Shape-Memory Tissue Gripper Resists Plastic Deformation
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Solution Overview
Problem
Existing tissue fixation devices for treating mitral valve regurgitation face challenges such as premature degradation due to plastic deformation during deployment and positioning, and the need for flexibility to accommodate physiological movement, which can lead to reduced durability and increased risk of failure.
Innovation Solution
The use of a tissue gripping device formed from a shape-memory material, such as nitinol, which exhibits superelasticity in a physiological environment, allowing the device to maintain elasticity and resist deformation, thereby enhancing durability and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fixation device uses traditional materials to grip and hold tissue, then the device can provide initial gripping force, but the device undergoes plastic deformation during deployment and positioning leading to premature degradation
Solution Approach 1:
The patent applies parameter changes by transitioning from traditional materials to shape-memory materials that exhibit superelasticity. This material parameter change enables the device to undergo large deformations during deployment and positioning without permanent plastic deformation, thereby maintaining structural integrity and preventing premature degradation while providing reliable tissue gripping throughout the device lifespan.
Solution Approach 2:
The patent utilizes shape-memory alloys as composite materials that combine elastic and superelastic properties. These materials allow the fixation device to maintain both gripping force and resistance to permanent deformation, resolving the contradiction between providing initial grip and preventing plastic deformation during complex deployment maneuvers.
2Reliability
If the fixation device is made rigid to maintain positioning, then the device provides stable fixation, but the device cannot accommodate physiological movement leading to increased failure risk
Solution Approach 1:
The patent changes the mechanical parameters of the fixation device by using shape-memory materials with superelastic properties. This enables the device to exhibit both rigidity for stable fixation and flexibility to accommodate physiological movements. The material can withstand cyclic deformations from heart valve movements without losing its fixation capability, thereby maintaining reliability while adapting to physiological conditions.
3Ease of operation
If the device components are flexed through wide ranges of angles for positioning, then the device can be properly positioned relative to target tissue, but the components experience plastic deformation and weakening
Solution Approach 1:
The patent applies parameter changes by utilizing the superelastic property of shape-memory materials, which allows the device components to be flexed through wide ranges of angles during positioning without undergoing permanent plastic deformation. The material's stress-strain characteristics enable reversible large deformations, maintaining component strength while providing the necessary positioning capability for proper device placement relative to target tissue.
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 shape-memory material-based tissue gripping device provides improved elasticity and durability, reducing the risk of premature failure and maintaining effective tissue gripping and fixation capabilities throughout the device's lifespan.
Implementation Method 1
a first arm having a first end coupled to the base section, and a free end extending from the base section; wherein the base section and the arm are formed of a shape-memory material configured to exhibit superelasticity in a physiological environment
Data Source
AI summary
A tissue gripping device is formed from a shape-memory material, and has a base section, a first arm, and a second arm disposed opposite the first arm, each arm having a first end coupled to the base section and a free end extending from the base section. The arms of the tissue gripping device are configured to resiliently flex toward a relaxed configuration in a distal direction as the tissue gripping device is moved from a pre-deployed configuration toward a deployed configuration. The tissue gripping device is usable in a method for gripping tissue. The method includes positioning the tissue gripping device near target tissue and moving the tissue gripping device from a pre-deployed configuration toward a deployed configuration in order to grip the target tissue.