Syringe Needle Hub Contact Surface for Cannula Depth Control
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Solution Overview
Problem
Existing injection devices struggle to consistently control the depth of cannula penetration into the skin, leading to unintended deep penetration and discomfort, particularly with shorter needles used for subcutaneous injections.
Innovation Solution
A syringe needle hub design featuring a center post and outer collar that provide a controlled skin contact surface, distributing insertion force over a larger area to manage cannula depth and reduce skin indentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the hub edge engages the skin during angled insertion, then the cannula insertion is interfered with, but the hub provides structural support
Solution Approach 1:
The patent removes the interfering hub edge from the skin contact interface by introducing a separate skin contact surface (flat face or bell-shaped surface) that extends beyond the hub. This extracted surface prevents the hub edge from engaging the skin during insertion, allowing smooth cannula penetration while maintaining the hub's structural support function.
Solution Approach 2:
The patent introduces a skin contact surface (flat face or bell-shaped surface) as an intermediary element between the hub and the skin. This intermediary surface distributes insertion forces and prevents direct engagement between the hub edge and skin, resolving the conflict between structural support and smooth insertion.
2Device complexity
If a narrow post supports the cannula, then the device structure is simple, but the skin indentation is deep and penetration depth is uncontrolled
Solution Approach 1:
The patent transitions from a narrow one-dimensional post to a broader two-dimensional skin contact surface (flat face or bell-shaped surface). This dimensional expansion distributes insertion forces over a larger area, controlling skin indentation depth and preventing excessive cannula penetration while maintaining structural simplicity.
3Object-affected harmful factors
If the hub contact surface is large, then the insertion force is distributed, but the cannula penetration depth cannot be controlled at angled approaches
Solution Approach 1:
The patent positions the skin contact surface (flat face or bell-shaped surface) to contact the skin before the cannula tip reaches the skin. This preliminary action establishes a controlled reference plane that guides the cannula insertion depth regardless of the approach angle, preventing both excessive penetration and insertion interference.
Data Source
AI summary
A syringe and needle hub for a syringe has distal patient-facing side having a surface for contact with the subject's skin during injection. The contact surface is formed by a distal face of a post supporting a cannula and an outer collar surrounding the post. The axial distance between the distal face of the post and the distal face of the collar provided a contact surface with a radius of curvature to control the desired injection. The syringe barrel can have finger flanges extending outwardly where the flanges have a tactile member such as a dimple projecting from a proximal face of the flange and recess in a distal face of the flange.