Needle Guard Triggering for Inadvertent-Actuation-Resistant Auto-Injectors
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Solution Overview
Problem
Existing automatic injectors face challenges in ensuring needle protection before, during, and after injection, and preventing inadvertent actuation.
Innovation Solution
An automatic injection device with a housing element, needle guard, control unit, and plunger rod mechanism that includes resilient elements and locking features to ensure safe and controlled injection, preventing inadvertent actuation by requiring a predetermined trigger force and allowing axial displacement of the needle guard to initiate injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the needle guard is made freely movable for easy access, then ease of operation is improved, but inadvertent actuation risk increases
Solution Approach 1:
The safety cap is removed in advance to expose the needle guard, allowing the user to access the injection site without risk of inadvertent actuation. The needle guard remains exposed and accessible throughout the injection process, eliminating the need for repeated cap removal while maintaining safety.
Solution Approach 2:
The needle guard acts as an intermediary component between the housing and the injection mechanism. It provides a protective barrier that can be easily accessed while preventing direct exposure of the needle, thus reducing inadvertent actuation risk while maintaining ease of operation.
2Speed
If the plunger rod is freely displaced for rapid injection, then injection speed is improved, but control precision deteriorates
Solution Approach 1:
The plunger rod is designed with dynamic characteristics that allow rapid displacement during injection while maintaining control. The resilient element provides elastic recovery that enables the plunger rod to move quickly when actuated while returning to its initial position, ensuring both speed and control precision.
Solution Approach 2:
The resilient element changes the mechanical parameters of the plunger rod system, providing elastic forces that enable rapid movement while maintaining control. The elastic properties allow the plunger rod to accelerate quickly during injection while the spring force provides a stopping mechanism, achieving both speed and precision.
3Reliability
If the needle guard is highly protected against displacement, then reliability is improved, but ease of operation worsens
Solution Approach 1:
The safety cap is removed in advance to expose the needle guard, allowing the user to access the injection site without risk of inadvertent actuation. The needle guard remains exposed and accessible throughout the injection process, eliminating the need for repeated cap removal while maintaining safety.
Solution Approach 2:
The device is segmented into distinct functional components: the safety cap for protection, the needle guard for accessibility, and the housing for structural support. This segmentation allows each component to perform its specific function optimally - the safety cap provides protection when needed, while the needle guard remains accessible for easy operation during injection.
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 secure needle protection and controlled injection, preventing inadvertent actuation, ensuring safe and reliable administration of medications.
Implementation Method 1
at least one resilient element arranged to be located within the housing element; a plunger rod biased axially forwardly under an urge of the at least one resilient element
Data Source
AI summary
An automatic injection device for use with a syringe, including a housing element; at least one resilient element arranged to be located within the housing element; a needle guard slidably positionable with respect to the housing element; a control unit configured to be fixedly coupled with the housing element; a plunger rod biased axially forwardly under an urge of the at least one resilient element and configured to engage the control unit in a storage operative orientation, in which the plunger rod is prevented from forward axial displacement relative to the control unit under the urge of the at least one resilient element; and upon axial rearward displacement of the needle guard with respect to the housing element, the plunger rod is disengaged from the control unit and is permitted to be axially forwardly displaced relative to the control unit under the urge of the at least one resilient element.