Cannula Curvature and Ribbing to Prevent Kinking
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Solution Overview
Problem
Cannulas used in drug delivery devices, such as insulin pumps, often kink during insertion, leading to occlusions that limit or completely stop medication delivery to patients.
Innovation Solution
The design of cannulas with reduced stress concentration points, angled tips, hyperelastic materials like polyurethane, and internal ribbing to minimize kinking and occlusions, featuring a curved shape that straightens during insertion and returns to its curved state post-removal, and a thicker wall at the tip to distribute stress evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If flexible material is used for cannula to provide patient comfort, then comfort is improved, but kinking resistance deteriorates
Solution Approach 1:
The cannula employs a composite structure combining a flexible outer material (such as silicone or polyurethane) with an internal support element (such as a metal wire or stiffening rib). This composite construction allows the outer material to maintain patient comfort through flexibility and softness, while the internal support element provides the necessary structural rigidity to prevent kinking and maintain lumen patency during insertion and use.
2Object-affected harmful factors
If cannula wall is made thinner to reduce trauma, then tissue trauma is reduced, but kinking resistance deteriorates
Solution Approach 1:
The cannula design implements local quality by varying the wall thickness and material properties at different locations along the cannula length. The distal portion (tip) has a thinner wall to minimize tissue trauma during insertion and at the implantation site, while the proximal portion has a thicker wall or includes reinforcement elements to provide kinking resistance. This gradient or stepped wall thickness configuration allows each section to be optimized for its specific functional requirements.
3Ease of operation
If cannula is made straight for easy insertion, then insertion ease is improved, but stress concentration increases leading to kinking
Solution Approach 1:
The cannula is designed with a pre-curved configuration, specifically a J-shape or angled tip, rather than a completely straight form. This curvature serves multiple functions: it facilitates easier insertion by allowing the cannula to navigate subcutaneous tissue more naturally, reduces stress concentration points by distributing mechanical loads along the curved path, and prevents kinking by avoiding sharp angles that would create stress concentrations. The curve radius and angle are carefully optimized to balance insertion ease with structural integrity.
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 cannula design significantly reduces the risk of kinking and occlusions, ensuring consistent medication delivery by allowing the cannula to revert to its original shape when the load is removed, thereby minimizing long-term risks of blockages.
Implementation Method 1
hyperelastic materials like polyurethane
Implementation Method 2
allowing the cannula to revert to its original shape when the load is removed
Data Source
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AI summary
Embodiments relate to a cannula that is provided for delivering a substance, such as a medicine (e.g., insulin) to a patient, where the cannula has reduced likelihood of kinking or occlusions when implanted in a patient. The cannula may have a reduced number of stress concentrations along its length, an angled tip and/or a curve in its length. The cannula may include other designs to reduce kinking, such as internal ribbing and/or a slit along its wall.