Autoinjector Audible Completion Mechanism for Full Dose Delivery

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Solution Overview

Problem

Existing automatic injection devices lack a reliable mechanism to inform users when the injection is complete, particularly for self-administering patients who may not be medically trained, risking incomplete dosing.

Innovation Solution

An automatic injection device with a piston system that includes an intermediate part and flexible part to produce an audible indicator when the piston nears the container end, ensuring complete expulsion of the product, utilizing coil springs and a clapping part to generate a sound upon return to the non-deflected position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If automatic injection means are provided to simplify patient self-injection, then ease of operation is improved, but reliability of complete dose delivery deteriorates due to lack of user feedback on injection completion

Engineering Contradiction:
Improveease of self-injectionVSAvoidreliability of complete dose delivery
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent implements an audible feedback mechanism through a sound-producing assembly that generates a distinct sound when the piston reaches the distal end of the container, providing clear confirmation to the user that the injection is complete. This feedback loop ensures reliable dose delivery by eliminating uncertainty about injection completion.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent introduces an intermediate part that acts as a mediator between the piston rod and the sound-producing assembly. This intermediary component transfers the mechanical motion of the piston to the flexible part, enabling the sound generation mechanism without requiring direct connection, thus maintaining system reliability while enabling user feedback.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If simple automatic injection devices are provided for patient use, then ease of operation is improved, but device complexity increases due to additional controlling means for audible indication

Engineering Contradiction:
Improvesimplicity of useVSAvoidcomplexity of controlling means
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The sound-producing assembly is designed to activate automatically through the natural motion of the piston during injection. The flexible part and intermediate part work together such that the piston's own movement drives the sound generation mechanism without requiring separate control systems, power sources, or complex electronics, thereby maintaining simplicity while providing feedback.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces electronic or complex mechanical control systems with a simple passive mechanical sound-producing assembly. The flexible part and intermediate part create sound through pure mechanical interaction driven by piston motion, eliminating the need for batteries, motors, or complex control circuits.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If audible indication is provided at injection completion, then reliability of dose delivery is improved, but device complexity increases due to additional sound-producing components

Engineering Contradiction:
Improvereliability of injection completion indicationVSAvoidcomplexity of sound-producing assembly
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the sound-producing function with the existing piston and container structure. The intermediate part is integrated into the piston rod assembly, and the flexible part is positioned within the housing, combining the indication function with the injection mechanism rather than adding separate independent components.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The sound-producing assembly uses simple, inexpensive components including a flexible part and intermediate part that can be easily manufactured and integrated. These components are designed to function reliably for the single use of the device without requiring maintenance or complex materials.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 device provides clear auditory feedback to users that the injection is complete, ensuring a controlled and complete dose delivery.

Implementation Method 1

said automatic injection means cooperating with said intermediate part to release said flexible part allowing said at least a flexible part to return to a non-deflected position thereby generating a sound

Methodology Applied
Scientific EffectElastic recovery: Elasticity

Implementation Method 2

said elastic means comprise a distal coil spring and a proximal coil spring serially mounted

Methodology Applied
Scientific EffectSpring energy storage and release: Spring

Data Source

PatentEP3508237B9Autoinjector with audible indication of completed delivery
Publication Date: 2026.04.22 BECTON DICKINSON FRANCE SAS
  • EP3508237B9 patent drawingFigure 1~4

AI summary

A device (1) for automatic injection of a product into an injection site, the device (1) comprising: a housing (9) having a proximal end and a distal end; a flexible part (10) at the distal end of the housing (9) projecting inwardly and toward the distal end of the housing (9) in a non-deflected position, the flexible part (10) transitionable between the non-deflected position and a deflected position; a piston rod (7) movably disposed within the housing (9); and an intermediate part (12) mounted around the piston rod (7), wherein as the intermediate part (12) is moved axially towards the distal end of the housing (9), the intermediate part (12) deflects the flexible part (10) outward to the deflected position, and once the intermediate part (12) is advanced beyond the distal end of the housing (9), the flexible part (10) returns to the non-deflected position thereby generating an audible indication.