Multi-Material Syringe Needle Shield for Coring Prevention
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Solution Overview
Problem
Existing needle shields for syringes face manufacturing inefficiencies due to a three-step process and issues like coring, where the soft component is cut during assembly, leading to potential clogging and damage to the needle tip.
Innovation Solution
A needle shield design featuring a co-injection molded elastomeric skin layer with an embedded rigid core, formed in a single step, and a bi-material inner casing with varying hardness for improved assembly and reduced coring risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a three-step manufacturing process is used to form rigid and soft components separately and then assemble them, then manufacturing flexibility is improved, but manufacturing time and cost increase
Solution Approach 1:
The patent combines the rigid component and soft component into a single integrated needle shield formed by co-injection molding. The mold includes a rigid component cavity and a soft component cavity that are filled in sequence during a single molding cycle, eliminating the need for separate manufacturing and assembly steps while maintaining design flexibility through controlled material injection.
2Adaptability or versatility
If a three-step manufacturing process with separate molding of rigid and soft components is used, then component design freedom is improved, but assembly complexity increases
Solution Approach 1:
The rigid and soft components are merged into a single co-injected molded piece, eliminating assembly operations. The mold design allows both components to be formed simultaneously in one cavity system, with the rigid component formed first followed by the soft component, resulting in an integrated structure that requires no post-assembly.
3Reliability
If the needle is pricked into the soft component to ensure sealing, then sealing reliability is improved, but coring occurs causing needle clogging
Solution Approach 1:
The patent modifies the physical parameters of the soft component by controlling its hardness and elasticity through material selection and formulation. The soft component is designed with optimized Shore A hardness (e.g., 40-70) and elastic properties to allow needle insertion without coring, while still maintaining adequate sealing force through controlled deformation and recovery.
Solution Approach 2:
The soft component is designed with non-uniform properties, being softer at the needle insertion region to prevent coring, while maintaining sufficient firmness in other areas to ensure sealing. The material composition and cross-linking density are locally optimized to balance needle penetration ease with sealing effectiveness.
4Object-generated harmful factors
If the soft component is made softer to prevent coring, then needle protection is improved, but sealing force decreases
Solution Approach 1:
The patent optimizes the hardness parameter of the soft component within a specific range (Shore A 40-70) to achieve the right balance. This parameter optimization allows the material to be soft enough to prevent coring during needle insertion while remaining firm enough to provide adequate sealing force against the syringe hub and maintain liquid containment.
Solution Approach 2:
The soft component is formulated as a composite elastomeric material with tailored properties, combining different polymer blends, plasticizers, and cross-linking agents to achieve the desired balance between softness for needle insertion and firmness for sealing. The composite structure allows independent optimization of penetration resistance and sealing force.
Data Source
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Figure 3A~3B
AI summary
Provided herein is a needle shield for use with a syringe comprising a needle and a barrel. The needle shield includes an elastomeric skin layer configured to receive the needle therein and maintain tightness between the needle shield and the needle when the needle shield is positioned on the syringe, and a rigid core embedded within the elastomeric skin layer.