Prefilled Injection Stopper Assembly with Fluid-Isolating Seal
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Solution Overview
Problem
Existing injection devices face challenges in maintaining medicinal fluid potency during storage due to interaction between the fluid and the stopper, and they may require additional regulatory approval and modify the actuation force, leading to unexpected injection rates.
Innovation Solution
A stopper assembly with a sealing element that isolates the stopper from the medicinal fluid using a chemically inert polymeric material, maintaining fluid isolation and consistent actuation force by compressing the stopper within the barrel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resin film is laminated on the sealing stopper to prevent contact between medicinal fluid and stopper, then the medicinal fluid potency is maintained during storage, but additional regulatory approval is required and the actuation force varies
Solution Approach 1:
The stopper assembly is divided into separate functional components: a stopper element and a sealing element. The stopper element provides the sealing function against the barrel, while the sealing element specifically prevents contact between the medicinal fluid and stopper material. This segmentation allows each component to be optimized independently and reduces regulatory complexity by clearly defining functional boundaries.
Solution Approach 2:
The sealing element acts as an intermediary component between the stopper and the medicinal fluid. It is positioned to prevent direct contact between the medicinal fluid and the stopper material, thereby maintaining fluid potency without requiring the stopper material itself to be chemically inert. This intermediary approach simplifies material selection and regulatory approval.
2Reliability
If a resin film is laminated on the sealing stopper to prevent contact between medicinal fluid and stopper, then the medicinal fluid potency is maintained during storage, but the actuation force varies and injection rate is unexpectedly modified
Solution Approach 1:
By separating the stopper into a stopper element and a sealing element, the friction interface with the barrel is provided by the stopper element whose material and surface properties can be optimized for consistent actuation force. The sealing element handles the chemical isolation function, allowing independent optimization of both sealing performance and actuation characteristics.
Solution Approach 2:
Different parts of the stopper assembly have different material properties optimized for their specific functions. The stopper element has surface characteristics optimized for friction control and consistent actuation, while the sealing element has material properties optimized for chemical inertness and fluid isolation. This local quality differentiation ensures both reliable potency maintenance and consistent user operation.
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 maintains medicinal fluid potency over time and ensures consistent actuation force without affecting the injection rate, while preventing blood reflux and reducing the need for additional regulatory approvals.
Implementation Method 1
The sealing element has a laterally outermost surface configured to be directly engaged with the inner surface of the barrel and to sealingly isolate the stopper from the medicinal fluid in the barrel
Implementation Method 2
maintaining fluid isolation and consistent actuation force by compressing the stopper within the barrel
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The present disclosure relates to a stopper assembly (120, 220) configured to be disposed in a barrel (102, 202) of an injection device containing a medicinal fluid. The stopper assembly (120, 220) comprises a stopper (130) having a laterally outermost surface (132) configured to be directly engaged with an inner surface (108, 208) of the barrel (102, 202). The stopper assembly (120, 220) also comprises a sealing element (140, 240) coupled to and axially distal relative to the stopper (130) in the barrel (102, 202). The sealing element (140, 240) having a laterally outermost surface (142, 242) configured to be directly engaged with the inner surface (108, 208) of the barrel (102, 202) and to sealingly isolate the stopper (130) from the medicinal fluid in the barrel (102, 202). The present disclosure further relates to an injection device (100, 200) comprising the stopper assembly (120, 220).