Open Microfluidic Channels Spontaneous Capillary Flow
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Solution Overview
Problem
Existing open microfluidic channels face challenges in controlling fluid flow, inserting or removing fluid, and creating complex networks due to limitations in understanding flow dynamics and manufacturing processes, leading to unreliable and inefficient fluid handling systems.
Innovation Solution
The development of shallow open microfluidic channels with spontaneous capillary flow (SCF) driven by capillary forces, utilizing the SCF relation to design channels with specific geometries that allow fluid flow through open liquid-air interfaces, enabling precise control and manipulation of fluids within complex networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional closed microchannel structures are used, then air bubbles are trapped causing reliability issues, but open microchannel structures were previously unable to control fluid flow
Solution Approach 1:
The patent extracts the top wall from the microchannel structure to create an open microchannel with an exposed liquid-air interface. This removes the problematic trapped air bubble issue while maintaining fluid containment through capillary forces at the open interface, enabling both reliability improvement and flow control capability
Solution Approach 2:
The open microchannel structure utilizes spontaneous capillary flow to automatically control fluid movement without external pumping or complex control mechanisms. The capillary forces at the open liquid-air interface self-regulate the flow, providing ease of operation while maintaining reliability
2Reliability
If open microchannel structures are used, then air bubbles can escape improving reliability, but the ability to control fluid flow and manipulate samples is limited
Solution Approach 1:
The patent divides the microfluidic system into multiple functional zones within the open microchannel, including sample introduction regions, separation regions, and detection regions. This segmentation enables complex fluid handling operations and sample manipulation while maintaining the reliability benefits of the open structure
Solution Approach 2:
The patent utilizes the open liquid-air interface as an additional functional dimension, allowing for evaporation-based concentration, atmospheric reagent addition, and optical detection from above. This dimensional addition enhances fluid handling versatility while preserving reliability
3Adaptability or versatility
If complex microfluidic networks are created, then advanced fluid handling is enabled, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines multiple microchannel structures into a single monolithic substrate, integrating sample introduction, separation, and detection functions into one fabricated component. This merging approach enables complex fluid handling networks while simplifying manufacturing through single-substrate fabrication processes
Solution Approach 2:
The open microchannel structure serves multiple functions simultaneously: it contains fluid through capillary forces, allows atmospheric interaction for reagent addition and evaporation, enables optical detection from above, and provides pathways for complex fluid routing. This multi-functionality reduces the need for separate components, lowering manufacturing complexity
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 enables reliable, scalable, and cost-effective fabrication of complex microfluidic networks for diagnostic devices, allowing for precise fluid handling, insertion, and removal, while preventing air bubble entrapment and enabling advanced fluidic control mechanisms.
Implementation Method 1
spontaneous capillary flow (SCF) driven by capillary forces
Implementation Method 2
an analysis of capillary force was developed, to define a design guideline ensuring that the capillary force provided by the walls of the microfluidic channel overcomes the resistance created by the open sections of the microfluidic channel
Implementation Method 3
the wetted perimeter (p w ), defined by the length of the cross-section made up of solid hydrophilic material
Data Source
Figure 1A~1D
Figure 1E~1H
Figure 2A~2D
AI summary
The various embodiments described herein relate to fabricating and using open microfluidic networks according to methods, systems, and devices that can be used in applications ranging from home-testing, diagnosis, and research laboratories. Open microfluidic networks allow the input, handling, and extraction of fluids or components of the fluid into or out of the open microfluidic network. Fluids can be inserted into an open microfluidic channel by using open sections of the open microfluidic network. Passive valves can be created in the microfluidic network, allowing the creation of logic circuits and conditional flow and volume valves. The fluid can be presented via the microfluidic network to diagnostic and analysis components. Fluids and components of the fluid can be extracted from the open microfluidic network via functional open sections that are easily interfaced with other microfluidic networks or common laboratory tools.