Helical Track Torsion Spring Cannula Insertion
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Solution Overview
Problem
Current insulin infusion systems face challenges in efficiently and reliably inserting cannulas into subcutaneous tissue, particularly in transitioning the introducer needle and cannula between insertion positions, which affects the accuracy and comfort of insulin delivery.
Innovation Solution
A torsional insertion mechanism utilizing a torsion spring to rotate a bushing between spring positions, an angled ramp to move the insertion assembly, and a stop member to control rotation, enabling the captive introducer needle and cannula to pierce and retract tissue effectively, with a fluid flow path for insulin delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional linear insertion mechanism is used, then the structure is simple, but the insertion reliability and precision are insufficient
Solution Approach 1:
The patent applies a helical track with curved geometry instead of a linear path. The helical track guides the introducer needle and cannula through a rotational motion that converts linear insertion force into controlled helical movement, improving insertion reliability by distributing mechanical stress and enhancing tissue penetration efficiency.
Solution Approach 2:
The insertion mechanism transitions from a static linear guide to a dynamic helical track system. The helical track enables rotational movement of the bushing assembly, creating a dynamic insertion process that adapts to tissue resistance and improves penetration reliability through controlled angular motion.
2Ease of operation
If the bushing rotates freely, then the insertion assembly moves smoothly, but the rotation cannot be controlled precisely
Solution Approach 1:
The stop member engages with the helical track at specific angular positions to provide feedback-controlled rotation limits. This ensures the bushing rotates precisely through the required angle for proper needle and cannula insertion while maintaining smooth motion through the helical guidance path.
Solution Approach 2:
The helical track acts as an intermediary between the free-rotating bushing and the stop member. It translates unrestricted rotation into controlled angular movement, allowing smooth operation while achieving precise rotation control through the geometric constraints of the helical path.
3Reliability
If the introducer needle and cannula are moved together, then the fluid flow path is maintained, but the insertion force required is high
Solution Approach 1:
The cannula is nested within the introducer needle, with the needle serving as a guide and protective sheath. This nested configuration allows the sharper needle to penetrate tissue first, reducing the force required for overall insertion while maintaining the fluid flow path through the concentric arrangement of needle and cannula.
Solution Approach 2:
The helical track provides a curved insertion path that reduces mechanical resistance during penetration. By following a helical trajectory rather than a straight linear path, the distributed force required for insertion is reduced while maintaining the connected fluid pathway through the nested needle-cannula arrangement.
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 mechanism ensures precise and comfortable cannula insertion, facilitating reliable insulin delivery by efficiently moving the needle and cannula through tissue, enhancing the usability of insulin infusion systems.
Implementation Method 1
a torsion spring configured to rotate a bushing between a first spring position and a second spring position
Data Source
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AI summary
A torsional insertion mechanism includes a torsion spring configured to rotate a bushing between a first spring position and a second spring position and an insertion assembly configured to move from a first insertion position to a second insertion position in response to rotation of the bushing. The insertion assembly includes a cannula and a captive introducer needle configured to pierce tissue.