Composite Grasping Members for Medical Retrieval Devices
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Solution Overview
Problem
Medical retrieval devices made from metal components within polymer tubes face durability issues due to repeated stress and degradation, leading to decreased performance or failure during operations like percutaneous nephrolithotomy and ureteroscopy.
Innovation Solution
The medical retrieval device features grasping members with sections made of different materials, including a stiffer outer material and a more flexible core material, with a unique structural configuration that allows for radial expansion and retraction, reducing stress on the polymer tube and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If metal components are placed within polymer tubes for medical retrieval devices, then the device can perform reciprocating movements for grasping and releasing objects, but the repeated stress degrades the polymer tubes resulting in decreased performance or failure
Solution Approach 1:
The grasping member is constructed as a composite structure with an inner core made of one material and an outer layer made of a different material. This composite construction allows the device to maintain structural integrity under repeated stress while providing the necessary flexibility for reciprocating movements, thereby resolving the contradiction between operational capability and durability.
Solution Approach 2:
Different sections of the grasping member have different material compositions - the inner core provides structural support while the outer layer provides flexibility and stress distribution. This local differentiation of material properties allows the device to withstand repeated stress without degrading the polymer tube, while still enabling effective grasping and releasing operations.
2Ease of manufacture
If the grasping member is made from a single material, then the manufacturing process is simpler, but the device cannot effectively distribute stress during reciprocating movements
Solution Approach 1:
The invention employs a composite structure with an inner core and an outer layer made of different materials. This composite construction enables effective stress distribution during reciprocating movements while maintaining a relatively simple manufacturing process through techniques such as co-extrusion or layered construction, thus resolving the contradiction between manufacturing simplicity and stress distribution capability.
3Reliability
If the polymer tube thickness is increased to improve durability, then the device can withstand repeated stress better, but the device profile becomes larger and harder to navigate through body cavities
Solution Approach 1:
The composite structure with an inner core and outer layer allows for optimized stress distribution without requiring increased overall thickness. The different materials in the composite construction provide enhanced durability while maintaining a compact profile suitable for navigation through body cavities, resolving the contradiction between stress resistance and device size.
Solution Approach 2:
The inner core and outer layer are designed with different material properties optimized for their specific functions - the core provides structural support while the outer layer provides flexibility and stress distribution. This local optimization allows the device to achieve high stress resistance without increasing the overall profile thickness, maintaining navigability through body cavities.
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 device achieves improved durability and performance by distributing stress more effectively, reducing wear and fatigue, and allowing for efficient capture and removal of obstructive materials within the body without compromising the polymer tube's integrity.
Implementation Method 1
Each of the grasping members may include at least one first section formed of a first material and a second material, and a second section located at the distal end of the grasping member. The second section may be formed without the first material and having a different stiffness than the at least one first section.
Data Source
AI summary
A medical device may include an elongate member, and a plurality of grasping members extending from the elongate member. Each of the grasping members may include a proximal end, and a distal end. Each of the grasping members may include at least one first section formed of a first material and a second material, and a second section located at the distal end of the grasping member. The second section may be formed without the first material and being less stiff than the at least one first section.