Needle Shield Remover with Guiding Interface for Drug Delivery
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Solution Overview
Problem
Drug delivery devices, such as auto-injectors, require high forces to remove the needle shield, making it difficult for infirm patients or those in cold temperatures due to increased friction and stiction, which can lead to user difficulty in administering medication.
Innovation Solution
An arrangement with a needle shield remover that rotates and moves axially relative to the housing, guided by a sloped guide track and interaction features, reducing the force needed to remove the cap by transferring user force directly to the needle shield, and allowing the cap and needle shield remover to rotate together, ensuring efficient power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cap and needle shield are tightly fitted to the housing to ensure secure attachment, then the reliability of the device is improved, but the force required to remove the cap increases making it difficult for infirm patients
Solution Approach 1:
The removal mechanism transitions from a static friction-based interface to a dynamic screw-threaded interface. The screw thread converts rotational motion into axial motion, allowing the cap to be removed through a controlled threading action rather than overcoming static friction directly. This dynamic mechanism reduces the peak force required while maintaining secure attachment during use.
Solution Approach 2:
The needle shield remover acts as an intermediary tool between the user and the cap assembly. It engages with the screw thread features on the cap and provides mechanical advantage through its lever arm and threaded engagement, amplifying the user's input force while reducing the effort needed to overcome the frictional interface between the cap and housing.
2Reliability
If the materials are designed to shrink at cold temperatures to maintain tight fits, then the reliability of the connection is improved, but the stiction between needle shield and syringe increases making removal more difficult
Solution Approach 1:
The screw thread mechanism transforms the removal action from a direct axial pull (which must overcome cold-induced stiction) into a rotational threading motion. This dynamic approach allows gradual engagement and disengagement through the threads, reducing the peak force required to overcome the increased static friction at cold temperatures.
Solution Approach 2:
The removal mechanism adds a rotational dimension to the removal process. Instead of pulling the cap off axially (one-dimensional motion that directly opposes friction), the screw thread enables removal through rotational motion combined with axial progression, effectively converting a high-friction problem into a lower-friction threaded disengagement.
3Reliability
If the needle shield is firmly attached to the syringe to prevent accidental detachment, then the reliability is improved, but the force required to rotate and remove the needle shield increases
Solution Approach 1:
The screw thread features on the needle shield and needle shield remover create a dynamic threaded engagement mechanism. This converts the removal action from overcoming static friction through direct pulling into a controlled rotational threading motion, reducing the peak torque required while maintaining secure attachment during injection.
Solution Approach 2:
The needle shield remover serves as a mechanical intermediary that engages with the screw thread on the needle shield. It provides leverage through its handle and amplifies the user's input torque while reducing the effort needed to overcome the firm attachment between the needle shield and syringe.
4Ease of operation
If the cap assembly is designed to rotate for removal, then the ease of operation is improved, but the complexity of the guiding interface increases
Solution Approach 1:
The screw thread features serve multiple functions: they guide the rotational motion of the cap during removal, provide mechanical advantage through their inclined plane geometry, and ensure proper alignment between the cap and needle shield remover. This multi-functionality reduces the need for separate guiding mechanisms, balancing ease of operation with acceptable complexity.
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
This solution significantly reduces the force required to remove the needle shield, making it easier for users, especially in cold conditions, and prevents twisting of the needle shield, thereby simplifying the administration process and reducing the risk of damage.
Implementation Method 1
the guiding interface is configured such that, when the needle shield remover rotates with respect to the housing from a state in which the needle shield remover is connected to the housing, the guiding interface guides movement of the needle shield remover relative to the housing in a direction away from the proximal end of the housing to disconnect the needle shield remover from the housing
Data Source
AI summary
An arrangement for a drug delivery device includes a housing with a proximal end and a distal end, a needle shield remover configured to be rotationally locked to a needle shield covering a needle, and a guiding interface. The needle shield remover is releasably connectable to the housing. The guiding interface is configured such that, when the needle shield remover rotates with respect to the housing from a state in which the needle shield remover is connected to the housing, the guiding interface guides a movement of the needle shield remover relative to the housing in a direction away from the proximal end of the housing to disconnect the needle shield remover from the housing. Movement of the needle shield remover relative to the housing to disconnect the needle shield remover includes an axial movement and a rotational movement of the needle shield remover relative to the housing.