Time-of-use Activated Syringe Stopper Sealing
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Solution Overview
Problem
Conventional syringe systems face issues with high compression/deformation, material degradation, and high forces required for operation due to significant interference between the stopper and syringe barrel, leading to poor performance in low pressure applications and increased manufacturing costs.
Innovation Solution
A stopper/plunger rod arrangement with an activation mechanism that applies a radial force to a perimetrical skirt upon transition from a pre-loaded to a ready-to-use position, allowing for a leak-free seal in both high and low pressure applications without the need for lubricants, and using bio-based or rigid polymeric materials with wider tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If significant interference between stopper outer diameter and barrel inner diameter is used to create adequate seal, then sealing capability is improved, but compression deformation and contact forces increase leading to material degradation and high operating forces
Solution Approach 1:
The stopper transitions from a static interference fit to a dynamic sealing mechanism where the perimetrical skirt is actively engaged by the activation mechanism. The skirt deforms elastically under radial force to create the seal, allowing the system to adapt sealing pressure dynamically rather than maintaining constant high compression throughout storage and use.
Solution Approach 2:
The invention changes the sealing parameter from constant high compression (static interference) to controlled radial force application (dynamic engagement). By using an elastic material for the perimetrical skirt and applying force only when needed, the system maintains sealing capability while reducing cumulative compression damage during storage.
2Reliability
If high compression force is applied to maintain seal during storage, then sealing reliability is improved, but break-loose and sustaining forces increase during operation
Solution Approach 1:
The system prepares for sealing in advance by positioning the perimetrical skirt in contact with the barrel inner wall during storage, but without applying significant compression force. The activation mechanism is pre-loaded and ready to apply radial force only when needed, separating the storage phase from the operation phase force requirements.
Solution Approach 2:
The sealing function is segmented into two phases: passive contact during storage (minimal force) and active sealing during operation (high radial force). The activation mechanism acts as a separate component that bridges these phases, allowing the stopper body to remain relatively stress-free during storage while enabling strong sealing when activated.
3Reliability
If elastomeric stopper material is used to provide flexibility and seal, then sealing capability is improved, but friction coefficient increases requiring liquid lubricants
Solution Approach 1:
The perimetrical skirt is made of elastomeric material specifically at the sealing interface where flexibility and conformability are needed, while the main stopper body can be made of rigid or semi-rigid polymeric material. This localized elastomeric construction provides sealing capability without requiring the entire stopper to have high friction characteristics, reducing or eliminating the need for lubricants.
4Stability of the object's composition
If rigid or semi-rigid polymeric stopper material is used to reduce compression set, then resistance to deformation is improved, but sealing capability in low pressure applications deteriorates
Solution Approach 1:
The stopper employs a composite construction combining rigid or semi-rigid polymeric material for the main body (providing structural stability and resistance to compression set) with an elastomeric perimetrical skirt (providing sealing capability). This composite approach allows the rigid material to resist deformation during storage while the elastomeric skirt maintains sealing effectiveness in both high and low pressure applications through its ability to deform and conform.
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 need for fine-tuning of seal pressures, minimizes material creep, and lowers manufacturing costs while maintaining a high percentage of acceptable parts, improving the syringe's sealing performance and reducing sticktion effects.
Implementation Method 1
The plunger rod is configured for transition between a pre-loaded position in which the activation mechanism is unactivated and a loaded, ready-to-use position in which the activation mechanism is activated so that it applies a radial force to the first perimetrical skirt causing the first perimetrical skirt to seal against an inner wall of the syringe barrel
Implementation Method 2
The first perimetrical skirt is configured for sealing against an inner wall of the syringe barrel
Data Source
AI summary
A time-of-use activated syringe assembly includes a syringe barrel defining a chamber, a plunger rod having a forward attachment end located within the chamber of the barrel, and a stopper located within the chamber of the barrel and including a rearward end adapted to receive the plunger rod. The stopper includes a first perimetrical skirt extending around an outer circumference thereof and extending toward a front end of the stopper. An activation mechanism is associated with at least one of the stopper and the plunger rod, and the plunger rod is configured for transition between a pre-loaded position in which the activation mechanism is unactivated and a loaded position in which the activation mechanism is activated. Upon activation, the activation mechanism applies a radial force to the first perimetrical skirt causing the skirt to seal against an inner wall of the syringe barrel.