Flared Flexible Cannula Resisting Buckling
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Solution Overview
Problem
Current medical devices employing cannula tubing for fluid media delivery, such as insulin infusion systems, face challenges in ensuring secure and comfortable insertion, maintaining fluid flow integrity, and preventing kinking or buckling, particularly in flexible tubing configurations.
Innovation Solution
The design incorporates a cannula with a hollow tube configuration that includes a flared section for enhanced sealing and rigidity, featuring a micromolded structure with varying outer and inner diameters to ensure reliable fluid flow and resistance to kinking, along with a needle guide for assisted insertion and a secure base for skin adherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If flexible tubing is used for cannula, then ease of insertion and comfort are improved, but resistance to kinking and buckling deteriorates
Solution Approach 1:
The cannula incorporates a flared section with varying wall thickness (thicker at the flare, thinner toward the distal end) to provide localized rigidity where needed for buckling resistance, while maintaining flexibility in other sections for ease of insertion. This non-uniform structure allows different parts of the cannula to have different mechanical properties optimized for their specific functions.
Solution Approach 2:
The cannula is formed from a single piece of flexible tubing material through micromolding, creating a composite-like structure with varying density and thickness zones. The flared section acts as a reinforced zone within the otherwise flexible tube, providing structural support without requiring separate materials or components.
2Strength
If flared section with varying diameter is incorporated, then resistance to buckling is improved, but device complexity increases
Solution Approach 1:
The cannula is divided into distinct functional sections: a flared section with varying diameter for buckling resistance, a needle guide section for insertion assistance, and a distal section for fluid delivery. This segmentation allows each portion to be optimized for its specific function while maintaining overall structural integrity through a unified micromolded construction.
Solution Approach 2:
The flared section is pre-formed during the micromolding manufacturing process, creating the buckling-resistant structure before the cannula is inserted into the patient. This preliminary formation of the reinforced structure eliminates the need for post-manufacturing assembly or additional reinforcement components.
3Reliability
If micromolded structure with varying wall thickness is used, then fluid flow integrity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The micromolding process enables precise control of wall thickness as a varying parameter along the length of the cannula. By programming the mold cavity with different depths and reinforcement zones, the manufacturing process automatically creates the desired non-uniform wall thickness profile, ensuring consistent fluid flow characteristics and structural performance.
Data Source
AI summary
A cannula includes a tubular body having an axial dimension through which a flow channel extends. The tubular body has a first end for insertion into a subject, and a second end configured to be held within a base of a medical device. The tubular body has a first length portion extending along the axial dimension from the first end toward the second end. A second length portion extends along the axial dimension from the first length portion toward the second end, and has an outer dimension that flares outward to be larger than the outer dimension of the first length portion. The second length portion also has a tubing wall thickness that is greater than the tubing wall thickness of the first length portion.