Cuffed Medical Tubes Adhesive Seepage Control

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Solution Overview

Problem

Cuffs made of highly elastic materials like silicone on medical tubes, such as tracheal tubes, face issues with adhesive seepage and irregular shape inflation due to poor attachment methods, especially when deflated, leading to a poorly defined attachment border and longer cure times of adhesives.

Innovation Solution

The implementation of annular ribs on the shaft and recesses with frusto-conical surfaces at the attachment regions restricts adhesive flow to the inflatable portion, ensuring a tight, even bond and smooth transition between the shaft and cuff, preventing adhesive seepage and facilitating a stepless transition for improved shape retention and insertion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If adhesive or solvent is applied to attach the cuff to the shaft, then the cuff is securely bonded to the shaft, but the adhesive seeps from the cuff region towards the inflatable region causing poorly-defined attachment border and irregular shape

Engineering Contradiction:

Improvebond strengthVSAvoidattachment border definition

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The shaft surface is modified locally at the attachment regions by providing recesses with frusto-conical surfaces. These recesses create localized zones where adhesive is contained and controlled, allowing strong bonding at the attachment regions while preventing adhesive migration to the inflatable region. The local structural modification enables differential adhesive behavior in different zones of the shaft.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The recesses with frusto-conical surfaces act as intermediary structures between the adhesive and the shaft surface. These recesses capture and contain the adhesive, providing a controlled interface for bonding the cuff collars to the shaft while preventing uncontrolled adhesive flow. The intermediary recesses mediate between the need for strong adhesion and the need to prevent adhesive seepage.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If adhesive with longer cure time is used to ensure good bond, then bonding strength is improved, but it becomes more difficult to form a good join and manufacturing complexity increases

Engineering Contradiction:

Improvebond strengthVSAvoidjoin formation difficulty

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The recesses with frusto-conical surfaces are pre-formed on the shaft before adhesive application. This preliminary structural preparation creates built-in adhesive containment features that guide the adhesive into proper positions and prevent premature curing issues. The pre-formed recesses ensure that even with longer cure time adhesives, the adhesive remains in controlled zones, facilitating easier and more reliable join formation.

Inventive Principle:

Principle #10Preliminary action

3Strength

If the cuff is made as a tight fit on the shaft when deflated, then the attachment security is improved, but adhesive seepage increases and attachment border definition deteriorates

Engineering Contradiction:

Improveattachment securityVSAvoidattachment border definition

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

4Ease of manufacture

If PVC material is used for the tube, then attachment methods work well, but the tube cannot achieve the same benefits with silicone or highly elastic materials

Engineering Contradiction:

Improveattachment easeVSAvoidmaterial compatibility

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The recess structure with frusto-conical surfaces provides a universal attachment solution that works effectively with different materials including PVC, silicone, and other highly elastic materials. The geometric containment of adhesive in recesses creates a material-independent bonding mechanism that adapts to the specific properties of different cuff and shaft materials, enabling consistent manufacturing quality across material types.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP2097128B1Cuffed medical tubes

Publication Date: 2018.01.31 SMITHS GROUP PLC

Figure 1
Figure 2~3

AI summary

A cuffed silicone tracheostomy tube has two tapered recesses (17) and (18) on its outer surface in which opposite ends (7) and (8) of a resilient cuff 6 are bonded using an adhesive or solvent. Two shallow ribs (22) and (23) extend around the tube on the inner edge of each recess (17) and (18), projecting outwardly to prevent the adhesive or solvent spreading onto the inflatable portion (10) of the cuff (6). The cuff (6) has several shallow ribs (9) extending around the cuff and spaced along its inflatable portion (10) to promote even inflation.