Composite Piston for Syringe Sealing and Sliding
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Solution Overview
Problem
Syringes used in capillary electrophoresis devices face challenges with high pressure resistance, stability, and manufacturing cost, as existing solutions either fail to maintain sealing performance under high pressure or have high sliding resistance, and are either expensive or difficult to produce precisely.
Innovation Solution
A piston design that combines a soft portion made of highly elastic material and a rigid portion, connected in series, where the soft portion contacts the medium and the rigid portion does not, with the soft portion having a hollow surface and a larger outer diameter than the rigid portion, allowing for improved sealing and reduced sliding resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a plastic syringe is used for mass production, then manufacturing cost is reduced, but pressure resistance performance deteriorates
Solution Approach 1:
The piston tip is formed with a flexible resin that can elastically deform under pressure to seal against the syringe inner wall, while the piston body uses a rigid resin for structural strength. This combination allows the use of injection-molded plastic components that can be mass-produced at low cost while achieving high pressure resistance through the elastic sealing action of the flexible tip portion.
Solution Approach 2:
The piston is constructed as a composite structure with a rigid resin body and a flexible resin tip, combining the advantages of both material types. The rigid portion provides structural integrity and dimensional stability for mass production, while the flexible portion provides elastic sealing capability under high pressure, resolving the contradiction between manufacturing cost and pressure resistance.
2Strength
If the piston tip is crushed and pushed into the syringe to improve sealing, then pressure resistance improves, but sliding resistance increases
Solution Approach 1:
The piston tip is designed with dynamic elastic deformation capability rather than static crushing. The flexible resin tip elastically deforms radially outward under pressure to seal against the syringe wall, then returns to its original shape during retraction, providing continuous sealing without permanent deformation or increased friction, thus maintaining low sliding resistance.
Solution Approach 2:
The material properties of the piston tip are changed to use a flexible resin with appropriate elasticity, allowing the tip to dynamically adjust its sealing pressure through elastic deformation rather than requiring high mechanical crushing forces. This parameter change in material flexibility enables sealing performance without increasing sliding resistance.
3Strength
If a gas-tight syringe made of glass is used, then pressure resistance performance improves, but manufacturing cost increases and durability deteriorates
Solution Approach 1:
The flexible resin tip of the piston provides elastic sealing capability that mimics the gas-tight performance of glass syringes, while the entire syringe can be made of injection-molded plastic. This flexible sealing mechanism achieves high pressure resistance and durability without requiring expensive glass construction, enabling mass production at low cost.
Solution Approach 2:
The composite piston structure with rigid and flexible resin portions provides glass-like pressure resistance through the elastic sealing action of the flexible tip, while allowing the syringe system to be manufactured using cost-effective injection molding processes. This material combination achieves the performance of glass syringes with the manufacturing advantages of plastic.
4Manufacturing precision
If the piston tip is made rigid for structural strength, then manufacturing precision improves, but sealing performance under high pressure deteriorates
Solution Approach 1:
The piston is segmented into a rigid body portion that can be precisely manufactured by injection molding and a flexible tip portion that provides elastic sealing. This segmentation allows the majority of the piston to be made with high manufacturing precision using standard plastic molding techniques, while the flexible tip compensates for any minor dimensional variations and provides adaptive sealing under pressure.
Solution Approach 2:
Only the tip portion of the piston requires flexible material properties for sealing, while the main body can be rigid for structural strength and manufacturing precision. This local quality differentiation allows the majority of the component to be manufactured with high precision using cost-effective methods, while the critical sealing zone has the necessary flexibility.
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 piston achieves high pressure resistance and low sliding resistance while being cost-effective, enabling efficient and stable liquid handling in capillary electrophoresis devices without the need for expensive materials or complex manufacturing processes.
Implementation Method 1
the tip of the piston is pushed to be widened in the radially outside direction of the syringe as the pressure increases
Data Source
AI summary
In order to provide a piston and a syringe with good sliding performance and pressure resistance performance, the piston contained in the syringe that pressurizes or decompresses an internal medium is configured such that a soft portion made of a soft material and a rigid portion made of a material having rigidity higher than rigidity of the soft portion, are connected in series, and arranged such that the soft portion is in contact with the medium and the rigid portion is not in contact with the medium. The soft portion includes a hollow on a surface in contact with the medium. The rigid portion has an end surface facing the soft portion, the end surface including at least an outer peripheral portion in contact with the soft portion. The outer diameter of the soft portion is larger than the outer diameter of the rigid portion, and the outer diameter of the rigid portion is slightly smaller than the inner diameter of an outer cylinder of the syringe.