Helical Dilatation Device Axial Concertina Collapse

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Solution Overview

Problem

Prior art inflatable dilatators experience excessive radial collapse when subjected to a partial vacuum, leading to a disproportionate reduction in radial protrusion compared to axial length, which is not effectively addressed by existing helical designs.

Innovation Solution

A dilatation device featuring helically wound inflatable tubes with alternating inflatable and intermediate zones, where the axial critical buckling load is less than the radial critical buckling load, causing the inflatable zones to concertina axially upon depressurization, thereby reducing the radial dimension of the helical dilatator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If an inflatable tube is wound helically around a support rod, then the device can maintain a central lumen for blood flow, but the device experiences excessive radial collapse when subjected to partial vacuum

Engineering Contradiction:

Improveability to reduce helical diameter for insertion/extractionVSAvoidradial collapse proportion

Core Design Contradiction:

Ease of operationVSShape

Solution Approach 1:

The inflatable tube is divided into multiple inflatable zones separated by intermediate zones. This segmentation allows different portions of the tube to behave differently during collapse - the inflatable zones can concertina axially while the intermediate zones maintain structural integrity, preventing excessive radial collapse and maintaining the helical shape for proper device function during insertion and extraction

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different zones of the inflatable tube are given different properties - the inflatable zones are designed to be more compliant and capable of axial concertina collapse, while the intermediate zones are designed with higher radial strength to resist collapse. This local differentiation of mechanical properties allows the device to achieve the desired size reduction without compromising the overall structural integrity and helical configuration

Inventive Principle:

Principle #3Local quality

2Strength

If the inflatable tube forms bulbous segments upon inflation, then the device can provide effective dilatation, but the radial protrusion reduces disproportionately compared to axial length when collapsed

Engineering Contradiction:

Improvedilatation effectivenessVSAvoidproportional reduction in radial protrusion vs axial length

Core Design Contradiction:

StrengthVSShape

Solution Approach 1:

Instead of allowing the bulbous segments to collapse radially (which would reduce dilatation effectiveness), the design inverts the collapse mechanism by enabling axial concertina collapse of the inflatable zones. This inversion of the collapse direction maintains the radial protrusion necessary for effective dilatation while achieving size reduction through axial shortening, thereby preserving both dilatation effectiveness and proportional shape characteristics

Inventive Principle:

Principle #13The other way round (Inversion)

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 achieves a greater reduction in radial dimension than axial length upon collapse, enhancing the dilatation device's ability to reduce its helical diameter, facilitating easier insertion and extraction while maintaining a central lumen for blood flow.

Implementation Method 1

The inflatable tube defines a fluid inlet for: (i) introducing fluid into the inflatable tube to inflate the inflatable zones; and (ii) extracting fluid from the inflatable tube to deflate the inflatable tube

Methodology Applied

Scientific EffectFluid introduction and extraction:

Implementation Method 2

wherein when the inflatable zones of the inflatable tube are subjected to a partial vacuum, each inflatable zone collapses axially, reducing the longitudinal axial length of the inflatable zone more than the radial protrusion of the inflatable zone from the longitudinal axis of the inflatable zone

Methodology Applied

Scientific EffectAxial collapse under partial vacuum: Vacuum

Implementation Method 3

wherein axial contraction of the helically wound tube causes the radial dimension of the helical dilatator to reduce

Methodology Applied

Scientific EffectHelical geometry transformation: Helix

Data Source

PatentUS11083876B2Dilation device

Publication Date: 2021.08.10 TEVAR PTY LTD

AI summary

A dilatation device 10 includes a support 14 and at least one inflatable tube 16. The inflatable tube is wound helically around the support and also defines a series of inflatable zones 26 along its length, with successive inflatable zones spaced by an intermediate zone 28 that is more resistive to radial expansion than the inflatable zones. The inflatable tube further defines a fluid inlet 22, 24 for: introducing fluid to inflate the inflatable zones; and extracting fluid from the inflatable tube to deflate it, with each inflatable zone being in fluid communication with its successive inflatable zones via the intermediate zones. The axial critical buckling load of the inflatable zones is less than the radial critical buckling load of the inflatable zones, to cause the inflatable zones to concertina axially when the inflatable tube is depressurized, thereby causing the intermediate zones to displace towards each other.