Reusable Auto-Injector with Electric Motor Plunger Reset
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Solution Overview
Problem
Conventional injection devices, particularly manual devices, pose challenges for users due to the need for continuous force application and dexterity, which can be difficult for elderly or arthritic patients, and autoinjectors may not ensure complete drug delivery if not used correctly.
Innovation Solution
A re-usable auto-injector with a drive spring and reset mechanism, coupled with an electric motor for retracting the plunger, provides a user-friendly mechanism for administering injections with minimal technical training, featuring a ratchet wheel for easy spring reset and audible/tactile feedback, ensuring complete drug delivery and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a manual injection device is used, then the device structure is simple, but the user requires continuous force application and dexterity which is difficult for elderly or arthritic patients
Solution Approach 1:
The auto-injector device performs the injection function automatically without requiring continuous user force application. The spring-loaded plunger mechanism self-activates upon trigger engagement, eliminating the need for users to maintain manual pressure during injection, thereby serving itself rather than requiring continuous user intervention.
Solution Approach 2:
The patent replaces the manual mechanical force application system with an automatic spring-loaded plunger system. The mechanical energy stored in the compressed spring is converted to drive the plunger automatically, substituting the user's manual mechanical effort with a pre-loaded mechanical energy storage system.
2Loss of substance
If a reusable auto-injector is used, then the device can be used multiple times reducing waste, but the device complexity increases with reset mechanisms
Solution Approach 1:
The patent implements a reusable device body that can be reset and used multiple times, while only the syringe and needle components are discarded after single use. The reset mechanism recovers the spring energy and repositions the plunger, allowing the main device housing to be recovered and reused, thereby reducing waste of substantial components.
Solution Approach 2:
The patent changes the state of the spring from compressed (energy stored) to extended (energy released) during injection, and then resets it back to compressed state for reuse. This parameter change (compression ratio, plunger position) enables the device to cycle through multiple injection events, achieving reusability through state transformation rather than single-use disposal.
3Device complexity
If the plunger is retracted manually by rotating the rear case, then the reset mechanism is simple, but the operation requires user dexterity and effort
Solution Approach 1:
The patent replaces the manual rotation operation with an electric motor system that automatically retracts the plunger. The motor converts electrical energy to mechanical motion, substituting the user's manual rotational effort with an automated electromechanical system, thereby improving ease of operation for users with limited dexterity or strength.
4Ease of operation
If an electric motor is used to retract the plunger, then the operation is automated improving ease of use, but the device complexity and power requirements increase
Solution Approach 1:
The patent introduces an electric motor to automate the plunger retraction process, replacing manual mechanical operation with electromechanical automation. This substitution provides ease of operation by eliminating the need for user rotation effort, while accepting increased device complexity through the addition of motor, battery, and control components.
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 auto-injector simplifies the injection process, reduces waste, and minimizes environmental impact by allowing multiple uses of the device with disposable syringes, providing a safe and effective means for self-administration with reduced need for clinical assistance.
Implementation Method 1
a drive spring arranged to advance a plunger relative to the syringe
Implementation Method 2
a screw nut is arranged as a ratchet wheel coupled to at least one ratchet drive feature in the rear case thus coupling the ratchet wheel to the rear case in one sense of rotation and allowing rotation of the ratchet wheel within the rear case in an opposite sense of rotation
Implementation Method 3
the plunger comprises a threaded extension and wherein a screw nut is arranged in the rear case in a manner releasably engaging the threaded extension such that the plunger is retractable by rotation of the rear case relative to the front case
Implementation Method 4
an electric motor powered by a battery is arranged for retracting the plunger
Implementation Method 5
a gear train is arranged to convert rotation of the electric motor into linear motion of the plunger, wherein the gear train comprises a rack (16.6) and a pinion gear
Data Source
AI summary
Described is an auto-injector for administering a medicament comprising a case arranged to receive a packaged syringe comprising an injection needle, wherein the case comprises a front case rotatably coupled to a rear case, and a drive spring arranged to advance a plunger relative to the packaged syringe, and a reset mechanism for the drive spring arranged to retract the plunger and compress the drive spring when the front case is rotated relative to the rear case.