Auto-injector Reloadable Housing and Detent Activation
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Solution Overview
Problem
Auto-injectors, particularly those for adrenaline, have a short expiration date, leading to costly replacements, and often fail to penetrate to the desired depth in the body, causing inefficiencies and user confusion due to incorrect activation mechanisms.
Innovation Solution
An auto-injector design with a housing that allows for the syringe to be replaced, featuring a compressible motive source and a detent mechanism with inclined teeth for precise activation, ensuring correct orientation and depth of needle penetration, and a user-friendly interface to prevent accidental injuries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the auto-injector uses a spring-loaded syringe activated by pushing against the body, then the device can deliver a preloaded dose of drug, but the device must be completely discarded after expiration even if unused, leading to high costs
Solution Approach 1:
The auto-injector is divided into separate functional components: a reusable housing with activation mechanism and a replaceable syringe cartridge. This allows the syringe containing the drug to be replaced after expiration while the housing can be reused, reducing waste and cost.
Solution Approach 2:
The design enables selective discarding of only the syringe cartridge after drug expiration or use, while recovering and retaining the reusable housing component for future use with new syringes, minimizing overall device waste.
2Extent of automation
If the auto-injector requires a swing motion of the arm to plunge against muscle, then the device can be activated, but the high pressure applied adversely affects drug administration efficiency and causes leakage due to backlash
Solution Approach 1:
The activation mechanism is designed to be self-regulating, where the spring-loaded plunger automatically controls the injection force and rate without requiring the user to apply variable manual pressure, ensuring consistent and efficient drug delivery.
Solution Approach 2:
The spring mechanism provides controlled cushioning during activation, absorbing excess force and preventing backlash or leakage by maintaining steady pressure throughout the injection process rather than allowing sudden pressure spikes.
3Ease of operation
If the safety release is located at the back of the device separate from the activation mechanism, then the device can have distinct safety and activation functions, but this causes user confusion and incorrect injection locations
Solution Approach 1:
The safety release and activation mechanisms are merged into a single integrated button at the front of the device, eliminating spatial separation that caused user confusion. The same button performs both safety release and injection activation functions.
Solution Approach 2:
The single button mechanism serves multiple functions: it acts as both the safety release and the activation trigger for injection, reducing the number of separate components and simplifying the user interface while maintaining functional distinction through sequential operation.
4Device complexity
If the auto-injector does not penetrate to the desired depth, then the device structure can be simpler, but the medication absorption rate decreases and life-saving probability is reduced
Solution Approach 1:
The spring mechanism parameters (force, compression distance) are optimized to ensure the needle penetrates to the required depth for effective intramuscular injection, balancing penetration capability with device simplicity and user safety.
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 provides efficient and cost-effective drug delivery with precise needle penetration, reducing waste and user error, allowing for reloadable components and customizable settings for various user anatomical needs.
Implementation Method 1
The plunger is operable through a bias provided by a motive source in the body
Implementation Method 2
the piston being held in the loaded condition against the bias by a detent extending from the body and which can be selectively released by operation of an actuator
Data Source
AI summary
An auto-injector is provided which includes a housing with a syringe slidably received therein. The syringe has a barrel with a piston movable therein and a needle extending therefrom. The piston is releasably secured to one end of a plunger which is slidably secured within a body in the housing and is operable through a bias provided by a motive source. In use, the plunger moves under the bias from a loaded condition to a discharged condition to move the syringe so that the needle extends from a tip at an injection end of the housing and to slide the piston within the barrel to expel the contents of the syringe. The plunger is held in the loaded condition against the bias by a detent extending from the body and which can be selectively released by operation of an actuator when pressure is applied to the tip.