Capillary Stop Membrane for Microfluidic Priming
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Solution Overview
Problem
Microfluidic systems face challenges in priming due to significant surface tension forces in sub-millimeter channels, leading to prolonged priming times and air flow resistance issues, which hinder the efficient introduction and movement of fluids.
Innovation Solution
A microfluidic system incorporating a membrane with apertures of 0.1 to 50 μm radius, utilizing capillary forces and pressure differences to manage fluid flow, allowing for a capillary-based liquid stop within the fluidic path, thereby reducing priming time and enhancing fluid movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If sub-millimeter fluidic channels are used in microfluidic systems, then the system can achieve miniaturization and integration, but surface tension forces significantly increase leading to prolonged priming times
Solution Approach 1:
The system pre-fills the fluidic channel with liquid before operation, and uses a valve mechanism to trap the liquid in place, preventing air re-entry. This preliminary action eliminates the need for repeated priming operations during system use.
Solution Approach 2:
The invention extracts and isolates the priming function into a separate priming port and priming volume, distinct from the main fluidic channel. This allows priming to be performed independently without affecting the main system operation.
2Device complexity
If sub-millimeter fluidic channels are used, then system integration is improved, but air flow resistance increases hindering efficient fluid movement
Solution Approach 1:
The invention separates the air venting function from the main fluidic path by providing a dedicated priming port that allows air to be evacuated separately. This extraction of the air removal function eliminates air flow resistance from the main fluidic channel.
Solution Approach 2:
The valve acts as an intermediary mechanism that controls fluid flow selectively. It allows liquid to be introduced through the priming port while preventing air from entering the main channel, mediating between the priming requirement and the main fluidic operation.
3Ease of manufacture
If conventional sealing methods are used in microfluidic systems, then manufacturing is simpler, but seal resistance is low (10-50 MΩ) resulting in large electrical noise
Solution Approach 1:
The system uses the fluid's own surface tension and the capillary action in the aperture to create an automatic seal that requires no external components. The liquid naturally forms a meniscus at the aperture, creating a seal through physical properties rather than mechanical components.
Solution Approach 2:
The invention uses the hydraulic properties of the liquid, specifically surface tension and capillary pressure, to create the seal. The negative pressure generated by surface tension at the aperture prevents air leakage without requiring mechanical sealing components.
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 system effectively reduces priming time by utilizing capillary forces and controlled pressure differences to manage fluid flow, ensuring efficient fluid introduction and movement, even in systems with high air flow resistance.
Implementation Method 1
a first membrane positioned between the inlet and outlet and comprising an aperture having a radius within the range 0.1 to 50 μm... movement of a fluid within the channel will be halted at the first membrane, due to a surface tension created in the fluid at the aperture
Implementation Method 2
movement of a fluid within the channel will be halted at the first membrane, due to a surface tension created in the fluid at the aperture
Implementation Method 3
pressure means for creating a pressure difference between the inlet and the outlet, whereby, in use movement of a fluid within the channel will be halted at the first membrane, due to a surface tension created in the fluid at the aperture, until the pressure means creates a pressure difference between the inlet and the outlet that exceeds the surface tension created at the aperture
Data Source
AI summary
A microfluidics system comprising a channel having an inlet (32) and an outlet (38); a first membrane (31) positioned between the inlet (32) and outlet (38) and comprising an aperture having a radius within the range 0.1 to 50 μm, the inlet (32) and the outlet (38) being in hydraulic communication with one another, such that a fluid can move along the channel from the inlet to the outlet.