Variable Length Injection Syringe with Movable Shield
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Solution Overview
Problem
Existing injection devices lack the ability to consistently control the depth of cannula penetration for delivering drugs to a selected target area, particularly in subcutaneous regions, and do not effectively prevent accidental needle sticks after use.
Innovation Solution
A syringe assembly with a movable shield that slides relative to the syringe, allowing for adjustable needle exposure lengths for aspiration and injection, and locks in an extended position to cover the needle after use, preventing reuse and accidental needle sticks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the needle is made longer to ensure penetration through the septum, then the reliability of aspiration is improved, but the precision of injection depth control deteriorates
Solution Approach 1:
The syringe assembly is divided into functional segments: a first portion for aspiration through the septum and a second portion for injection into the patient. This segmentation allows each portion to be optimized for its specific function, with the first portion being longer for reliable septum penetration and the second portion providing controlled injection depth.
Solution Approach 2:
The syringe assembly incorporates a movable shield that can dynamically adjust the exposed length of the needle. The shield transitions between positions to expose different lengths of the needle, allowing the system to adapt between aspiration mode (longer exposure) and injection mode (shorter exposure for depth control).
2Ease of operation
If the needle exposed length is increased for easier aspiration, then the ease of operation is improved, but the safety against accidental needle sticks deteriorates
Solution Approach 1:
The movable shield dynamically adjusts the exposed needle length based on the operational phase. During aspiration, the shield retracts to expose more needle for ease of operation. During injection and after use, the shield extends to cover the needle, reducing exposure and preventing accidental needle sticks.
Solution Approach 2:
The movable shield acts as an intermediary element between the needle and the external environment. It provides a protective barrier that can be positioned to either expose the needle for operation or cover it for safety, mediating between the conflicting requirements of ease of operation and safety.
3Device complexity
If a fixed needle length is used to simplify the device, then the device complexity is reduced, but the adaptability to different injection depths deteriorates
Solution Approach 1:
Instead of using multiple fixed-length needles or complex adjustable mechanisms, the invention employs a simple movable shield that slides along the needle shaft. This dynamic component allows a single needle to effectively provide multiple exposure lengths, achieving adaptability without significant complexity increase.
Solution Approach 2:
The movable shield enables the needle to serve multiple functions with different exposure lengths. The same needle structure can be used for aspiration, injection at various depths, and post-use protection, making the device universally applicable to different injection scenarios without requiring multiple specialized components.
Data Source
AI summary
A syringe assembly includes a syringe barrel (12) having a proximal end and a distal end, a needle hub (20) supporting the needle and coupled to the distal end of the syringe barrel (12). A moveable shield (36) is included for sliding from a first position where the needle is exposed a first length, a second position where the needle is exposed a second length less than said first length, and a third position covering a distal end of the needle. A locking mechanism (48, 86) is included to retain the shield in the second position while enabling the shield to slide to the third position, and to lock the shield in the third position to prevent re-use of the syringe.