Passive Syringe Reuse Prevention via Flange Lock

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Solution Overview

Problem

Existing syringe designs fail to effectively prevent reuse without requiring a specific user intent or action, and often impose dosage limitations or increased costs due to automatic locking mechanisms.

Innovation Solution

A syringe with a passive reuse prevention mechanism using a flange lock that is activated through normal use, allowing for variable dosing and disabling the syringe upon completion of an injection cycle without conscious user action, featuring a plunger assembly with a locking flange and flexible protrusions that engage to prevent plunger removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If automatic locking mechanisms are used to prevent syringe reuse, then reuse prevention is improved, but device complexity and cost increase

Engineering Contradiction:

Improvereuse preventionVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The syringe automatically disables itself through normal use. The flange lock and locking flange engage passively when the plunger rod is inserted and the injection cycle is completed, without requiring any additional user action or complex electronic controls. The system serves itself by using the natural movements during injection to activate the locking mechanism.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The reuse prevention mechanism uses simple, low-cost mechanical components (flange lock, locking flange) rather than expensive electronic or complex mechanical systems. The design embraces the disposable nature of syringes by providing an inexpensive passive locking mechanism that prevents reuse without adding significant cost.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If automatic locking mechanisms are used to prevent syringe reuse, then reuse prevention is improved, but manufacturing cost increases

Engineering Contradiction:

Improvereuse preventionVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The mechanism uses simple plastic components (flange lock molded into the barrel, locking flange on the plunger rod) that are inexpensive to manufacture. The design avoids expensive materials or complex assembly processes, making it suitable for high-volume production of disposable medical devices.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The flange lock is molded as an integral part of the syringe barrel, and the locking flange is formed as part of the plunger rod assembly. This integration reduces the number of separate parts and assembly steps, lowering manufacturing complexity and cost.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If passive reuse prevention mechanism is used, then ease of operation is improved, but reliability may worsen due to unintended activation

Engineering Contradiction:

Improveease of operationVSAvoidreuse prevention effectiveness

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The flange lock and locking flange are pre-positioned on the syringe barrel and plunger rod respectively. During normal insertion and injection, the plunger rod naturally moves the locking flange into engagement with the flange lock, activating the prevention mechanism as part of the standard procedure without requiring additional user actions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The locking mechanism is designed to engage at a specific location and under specific conditions (when the plunger rod is fully inserted and the injection cycle is complete). The flange lock only engages the locking flange when the plunger reaches its final position, ensuring activation only under the intended circumstances.

Inventive Principle:

Principle #3Local quality

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 effectively prevents syringe reuse without user intent, allows for variable dosing, reduces costs, and ensures the syringe is disabled after use, addressing the limitations of existing technologies.

Implementation Method 1

a flange lock disposed at the open proximal end of the barrel, the flange lock including a plurality of flexible protrusions... the protrusions are adapted to be deflected by the plunger rod such that the at least one protrusion engages the locking flange

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentEP3146988B1Passive reuse prevention syringe that uses a flange lock

Publication Date: 2019.09.11 BECTON DICKINSON & CO

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AI summary

A syringe assembly includes a syringe barrel having an inside surface defining a chamber, an open proximal end, a distal end, and an outlet; a plunger assembly disposed at least partially within the syringe barrel, including an elongate plunger rod having a locking flange formed thereon; and a plunger head having a distal sealing surface, the plunger rod being engageable with the plunger head such that the plunger rod is adapted to move the plunger head within the chamber of the syringe barrel through an injection cycle; and a flange lock disposed at the open proximal end of the barrel. The flange lock is integral with the open proximal end of the syringe barrel. During the injection cycle, the flange lock engages the locking flange of the plunger rod so as to prevent removal of the plunger rod from the syringe barrel.