Monolithic Polymer Cuff for Artificial Urinary Sphincter
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Solution Overview
Problem
Existing artificial urinary sphincter systems face issues with creasing and stress concentration in inflatable balloons, leading to potential leakage and tissue pinching, which can result in system failure and discomfort.
Innovation Solution
A one-piece monolithic polymer cuff with a smooth interior wall and a closed cavity, where the interior wall is thinner than the exterior wall, providing even inflation and reducing stress points, and a separable part line for easy placement around the urethra, minimizing creasing and tissue pinching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional inflatable balloon cuff is used, then the cuff can be inflated to close the urethra, but creasing and stress concentration occur leading to potential leakage and tissue pinching
Solution Approach 1:
The cuff is constructed as a thin-walled cylindrical structure with uniform wall thickness, allowing even distribution of inflation pressure without creasing or stress concentration. The flexible thin film design enables smooth coaptation of the urethra without creating pinching points that could lead to tissue damage or leakage.
Solution Approach 2:
The cuff employs a circular cross-sectional geometry that conforms to the cylindrical shape of the urethra, distributing pressure uniformly around the circumference. This curved, symmetric design eliminates creases and stress concentration points that would occur with non-uniform or angular geometries.
2Strength
If a thick-walled cuff is used, then structural strength is improved, but even inflation is compromised and stress points increase
Solution Approach 1:
The cuff utilizes a thin-walled design where the wall thickness is optimized to be sufficiently thin to allow even inflation and pressure distribution, yet sufficiently strong to maintain structural integrity. This thin-film approach eliminates stress concentrations that would occur in thick-walled structures while maintaining necessary strength through material selection and geometric optimization.
Solution Approach 2:
The wall thickness parameter is precisely controlled and optimized to achieve the desired balance between strength and inflation uniformity. By maintaining uniform wall thickness throughout the cuff structure, the design ensures even stress distribution during inflation while preventing the formation of stress concentration points.
3Ease of manufacture
If a one-piece monolithic structure is used, then manufacturing complexity is reduced, but placement around the urethra becomes difficult
Solution Approach 1:
The one-piece monolithic cuff incorporates a longitudinal split or separation along its length, dividing the circular structure into two separable halves. This segmentation allows the cuff to be opened and placed around the urethra during surgery, then closed to form the complete circular structure for optimal function, combining manufacturing simplicity with placement ease.
Solution Approach 2:
The cuff transitions from a static, pre-assembled structure to a dynamic, adaptable structure that can be opened for placement and then closed to its functional configuration. The longitudinal split enables the cuff to dynamically change its state from separable components to a unified circular structure, facilitating easy placement while maintaining structural integrity during use.
Data Source
AI summary
A cuff for an artificial urinary sphincter (AUS) system includes an interior wall that is smooth and characterized by an absence of creases, an exterior wall that provides the cuff with a backboard adapted to support movement of the interior wall, and endwalls. A cavity is located between the interior wall, the exterior wall, and the pair of endwalls and is adapted to contain a liquid. Liquid in the cavity is maintained at an equilibrium pressure that is selected to displace the interior wall and maintain the cuff in a closed position around the urethra to provide the user with urinary continence.