Asymmetric Locking Mechanism Prevents Injection Device Reuse

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Solution Overview

Problem

Existing injection devices often spring back to their starting position after use, allowing potential reuse and increasing the risk of needlestick injuries and contamination.

Innovation Solution

A safety device with a sleeve and collar locking mechanism, featuring ribs and protrusions with different flank angles, and a spring system that prevents the collar from rotating back to the starting position, ensuring the needle remains locked in a safe position after use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a spring mechanism is used to return the collar to the starting position, then the device can be reused, but the risk of needlestick injuries and contamination increases

Engineering Contradiction:

ImprovereusabilityVSAvoidneedlestick injury risk

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The locking mechanism employs asymmetric rib-protrusion geometry where the protrusions on the collar have inclined surfaces that engage with the ribs on the sleeve. The asymmetric design allows the collar to be locked in the distal position during injection but prevents it from returning to the starting position, thereby preventing needle reuse while maintaining the spring mechanism's ability to provide injection force.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The invention transforms the injection device into a single-use disposable item by implementing an irreversible locking mechanism. The collar becomes permanently locked in the distal position after injection, rendering the needle non-reusable. This approach eliminates the risk of needlestick injuries from reused needles while maintaining the mechanical simplicity of the spring return mechanism.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Ease of operation

If the collar is allowed to rotate freely on the curved guide, then the spring can relax and return the device to starting position, but the needle may be exposed causing contamination

Engineering Contradiction:

Improvespring relaxationVSAvoidcontamination risk

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The locking action occurs automatically as a preliminary result of the injection process itself. As the collar moves to the distal position during needle exposure, the protrusions engage with the ribs and lock the collar in place. This preliminary locking action ensures that when the spring subsequently relaxes, the collar cannot return to the starting position, thereby preventing contamination while allowing spring relaxation.

Inventive Principle:

Principle #10Preliminary action

3Object-affected harmful factors

If the collar locks in the distal position, then needlestick injury risk is reduced, but the device cannot be reused

Engineering Contradiction:

Improveneedlestick injury riskVSAvoidreusability

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The asymmetric rib-protrusion geometry creates a one-way locking mechanism. The inclined surfaces of the protrusions allow engagement with the ribs when the collar moves distally, but the geometry prevents disengagement and return to the starting position. This asymmetric design achieves permanent locking to prevent needlestick injuries while maintaining the simplicity of a mechanical spring-based system.

Inventive Principle:

Principle #4Asymmetry

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

Prevents reuse of the injection device and reduces the risk of needlestick injuries by securely locking the needle in a safe position, providing additional safety against contamination and ensuring the needle is safely disposed of.

Implementation Method 1

there is also at least one spring (17), which is designed to counteract a movement of the sleeve (8) relative to the safety device (2)

Methodology Applied

Scientific EffectSpring force: Spring

Implementation Method 2

the collar (3) is arranged to rotate in a circumferential direction on the distal end region of the body (1)

Methodology Applied

Scientific EffectMechanical rotation:

Implementation Method 3

the cap (15) can be arranged at least in part over the sleeve (8) and by which the sleeve (8) can be locked in respect of a movement of the body (1) relative to the sleeve (8)

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS11833315B2Additional function of a safety device for injection devices

Publication Date: 2023.12.05 GERRESHEIMER REGENSBURGH GMBH

AI summary

A safety device for injection devices is described. The safety device includes a sleeve extending along a longitudinal axis of the injection device's body, at least partially enclosing the injection device's needle and body, and including a guide slot; a collar attached to a distal end region of the body and locking the safety device in an axial direction; and a cap that can be arranged at least in part over the sleeve to prevent the body from moving relative to the sleeve. The cap includes a receptacle for the needle. The collar includes a guide pin that engages the guide slot. The collar can be arranged to rotate relative to the sleeve, and the receptacle of the cap can engage the collar and prevent the collar from rotating. The sleeve and the collar can each include a lock.