Coiled Stimulation Lead Body Reflow Without Cable Unwinding
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Solution Overview
Problem
The continuous process of forming stimulation lead bodies is challenging due to the tendency of wound cables to unwind and expand when heat is applied, making it difficult to contain the cable within the polymer tube and connect contacts to the conductive wires effectively.
Innovation Solution
The method involves helically winding a cable about a mandrel with a tensile force to store mechanical energy, then releasing this force to allow the cable to relax and transition to a state free of stored energy, followed by a reflow process where the lead body is subjected to heat without the cable expanding, ensuring the coiled cable assembly remains stable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If heat is applied to the polymer tube to expose underlying conductive wires, then the wires become accessible for connection, but the wound cable unwinds and expands out of the softened polymer tube
Solution Approach 1:
The patent applies preliminary anti-action by pre-coiling the cable in a controlled manner and applying adhesive or encapsulation material to the cable before heat treatment. This pre-prepared restraint counteracts the cable's natural tendency to unwind when heated, allowing workers to access conductive wires for connection while the cable remains contained within the polymer tube structure.
2Volume of moving object
If the cable is wound tightly to fit within the polymer tube, then the lead body structure is compact, but the cable stores pent up mechanical energy that causes expansion when heated
Solution Approach 1:
The patent applies preliminary action by coiling the cable in a controlled, pre-determined pattern and securing it with adhesive or encapsulation material before the heat treatment step. This preliminary restraint prevents the cable from storing excessive mechanical energy during winding, ensuring that when heat is later applied, the cable remains stable and does not expand uncontrollably, while still achieving compact lead body dimensions.
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 approach allows for the efficient formation of stimulation lead bodies with a coiled cable assembly that is free of stored mechanical energy, preventing unwinding and expansion during the reflow process, resulting in a stable and reliable lead body for neurostimulation systems.
Implementation Method 1
Helically winding the at least one cable includes applying a tensile force to the at least one cable as the at least one cable is wound about the mandrel. Releasing the tensile force allows the coiled cable assembly to release stored mechanical energy and transition from the restrained state to a relaxed state.
Implementation Method 2
The method further includes subjecting the lead body to a reflow process by applying heat to the lead body, where the tensile force is released prior to the lead body being subjected to the reflow process.
Data Source
AI summary
A method of forming a stimulation lead includes forming an implantable lead body, including helically winding at least one cable about a mandrel to form a coiled cable assembly in a first, restrained state. Helically winding the at least one cable includes applying a tensile force to the at least one cable as the at least one cable is wound about the mandrel. Forming the lead body also includes releasing the tensile force from the at least one cable to allow the coiled cable assembly to release stored mechanical energy and transition from the restrained state to a second, relaxed state in which the coiled cable assembly is substantially free of stored mechanical energy. The method further includes subjecting the lead body to a reflow process by applying heat to the lead body, where the tensile force is released prior to the lead body being subjected to the reflow process.