Variable Stiffness Flexure for Intrauterine Device Sheath
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Solution Overview
Problem
Intrauterine medical devices face challenges in reducing the diameter of their sheath while maintaining strength and robustness, leading to increased patient discomfort and potential cervical injury during insertion.
Innovation Solution
The design incorporates central support members and flexures with varying stiffness sections, including internal and external flexures that can extend from a collapsed position to a deployed position, allowing for a smaller diameter sheath while maintaining mechanical durability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the sheath diameter is reduced to improve ease of insertion and decrease patient discomfort, then the device becomes easier to insert and more comfortable for the patient, but the strength and robustness of the device deteriorates
Solution Approach 1:
The flexure is divided into multiple sections with different stiffness characteristics. The first section (proximal) has higher stiffness for structural support, the second section (distal) has lower stiffness for flexibility and comfort, and the third section has intermediate stiffness. This segmentation allows the sheath to maintain adequate strength while reducing diameter for easier insertion.
Solution Approach 2:
Different portions of the flexure are assigned different mechanical properties (stiffness values). The proximal section has higher stiffness to maintain structural integrity, while the distal section has lower stiffness to facilitate flexibility and patient comfort. This local differentiation of material properties enables the sheath to be stronger where needed and more flexible where needed, resolving the contradiction between strength and ease of insertion.
2Ease of operation
If the sheath diameter is reduced to improve ease of operation, then patient discomfort decreases, but the reliability of device deployment deteriorates
Solution Approach 1:
The flexure is segmented into sections with different stiffness values to ensure reliable deployment. The first and third sections provide structural stability for deployment, while the second section provides flexibility. This segmentation ensures that even with reduced sheath diameter, the device maintains sufficient reliability for proper deployment and function.
Solution Approach 2:
The stiffness parameter of the flexure is varied along its length to optimize both ease of insertion and deployment reliability. By changing the stiffness parameter from higher values in the proximal section to lower values in the distal section and back again, the device achieves both reduced diameter for ease of insertion and sufficient rigidity for reliable deployment.
3Volume of moving object
If the sheath diameter is reduced, then the device profile becomes smaller, but the manufacturing complexity increases
Solution Approach 1:
The flexure is segmented into three distinct sections with different stiffness characteristics. This segmentation, while increasing structural complexity, enables the achievement of a reduced device diameter. The complex multi-section design allows for optimized mechanical properties that simplify the overall device profile and improve ease of insertion.
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
This design enables a smaller-diameter sheath for intrauterine devices, reducing patient discomfort and minimizing the risk of cervical injury during insertion while maintaining the device's strength and deployment reliability.
Implementation Method 1
The first and second external flexures, in combination with the first and second internal flexures, are configured to extend from a collapsed position parallel to the central support member to a deployed position flexing away from the central support member
Data Source
AI summary
An intrauterine device includes a central support member, first and second internal flexures and first and second external flexures. The first and second internal flexures each include a first section having a first stiffness, a second section having a second stiffness, and third section having a third stiffness, wherein the second stiffness is more flexible than the first and third stiffness and wherein the first section of each internal flexure is coupled to the central support member. The first and second external flexures are coupled to the central support member and coupled to the third sections of the first and second internal flexures, the first and second external flexures in combination with the first and second internal flexures being configured to extend from a collapsed position parallel to the central support member to a deployed position flexing away from the central support member.