Lead Passageway Seal Structure for Electrical Isolation Under Lead Movement
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Solution Overview
Problem
Existing seals in implantable medical devices fail to maintain effective electrical isolation during lead movement, allowing small amounts of body fluid to ingress and cause signal leakage, particularly when sensing small neurological signals amidst larger cardiac signals.
Innovation Solution
A seal design featuring radially extending protrusions that bend to create a cylindrical engagement with the lead body, allowing for lateral and off-axis movement while maintaining a sealed configuration, using a body with circumferential protrusions and depressions to accommodate lead insertion and movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal with circumferential protrusions is used to provide electrical isolation, then electrical isolation is improved, but the seal fails to accommodate lead movement causing fluid ingress
Solution Approach 1:
The seal incorporates a flexible membrane structure that can deform to accommodate radial and off-axis lead movements while maintaining the sealing function. The membrane acts as a compliant element that flexes with lead motion rather than creating rigid constraints, preventing fluid ingress pathways from forming during movement.
Solution Approach 2:
The seal transitions from a static rigid structure to a dynamic flexible membrane system that adapts its shape and position in response to lead movement. The membrane's ability to dynamically deform allows the seal to maintain electrical isolation reliability across various lead positions and movement states.
2Reliability
If the seal is made rigid to maintain sealing contact, then sealing effectiveness is improved, but lateral and off-axis lead movement is restricted
Solution Approach 1:
The flexible membrane replaces rigid sealing structures, allowing the lead to move laterally and off-axis while the membrane flexes to maintain continuous sealing contact. This eliminates the trade-off between sealing effectiveness and movement freedom by using material compliance rather than mechanical constraints.
Solution Approach 2:
The seal's physical parameters (flexibility, deformation capability) are changed to enable simultaneous achievement of effective sealing and movement accommodation. The membrane's elastic properties allow it to deform under lead movement forces while maintaining sealing pressure, resolving the contradiction between rigidity and flexibility.
3Reliability
If the seal protrusions are made to contact the lead body, then electrical isolation is improved, but signal leakage occurs when small neurological signals are sensed amidst larger cardiac signals
Solution Approach 1:
The flexible membrane creates a more uniform and consistent sealing interface that reduces signal leakage pathways. By maintaining reliable electrical isolation without creating rigid contact points, the membrane seal prevents cardiac signal contamination of neurological signals, improving measurement precision while maintaining electrical isolation.
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 seal effectively prevents signal leakage by maintaining contact with the lead body during radial and off-axis movements, enhancing electrical isolation and reducing fluid ingress, thus preserving signal integrity.
Implementation Method 1
a radially extending protrusion that the lead contacts upon insertion which causes the radially extending portion to bend and create a cylindrical shape that engages the lead body
Data Source
AI summary
Seals used within lead passageways of implantable medical devices for creating a seal to implantable medical leads inserted into the lead passageways include a body defining a lead passageway with an axial dimension. The body further defines a first circumferential protrusion extending radially a first distance into the lead passageway, and the body further defines a second circumferential protrusion separated from the first circumferential protrusion along the axial dimension. The second circumferential protrusion extends radially a second distance into the lead passageway, the second distance being less than the first distance. The body further defines a first circumferential depression immediately adjacent the first circumferential protrusion and between the first circumferential protrusion and the second circumferential protrusion.