Dual Material Plunger Tip for Syringe Sealing
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Solution Overview
Problem
Elastomeric plunger tips for syringes tend to break down and contaminate syringe contents, stick to the syringe barrel, and cause misalignment with the plunger due to their flexible nature, leading to uneven pressure and increased force requirements for movement.
Innovation Solution
A dual-material plunger tip with a rigid polymeric core and an elastomeric sleeve, where the elastomeric sleeve is co-injection molded onto the core, reducing elastomeric material contact with the syringe contents and barrel, and featuring circumferential ridges for enhanced engagement and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an elastomeric plunger tip is used, then flexibility and sealing are improved, but the plunger tip interacts with syringe contents causing breakdown and contamination
Solution Approach 1:
The plunger tip is divided into two distinct material zones: an inner core made of inert polymeric material that contacts the syringe contents, and an outer elastomeric layer that provides flexibility and sealing. This segmentation allows each material to perform its optimal function without the drawbacks of using a single material throughout.
Solution Approach 2:
Different regions of the plunger tip have different material properties: the inner core uses inert polymeric material resistant to chemical interaction with syringe contents, while the outer layer uses elastomeric material for flexibility and sealing. This local differentiation of material quality resolves the contradiction between chemical inertness and mechanical flexibility.
2Reliability
If an elastomeric plunger tip is used, then sealing capability is improved, but the plunger tip sticks to the syringe barrel requiring increased force for movement
Solution Approach 1:
The plunger tip is segmented into an inner inert core and an outer elastomeric layer. The elastomeric layer maintains sealing capability while the inert core reduces the overall surface area of elastomeric material contacting the syringe barrel, thereby reducing adhesion and the force required for movement.
Solution Approach 2:
The plunger tip uses a composite structure combining inert polymeric material and elastomeric material. This composite design allows the elastomeric portion to provide sealing while the inert core reduces total elastomeric surface area contact with the barrel, minimizing sticking and reducing the force needed for plunger movement.
3Reliability
If a flexible elastomeric plunger tip is used, then sealing is improved, but the connection between plunger and plunger tip becomes unstable causing misalignment
Solution Approach 1:
The plunger tip is segmented into an inner core that provides structural rigidity for stable alignment with the plunger, and an outer elastomeric layer that provides sealing. The rigid core acts as a stable backbone that prevents misalignment while the elastomeric outer layer maintains sealing capability.
Solution Approach 2:
The composite structure combines rigid inert polymeric material for structural stability and alignment with flexible elastomeric material for sealing. This composite design resolves the contradiction by allowing each material to fulfill its primary function: the rigid core ensures stable connection and alignment, while the elastomeric outer layer provides reliable sealing.
Data Source
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AI summary
A plunger tip for being located on a distal end of a syringe plunger and for sliding sealed engagement with an interior surface of a syringe barrel includes a core constructed of a generally rigid material. The core has a dirst end for being secured to the plunger, a second end and an endless sidewall between the first and second ends. An elastomeric sleeve at least partially surrounds the endless sidewall of the core.