Microfluidic Channel Trenches for Hydrogel Flow Isolation
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Solution Overview
Problem
Existing microfluidic devices face challenges in controlling fluid flow, particularly when modeling the extracellular matrix (ECM) with hydrogels, as hydrophilic fluids tend to bead up on hydrophobic surfaces, leading to inconsistent fluid distribution and interference with cellular functions.
Innovation Solution
The use of trenches and overhang regions in microfluidic channels to separate fluid flow, preventing fluid from crossing into adjacent channels without physical barriers, allowing hydrogels to be contained within one channel while maintaining interaction with other fluids through a trench that is longer than the interface length and features overhangs to prevent fluid access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrophilic fluid is added to hydrophobic thermoplastic surface, then fluid adhesion is improved, but fluid flow control deteriorates due to beading and surface tension
Solution Approach 1:
The device segments the fluidic system into distinct channels with hydrophobic walls and a hydrophilic floor. This segmentation allows the fluid to adhere reliably to the hydrophilic floor while the hydrophobic walls prevent unwanted adhesion and maintain flow control through the segmented channel structure.
Solution Approach 2:
The channel structure implements local quality by having different surface properties in different locations: the floor is hydrophilic to promote fluid adhesion and flow, while the walls are hydrophobic to prevent adhesion. This local differentiation resolves the contradiction between overall fluid adhesion and flow control.
2Reliability
If physical barriers are used to separate fluid flow between channels, then fluid isolation is improved, but device complexity increases
Solution Approach 1:
The invention extracts the separation function from physical barriers and implements it through the trench structure combined with hydrophobic surface properties. The trenches, which are voids in the substrate, provide fluid isolation without requiring solid barriers, thereby reducing device complexity while maintaining reliable fluid isolation.
Solution Approach 2:
The hydrophobic surface treatment acts as an intermediary between the physical trench structure and the fluid. It mediates the interaction by preventing fluid adhesion to the trench walls, ensuring complete fluid isolation without requiring the trenches to be filled with solid barrier materials.
3Reliability
If trench length is increased beyond interface length to prevent fluid crossover, then fluid containment is improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention changes the surface energy parameter of the trench walls through hydrophobic treatment. This parameter change ensures that even with moderate trench lengths exceeding the interface length, complete fluid containment is achieved because the hydrophobic surface prevents any fluid adhesion to the trench walls, reducing sensitivity to precise trench dimensional control.
4Reliability
If hydrogel is contained within one channel, then hydrogel functionality is improved, but fluid interaction with adjacent channels is reduced
Solution Approach 1:
The invention uses the vertical dimension created by the trenches to achieve horizontal fluid isolation. The trenches extend downward into the substrate, creating a three-dimensional separation that contains the hydrogel within its channel while allowing the device to maintain multiple functional channels that can interact with different fluids independently.
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 configuration enables controlled fluid flow within microfluidic devices, allowing for more physiologically relevant cell culture environments by preventing fluid crossover and facilitating interaction with hydrogels, enhancing cellular behavior and functionality.
Implementation Method 1
the fluid tends to bead up due to surface tension between the two materials
Implementation Method 2
the trench has a length longer than a length of an interface between the first microfluidic channel and the second microfluidic channel
Data Source
AI summary
The present disclosure generally relates to microfluidics, and to systems and methods for controlling the flow of fluids. Certain aspects are generally directed to microfluidic channels that are parallel to each other, e.g., within a microfluidic interconnected region of a microfluidic device. In some embodiments, a fluid in a first microfluidic channel may be prevented from entering a second microfluidic channel due to a trench or other feature separating the channels. The trench may include features that at least partially prevent fluid from crossing. For example, the ends of the trench may be positioned such that fluids cannot access the ends, e.g., due to overhang regions between the trench and the microfluidic channels. This may keep the fluids pinned within the channels in some embodiments. Thus, for example, a fluid in a first microfluidic channel may be hardened to form a hydrogel, while the second microfluidic channel may remain free of the fluid and the hydrogel, due to the trench. Other embodiments are generally directed to devices containing such structures, methods or kits using such structures, or the like.