Autoinjector Spring Mechanism for Complete Dose Delivery
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Solution Overview
Problem
Conventional injection devices, including manual and autoinjectors, face challenges such as incomplete medicament delivery and difficulty in use for elderly or dexterity-impaired individuals due to the need for manual force to depress a plunger, leading to inconsistent administration.
Innovation Solution
An autoinjector design featuring a spring holder, guide cylinder, drive assembly, and trigger button with a ramped base and resilient arms, which allows for automatic and controlled delivery of the medicament without requiring significant user force, ensuring full dose delivery and ease of use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a manual device is used where the user must provide force to drive the medicament out, then the device structure is simple, but the ease of operation deteriorates and incomplete dose delivery occurs
Solution Approach 1:
The drive spring is pre-loaded in a compressed state during device assembly, storing mechanical energy that is automatically released during operation. This preliminary action eliminates the need for the user to manually depress the plunger, ensuring complete dose delivery without requiring user strength or dexterity.
Solution Approach 2:
The autoinjector is designed to automatically perform the injection function using its own internal mechanisms (spring-loaded drive assembly). The device serves itself by automatically advancing the plunger and delivering the full medicament dose without requiring external manual force from the user.
2Reliability
If manual force is required to depress the plunger, then the device complexity is low, but the reliability of complete dose delivery deteriorates
Solution Approach 1:
The drive spring is pre-loaded and positioned to automatically advance the plunger upon activation. This preliminary preparation ensures that the full medicament dose is reliably delivered without depending on user strength or stability, making the injection process reliable even for users with dexterity problems.
Solution Approach 2:
The device automatically completes the injection function through its internal spring-loaded mechanism, ensuring reliable dose delivery independent of user capability. The system self-regulates the plunger advancement to deliver the complete prescribed dose.
3Manufacturing precision
If the user must manually control the injection process, then the device structure is simple, but the consistency of dose delivery deteriorates
Solution Approach 1:
The drive spring is pre-compressed to a specific position that corresponds to the full dose volume. This preliminary positioning ensures that when activated, the plunger advances precisely to deliver the complete dose, eliminating variability caused by manual control and ensuring consistent dose delivery across all users.
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 autoinjector ensures consistent and complete delivery of the medicament with reduced user effort, enhancing usability for individuals with dexterity issues and preventing incomplete doses by using a combination of springs and mechanical engagements to manage the injection process.
Implementation Method 1
a drive spring adapted to apply a force on the drive assembly
Implementation Method 2
a penetration spring adapted to apply a force on the guide cylinder
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Described is an autoinjector (1) comprising a spring holder (19), a guide cylinder (15) releasably coupled to the spring holder (19), a drive assembly (17) releasably coupled to the spring holder (19), a drive spring (16) adapted to apply a force on the drive assembly (17), and a penetration spring (20) adapted to apply a force on the guide cylinder (15). The guide cylinder (15) is adapted to accommodate a syringe (2) having a plunger. The drive assembly (17) is coupled to the guide cylinder (15) and adapted to engage the plunger.