Capillary Connector Crimp Seal for Low-Dead-Volume Assembly

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Solution Overview

Problem

Existing fittings for capillary tubes in chromatographic systems are difficult to assemble reliably, often causing damage and resulting in increased dead volume and band broadening, which affects the performance and accuracy of liquid separation.

Innovation Solution

A connector fitting with a deformable portion that crimps a compliant material sleeve around the capillary tubing to create a seal, minimizing dead volume and ensuring a reliable assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional fittings are used to connect capillary tubes, then the assembly process becomes difficult and unreliable, but the capillary end may be damaged or crushed

Engineering Contradiction:
Improveassembly reliabilityVSAvoidassembly difficulty
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent uses a flexible deformable portion (sleeve or collar) that can be crimped onto the capillary tube. This flexible element deforms under applied force to create a secure connection without requiring complex assembly tools or procedures, thereby improving reliability while maintaining ease of operation.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent replaces traditional mechanical connection methods (such as threading or clamping) with a deformation-based connection system. The deformable portion is crimped onto the capillary tube, creating a permanent mechanical bond that is both reliable and simple to assemble, eliminating the need for complex mechanical assembly procedures.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If traditional fittings are used to connect capillary tubes, then the assembly process becomes difficult, but dead volume increases and band broadening occurs

Engineering Contradiction:
Improvechromatographic separation accuracyVSAvoidfitting structure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The connector is divided into distinct functional segments: a capillary recess for receiving the capillary tube, a deformable portion for creating the seal, and a receiving portion for the fluid conduit fitting. This segmentation allows each part to be optimized for its specific function, minimizing dead volume while keeping the overall structure simple.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The deformable portion acts as an intermediary element between the capillary tube and the connector body. It provides the sealing function without requiring complex internal structures or large volumes, thereby maintaining manufacturing precision while simplifying the device structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Strength

If the capillary tube is securely connected, then pressure sealing is achieved, but the capillary end may be damaged during assembly

Engineering Contradiction:
Improvepressure sealing capabilityVSAvoidcapillary tube damage
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The capillary recess provides a cushioning effect by receiving and supporting the capillary tube end before the deformable portion is crimped. This preliminary support prevents the capillary tube from being damaged during the subsequent crimping operation, while still allowing the deformable portion to create a strong pressure seal.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The deformable portion is designed as a flexible element that can be deformed during assembly to create the seal, then maintains its shape under pressure. This flexibility allows it to conform to the capillary tube without exerting excessive localized stress that could damage the tube, while still achieving strong pressure sealing capability.

Inventive Principle:
Principle #30Flexible shells and thin films

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 connector provides a secure, low-dead-volume connection capable of withstanding high pressures, reducing band broadening and enhancing the accuracy of chromatographic separations.

Implementation Method 1

a deformable portion configured for deforming so that the compliant material of a capillary received in the capillary recess is deformed to create a seal between the inner capillary tubing and the connector

Methodology Applied
Scientific EffectDeformation: Deformation

Implementation Method 2

Due to the high pressure applied in most high performance liquid chromatography (HPLC) and ultra-high performance liquid chromatography (UHPLC) systems, pressure sealing of the components in and along the fluid flow path is required

Methodology Applied
Scientific EffectPressure: Pressure Increase

Data Source

PatentEP3746690B1Capillary fitting and method of use
Publication Date: 2025.08.06 ION OPTICKS RES PTY LTD
  • EP3746690B1 patent drawingFigure 1
  • EP3746690B1 patent drawingFigure 2
  • EP3746690B1 patent drawingFigure 3a

AI summary

Fittings for capillaries, such as those in chromatographic systems, can be difficult to reliably assemble. The invention relates to a connector for providing a fluid connection between a capillary and a fluid conduit, said connector comprising: a capillary holder for receiving an end of the capillary, said capillary comprising inner capillary tubing, wherein the inner capillary tubing of the received end of the capillary is located within a compliant material sleeve; a deformable portion configured for deforming so that the compliant material of the sleeve in the capillary holder is deformed to create a seal between the inner capillary tubing and the connector; and a receiving portion configured to receive a fitting at an end of the fluid conduit; wherein the capillary holder and the receiving portion are connected so that the connector is configured to fluidly connect the capillary and the fluid conduit.