Capillary Pressure Reset via Soluble Matrix for Filtration
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Solution Overview
Problem
Existing filtration systems, particularly in medical diagnostics, face challenges with high initial pressure spikes when passing liquid through hydrophilic membranes, which can be costly and impractical for low-cost, handheld systems, and are difficult to manage due to capillary forces that require significant pressure to initiate flow but cease once flow is established.
Innovation Solution
A method using a soluble matrix with higher capillarity than the initial membrane, which dissolves in the liquid, allowing capillary forces to draw the liquid out without additional pressure, effectively resetting capillary pressures and eliminating the need for high initial pressure transients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a hydrophilic membrane is used for filtration, then liquid flow is facilitated once flow is established, but high initial pressure spike is required to overcome capillary forces and initiate flow
Solution Approach 1:
A soluble matrix material is introduced as an intermediary substance between the hydrophilic membrane and the liquid sample. This matrix material has higher capillarity than the membrane itself, allowing it to draw liquid through the membrane first. Once the liquid flow is initiated and the membrane is wetted, the soluble matrix dissolves, eliminating the capillary barrier. This intermediary approach allows the system to overcome the initial pressure spike problem while maintaining the ease of operation benefits of hydrophilic membranes.
Solution Approach 2:
The invention changes the capillarity parameter of the filtration system by introducing a soluble matrix material with higher capillarity than the membrane. This temporary parameter change allows liquid to overcome the membrane's capillary forces without requiring high pressure. As the matrix dissolves, the system transitions to the membrane's native capillarity, maintaining facilitated flow while eliminating the initial pressure requirement.
2Productivity
If high pressure is applied to force liquid through the membrane initially, then flow is initiated, but the system becomes impractical for low-cost, handheld applications
Solution Approach 1:
The soluble matrix acts as a temporary intermediary that enables flow initiation without high pressure. By placing this matrix in contact with the membrane, liquid is drawn through via capillary action alone, eliminating the need for pressure-generating components. This makes the system practical for low-cost, handheld applications while maintaining productivity.
Solution Approach 2:
The invention replaces the mechanical pressure system with a capillary-driven system. Instead of using pumps or pressure sources to initiate flow, the system uses the capillary forces of the soluble matrix to draw liquid through the membrane. This substitution eliminates complex mechanical components, reducing cost and improving practicality for handheld devices.
3Productivity
If the soluble matrix remains in the system after dissolution, then it may interfere with downstream processing, but removing it adds system complexity
Solution Approach 1:
The soluble matrix is designed as a temporary, consumable component that dissolves completely during the filtration process. Since it is water-soluble and used in small amounts, its complete dissolution does not significantly interfere with downstream processing. This approach avoids the complexity of removal mechanisms while maintaining filtrate quality, treating the matrix as a disposable facilitator rather than a permanent system component.
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
This approach reduces or eliminates the need for high initial pressure to initiate flow through membranes, making it suitable for low-cost, handheld systems and enabling efficient plasma separation from whole blood without damaging red blood cells, while allowing for easy collection and further processing of the filtrate.
Implementation Method 1
A soluble matrix with higher capillarity than the initial membrane is placed in physical contact with a downstream surface of the initial membrane... capillary forces to draw the liquid out
Data Source
AI summary
Many hand-held diagnostics are limited in their functionality due to the challenging physics associated with small dimensional systems. An example of this is capillary forces in hydrophilic systems, such as the tight retention of liquid passing through a small pore filtration membrane, or capillary force driven microfluidics where, to keep liquid flowing the dimensions of the system become so small that the flow rates are too low to be useful, or the manufacturing of such devices becomes uneconomical. This disclosure details methods to ‘reset’ the capillary force condition to avoid the requirement of transient pressure spikes associated with the breakthrough pressure of small pore membranes, and avoid the necessity of extremely small microfluidic channels, which can be useful in applications such as filtration of whole blood to plasma using only suction pressure or passive capillary pressure.