Retractable Pen Needle Shield with Spring-Locked Safety Mechanism
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Solution Overview
Problem
Existing pen needles lack effective mechanisms for automatic shielding of the needle after use, leading to potential reuse and accidental needle sticks.
Innovation Solution
A pen needle design featuring a retractable distal needle shield that automatically extends to cover the needle after use, with a locking mechanism to prevent re-use, and a proximal needle shield that covers the non-patient end of the needle when separated from the delivery device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a retractable needle shield is added to automatically cover the needle after use, then safety against accidental needle sticks is improved, but device complexity increases
Solution Approach 1:
The needle shield is designed to automatically retract and extend without user intervention. The spring mechanism self-activates when the needle is inserted into the hub, causing the shield to retract. After use, when the needle is removed, the spring automatically propels the shield back to cover the needle, eliminating the need for manual operation and ensuring consistent safety action.
Solution Approach 2:
The needle shield transitions from a static protective cover to a dynamic component that changes position based on operational state. The shield moves between retracted (during injection) and extended (after use) positions, allowing the system to adapt its protective function to the current operational phase while maintaining safety.
2Reliability
If a locking mechanism is added to prevent re-use, then reliability is improved, but device complexity increases
Solution Approach 1:
The locking mechanism is pre-configured to automatically engage when the needle shield extends after use. The spring-loaded design ensures that as the shield moves to its extended position, it triggers the locking feature to secure the shield and prevent any attempt at retraction or re-use, eliminating the need for separate manual locking actions.
Solution Approach 2:
The needle shield itself serves as an intermediary component that performs dual functions: protection during use and locking after use. The shield's movement and positioning mechanism inherently triggers the locking action, using the shield's own motion to engage the prevention mechanism rather than requiring a completely separate locking system.
3Ease of operation
If automatic shielding is implemented, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The system performs the shielding action automatically based on the operational state. During injection, the shield retracts self-activating when the needle is inserted. After use, the shield automatically returns to cover the needle when the needle is removed from the hub, eliminating the need for users to manually operate shielding mechanisms and simplifying the user interaction.
Solution Approach 2:
The complex spring-loaded automatic shielding mechanism is extracted as a separate functional module within the hub assembly. This modular approach isolates the complexity into a self-contained unit that operates independently, allowing the rest of the injection device to remain simple and easy to operate while the extracted shielding subsystem handles the automated protection functions.
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 the needle is securely shielded after use, preventing accidental reuse and exposure, thereby enhancing user safety and reducing the risk of needle sticks.
Implementation Method 1
A biasing member, such as spring, is included to bias the distal needle shield and proximal needle shield to the respective extended position.
Data Source
AI summary
A pen needle (30) for a delivery device includes a hub (32) supporting a needle (54) and a distal needle shield (70) that can retract to expose the needle during injection and return to the extended position after use and lock in the extended position to cover the needle. A proximal needle shield (0.102) moves from a retracted position to an extended position with respect to the hub to shield or cover a proximal end of the needle when the needle hub is separated from the delivery device. A spring (130) extends between the distal needle shield and the proximal needle shield to bias each needle shield to the respective extended position. The distal needle shield (70) is coupled to the proximal needle shield (102) in an initial position to retain the spring (130) in a compressed state. The distal needle shield (70) is depressed to disengage the distal needle shield from the proximal needle shield (102) so that the spring expands to an extended state and moves the shields to the extended positions. A locking member (142, 156) can be provided to lock the proximal needle shield (70) and distal needle shield (102) in the extended position.