Nested Balloon Structure for High Burst Pressure and Flexibility
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Solution Overview
Problem
Existing balloon catheters face limitations in exerting force without bursting due to radial and axial stress, and increasing wall thickness for higher pressure leads to stiffness and difficulty in navigation, with prior multi-layer balloons having deficiencies.
Innovation Solution
The development of nested balloons with at least two balloons, each with optimized stretch properties, annealed under specific conditions, and potentially different materials, to enhance burst pressure, hoop stress, and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If balloon wall thickness is increased to withstand higher pressure, then burst pressure is improved, but balloon stiffness increases making navigation difficult
Solution Approach 1:
The balloon is divided into multiple thin-walled layers (typically 3-5 layers) rather than using a single thick wall. Each layer has optimized thickness to balance strength and flexibility. The segmented structure allows the balloon to withstand high pressures through cumulative layer strength while maintaining overall flexibility for navigation.
Solution Approach 2:
Different polymer materials are used for different balloon layers, with each material selected for specific properties. Common combinations include nylon, polyethylene, and polyurethane layers, where each material contributes different characteristics such as tensile strength, elasticity, and friction properties. This composite approach optimizes both burst pressure resistance and navigation flexibility.
2Reliability
If balloon wall thickness is increased to prevent bursting, then reliability is improved, but the balloon cannot be tightly wrapped around the catheter shaft
Solution Approach 1:
The balloon wall is segmented into multiple thin layers that can be tightly wrapped around the catheter shaft without excessive stiffness. The thin individual layers collectively provide the necessary burst resistance while maintaining the flexibility required for tight wrapping and secure attachment to the catheter.
Solution Approach 2:
Composite polymer structures with optimized layer thicknesses and material combinations provide sufficient burst resistance in a thin-walled configuration, enabling the balloon to be tightly wrapped around the catheter shaft while maintaining reliability.
3Force
If higher pressure is applied to achieve treatment effect, then treatment efficacy is improved, but radial stress causes axial bursting
Solution Approach 1:
Multiple balloon layers distribute the radial stress more effectively throughout the wall structure. The segmented layered design prevents stress concentration that would lead to axial bursting, allowing higher treatment pressures to be applied safely while maintaining axial strength.
Solution Approach 2:
Composite polymer layers with different mechanical properties work together to resist both radial and axial stresses. The material combinations are selected to provide balanced resistance to multi-directional forces, enabling effective treatment pressure application without axial bursting.
4Ease of operation
If balloon wall thickness is reduced to improve flexibility, then ease of operation is improved, but burst pressure decreases
Solution Approach 1:
The balloon uses multiple thin layers instead of a single thick wall, achieving flexibility through the thin individual layers while maintaining burst pressure resistance through the cumulative strength of all layers working together.
Solution Approach 2:
Composite polymer structures provide enhanced strength-to-weight ratio, allowing thin-walled flexible balloons to achieve the required burst pressure ratings through optimized material combinations and layer configurations.
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 nested balloons achieve significantly higher burst pressure and hoop stress while maintaining flexibility, reducing the risk of bursting and improving navigation through the body.
Implementation Method 1
annealing the first balloon layer and the second balloon layer in a mold at a temperature of between about 200° F. and about 270° F. for a time period of between about 10 minutes and about 60 minutes. In some embodiments, annealing comprises pressurizing the nested balloon at a pressure of between about 5 atm and about 30 atm and stretching the balloon with a stretch force of between about 1 pound and about 5 pounds.
Data Source
AI summary
A nested balloon is provided where each balloon is formed from tubing that optimizes the inner wall stretch thus providing maximum balloon strength. The high pressure, nested balloon is provided with layers that allow for slipping, such that the balloon has a very high pressure rating and toughness, yet excellent folding characteristics. Methods for producing such nested balloons using existing balloon forming equipment are also provided. The nested balloons can have layers with low-friction surfaces. The nested balloons are preferably manufactured using a variety of methods, including pressurized constrained annealing.