Autoinjector Frontal Buttress for Accurate Needle Depth
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Solution Overview
Problem
Conventional autoinjectors face challenges with fragile and dimensionally variable glass syringes, leading to inconsistent needle insertion depth and dose delivery, due to their reliance on syringe flanges for registration and the stress imposed on fragile components, resulting in variability and increased risk of fracture and medicament waste.
Innovation Solution
An autoinjector design that registers the syringe stop based on the front end of the syringe, utilizing a modular configuration with an automatically deployable frontal buttress to engage the syringe shoulder, reducing stress on the flange and accommodating variability in syringe lengths, and allowing for precise needle insertion and dose delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional autoinjectors use syringe flanges for registration and stopping, then the device structure is simple, but needle insertion depth becomes variable and inaccurate due to dimensional variability of glass syringes
Solution Approach 1:
The registration function is segmented from the flange and transferred to a dedicated frontal buttress structure. The buttress is divided into multiple flexible members that can independently engage with the syringe shoulder, allowing precise registration without relying on the variable flange dimensions.
Solution Approach 2:
The frontal buttress acts as an intermediary component between the syringe and the housing. Instead of directly using the flange for registration, the buttress mediates the interaction by providing a stable reference surface that compensates for syringe dimensional variations.
2Reliability
If conventional autoinjectors rely on flange registration, then manufacturing is simpler, but the fragile flange experiences high stress and bending moment increasing fracture risk
Solution Approach 1:
The registration function is extracted from the flange and relocated to the frontal buttress. This removes the harmful stress concentration from the fragile flange by eliminating the need for the flange to serve as the stopping surface, thereby reducing fracture risk.
Solution Approach 2:
The flexible members of the frontal buttress are pre-configured to deform elastically during engagement, cushioning the impact forces before they can be transmitted to the fragile flange. This prior cushioning protects the flange from stress concentration.
3Manufacturing precision
If conventional autoinjectors use fixed stroke length, then device design is simpler, but residual medicament volume becomes variable leading to medicament waste
Solution Approach 1:
The stroke length is made dynamic rather than fixed. The flexible members of the frontal buttress can deform to accommodate variations in syringe length and shoulder position, allowing the injection mechanism to automatically adjust the effective stroke length to deliver the correct dose despite manufacturing tolerances.
Solution Approach 2:
The physical state of the flexible members changes from a rigid constraint to a compliant interaction. This parameter change allows the system to adapt to different syringe dimensions, ensuring consistent dose delivery by adjusting the engagement point based on actual syringe geometry.
4Adaptability or versatility
If conventional autoinjectors use glass syringes with cut flanges, then compatibility with existing syringes is maintained, but dimensional variability and irregularity cause inconsistent needle extension and injection performance
Solution Approach 1:
The frontal buttress with flexible members provides a universal registration mechanism that works with various syringe types and dimensions. The flexible members can adapt to different syringe shoulder positions and geometries, maintaining compatibility while ensuring consistent needle extension length through reliable engagement.
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 provides consistent and accurate needle insertion depth and dose delivery, reduces the risk of syringe fracture, minimizes residual medicament volume, and enhances manufacturing efficiency by eliminating the need for additional sterilization and allowing for separate assembly of syringe and autoinjector components.
Implementation Method 1
Conventional autoinjectors generally provide a compression spring-based mechanism to drive the syringe in the distal direction within a housing
Implementation Method 2
The spring, typically acting through one or more surrogate components, impinges upon the syringe, and/or an elastomeric piston element thereof, causing the syringe to translate in the distal direction
Data Source
AI summary
The present invention provides for an autoinjector that registers off a distal end of a syringe to provide for a more accurate needle insertion depth. The autoinjector employs an automatically deployable frontal buttress for registration of the distal end or shoulder of the syringe.