Stent Delivery Outer Sheath with Reinforcement Layer

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Solution Overview

Problem

Existing stent device delivery systems face challenges with high frictional forces during deployment, leading to reliability issues and the need for stronger materials, which increases the cross-sectional profile and deployment force, particularly in longer stent devices.

Innovation Solution

A stent device delivery system featuring a laminated outer sheath with a polymeric first layer and a reinforcement layer, glued together with a glue layer, which allows for a thin, strong, and reliable deployment mechanism, along with a tapering stent bed profile to reduce deployment force and prevent sticking during retraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a single-layer outer sheath is used in pullback delivery systems, then the cross-sectional profile is reduced, but frictional forces increase and reliability decreases

Engineering Contradiction:

Improvecross-sectional profileVSAvoiddeployment reliability

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The outer sheath is constructed as a composite structure with an inner layer and an outer layer made of different polymeric materials. The inner layer provides flexibility and conformability to the stent, while the outer layer provides strength and resistance to frictional forces during pullback deployment, thereby resolving the contradiction between reduced profile and improved reliability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The outer sheath is divided into two distinct layers with different material properties and functions. The inner layer contacts the stent and provides radial support, while the outer layer contacts the delivery catheter and provides mechanical strength, allowing each layer to be optimized for its specific function rather than requiring a single thick layer.

Inventive Principle:

Principle #1Segmentation

2Reliability

If stronger materials are used in the outer sheath to overcome friction, then deployment reliability improves, but the cross-sectional profile increases

Engineering Contradiction:

Improvedeployment reliabilityVSAvoidcross-sectional profile

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

By using composite materials with different properties in each layer, the system achieves the necessary strength to overcome friction without requiring a single thick layer, thus maintaining a low cross-sectional profile while ensuring deployment reliability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The outer layer is specifically designed with higher strength properties where it is needed to resist frictional forces during pullback, while the inner layer maintains lower strength to provide flexibility. This localized optimization of material properties allows the system to achieve reliability without increasing overall profile.

Inventive Principle:

Principle #3Local quality

3Force

If a rolling outer sheath mechanism is used, then deployment force is reduced, but friction during rollback increases and may exceed material strength

Engineering Contradiction:

Improvedeployment forceVSAvoidrollback reliability

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The outer layer is made of a strong polymeric material that can withstand the high frictional forces generated during the rolling rollback motion, preventing material failure while maintaining the low deployment force advantage of the rolling mechanism.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The rolling mechanism uses a curved fold-over portion that rolls over the stent during deployment. The outer layer's strength prevents this curved structure from failing under the frictional loads generated during rolling, enabling the mechanism to function reliably.

Inventive Principle:

Principle #14Spheroidality (Curvature)

4Volume of moving object

If the outer sheath is made thinner to reduce profile, then the cross-sectional profile is reduced, but the outer sheath strength decreases

Engineering Contradiction:

Improvecross-sectional profileVSAvoidouter sheath strength

Core Design Contradiction:

Volume of moving objectVSStrength

Solution Approach 1:

The composite structure allows each layer to be thin yet collectively provide the necessary strength. The inner layer can be thin to maintain low profile, while the outer layer compensates for the reduced thickness by providing the required mechanical strength through its superior material properties.

Inventive Principle:

Principle #40Composite materials

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 system achieves reliable deployment of stents with reduced deployment force and increased reliability, enabling the use of thinner materials while maintaining a low profile and preventing mechanical failure.

Implementation Method 1

a reinforcement layer of polymeric material that are laminated together

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS10449072B2Stent device delivery system with an outer sheath polymeric reinforcement layer

Publication Date: 2019.10.22 CR BARD INC

AI summary

A stent device delivery system and method of making. The stent device delivery system includes a stent device and an outer sheath overlaying the stent device in a radially compact, delivery configuration of the stent device. The outer sheath may include a first layer of polymeric material and a reinforcement layer of polymeric material that are laminated together.