Ferrule Chuck Micro-Grip for High-Pressure Capillary Sealing

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Solution Overview

Problem

Existing fittings for fluidic devices, particularly in liquid chromatography, face challenges in maintaining sealing performance and mechanical stability under increasing operation pressures, such as those above 2000 bar, where conventional approaches often result in macroscopic damage to capillaries, limiting reuse and selectivity of relative positioning.

Innovation Solution

A fitting with a ferrule chuck and microstructure featuring multiple microprotrusions on its surface, which forms a form-fit connection with the capillary by embossing microindentations, providing a strong and reusable connection while avoiding macroscopic damage, thus maintaining the freedom of relative positioning and supporting high-pressure applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional fittings are used to secure capillaries under high pressure, then sealing performance is achieved, but macroscopic damage occurs to the capillary limiting reuse

Engineering Contradiction:
Improvesealing performanceVSAvoidcapillary integrity
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The ferrule chuck surface is provided with a microstructure comprising a plurality of microprotrusions that penetrate into the capillary wall to a depth of 5-50 μm, creating a porous-like penetration pattern that secures the capillary without causing macroscopic damage. This allows the capillary to be reused while maintaining sealing performance under high pressure.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The microstructure creates localized penetration points distributed across the ferrule chuck surface, with each microprotrusion creating a small localized form-fit connection. This distributed local quality approach prevents concentrated stress that would cause macroscopic damage while maintaining overall capillary integrity.

Inventive Principle:
Principle #3Local quality

2Stability of the object's composition

If conventional gripping mechanisms are used, then mechanical stability is achieved, but the capillary positioning freedom is lost

Engineering Contradiction:
Improvemechanical stabilityVSAvoidpositioning freedom
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The microprotrusion pattern creates a porous-like distribution of grip points that allow the capillary to be held securely in multiple positions. The distributed micro-grip points provide mechanical stability while the random pattern maintains positioning freedom, allowing the capillary to be inserted at different orientations.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The microprotrusions are arranged in an asymmetric, non-uniform pattern across the ferrule chuck surface, which prevents preferential alignment of the capillary. This asymmetric distribution maintains mechanical stability through form-fit connections while preserving the ability to position the capillary freely.

Inventive Principle:
Principle #4Asymmetry

3Reliability

If high pressure sealing is achieved through conventional means, then fluid-tight seal is provided, but capillary damage occurs

Engineering Contradiction:
Improvefluid-tight sealVSAvoidcapillary damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The microprotrusions create a porous-like penetration pattern that distributes sealing forces across multiple small contact points rather than a single macroscopic interface. This distributes the stress from high pressure (up to 2000 bar) across many micro-contacts, preventing capillary damage while maintaining fluid-tight sealing.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The sealing mechanism transitions from a macroscopic surface contact to a microscopic dimension with numerous microprotrusions penetrating the capillary wall. This dimensional change from macro to micro scale allows high-pressure sealing without the concentrated stresses that cause damage in conventional macroscopic sealing interfaces.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 microstructure-based form-fit connection ensures a robust, reusable, and fluid-tight seal at pressures up to 2000 bar, preventing capillary damage and allowing user-defined positioning, thereby meeting the stringent requirements of modern liquid chromatography.

Implementation Method 1

forming a form-fit connection with an enclosed back part of the capillary by embossing a micropattern in a surface of the capillary

Methodology Applied
Scientific EffectEmbossing:

Implementation Method 2

The microstructure comprises multiple microprotrusions... generating a form fit with the enclosed back part of the capillary

Methodology Applied
Scientific EffectMechanical interlocking:

Data Source

PatentEP2626698B1Ferrule chuck with surface micro-grip
Publication Date: 2020.07.08 AGILENT TECHNOLOGIES INC
  • EP2626698B1 patent drawingFigure 1~3
  • EP2626698B1 patent drawingFigure 4~6

AI summary

A fitting (100) for coupling a capillary (102) to another component (330) of a fluidic device (300), the fitting (100) comprising a ferrule (106) configured for enclosing a front part of the capillary (102) and for contributing to a fluidic sealing between the fitting (100) and the other component (330), a ferrule chuck (108) configured for enclosing a back part of the capillary (102), a housing (104) configured for accommodating at least a part of the ferrule chuck (108) and for pushing the ferrule chuck (108) against the ferrule (106), and a microstructure (110) formed as multiple microprotrusions (120) on at least a part of a surface of the ferrule chuck (108) for generating, upon tightening the fitting (100) at the other component (330), a form fit with the enclosed back part of the capillary (102) over a contact area between the ferrule chuck (108) and the capillary (102).