Barb Geometry Reduces Peak Strain for Fatigue Life
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing anchoring barbs for implantable medical devices in body vessels experience premature fracture due to cyclic loading from hemodynamic forces, leading to fatigue failure and reduced durability.
Innovation Solution
The design of the barb features a non-constant radius of curvature for the base portion and a substantially straight tip portion, distributing strain over a larger region, with the base portion extending over 25-50% of the penetrating element's length, reducing peak principal strain and enhancing fatigue life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the barb uses a conventional geometry with constant curvature, then the manufacturing is simple, but the fatigue life is short due to stress concentration
Solution Approach 1:
The barb employs different geometric characteristics in different regions: the base portion has a first curvature with a larger radius of curvature to reduce stress concentration, while the tip portion has a second curvature with a smaller radius of curvature for effective tissue penetration. This local differentiation of geometric properties allows the structure to optimize both fatigue resistance and anchoring function.
Solution Approach 2:
The barb is divided into distinct segments: a base portion and a tip portion, each with specific geometric characteristics. The base portion extends from the body portion and has different curvature properties than the tip portion, creating segmented zones that perform different functions - the base portion resists fatigue while the tip portion penetrates tissue.
2Reliability
If the base portion is made longer to distribute strain, then the fatigue life increases, but the overall device length increases
Solution Approach 1:
The invention optimizes the radius of curvature parameter in the base portion to achieve better strain distribution. By adjusting the curvature radius rather than simply extending the base portion length, the design distributes stress more effectively while controlling the overall length of the penetrating element.
3Reliability
If the barb uses a straight tip portion, then the strain distribution improves, but the anchoring penetration capability may be reduced
Solution Approach 1:
The tip portion maintains a curved geometry with a smaller radius of curvature to preserve tissue penetration capability, while the base portion has a larger radius of curvature to improve strain distribution. This local differentiation ensures that each region performs its intended function optimally.
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
A barb for anchoring an implantable medical device to a body vessel comprises a thin-walled body portion for engagement with a structural element of an implantable medical device and a penetrating element extending from the body portion. The body portion has a longitudinal axis. The penetrating element includes a tip portion for anchoring into tissue and a base portion between the tip portion and the body portion. In a deployed configuration of the barb, the base portion curves away from the longitudinal axis at a first curvature and the tip portion curves toward the longitudinal axis at a second curvature which is opposite in sign from the first.