Pre-filled Syringe Cap with Breakable Seal for Steam Sterilization
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Solution Overview
Problem
Pre-filled hypodermic syringes face challenges in sterilization due to the leaktight removable cap, which prevents steam from reaching the outer face of the tip, requiring longer dry heat sterilization, leading to increased costs and potential degradation of materials and active ingredients. Additionally, the breakable zone in existing designs experiences uneven stress distribution, making clean separation uncertain and potentially contaminating the solution.
Innovation Solution
A pre-filled hypodermic syringe design with a breakable zone featuring an annular thinning for homogeneous stress distribution during cap rotation, accompanied by a cap with ergonomic rotation means and a conical chimney for secure retention, allowing easy and clean separation of the cap from the end piece, and an orifice for steam access during moist heat sterilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a removable cap is mounted in a leaktight manner on the end piece, then the seal between cap and tip is ensured, but steam cannot reach the outer face of the tip during moist heat sterilization
Solution Approach 1:
The cap is designed with a breakable seal that allows steam to pass through during sterilization. This preliminary design feature enables the cap to maintain its sealing function during storage and transport, while automatically allowing steam penetration when exposed to sterilization conditions, thus resolving the contradiction between maintaining seal integrity and allowing sterilization access.
2Reliability
If dry heat sterilization is used to sterilize the area between cap and tip, then sterility is guaranteed, but sterilization time increases and material degradation occurs
Solution Approach 1:
The invention changes the sterilization parameter from dry heat to moist heat by designing the cap with a breakable seal that allows steam penetration. This parameter change enables the use of moist heat sterilization, which is faster and causes less material degradation while still achieving the required sterility level, thus resolving the contradiction between sterility assurance and sterilization time.
3Manufacturing precision
If the breakable zone has sufficient thickness to ensure material continuity, then manufacturing tolerance is compensated, but clean separation becomes uncertain and contamination risk increases
Solution Approach 1:
The breakable seal is designed as a composite structure combining a plastic portion and an elastomeric portion with different mechanical properties. The plastic portion provides structural integrity and material continuity, while the elastomeric portion provides flexibility and clean break characteristics. This composite design resolves the contradiction by allowing sufficient thickness for manufacturing tolerance compensation while ensuring clean separation during cap removal.
4Strength
If polypropylene cap is screwed onto Luer-Lock tip, then secure mounting is achieved, but tightening releases during sterilization due to softening
Solution Approach 1:
The cap is designed as a composite structure with a plastic portion for structural support and an elastomeric portion for sealing and temperature resistance. The elastomeric material maintains its mechanical properties at sterilization temperatures, preventing the loosening that occurs with pure polypropylene, thus resolving the contradiction between mounting strength and tightening stability during sterilization.
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
Facilitates efficient and cost-effective sterilization without material degradation, ensures a perfect seal, and allows for clean separation of the cap from the end piece, preventing contamination and ensuring sterility.
Implementation Method 1
the breakable zone (14) connecting the obturator (13) and the end piece (9) being subjected to a homogeneous distribution of stresses resulting from the rotation of the cap (15) around a longitudinal axis of the syringe (1)
Implementation Method 2
the cap (15) having an orifice (25) for access by steam during a sterilization in moist heat
Implementation Method 3
In the case of the use of an elastomer plug mounted by elastic clamping on the endpiece
Data Source
Figure 1
Figure 2~4
Figure 5~7
AI summary
The invention relates to a pre-filled hypodermic syringe comprising: a tubular body (1) having two open ends (2, 3) and containing a fluid to be administered to a patient; a plunger (6) which, having at one of its ends a piston (4) mounted to slide in the tubular body (1), passes through the opening of the first end (2) of the tubular body; a tip (9) for connection in the form of a cone of the Luer or Luer-Lock type, for example for connecting to a needle or to a drip, intended to pass the fluid that is to be administered and comprising a tubular part (10) communicating with the opening of the second end (3); the tip (9) comprising an obturator (13) connected by a frangible region (14) to the free end of its tubular part (10), the syringe being made of a synthetic material and obtained by moulding, the obturator (13) being moulded as one piece with the tip (9) and the tubular body (10).