Needle Shield Interface Design for Low-Force Syringe Removal
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Solution Overview
Problem
Existing syringe needle shields are often secured too tightly to the syringe, requiring excessive force for removal, which can be beyond the capability of some users, posing challenges in maintaining sterility and safety.
Innovation Solution
A syringe assembly with a reduced friction interface between the needle shield and syringe, featuring contoured features such as annular grooves, ridges, dimples, or protrusions, which reduce the surface area of contact and the force required for removal, ensuring ease of detachment while maintaining sterility and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the needle shield is secured tightly to the syringe to maintain sterility and protect the needle, then the reliability of maintaining sterility and safety is improved, but the force required to remove the needle shield increases excessively
Solution Approach 1:
The interface between the needle shield and syringe is segmented into distinct functional zones: a proximal frictional engagement portion that provides secure attachment, and a distal reduced friction portion with contoured features (annular grooves, ridges, dimples, or protrusions) that minimize removal force. This segmentation allows different regions to serve different purposes simultaneously.
Solution Approach 2:
Different portions of the needle shield-syringe interface are given different frictional characteristics. The proximal end has high friction for secure retention, while the distal end features localized reduced friction zones with contoured features that create low-resistance removal paths. This local differentiation resolves the contradiction between secure attachment and easy removal.
2Reliability
If the needle shield is secured tightly to prevent accidental needle sticks, then the safety is improved, but the ease of operation for removal deteriorates
Solution Approach 1:
The interface is divided into functional segments: a proximal high-friction engagement zone for secure safety, and a distal low-friction removal zone with contoured features. This segmentation enables the needle shield to be both securely attached (safety) and easily removed (ease of operation).
Solution Approach 2:
The contoured features (annular grooves, ridges, dimples, or protrusions) act as intermediary elements between the needle shield and syringe. These features create a controlled friction interface that mediates between the need for secure attachment and the need for easy removal, reducing the force required while maintaining safety.
3Ease of manufacture
If a standard friction interface is used to secure the needle shield, then the manufacturing simplicity is maintained, but the ease of operation for removal is worsened
Solution Approach 1:
Rather than making the entire interface complex, the invention applies reduced friction features only locally at the distal end where removal occurs. The proximal end maintains a standard frictional interface for secure attachment. This localized approach preserves manufacturing simplicity while improving ease of removal.
Solution Approach 2:
The invention applies reduced friction only to the portion of the interface where it is needed for removal (the distal end), while leaving the proximal end with standard frictional characteristics. This partial application of the reduced friction principle maintains manufacturing simplicity while achieving the desired ease of removal.
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 reduced friction interface allows for easy removal of the needle shield with forces less than or equal to approximately 10 N, enhancing user convenience and safety by minimizing the risk of accidental needle sticks and maintaining needle sterility during transportation and storage.
Implementation Method 1
the interface between the syringe and needle shield may create substantial resistance to a force applied to remove the needle shield from the syringe
Data Source
AI summary
A syringe assembly includes a syringe having a barrel and a needle hub disposed at a distal end of the syringe and a needle shield including an inner surface and a cavity for receiving the needle hub. The inner surface of the needle shield engaging an outer surface of the needle hub to form a sealing interface therebetween and removably couple the needle hub and the needle shield when the needle shield is disposed on the syringe. In some examples, the sealing interface comprises at least one contoured feature configured to limit or reduce an amount of force required to remove the needle shield from the syringe.