Thermoplastic Sheath Fusion for Medical Cable Connections

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Solution Overview

Problem

Current methods for producing flexible medical electrodes and catheters face challenges in creating durable, reliable, and cost-effective electrical connections, particularly for longer lengths, which often require assembly of multiple sections and use of non-biocompatible materials.

Innovation Solution

A method involving thermally fusing semi-finished products with specially shaped connection points, where the conductor is partially exposed and embedded in a thermoplastic sheath, allowing for a permanent and inseparable electrical connection without additional materials, using a key-lock principle and ultrasonic treatment to ensure a hermetically sealed joint.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If multiple cable sections are assembled to achieve longer lengths, then the required cable length is increased, but the electrical connection reliability deteriorates due to additional connection points and potential use of non-biocompatible materials

Engineering Contradiction:
Improvecable section lengthVSAvoidelectrical connection reliability
Core Design Contradiction:
Length of moving objectVSReliability

Solution Approach 1:

The cable is divided into modular semi-finished products with standardized connection points that can be assembled to achieve desired lengths. Each segment contains conductors embedded in biocompatible insulating material with exposed contact surfaces designed for reliable connection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple cable sections are permanently joined through thermal fusion of thermoplastic materials at connection points, creating a unified structure that maintains electrical reliability and biocompatibility across the entire assembled cable length.

Inventive Principle:
Principle #5Merging (Combining)

2Ease of manufacture

If conventional connection methods are used to join cable sections, then the manufacturing cost is reduced, but the electrical resistance increases due to transition resistance at connection points

Engineering Contradiction:
Improvemanufacturing costVSAvoidelectrical resistance
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The mechanical connection process is replaced with thermal fusion that directly bonds the thermoplastic insulating materials together, creating a seamless connection that eliminates traditional mechanical connectors and reduces transition resistance.

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

Solution Approach 2:

The connection process utilizes controlled thermal parameters to melt and fuse the thermoplastic materials at connection points, transforming the physical state of the material to create a low-resistance electrical pathway while maintaining structural integrity.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If biocompatible materials are used for all components, then the safety for intracorporeal use is improved, but the available connection methods are limited

Engineering Contradiction:
ImprovebiocompatibilityVSAvoidconnection method options
Core Design Contradiction:
Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The insulating material surrounding the conductors is made from homogeneous biocompatible thermoplastic material throughout the entire cable structure, including at connection points, ensuring uniform biocompatibility while enabling thermal fusion connection methods.

Inventive Principle:
Principle #33Homogeneity

Solution Approach 2:

The cable structure combines conductive metal elements with biocompatible thermoplastic insulating material to create a composite structure that maintains electrical functionality while ensuring biocompatibility and enabling thermal fusion for connections.

Inventive Principle:
Principle #40Composite materials

4Duration of action of stationary object

If additional materials are used to create connections, then the connection durability is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improveconnection durabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The thermoplastic insulating material serves dual functions: it provides electrical insulation and acts as the bonding agent for connections through thermal fusion, eliminating the need for separate connection materials or additional manufacturing steps.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The thermoplastic material performs multiple functions including insulation, structural support, and connection medium, simplifying the overall manufacturing process by eliminating the need for separate materials dedicated to each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 method enables reliable, cost-effective, and biocompatible electrical connections for medical devices, allowing for longer cable sections without increasing electrical resistance, and maintains mechanical integrity through a tightly enclosing plastic body.

Implementation Method 1

c) Thermal fusing of the thermoplastic material in the area of the joints

Methodology Applied
Scientific EffectThermal fusion: Melting

Implementation Method 2

using a key-lock principle and ultrasonic treatment to ensure a hermetically sealed joint

Methodology Applied
Scientific EffectUltrasonic treatment: Ultrasonic Vibration

Data Source

PatentEP3207956B1Method for producing an electrode lead or a catheter
Publication Date: 2018.09.05 BIOTRONIK SE & CO KG
  • EP3207956B1 patent drawingFigure 1~2
  • EP3207956B1 patent drawingFigure 3~4
  • EP3207956B1 patent drawingFigure 5~6

AI summary

The invention relates to a method for manufacturing a medical electrode lead or catheter and an associated semi-finished product (10). The semi-finished product (10) comprises a cable (12) with at least one electrical conductor (16) embedded in a sheath (18) made of an electrically insulating thermoplastic material. It is characterized in that the cable (12) forms a connection point (20) at at least one cable end (14) via which the conductor (16) can be permanently and inseparably connected to other components, wherein: - a portion of the surface of the conductor (16) is exposed in the region of the connection point (20) and forms a contact surface, and - the sheath (18) has a recess (22) extending longitudinally along the cable (12) in the region of the connection point (2).