Implantable Optical Lead Connector Hermetic Seal

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Solution Overview

Problem

Existing implantable medical devices face challenges in forming reliable hermetic seals for optical feedthroughs, which are crucial for maintaining the integrity of optical connections and preventing fluid ingress, especially when subjected to thermal expansion mismatches between materials.

Innovation Solution

The implementation of a solid state light source within a hermetic housing of an implantable medical device, coupled with an optical lead connector receptacle that includes an optical feedthrough, allows for both optical and electrical coupling, utilizing a hermetic seal formed via brazing or diffusion bonding to secure the optical fiber, ensuring a secure and reliable connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional brazing or diffusion bonding processes are used to form hermetic seals, then reliable sealing is achieved, but the device is subjected to high thermal expansion stresses that may cause seal failure

Engineering Contradiction:
Improvehermetic seal reliabilityVSAvoidthermal expansion stress
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the fundamental parameter of seal formation from thermal processes (brazing/diffusion bonding at high temperatures) to a mechanical cold-welding process. This eliminates thermal expansion stresses while maintaining hermetic seal reliability through direct metal-to-glass contact and cold welding of the ferrule to the optical feedthrough.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the thermal-field-based sealing mechanism (brazing/diffusion bonding) with a mechanical-based cold-welding mechanism. The mechanical press-fitting and cold-welding process directly joins the ferrule to the optical feedthrough without thermal input, eliminating the harmful thermal expansion effects while achieving reliable hermetic sealing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If hermetic seals are formed using high-temperature processes, then secure optical fiber attachment is achieved, but the optical alignment precision may be compromised due to thermal distortion

Engineering Contradiction:
Improveoptical fiber securityVSAvoidoptical alignment precision
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent changes the temperature parameter from high-temperature thermal processes to room-temperature mechanical cold-welding. This eliminates thermal distortion that would compromise optical alignment precision while maintaining secure optical fiber attachment through the mechanical press-fitting and cold-welding of the ferrule assembly.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If complex hermetic sealing processes are used, then reliable hermetic seals are formed, but the manufacturing complexity and time increase

Engineering Contradiction:
Improvehermetic seal integrityVSAvoidsealing process complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces complex multi-step thermal sealing processes (brazing or diffusion bonding requiring furnaces, temperature control, and extended time) with a simple mechanical cold-welding process. This involves press-fitting the ferrule into the optical feedthrough and allowing cold welding to occur at room temperature, dramatically simplifying manufacturing while maintaining hermetic seal integrity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

This configuration enables precise and reliable optical stimulation and sensing, reducing the risk of hermetic seal failure due to thermal expansion and providing a secure interface for both light and electrical therapies, enhancing the device's performance and longevity.

Implementation Method 1

The hermetic seal has been formed by way of a co-firing, diffusion bonding or brazing process

Methodology Applied
Scientific EffectBrazing: Brazing

Implementation Method 2

The hermetic seal has been formed by way of a co-firing, diffusion bonding or brazing process

Methodology Applied
Scientific EffectDiffusion bonding: Diffusion Welding

Implementation Method 3

a solid state light source is disposed within the hermetic cavity and optically coupled to the lead connector receptacle

Methodology Applied
Scientific EffectLight emission: Light Emitting Diode

Data Source

PatentEP3134180B1Implantable device with optical lead connector
Publication Date: 2019.10.02 MEDTRONIC INC
  • EP3134180B1 patent drawingFigure 1
  • EP3134180B1 patent drawingFigure 2~4
  • EP3134180B1 patent drawingFigure 5~6

AI summary

An implantable active medical device includes a housing defining a hermetic cavity, a lead connector receptacle extending into the implantable active medical device, and a solid state light source disposed within the hermetic cavity and optically coupled to the lead connector receptacle.