Lead Passageway Seal Geometry for Fluid Ingress and Signal Leakage
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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 large 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
1Ease of manufacture
If a seal with a simple open center is used to allow lead insertion, then ease of manufacture and simplicity are improved, but the seal cannot maintain effective electrical isolation during lead movement, allowing fluid ingress and signal leakage
Solution Approach 1:
The seal is segmented into multiple circumferential protrusions (first, second, third protrusions) that can independently deform and contact the lead body at different locations. This segmentation allows each protrusion to function as an independent sealing element, maintaining electrical isolation even when the lead moves radially or off-axis, while keeping the overall structure manufacturable.
Solution Approach 2:
The seal incorporates dynamic elements that can deform and adapt to lead movement. The circumferential protrusions are designed to bend and follow the lead body during radial and off-axis movements, maintaining continuous contact and sealing. This dynamic behavior ensures reliable electrical isolation throughout the lead's range of motion without requiring a complex rigid structure.
2Reliability
If the seal is designed to be rigid to maintain sealing contact, then electrical isolation is improved, but the seal cannot accommodate lateral and off-axis movement of the lead
Solution Approach 1:
The seal transitions from a rigid structure to a dynamic one where circumferential protrusions can bend and deform. These protrusions are designed to flex and follow the lead body during radial and off-axis movements, maintaining sealing contact throughout the lead's range of motion. This dynamic design simultaneously achieves reliable electrical isolation and accommodates lead movement.
Solution Approach 2:
The seal's physical parameters (shape, position of protrusions) change in response to lead movement. The circumferential protrusions alter their configuration dynamically, bending and repositioning themselves to maintain contact with the lead body as it moves. This parameter change allows the seal to adapt to different lead positions while maintaining effective electrical isolation.
3Reliability
If multiple circumferential protrusions are added to the seal body, then sealing reliability during movement is improved, but device complexity increases
Solution Approach 1:
The seal is divided into multiple circumferential protrusions that are strategically positioned at different locations around the lead passageway. Each protrusion serves as an independent sealing element, ensuring that if one protrusion loses contact during lead movement, others maintain the seal. This segmentation approach improves reliability without requiring an overly complex multi-component structure.
Solution Approach 2:
The multiple circumferential protrusions serve multiple functions simultaneously: they provide sealing contact, accommodate radial movement, accommodate off-axis movement, and maintain electrical isolation. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving improved sealing reliability.
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.