substantially flat surfaces that face toward the ferrule has an average radius that is less than approximately 25% of a length of the corresponding edges

Methodology Applied

Scientific EffectStress concentration reduction:

Data Source

PatentUS9008779B2Insulator for a feedthrough

Publication Date: 2015.04.14 KYOCERA CORP

AI summary

A hermetic feedthrough for an implantable medical device includes an insulator body and a ferrule. The insulator body includes ceramic material and one or more electrically conductive conduits extending through the insulator body. The insulator is disposed in an opening of the ferrule. The insulator body includes a plurality of substantially flat surfaces that each include a plurality of edges. A rounded corner extends between adjacent edges of any two adjacent substantially flat surfaces. Each corner between any two adjacent substantially flat surfaces that face toward the ferrule has an average radius that is less than approximately 25% of a length of the corresponding edges.