Self-Sealing Vent Structure for Extracorporeal Fluid Circuits
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Solution Overview
Problem
Extracorporeal fluid circuits in hemodialysis face challenges in preventing fluid from contacting external environments and protecting components from contamination, particularly due to issues with air bubbles and condensation, which can lead to equipment contamination and inefficiencies in air removal processes.
Innovation Solution
The integration of a vent assembly with a micro-porous membrane and a self-sealing vent structure that expands when wet, preventing fluid flow and protecting the membrane from moisture, is used in extracorporeal medical fluid circuits. This assembly includes a porous material that swells upon moisture exposure, ensuring the circuit remains sealed and prevents contamination, while allowing gas to escape, thus maintaining the integrity of the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a micro-porous membrane is used to vent gas from the fluid circuit, then gas removal efficiency is improved, but the membrane may become wet from condensation or fluid leakage, causing liquid to pass through and contaminate external environments
Solution Approach 1:
A hydrophobic barrier layer is introduced as an intermediary between the micro-porous membrane and the external environment. This barrier layer allows gas to pass through while blocking liquid and condensation, preventing the membrane from becoming wet and eliminating the risk of fluid leakage without compromising gas venting efficiency
Solution Approach 2:
The vent assembly uses a composite structure combining a micro-porous membrane with a hydrophobic barrier layer. The micro-porous membrane provides gas permeability while the hydrophobic layer adds liquid-blocking capability, creating a multi-functional venting system that simultaneously achieves efficient gas removal and fluid containment
2Productivity
If the vent structure is made porous to allow gas passage, then air removal capability is improved, but fluid may flow through the pores and cause contamination
Solution Approach 1:
The invention uses a hydrophobic porous material for the vent structure that maintains open pores for gas passage while the hydrophobic surface tension prevents liquid from entering the pores. This allows the vent to remain porous for efficient air removal while the hydrophobic property blocks fluid flow through the same pores
Solution Approach 2:
The vent structure utilizes changes in surface energy parameters of the porous material to create hydrophobicity. By modifying the surface chemistry of the porous material to be hydrophobic, the system maintains high porosity for gas flow while preventing liquid infiltration through surface tension effects
3Object-affected harmful factors
If the vent assembly is designed to prevent fluid contact with external environment, then contamination risk is reduced, but gas venting efficiency may be compromised
Solution Approach 1:
The vent assembly applies different properties to different parts of the same structure: the micro-porous membrane provides gas permeability while the hydrophobic barrier layer provides liquid blocking. This local differentiation of material properties allows simultaneous achievement of fluid containment and efficient gas venting
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 effectively prevents fluid from contacting external environments, reduces contamination risks, and enhances the efficiency of air removal in hemodialysis systems by ensuring the circuit remains sealed even when the membrane is compromised, thereby maintaining system integrity and safety.
Implementation Method 1
The vent structure is porous, but expands when the vent structure becomes wet, thereby closing off the pores and inhibiting (e.g., preventing) fluid from flowing through the vent structure
Implementation Method 2
a first, liquid-wettable, microporous membrane carried in said housing so as to be in communication with the transfer line
Implementation Method 3
a second, non-liquid-wettable, gas permeable microporous membrane superimposed on said microporous membrane
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A vent assembly (150, 270) is described for use in an extracorporeal fluid unit (100). A vent structure (146, 264) adjacent to a micro-porous membrane (144, 260) forms the assembly. The vent structure is porous, but expands when the vent structure becomes wet, thereby closing off the pores and inhibiting (e.g., preventing) fluid from flowing through the vent structure. The vent structure also protects the membrane from becoming wet, such as from condensation.