Cannula Seal Assembly With Anti-Inversion Wiper Seal
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Solution Overview
Problem
Current cannula seals for minimally invasive surgery are prone to punctures and tears, require multiple seals for different instrument shaft diameters, cause high friction and inaccurate instrument control, and are costly to manufacture and assemble.
Innovation Solution
A wiper seal design with a thicker sealing portion and flexible flex portion that accommodates a range of shaft diameters, provides asymmetric friction during insertion and withdrawal, and includes an instrument guide to prevent inversion and damage, while using a single latch for secure attachment to the cannula.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a thin-membrane septum-type wiper seal is used, then the seal can accommodate various instrument shaft diameters, but it is prone to punctures and tears during instrument insertion
Solution Approach 1:
The wiper seal employs local quality by having a thicker sealing portion and a thinner flex portion with different properties. The thicker sealing portion provides puncture and tear resistance where the instrument shaft contacts the seal, while the thinner flex portion maintains flexibility for accommodating various shaft diameters. This localized differentiation resolves the contradiction between durability and adaptability.
Solution Approach 2:
The wiper seal is constructed as a composite structure combining a thicker sealing portion and a thinner flex portion, effectively creating a composite material solution. This composite design allows the seal to simultaneously achieve high strength where needed (sealing portion) and high flexibility where needed (flex portion), resolving the contradiction between puncture resistance and adaptability to various shaft diameters.
2Ease of manufacture
If a single wiper seal design is used for all instrument shaft diameters, then manufacturing costs are reduced, but friction against the instrument shaft increases
Solution Approach 1:
The wiper seal uses local quality by creating different structural zones: a thicker sealing portion for durability and a thinner flex portion for reduced friction. This localized differentiation allows a single seal design to accommodate various shaft diameters with acceptable friction levels while maintaining manufacturing simplicity, resolving the contradiction between ease of manufacture and ease of operation.
3Ease of operation
If the wiper seal is allowed to move freely during instrument withdrawal, then friction is reduced, but the seal may invert and become damaged
Solution Approach 1:
The instrument insertion guide applies preliminary anti-action by providing a guiding surface that prevents the wiper seal from inverting during instrument withdrawal. The guide structure anticipates the potential inversion problem and counteracts it beforehand through its geometric design, allowing the seal to move freely enough to maintain low friction while preventing damage through the guiding constraint.
4Manufacturing precision
If multiple seals are used to accommodate different instrument shaft diameters, then sealing precision is improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The wiper seal achieves universality by designing a single seal structure that can accommodate a wide range of instrument shaft diameters (e.g., 5-12 mm). The combination of the thicker sealing portion and thinner flex portion allows this single component to perform the sealing function for multiple shaft sizes, eliminating the need for multiple specialized seals and thereby reducing device complexity while maintaining sealing precision.
Solution Approach 2:
The wiper seal applies parameter changes by varying the thickness parameter across different portions of the seal. The thicker sealing portion provides durability, while the thinner flex portion provides flexibility to accommodate various shaft diameters. This parameter variation within a single component achieves sealing precision for different shaft sizes without requiring multiple separate seals, resolving the contradiction between sealing precision and device complexity.
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 design enhances sealing effectiveness, reduces friction and inversion, allows precise instrument control, and lowers manufacturing and assembly costs, improving the efficiency and accuracy of minimally invasive surgical procedures.
Implementation Method 1
a wiper seal design with a thicker sealing portion and flexible flex portion that accommodates a range of shaft diameters
Implementation Method 2
provides relatively higher friction against a surgical instrument shaft being inserted through the seal, and relatively lower friction against a surgical instrument shaft being withdrawn through the seal
Data Source
Figure 1
Figure 1A
Figure 2
AI summary
Gas-tight seal assemblies for use during minimally invasive surgery include various aspects. A wiper seal (104) includes a sealing portion (108) and a surrounding flex portion. Upper and lower faces of the sealing portions are angled with reference to an inserted instrument, the upper face's angle being more acute with reference to the instrument's shaft than the lower face's angle. The flex portion is corrugated, support ribs are in one or more corrugation grooves, and the support ribs allow the groove to easily collapse but resist the groove widening. The support ribs also prevent the sealing portion from inverting. An instrument insertion guide (105, 107) is positioned over the sealing portion and moves laterally with the sealing portion. A latch piece removably secures the seal assembly to a cannula. An anti-inversion piece prevents the wiper seal from inverting when an instrument is withdrawn. An assembly may include various combinations of the seal assembly, a cannula, a surgical instrument, an obturator, an endoscope, and a teleoperated medical device. The seal assembly may rotate within a cannula. The seal assembly may be used during manual or teleoperated surgery.