Conductive Adhesive Composition for Low-Temperature Implant Assembly

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Solution Overview

Problem

Current electrical connections in active implantable medical devices face challenges such as durability, biocompatibility, and the limitations of high-temperature assembly processes, which can lead to material fractures and reduced device lifetime, especially with the trend towards miniaturization.

Innovation Solution

An electrically conductive adhesive comprising a (meth)acrylate monomer, a biocompatible polymer, a biocompatible metal with a median particle size below 50 μm, and a polymerization initiator, which forms a conductive matrix suitable for connecting electronic parts in implantable medical devices under mild conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If welding or brazing processes are used to create electrical connections, then electrical connection reliability is improved, but high temperature causes material fractures and reduces device lifetime

Engineering Contradiction:
Improveelectrical connection reliabilityVSAvoiddevice lifetime
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The invention changes the temperature parameter from high (welding/brazing) to low (room temperature or mild heating), enabling electrical connections without thermal damage to surrounding materials. The adhesive composition is specifically designed to cure at low temperatures, transforming the processing conditions to avoid material fractures while maintaining connection reliability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention replaces the mechanical/thermal joining processes (welding, brazing) with a chemical bonding process using electrically conductive adhesive. This substitution eliminates the need for high temperature and mechanical stress during assembly, preventing microfractures in ceramic/metal composite feedthroughs while providing reliable electrical connections.

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

2Ease of manufacture

If mechanically fastening electrical components is used, then assembly is simplified, but connection durability decreases due to fatigue risk

Engineering Contradiction:
Improveassembly simplicityVSAvoidconnection durability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The invention merges the mechanical bonding function with electrical conductivity in a single adhesive material. The electrically conductive adhesive simultaneously provides mechanical attachment and electrical connection, eliminating the need for separate mechanical fasteners and reducing fatigue risks associated with mechanical connections.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention uses a composite material system consisting of adhesive matrix combined with electrically conductive filler particles. This composite provides both the mechanical properties needed for durable bonding and the electrical conductivity required for signal/ power transmission, creating a single integrated solution that avoids mechanical fatigue.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If conventional adhesives are used, then manufacturing is simplified, but electrical conductivity is insufficient for medical implant applications

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidelectrical conductivity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The invention creates an electrically conductive composite adhesive by dispersing conductive filler particles (such as metal powders or conductive carbon materials) within an adhesive matrix. This composite structure maintains the ease of application and bonding characteristics of conventional adhesives while introducing sufficient electrical conductivity for medical implant applications.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention applies local quality by concentrating electrical conductivity in specific regions through the distribution of conductive filler particles within the adhesive. The adhesive matrix provides bonding functionality while the locally distributed conductive particles provide electrical pathways, achieving both manufacturing simplicity and electrical reliability.

Inventive Principle:
Principle #3Local quality

4Strength

If high temperature processing is used, then electrical connection strength is improved, but biocompatibility is compromised due to material degradation

Engineering Contradiction:
Improveconnection strengthVSAvoidbiocompatibility
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The invention changes the curing temperature parameter from high temperature to low temperature processing. The adhesive formulation is specifically designed to achieve adequate bond strength at low temperatures through optimized chemistry and filler content, eliminating thermal damage to biocompatible materials while maintaining connection strength.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a single-shot adhesive application that cures at low temperature to create permanent bonds, replacing processes that require high temperature. This approach sacrifices the extreme heat resistance of welding but gains biocompatibility and suitability for sensitive medical implant materials, achieving adequate strength without thermal degradation.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 adhesive provides a durable, biocompatible, and reliable electrical connection suitable for miniaturized medical devices, reducing the risk of material failure and enabling long-term use within the body while avoiding high-temperature assembly limitations.

Implementation Method 1

an electrically conductive adhesive comprising a) a (meth)acrylate monomer, b) a polymer being soluble in the (meth)acrylate monomer, c) a biocompatible metal having a median particle size d50 of below 50 μm, and d) a polymerization initiator

Methodology Applied
Scientific EffectPolymerization: Photopolymerisation

Data Source

PatentEP3940035B1Electrically conductive adhesive
Publication Date: 2023.10.18 HERAEUS MEDEVIO GMBH & CO KG

AI summary

The present invention refers to an electrically conductive adhesive comprising a) a (meth)acrylate monomer, b) a polymer being soluble in the (meth)acrylate monomer, c) a biocompatible metal having a median particle size d50 of below 50 µm, and d) a polymerization initiator. The present invention also refers to a kit for preparing an electrically conductive adhesive, to an implantable medical device comprising such an electrically conductive adhesive, or a cured form thereof, and to the use of such an electrically conductive adhesive.