Syringe Plunger Locking Arrangement for Cryogenic Sterility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Medical syringes experience plunger motion due to thermal expansion and contraction, leading to sterility issues and failure to meet container closure integrity at low temperatures, especially around -80 degrees Celsius.
Innovation Solution
A locking arrangement with a deformable element that applies a locking force between the plunger rod and the container body, reducing plunger motion and enhancing sealing, while being reversible and adjustable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plunger is chosen according to tolerance characteristics dependent on temperature requirements, then sterility is maintained, but device complexity and inconvenience in supply and production increase
Solution Approach 1:
The locking arrangement is pre-configured on the plunger rod with deformable elements that automatically engage with the container body wall to limit plunger motion. This preliminary action eliminates the need for complex plunger selection based on temperature requirements, as the locking mechanism universally prevents excessive movement across all temperature conditions.
Solution Approach 2:
The deformable elements change their physical state from undeformed to deformed when applying locking force against the container body wall. This parameter change enables the locking mechanism to adapt to different temperature conditions automatically, maintaining sterility without requiring different plunger designs for different temperature requirements.
2Reliability
If glass syringes are used for storage at very low temperatures around minus 80 degrees Celsius, then container closure integrity is compromised, but switching to alternative materials may affect other performance characteristics
Solution Approach 1:
The locking arrangement with deformable elements applies a preliminary locking force to prevent plunger motion before thermal expansion or contraction can occur. This preliminary anti-action counteracts the harmful effects of temperature changes on container closure integrity, making the solution applicable to various container materials including glass syringes used at very low temperatures.
Solution Approach 2:
The deformable elements provide beforehand cushioning by maintaining continuous contact with the container body wall through elastic deformation. This cushioning effect compensates for dimensional changes in the container body due to temperature fluctuations, preserving container closure integrity across different materials and temperature conditions.
3Reliability
If the locking force is increased to reduce plunger motion, then sterility is better maintained, but the force required to operate the plunger rod increases
Solution Approach 1:
The deformable elements provide a dynamic locking force that adapts to the operating conditions. During normal operation, the elastic deformation allows smooth plunger movement with minimal resistance. When thermal expansion or contraction threatens to exceed sterility tolerances, the deformable elements automatically increase their locking force to prevent excessive motion, thus protecting sterility without permanently increasing operating force.
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 locking arrangement effectively minimizes plunger motion to less than 3 mm, maintains sterility, and ensures container tightness even under significant pressure differences and temperature fluctuations.
Implementation Method 1
a locking arrangement with a deformable element that applies a locking force between the plunger rod and the container body
Implementation Method 2
This motion is mainly due to thermal expansion and contraction of the content of the syringe during the temperature changes
Data Source
Figure 1~2A
Figure 2B~4
Figure 5i~6Aiii
AI summary
A container (100; 700), in particular a syringe or a cartridge, comprises a container body (110), a plunger (130; 530; 630) having a plunger rod (132; 332; 432; 532; 632), the plunger rod (132; 332; 432; 532; 632) disposed at least partially within the container body (110), and a locking arrangement (150; 350; 450; 550; 650) for locking a position of the plunger rod (132; 332; 432; 532; 632) relative to the container body (110). The locking arrangement (150; 350; 450; 550; 650) is operable between at least a locked position and an unlocked position. The locking arrangement (150; 350; 450; 550; 650) comprises at least one deformable element (152; 352; 452) which is configured for applying a locking force between the plunger rod (132; 332; 432; 532; 632) and an inner wall (112) of the container body (110) when the locking arrangement (150; 350; 450; 550; 650) is in the locked position and for releasing a locking force between the plunger rod (132; 332; 432; 532; 632) and the inner wall (112) of the container body (110) when the locking arrangement (150; 350; 450; 550; 650) is changed from the locked position to the unlocked position.