Automatic Injection Device Piston Inversion
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Solution Overview
Problem
Existing prefilled syringe designs for automatic injection devices are inefficient due to long piston push rods, air bubble formation, sterility issues, and mechanical stress, leading to device failure and inaccurate dosing, especially for pediatric patients.
Innovation Solution
An automatic injection device with a piston locked at a fixed position, a needle assembly at the opposite end, and medication filling from the needle end to reduce air bubbles and device size, featuring a tapered container body for easier molding and reduced friction, allowing for a smaller, more accurate, and reliable injection system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the piston push rod is made long to enable automatic injection, then the injection function is achieved, but the device size becomes unnecessarily large
Solution Approach 1:
The patent inverts the conventional design by placing the needle assembly at the proximal end and the piston at the distal end, opposite to the traditional arrangement. This inversion allows the piston push rod to be significantly shortened while maintaining the automatic injection function, directly resolving the contradiction between automation and device size.
2Ease of manufacture
If medication filling and piston placement happen at the same end of the syringe, then the manufacturing process is simplified, but air bubbles are unnecessarily formed after filling
Solution Approach 1:
The patent segments the syringe into distinct functional zones: the proximal end for needle assembly and the distal end for piston and medication filling. This spatial segmentation allows medication to be filled from the distal end without introducing air bubbles, while the needle assembly remains at the opposite end, resolving the contradiction between manufacturing simplicity and air bubble prevention.
3Ease of manufacture
If the syringe inner diameter is smaller at the needle end due to molding limits, then manufacturing is easier, but the piston driving spring requires stronger force causing component failure
Solution Approach 1:
By inverting the needle and piston positions, the patent allows the syringe to have a larger inner diameter at the needle end where the spring operates, reducing the mechanical force requirements for the piston driving spring. The molding process can still accommodate the needle end geometry while the overall syringe design benefits from the inverted arrangement, resolving the contradiction between manufacturing ease and spring strength requirements.
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 solution results in a smaller device size, reduced air injection, improved dosing accuracy, and enhanced sterility, minimizing mechanical stress on components and preventing premature injection events, thus ensuring reliable operation and patient safety.
Implementation Method 1
a piston (104) driven by a resilient spring (103) that pushes the medication out of the container body (105) during injection
Data Source
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AI summary
An automatic injection device is provided herein comprising a container body having a distal end and a proximal end; a piston locked at said proximal end of said container body before medication injection; a spring configured to bias said piston distally; a releasable restraining means configured to releasably restrain said piston in a locked state against said biasing of said spring, wherein, upon release of said releasable restraining means, said piston moves under force of said spring toward said distal end of said container body; an activation means configured to release said releasable means; a needle cap placed at said distal end of said container body; and a needle placed at said distal end of said container body.