Spring-Driven Autoinjector With Telescopic Needle Shroud
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Solution Overview
Problem
Conventional injection devices, both manual and autoinjectors, pose challenges for users due to the need for manual force application, alignment, and dexterity, which can be difficult for elderly, children, or arthritic patients, leading to incomplete doses and administration difficulties.
Innovation Solution
An autoinjector design featuring a telescopic needle shroud, a carrier with a plunger, and a collar mechanism, utilizing springs and compliant beams to automate the injection process, ensuring proper dose delivery without requiring continuous manual force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If manual force is used to drive medicament through a needle, then the injection can be administered, but the force required may be too high for elderly or children and continuous pressing is needed
Solution Approach 1:
The injection device uses a spring mechanism that automatically generates the force needed to push the medicament through the needle. The spring is pre-loaded and releases automatically when triggered, eliminating the need for the user to apply manual force continuously during injection.
Solution Approach 2:
The spring is pre-compressed and stored in an energized state before use. This preliminary action stores the necessary force in advance, so that when the injection is triggered, the force is already available and does not require real-time manual input from the user.
2Reliability
If a button/plunger is used for manual injection, then injection can be administered, but if released prematurely the injection stops and may not deliver intended dose
Solution Approach 1:
The spring-driven mechanism automatically completes the injection process once triggered. The spring maintains continuous force on the plunger throughout the injection, eliminating the need for the user to continuously press the button. This ensures the full dose is delivered even if the user releases the trigger early.
Solution Approach 2:
The device transitions from a static manual pressing mechanism to a dynamic spring-driven system that automatically progresses through the injection. The spring's elastic potential energy converts to kinetic energy, driving the plunger forward with controlled force and speed, ensuring complete dose delivery.
3Measurement precision
If alignment and dexterity are required for injection, then precise administration is possible, but elderly, children, or arthritic patients may not have the required dexterity
Solution Approach 1:
The device includes automatic alignment features that guide the needle to the correct injection site without requiring precise manual positioning by the user. The self-aligning mechanism compensates for user inability to maintain precise alignment, making the device usable by elderly, children, or arthritic patients.
4Reliability
If a telescopic needle shroud with collar mechanism is used, then proper dose delivery is ensured, but device complexity increases
Solution Approach 1:
The needle shroud is telescopic, with nested sections that slide within each other. The collar mechanism is integrated within the shroud structure. This nesting arrangement ensures proper sequencing of operations (needle extension, injection, retraction) while minimizing the overall size and reducing the apparent complexity of the device.
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 complete and consistent medicament delivery with user-friendly operation, providing audible and tactile feedback, and maintaining alignment during the injection process.
Implementation Method 1
a drive spring biasing the plunger relative to the carrier
Implementation Method 2
The carrier includes a compliant beam having a boss adapted to engage an opening in the plunger
Implementation Method 3
a collar rotatably and slidably disposed in the case and coupled to the needle shroud and the carrier
Data Source
AI summary
An autoinjector includes a case, a needle shroud telescopically coupled to the case, a carrier slidably arranged in the case, a collar rotatably and slidably disposed in the case and coupled to the needle shroud and the carrier, and a trigger button operably coupled to the carrier. The case includes a rib. The needle shroud is movable between a first extended position, a retracted position, and a locked second extended position. The carrier is adapted to hold a medicament container and movable from a first axial position to a second axial position relative to the case. The carrier abuts the rib in the first axial position and the needle shroud is in the first extended position and disengages the rib when the needle shroud is in the retracted position and the trigger button is pressed to advance the carrier to the second axial position.