Implantable Connector Seal Lip Undercuts for Low Insertion Force
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Solution Overview
Problem
Implantable medical devices face challenges in achieving low insertion force while maintaining adequate sealing of body fluids due to the miniature size and flexibility of leads with multiple in-line contacts and seals, which can lead to buckling and difficulty in insertion, especially with modern neurostimulators using seven or more alternating contacts and seals.
Innovation Solution
The use of elastomeric seals with undercuts in the interior wall surface to increase the slenderness ratio of the seal lip, allowing for axial deflection and reduced insertion force, along with a method of forming an in-line header connector with alternating seals and contact elements and a common bore, where the seal lips deflect axially during lead insertion to minimize insertion force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple in-line contacts and seals are used to maintain adequate sealing of body fluids, then sealing reliability is improved, but insertion force increases causing lead buckling and difficulty in insertion
Solution Approach 1:
The seal lip is designed to dynamically deflect axially during lead insertion, transitioning from a rigid barrier to a flexible component that accommodates the lead while maintaining sealing. This dynamic behavior allows the seal to reduce insertion force while preserving sealing reliability against body fluids.
Solution Approach 2:
The seal geometry is modified by adding undercuts to increase the slenderness ratio of the seal lip to at least 2:1 length to width. This parameter change enables the seal lip to deflect axially, transforming the sealing mechanism from radial compression to axial deflection, thereby reducing insertion force while maintaining sealing effectiveness.
2Reliability
If seal lip is made thicker to provide adequate sealing force, then sealing capability is improved, but insertion force increases
Solution Approach 1:
The seal lip geometry is transformed from a thick, radially-compressing structure to a slender, axially-deflecting structure with a slenderness ratio of at least 2:1. This parameter change allows the seal to maintain adequate sealing capability through axial deflection rather than radial thickness, thereby reducing insertion force.
Solution Approach 2:
The sealing mechanism transitions from radial dimension (thickness) to axial dimension (deflection). The seal lip's primary sealing action moves from radial compression to axial deflection, utilizing a different dimensional approach to achieve sealing while reducing insertion force.
3Adaptability or versatility
If lead diameter is reduced to miniature size for flexibility, then lead flexibility is improved, but insertion force decreases control and increases buckling risk
Solution Approach 1:
The seal lip slenderness ratio is increased to at least 2:1, changing the mechanical parameters of the sealing interface. This allows the seal to work effectively with miniature leads by providing controlled axial deflection that guides the lead through without excessive buckling, maintaining insertion force control despite the lead's small diameter.
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 effectively reduces the insertion force required for implantable medical devices, ensuring low force insertion and adequate sealing against body fluids, even with multiple contacts and seals, thereby facilitating easier implantation and preventing buckling.
Implementation Method 1
an elastomeric seal for use in an in-line header connector between electrical contacts tailored geometrically to provide adequate sealing of body fluids, the seal comprising undercuts in an interior wall surface to increase a slenderness ratio of a seal lip to at least 2:1 length to width
Data Source
AI summary
Aspects of the disclosed embodiments are directed toward specialized seals necessary between electrical connectors as used in Implantable Pulse Generators (IPG's) and other implantable connectors, the seals comprising a seal lip and undercuts in an interior wall surface to increase a length to width ratio of the seal lip to at least 2:1.