Friction-Based Needle Shield Retention for Safety Intravenous Catheters

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Solution Overview

Problem

Existing intravenous catheter needle shields are often bulky, difficult to use, require special features or techniques, and may leave the sharp distal tip exposed until manually activated, posing risks of accidental needle sticks due to contamination.

Innovation Solution

A catheter and introducer needle assembly with a resilient clip that frictionally retains the needle shield with the catheter hub using a cantilevered arm and pawl, ensuring secure retention until the introducer needle is fully withdrawn, then automatically preventing further displacement of the needle shield to safeguard against exposure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a needle shield is used to protect against accidental needle sticks, then safety is improved, but the device becomes bulky and difficult to use

Engineering Contradiction:

ImprovesafetyVSAvoidbulky and difficult to use

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The needle shield is merged with the catheter hub by frictionally engaging the shield's pawl against the hub's outer surface. This integration eliminates the need for separate retention mechanisms, reducing device complexity while maintaining safety functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The retention mechanism is extracted from the needle shield itself and transferred to the catheter hub. The hub's outer surface serves as the retention feature, simplifying the needle shield design and reducing overall device bulk.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If a needle shield with manual activation is used, then safety is improved, but the sharp distal tip remains exposed until activated, posing needle stick risks

Engineering Contradiction:

ImprovesafetyVSAvoidexposed sharp tip

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The needle shield is pre-positioned in a retained state against the catheter hub before use. The friction engagement between the pawl and hub surface ensures the shield remains in place during insertion, automatically protecting the sharp tip without requiring manual activation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The device performs self-protection through the friction-based retention mechanism. The needle shield automatically engages with the catheter hub and remains secured throughout the procedure, eliminating the need for manual intervention to maintain safety.

Inventive Principle:

Principle #25Self-service

3Reliability

If projection-recess interlock mechanisms are used to retain needle shield, then retention reliability is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveretention reliabilityVSAvoiddetailed or intricate molding

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of complex interlocking features, the solution uses a simple friction interface between the pawl and the hub's outer surface. This localized friction engagement provides sufficient retention reliability while avoiding intricate molding requirements.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The retention mechanism transitions from mechanical interlocking (projection-recess) to friction-based engagement. By changing the retention parameter from geometric interlock to surface friction, manufacturing complexity is reduced while maintaining reliability.

Inventive Principle:

Principle #35Parameter changes

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 solution provides a secure, user-friendly mechanism for retaining the needle shield with the catheter hub, reducing the risk of accidental needle stick injuries by ensuring the sharp tip is safely captured within the shield after use, enhancing safety and simplifying the handling process.

Implementation Method 1

the pawl frictionally contacts the uninterrupted outer surface portion of the catheter hub and thereby frictionally retains the needle shield with the catheter hub

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentEP4166187A1Safety intravenous catheter with friction-based retention and disabling feature

Publication Date: 2023.04.19 BECTON DICKINSON & CO

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AI summary

A catheter and introducer needle assembly (200, 300, 400), including a flexible catheter and a catheter hub (204, 304, 404) having an uninterrupted outer surface portion (226, 326, 426), a Luer-connecting feature, and a disabling feature (232, 332, 432). The assembly includes an introducer needle (206, 306, 406) disposed in the catheter, a needle shield (210, 310, 410) having a resilient clip (212, 312, 412) adapted to flex between first and second positions in a plane perpendicular to the introducer needle. The resilient clip includes a cantilevered arm (220, 320, 420) with a pawl (222, 322, 422). In the resilient clip's first position, the cantilevered arm is flexed so that the pawl frictionally contacts the catheter hub's uninterrupted outer surface portion and frictionally retains the needle shield with the catheter hub, and the pawl is axially aligned with and spaced apart from the disabling feature. In the second position, the pawl no longer frictionally contacts the hub's uninterrupted outer surface, thereby permitting needle shield displacement relative to the catheter hub.