Rotating-Collar Auto-Injector for Reduced Skin Pressure
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Solution Overview
Problem
Existing injection devices, both manual and auto-injectors, pose challenges such as the risk of underdosing, high injection forces, hand shaking, and potential needle stick injuries, particularly for users with dexterity issues or elderly individuals.
Innovation Solution
An auto-injector design featuring a rotating collar that dampens the pressure exerted on the skin during injection, a safety mechanism to prevent accidental needle stick injuries, and a single drive means for multiple functions, including needle insertion, medicament expulsion, and needle retraction, with intuitive operation and safety features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-driven auto-injector is used to eliminate manual pressing, then injection completeness is improved, but injection force becomes too high for elderly or dexterity-impaired users
Solution Approach 1:
The injection process is divided into two distinct phases: a high-force penetration phase (needle insertion) and a low-force delivery phase (medicament expulsion). The drive mechanism transitions from an engaged state during insertion to a disengaged state during delivery, allowing the spring force to be applied only when needed for penetration while eliminating excessive force during the delivery phase.
Solution Approach 2:
The drive mechanism dynamically changes its engagement state with the plunger throughout the injection process. Initially engaged to provide high force for needle insertion, it automatically disengages when the needle penetrates the skin, transitioning the system to a low-force state suitable for medicament delivery to elderly or dexterity-impaired users.
2Reliability
If a button/plunger is extended greatly to reach full extension, then complete dose delivery is improved, but user convenience deteriorates due to difficulty reaching
Solution Approach 1:
The auto-injector mechanism performs the full extension action automatically without requiring user intervention. The spring-driven system self-actuates to drive the plunger to its full extended position, ensuring complete dose delivery while eliminating the need for users to reach or manually extend any components.
3Reliability
If injection force and button extension are combined, then complete injection is achieved, but hand shaking increases causing discomfort and needle movement
Solution Approach 1:
The injection action is segmented into penetration (requiring high force) and delivery (requiring minimal force) phases. By applying high force only during the brief penetration phase and eliminating continuous force application during delivery, the system prevents the hand shaking that would otherwise occur from sustained force application and long button extension.
Solution Approach 2:
The mechanism automatically manages the force application timing and duration, eliminating the need for users to maintain continuous pressure. The spring-driven system self-regulates the force profile, applying high force only when needed for penetration and then maintaining stable, low-force delivery without user intervention that could cause shaking.
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
Reduces the risk of bruising and needle stick injuries while ensuring complete dose delivery with a compact, cost-effective design suitable for single-use, particularly for subcutaneous or intra-muscular injections of various medicaments.
Implementation Method 1
a rotating collar rotatably arranged within the housing. The needle shroud in the safe position surrounds the injection needle after the injection has been carried out. The rotating collar engages the needle shroud in a manner that forces the rotating collar to rotate within the housing when the needle shroud is translated in the proximal direction
Data Source
AI summary
According to the invention, an auto-injector for administering a dose of a liquid medicament (M) comprises of a substantially cylindrical housing arranged to contain a pre-filled syringe filled with the medicament (M), a needle shroud slidably arranged with respect to the housing and adapted to rest on the skin of a patient receiving an injection, a releasable drive means arranged within the housing that is capable of, upon release, translating the needle shroud in a proximal direction (P) towards a safe position (PS) and a rotating collar rotatably arranged within the housing. The needle shroud in the safe position (PS) surrounds the injection needle after the injection has been carried out. The rotating collar engages the needle shroud in a manner that forces the rotating collar to rotate within the housing when the needle shroud is translated in the proximal direction (P).