Variable Stiffness Catheter Vacuum Friction Control

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Solution Overview

Problem

Current catheters face challenges in navigating highly tortuous and angulated vascular systems due to issues of herniation and buckling, requiring multiple catheters and sheaths for staged stiffness, which complicates procedures like catheterization of branch vessels and neurovascular access.

Innovation Solution

A variable stiffness catheter with an inner layer, a middle layer having an annular lumen connected to a vacuum source, and an outer layer, allowing for adjustable flexural rigidity by altering frictional resistance and adhesion between layers, enabling the catheter to transition between low and high stiffness configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a stiff sheath is used to provide support for medical devices, then the catheter can support medical devices, but the catheter cannot navigate tortuous vasculature

Engineering Contradiction:

Improvesupport capabilityVSAvoidnavigation capability

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The catheter employs a dynamic stiffness control system where vacuum pressure can be applied to an intermediate layer to temporarily increase friction between layers, transforming the catheter from a flexible navigation state to a stiff support state on demand

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The catheter changes its physical parameter (stiffness) by applying vacuum pressure to alter the friction coefficient between the intermediate layer and other layers, enabling transition between flexible and stiff configurations

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If a floppy guide catheter is used to navigate vasculature, then the catheter can navigate tortuous vasculature, but the catheter cannot provide sufficient support for medical devices

Engineering Contradiction:

Improvenavigation capabilityVSAvoidsupport capability

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The catheter uses a nested three-layer structure with an inner layer, intermediate layer, and outer layer, where the intermediate layer can be vacuumed to create frictional coupling between all layers, enabling the soft catheter to stiffen when needed

Inventive Principle:

Principle #7Nested doll (Nesting)

3Strength

If multiple catheters and sheaths are used for staged stiffness, then the catheter can provide both navigation and support, but the device complexity increases

Engineering Contradiction:

Improvesupport capabilityVSAvoidsystem complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The invention merges the navigation and support functions into a single catheter by integrating a vacuum-controlled intermediate layer that can dynamically adjust stiffness, eliminating the need for separate guide catheters and sheaths

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single catheter performs multiple functions: navigation in flexible mode and support in stiffened mode, controlled by vacuum application to the intermediate layer, replacing the need for multiple specialized devices

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Strength

If vacuum is applied to the annular lumen to increase friction, then the flexural rigidity increases, but the energy consumption increases

Engineering Contradiction:

Improveflexural rigidityVSAvoidvacuum energy consumption

Core Design Contradiction:

StrengthVSUse of energy by moving object

Solution Approach 1:

The vacuum is applied periodically or temporarily only when support is needed, rather than continuously, reducing energy consumption while maintaining the ability to stiffen the catheter on demand during critical procedures

Inventive Principle:

Principle #19Periodic action

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 catheter effectively navigates tortuous vasculature while providing sufficient support for medical devices, reducing herniation and buckling by optimizing stiffness based on vacuum actuation, enhancing its ability to access complex vascular structures.

Implementation Method 1

The annular lumen being fluidly connected to a vacuum source, and applying the vacuum and evacuating the annular lumen of the middle layer alters a frictional resistance or adhesion between the inner layer and the outer layer

Methodology Applied

Scientific EffectVacuum: Vacuum

Implementation Method 2

evacuating the annular lumen of the middle layer causes an increase in the frictional resistance or adhesion that enables the inner layer, the middle layer, and the outer layer to flex as if they were a single layer

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS20230070264A1Variable stiffness catheter and methods thereof

Publication Date: 2023.03.09 WASHINGTON UNIV IN SAINT LOUIS

AI summary

The disclosure provides for a variable stiffness catheter. The catheter may include an inner layer forming an inner lumen, a middle layer surrounding the inner layer, and an outer layer surrounding the middle layer. The middle layer may include an annular lumen and a plurality of strings within the annular lumen, and the plurality of strings may be connected to the inner layer. Applying a vacuum and evacuating the annular lumen of the middle layer alters a frictional force between the inner layer and the outer layer and thereby changes the catheter's flexural rigidity.