Safety Syringe Sheath Deployment Linked to Plunger Stroke
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Solution Overview
Problem
Existing safety syringes with spring-loaded mechanisms are prone to misuse, exposing healthcare workers to needles due to improper engagement of safety mechanisms, and require needle removal before activation, also leading to potential blood splatter.
Innovation Solution
A sheath deployment mechanism actuated by a sheath actuator, where the sheath is extended over the needle during normal syringe operation, ensuring continuous engagement with the plunger movement without separate user action, and utilizing a ratioed movement system to enhance sheath deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-loaded safety mechanism is engaged by a separate action after needle removal, then the safety mechanism can be reliably engaged, but the healthcare worker is exposed to the needle and blood splatter may occur
Solution Approach 1:
The sheath is pre-positioned on the syringe barrel and automatically deploys at the sheath release point during the normal inward stroke of the plunger. This preliminary positioning and automatic deployment eliminates the need for separate user action to engage the safety mechanism, thereby preventing needle exposure and blood splatter while ensuring reliable safety engagement.
Solution Approach 2:
The safety mechanism is designed to deploy automatically through the continued inward stroke of the plunger after the sheath release point. The system serves itself by utilizing the existing plunger motion to trigger sheath deployment without requiring any additional user action, thus eliminating the harmful effects of separate engagement actions.
2Ease of operation
If the sheath is stationary relative to the needle until the sheath release point, then the needle remains accessible during injection, but the sheath may shift or misalign during syringe operation
Solution Approach 1:
The sheath transitions from a stationary state relative to the needle during the injection phase to a deployed state that covers the needle after the sheath release point. This dynamic behavior allows the sheath to remain out of the way during injection while automatically providing coverage when needed, resolving the contradiction between accessibility and alignment stability.
Solution Approach 2:
The sheath is pre-positioned on the syringe barrel in a stationary manner that does not interfere with needle accessibility during injection. At the sheath release point, the sheath is preliminarily prepared to deploy automatically, ensuring proper alignment and coverage without requiring user intervention.
3Manufacturing precision
If a rack and pinion mechanism is used for sheath deployment, then precise control of sheath movement is achieved, but the device complexity increases
Solution Approach 1:
The rack and pinion mechanism serves multiple functions: it provides precise control of sheath deployment, translates the linear motion of the plunger into the appropriate sheath movement, and ensures reliable engagement at the sheath release point. By integrating these functions into a single mechanism, the patent achieves precise deployment control while minimizing overall device complexity.
4Productivity
If the sheath actuator moves relative to the plunger after the sheath release point, then the sheath deploys automatically during normal operation, but the actuator may interfere with plunger movement before the release point
Solution Approach 1:
The sheath actuator is designed to be dynamically coupled to the plunger, remaining stationary relative to it before the sheath release point and becoming mobile after the release point. This dynamic coupling ensures smooth plunger movement during injection while enabling automatic sheath deployment when needed, resolving the contradiction between automatic engagement and operational smoothness.
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
Ensures safe and automatic needle coverage after use, preventing exposure to healthcare workers by integrating sheath deployment with syringe operation, reducing the risk of needle stick injuries and blood splatter.
Implementation Method 1
The sheath deployment mechanism comprises a pinion for interaction with a first rack on the sheath actuator and a second rack on the sheath.
Implementation Method 2
The sheath deployment mechanism comprises a threaded rod extending from the safety plunger, wherein the second thread is located on threaded rod and is configured to rotate the linkage on a continued syringe operation action by the user after the sheath release point.
Data Source
Figure 1~3
Figure 2(a)~2(d)
Figure 4(a)~4(d)
AI summary
An apparatus for use with a syringe for providing a safety syringe, the apparatus comprising: a sheath (100; 300; 500) deployable for at least partially covering a needle (126) of the syringe; and a sheath actuator (102; 302; 502) for deploying the sheath by interaction with a sheath deployment mechanism (104; 304; 504); wherein the sheath is configured to be stationary in relation to the needle until a syringe plunger (116; 316; 516) reaches a sheath release point on its inward stroke, and wherein the sheath actuator is configured for deployment of the sheath on movement of the sheath actuator relative to the syringe plunger after the sheath release point.