Pen Needle Assembly with Segmented Cannula and Depth Indicator
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Solution Overview
Problem
Conventional pen needles struggle to reliably pierce medication compartments and lack feedback for optimal penetration depth, leading to user uncertainty and potential discomfort or improper dosing.
Innovation Solution
A pen needle design featuring a larger diameter plastic non-patient end cannula for strength and a smaller gauge stainless steel patient end for comfort, along with a two-part construction and movable shield for audible, tactile, or visual penetration depth indication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a single thin gauge stainless steel cannula is used throughout the needle, then patient comfort during injection is improved, but the ability to reliably pierce the septum of the medication compartment deteriorates
Solution Approach 1:
The needle is divided into two distinct segments: a non-patient end cannula with larger outer diameter for reliable septum piercing, and a patient end needle with smaller gauge for comfortable injection. This segmentation allows each part to be optimized for its specific function, resolving the contradiction between piercing reliability and patient comfort.
Solution Approach 2:
Different portions of the needle have different structural properties tailored to their specific functions. The non-patient end has larger diameter and greater strength for piercing the septum, while the patient end has smaller gauge and softer characteristics for comfortable tissue penetration. This local differentiation of properties resolves the contradiction.
2Reliability
If the entire hub is made disposable, then sterility and ease of disposal are improved, but material usage and cost increase
Solution Approach 1:
The hub is segmented into a reusable adapter portion that remains on the medication delivery device and a disposable needle assembly that is discarded after use. This segmentation allows the expensive, complex adapter to be reused while only the simpler, sterile needle portion is disposed of, reducing material waste while maintaining sterility.
Solution Approach 2:
The reusable adapter is recovered and retained on the medication delivery device for multiple uses, while only the disposable needle assembly is discarded after a single use. This selective discarding and recovery strategy reduces overall material consumption while maintaining the necessary sterility for each injection.
3Device complexity
If no penetration depth indication is provided, then device complexity is reduced, but the precision of injection depth control deteriorates
Solution Approach 1:
A movable shield with visual indicators (such as colored zones or markings) provides penetration depth feedback to the user. As the needle advances, the shield moves to reveal different visual indicators that show when optimal penetration depth is reached, improving measurement precision without significantly increasing device complexity.
Solution Approach 2:
The movable shield mechanism provides real-time feedback to the user about needle penetration depth through visual, tactile, or audible indicators. This feedback loop allows the user to adjust the injection depth to achieve the optimal penetration, improving measurement precision while adding only a relatively simple indicator mechanism.
Data Source
AI summary
A pen needle, comprising a reusable adapter configured for attachment to a distal end of a medication pen, the adapter having a proximal needle for accessing the interior of the pen injector and a fitting on the distal side for mating with a patient end needle assembly, and a disposable patient-end needle assembly having a base configured for mating with the fitting on the distal side of the adapter and a patient-end needle extending from a distal end of the base.