Compact Drug Delivery Drive Assembly With Capstan And Tether
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Solution Overview
Problem
Existing drug delivery devices have large footprints due to complex drive assemblies, which increase size and manufacturing costs, and are not suitable for wearable injectors that require a compact design.
Innovation Solution
A drive assembly with a capstan and tether system that allows for a compact design by laterally offsetting the rotational axis of the capstan from the stopper's longitudinal axis, using a tether to regulate the expansion of the stopper biasing member, and incorporating a guide surface for tether direction change, along with a lock member for assembly ease.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a complex drive assembly with multiple components and mechanisms is used to control motion direction and speed, then the drug delivery functionality is improved, but the device footprint and overall size increase
Solution Approach 1:
The patent combines the capstan, tether, and biasing member into an integrated drive assembly that provides both motion control and drug expulsion functionality. The capstan rotates to wind and unwind the tether, which directly controls the biasing member's expansion and contraction, eliminating the need for separate control mechanisms and reducing overall device size while maintaining full drug delivery capability
Solution Approach 2:
The drive assembly components are nested within each other to minimize footprint. The tether is wound around the capstan, which is positioned within the drive housing, and the biasing member is contained within the same housing. This nested arrangement allows all functional components to occupy minimal space while maintaining their operational independence and effectiveness
2Adaptability or versatility
If a complex drive assembly with multiple components is used, then the drug delivery functionality is improved, but the manufacturing cost and assembly time increase
Solution Approach 1:
The drive assembly is segmented into distinct functional components (capstan, tether, biasing member, drive housing) that can be manufactured separately using standard processes and then assembled through simple, well-defined operations. This segmentation allows each component to be optimized for its specific function while simplifying the overall assembly process, reducing both manufacturing cost and assembly time compared to integrated complex mechanisms
Solution Approach 2:
The capstan serves multiple functions: it winds and unwinds the tether to control the biasing member's expansion, provides a mechanical advantage for force multiplication, and acts as a compact motion control element. This multi-functionality reduces the total number of components needed, simplifying assembly while maintaining comprehensive drug delivery functionality
3Area of stationary object
If the capstan rotational axis is laterally offset from the stopper longitudinal axis, then the device size is reduced, but the tether routing complexity increases
Solution Approach 1:
The lateral offset of the capstan rotational axis from the stopper longitudinal axis creates a three-dimensional tether routing path that allows the tether to wrap around the capstan in a compact configuration. This dimensional arrangement enables the tether to efficiently transmit force while accommodating the offset geometry, reducing overall device size without requiring complex additional routing components
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 reduces the overall size of the drug delivery device, simplifies assembly, and lowers manufacturing costs while maintaining effective drug expulsion functionality.
Implementation Method 1
the stopper biasing member is configured to expand to move the stopper through the reservoir when released from the energized state
Implementation Method 2
The tether is pulled taut against the guide surface of the drive housing by the stopper biasing member
Data Source
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Figure 3
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AI summary
Drug delivery devices and related methods of assembly are disclosed. The drug delivery device may include a main housing having an exterior surface releasably attachable to a patient, a container disposed in an enclosed space defined by an interior surface of the main housing, and a drive assembly. The container may include a reservoir containing a drug and a stopper. The drive assembly may include drive housing and a tether which slidably engages and is pulled taut against a guide surface of the drive housing. A first end of the tether may be wound around a capstan which is mounted rotatably relative to the drive housing. A second end of the tether may be operably connected to a stopper biasing member. The tether may initially retain the stopper biasing member in an energized state. When released, the stopper biasing member may expand to move the stopper through the reservoir.