Vascular Access Device With Adjustable Needle Length
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Solution Overview
Problem
Insulin syringes with fixed 6 mm needle cannulas face challenges in penetrating insulin vials while avoiding insertion into the muscle layer of the skin, leading to patient discomfort and inconsistent results due to the need for manual pinching and potential needlestick injuries.
Innovation Solution
A vascular access device with adjustable needle length features, including a flange with prongs that limit needle insertion depth, a compressible foam tip for extended needle penetration, and a cammed geometry to ensure the needle cannula is fully inserted into the vial but only partially into the skin, allowing for precise control over needle length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a 6 mm needle cannula is used to penetrate the insulin vial stopper, then the needle can reach the insulin for aspiration, but the needle may penetrate into the muscle layer of the skin which is not desirable
Solution Approach 1:
The flange with prongs provides a dynamic depth-limiting mechanism that adapts to different insertion scenarios. During vial access, the needle can penetrate fully (6 mm) to reach insulin. During skin injection, the flange contacts the skin surface and prevents further insertion, automatically limiting depth to subcutaneous tissue only. This dynamic behavior resolves the contradiction between needing full penetration for vial access and limited penetration for safe skin injection.
Solution Approach 2:
The flange with prongs acts as an intermediary element between the needle cannula and the skin/vial interface. It mediates the insertion depth by providing a physical stop that contacts the skin surface during injection, preventing the needle from penetrating too deeply into the muscle layer while still allowing full needle extension for vial penetration.
2Object-affected harmful factors
If manual pinching is used to avoid muscle penetration, then the needle can be kept out of the muscle layer, but the process becomes tedious and leads to patient discomfort and needlestick injuries
Solution Approach 1:
The flange with prongs provides self-regulating depth control without requiring manual intervention. The device itself limits needle insertion depth through the flange's geometric constraint, eliminating the need for practitioner pinching actions. This self-service mechanism reduces operational complexity, improves ease of use, and minimizes patient discomfort and injury risks associated with manual techniques.
Solution Approach 2:
The flange serves as an intermediary that automates the depth-control function previously requiring manual pinching. By providing a fixed geometric barrier, it transforms the complex manual skill of depth control into a simple passive mechanical constraint, making the injection process easier and safer.
3Object-affected harmful factors
If interchangeable needle hubs are used with different needle lengths, then the needle can be optimized for both vial penetration and skin injection, but this results in further waste
Solution Approach 1:
The single 6 mm needle cannula is designed to perform multiple functions: penetrating the vial stopper to access insulin and injecting into the subcutaneous layer. The flange with prongs enables this multi-functionality by providing context-dependent depth control - allowing full penetration for vial access while limiting depth for skin injection. This eliminates the need for multiple specialized needles, reducing waste while maintaining optimal performance for both tasks.
Solution Approach 2:
The effective needle length parameter is dynamically changed based on the application context. The same 6 mm needle cannula effectively becomes a longer needle during vial penetration (full length engaged) and a shorter needle during skin injection (depth limited by flange). This parameter change through mechanical constraint allows one needle to replace multiple needles of different lengths, reducing waste.
Data Source
AI summary
Vascular access devices which have needle-length adjustment features for penetrating a vial of a stopper with the full needle length and for penetrating the skin of a patient with a desired needle length, which is less than the full needle length.