Retractable Pen Needle Sleeve for Depth Control
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Solution Overview
Problem
Existing pen needles struggle to consistently control the penetration depth of the cannula during injections, especially when used at angles, due to the lack of effective skin shaping and sleeve mechanisms, which can lead to inefficiencies and increased risk of accidental needle sticks.
Innovation Solution
A pen needle hub assembly with retractable sleeves and a convex skin-shaping surface on the needle hub, allowing for controlled cannula penetration and automatic retraction to prevent needle sticks, featuring a resilient design that compresses and expands to expose and cover the cannula as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fixed needle hub design is used, then the structure is simple, but the penetration depth control is poor
Solution Approach 1:
The needle hub incorporates a resilient body that can be compressed and expand, transforming a static structure into a dynamic one. This dynamic characteristic allows the hub to adapt during insertion, improving penetration depth control while managing the complexity through elastic deformation rather than complex mechanical components.
Solution Approach 2:
The resilient needle hub changes its physical state from uncompressed to compressed during insertion, utilizing parameter changes in volume and shape. This allows the device to achieve better penetration control by modifying the hub's parameters under compression, balancing performance improvement with structural simplicity.
2Productivity
If the cannula is always exposed, then injection is fast, but the risk of accidental needle sticks increases
Solution Approach 1:
The retractable sleeve is pre-positioned to cover the cannula before injection. This preliminary protective action prevents accidental needle sticks while allowing rapid deployment when needed, resolving the contradiction between safety and injection speed by having the protective mechanism ready in advance.
Solution Approach 2:
The retractable sleeve acts as an intermediary element between the user and the exposed cannula. It provides a buffer that can quickly transition from covering to retracted state, enabling fast injection when the sleeve is pushed back while maintaining safety when retracted, thus mediating between the conflicting requirements.
3Object-affected harmful factors
If a retractable sleeve mechanism is added, then needle stick risk is reduced, but the device complexity increases
Solution Approach 1:
The retractable sleeve is constructed as a flexible, thin-walled structure that can easily deform and retract. This design reduces the complexity of the retraction mechanism by utilizing the inherent flexibility of the material rather than requiring complex mechanical actuators, thus lowering device complexity while maintaining safety functionality.
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 ensures precise cannula penetration depth control and reduces the risk of accidental needle sticks by using flexible, resilient sleeves that compress during insertion and return to cover the cannula post-use, maintaining sterility and safety.
Implementation Method 1
The sleeve is sufficiently flexible and resilient to fold and compress in the longitudinal direction of the sleeve in an accordion-like manner onto a portion of the hub to retract from the distal end of the cannula as the cannula is inserted into the patient. The resilience of the sleeve returns the sleeve to the original configuration when the cannula is withdrawn from the patient
Data Source
AI summary
A needle hub assembly for a pen needle includes a needle hub, a cannula or needle coupled to the needle hub, a retractable and compressible sleeve covering at least one end of the cannula, and an outer cover. The outer cover encloses the needle hub and the retractable sleeve. The retractable sleeve is coupled to the hub to cover the end of the cannula where the sleeve can pass through or can be pierced by the cannula and the sleeve retracts axially on the cannula. The sleeve is resilient and returns to an original configuration when an insertion force is released. The needle hub can have a first sleeve to cover a patient end of the cannula, and second sleeve to cover a non-patient end of the cannula where the sleeves retract onto the cannula or hub and expand to the original configuration to cover the ends of the cannula.