Rotary Needle Actuation for Compact, Reuse-Resistant Drug Delivery
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Solution Overview
Problem
Existing drug delivery devices with needle actuation mechanisms are either too bulky or complex for small, compact applications, and lack safety features to prevent reuse of disposable parts.
Innovation Solution
A drug delivery device with a compact needle actuation mechanism using a rotary actuator that translates and tilts the needle between retracted and extended positions, featuring a translation guide member and rotation guide member, and a locking mechanism to prevent reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional needle actuation mechanism with lever arm is used, then reliable needle actuation is achieved, but the device size becomes too large for small patch devices
Solution Approach 1:
The needle support is nested within the housing, allowing the needle to retract completely inside the device body. The translation guide member and rotation guide member are nested concentrically, with the rotation guide member positioned inside the translation guide member, maximizing space utilization and minimizing overall device volume while maintaining reliable actuation.
Solution Approach 2:
The needle support performs compound motion combining translation along the longitudinal axis and rotation around the same axis. This two-degree-of-freedom motion allows the needle to both extend/retract and tilt, achieving compact packaging by utilizing multiple spatial dimensions rather than requiring separate mechanisms for each function.
2Reliability
If a rotatable needle support with protected position is used, then needle safety is improved, but the mechanism becomes bulky and complicated
Solution Approach 1:
The translation guide member and rotation guide member are merged into a single integrated assembly that moves together as one unit. The engagement lever simultaneously controls both the translation and rotation functions through a single actuation motion, simplifying the overall mechanism while maintaining the safety benefits of the protected needle position.
Solution Approach 2:
The engagement lever with elastic engagement automatically engages and disengages the needle support at the appropriate positions during actuation. The elastic element provides automatic resetting and positioning, eliminating the need for complex control systems or multiple actuators, thereby reducing device complexity while ensuring reliable safety function.
3Volume of moving object
If a compact needle actuation mechanism is used, then device size is reduced, but the mechanism requires careful design to ensure reliability
Solution Approach 1:
The elastic engagement of the engagement lever provides built-in compliance and shock absorption. The elastic element can deflect to accommodate manufacturing tolerances and wear, preventing catastrophic failure and ensuring continuous reliable operation. This beforehand cushioning through elastic deformation maintains reliability in the compact design.
Solution Approach 2:
The mechanism utilizes changes in the engagement lever's position and orientation parameters to control needle movement. By varying the engagement angle and position of the lever, the system reliably controls both translation and rotation of the needle support, achieving dependable actuation within a compact volume through precise parameter control.
Data Source
AI summary
A drug delivery device (1) comprising a delivery unit (2) receiving a drug cartridge (3) containing a drug to be administered to a patient in need thereof, the delivery unit comprising a subcutaneous delivery mechanism (7) including a needle (24), a needle support (8) to which the needle is mounted, and a needle actuation mechanism (9) configured to move the needle from a retracted position within a housing (5) of the delivery unit (2), to an extended delivery position where the needle projects through a base wall (14) of the housing. The needle actuation mechanism comprises a rotary actuator (10) configured to engage an engagement lever (11) coupled to the needle support (8) for translating the needle support between retracted and extended delivery positions.