Medical Lead Boot Dual-Polymer Strain Relief and Seal
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Solution Overview
Problem
Existing electrical leads for implantable medical devices face challenges in achieving a leak-free seal while maintaining a low insertion force, leading to difficulties in coupling the leads to the pulse generator, which can result in leaks, internal electrical shorts, and reduced therapy effectiveness.
Innovation Solution
The use of a lead boot with a strain relief portion made from a first elastic polymer and a seal portion made from a second elastic polymer, where the hardness and coefficient of friction of the polymers are optimized to provide axial strength and compliance, respectively, allowing for a leak-free seal and reduced insertion force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single elastic polymer is used for both strain relief portion and seal portion, then manufacturing is simpler, but the seal may leak resulting in internal electrical shorts
Solution Approach 1:
The lead boot is segmented into two distinct portions: a strain relief portion and a seal portion. Each portion is formed from a different elastic polymer optimized for its specific function. The strain relief portion uses a first elastic polymer with higher hardness for mechanical strength, while the seal portion uses a second elastic polymer with lower hardness and lower coefficient of friction for optimal sealing. This segmentation allows each portion to independently perform its function without compromising the other.
Solution Approach 2:
Different regions of the lead boot are assigned different material properties to optimize local performance. The strain relief portion is made from a first elastic polymer with specific hardness characteristics for mechanical support, while the seal portion is made from a second elastic polymer with different hardness and friction characteristics for sealing. This local differentiation of material properties ensures that each region has the optimal characteristics for its specific function.
2Strength
If a harder elastic polymer is used for strain relief portion, then axial strength is improved, but insertion force increases making it difficult to couple
Solution Approach 1:
The lead boot is divided into two portions with different material properties. The strain relief portion uses a first elastic polymer with higher hardness for axial strength, while the seal portion uses a second elastic polymer with lower hardness and lower coefficient of friction. This segmentation allows the strain relief portion to provide necessary mechanical strength without requiring the entire boot to be made from hard material, thus reducing overall insertion force.
Solution Approach 2:
The strain relief portion is specifically engineered with a first elastic polymer that has optimal hardness for providing axial strength and mechanical support. The seal portion uses a second elastic polymer with different properties optimized for sealing and low friction. This local optimization allows the strain relief portion to be hard where needed for strength while the seal portion remains soft for easy insertion.
3Reliability
If a softer elastic polymer is used for seal portion, then seal compliance is improved, but axial strength of the boot is reduced
Solution Approach 1:
The lead boot is segmented into a strain relief portion and a seal portion, each made from different elastic polymers. The seal portion uses a second elastic polymer with lower hardness for optimal compliance and sealing, while the strain relief portion uses a first elastic polymer with higher hardness to compensate for the reduced axial strength. This segmentation allows the seal portion to be soft for compliance while the overall boot maintains sufficient strength through the strain relief portion.
Solution Approach 2:
The seal portion is locally optimized with a second elastic polymer that has lower hardness and lower coefficient of friction for maximum compliance and sealing effectiveness. The strain relief portion is locally optimized with a first elastic polymer that has higher hardness to provide the necessary axial strength. This local differentiation allows each portion to have optimal properties for its specific function.
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 a reliable, leak-free seal and low insertion force, enhancing the ease of use and effectiveness of the electrical lead connection, thereby ensuring consistent therapy delivery and extended product life.
Implementation Method 1
The strain relief portion is formed of a first elastic polymer and the seal portion is formed of a second elastic polymer
Data Source
AI summary
An implantable medical electrical lead connectable to an electrical header of an implantable medical device includes a lead body extending from a proximal end to a distal end, a lead terminal disposed at the proximal end of the lead body and configured to couple the lead to the electrical header, and a lead boot disposed at the lead terminal. The lead boot includes a strain relief portion and a seal portion. The strain relief portion is formed of a first elastic polymer and the seal portion is formed of a second elastic polymer. The first elastic polymer is different from the second elastic polymer.