IUD String Stiffness Segmentation for Curl Prevention
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Solution Overview
Problem
Intrauterine device (IUD) strings often curl up and retract into the uterus, leading to uncertainty about the device's presence and increasing the risk of expulsion, which existing technologies fail to address effectively.
Innovation Solution
The IUD strings are unified by methods such as fusion, coiling, interweaving, gluing, or twisting to create a thicker, stiffer section that prevents curling, while remaining soft for comfort and feelability, with optional identification marks for correct length trimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the string is made soft and flexible for comfort and feelability, then the woman can feel the string's presence and it causes less discomfort, but the string curls up and retracts into the uterus
Solution Approach 1:
The string is divided into multiple segments with different properties: a proximal segment with enhanced stiffness (through unification of multiple strings or thicker construction) to prevent curling, and a distal segment that remains soft and flexible for feelability. This segmentation allows each part to fulfill its specific function without compromise.
Solution Approach 2:
Different portions of the string have different physical properties. The proximal portion (closer to the IUD) has enhanced stiffness to resist curling forces, while the distal portion (extending into the vagina) maintains softness and flexibility for comfort and detectability. This local differentiation resolves the contradiction between stiffness and softness.
2Reliability
If multiple strings are used to improve reliability, then the risk of complete string loss is reduced, but the complexity of the device increases
Solution Approach 1:
Multiple individual strings are unified or combined together in the proximal region to form a single enhanced-stiffness structure. This merging provides the reliability of multiple strings while simplifying the overall configuration and reducing the complexity of managing separate strings. The unified structure prevents individual string curling while maintaining the security of having multiple strands.
3Reliability
If the string is made thicker to prevent curling, then the stiffness increases and curling is reduced, but the comfort and feelability may be compromised
Solution Approach 1:
The string thickness is segmented along its length. The proximal segment is thicker to provide enhanced stiffness and prevent curling, while the distal segment is thinner to maintain comfort and feelability. This gradual or stepped transition in thickness allows the system to achieve both objectives without compromise.
Solution Approach 2:
The string has non-uniform properties along its length, with local variations in thickness and stiffness. The thicker, stiffer proximal portion resists curling forces near the IUD, while the thinner, softer distal portion provides comfort and detectability in the vaginal cavity. This local quality differentiation resolves the contradiction between stiffness and comfort.
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
An intrauterine device (IUD) with a restricted movement of a string(s), the strings can be either a single string or two or more strings or a filament, emerging from the spherical bulge of IUD. The strings of IUD are of a differential strength so that the strings are soft and the hanging portion of the strings, "feelable" in the vaginal cavity, does not cause discomfort to the woman, nor bruise the organ of the partner during intercourse, at the same time the strings in the endocervical canal are relatively stiffer and not have the tendency to get curled up progressively. The strings optionally have marks to facilitate cutting by a surgeon to an accurate length.