Microfluidic Capillary Traps with Retaining Members
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Solution Overview
Problem
Existing microfluidic devices face challenges in effectively capturing and retaining objects such as crystals or biological cells within capillary traps, especially when the fluid flow direction changes, leading to object escape and reduced reproducibility of analysis results.
Innovation Solution
The microfluidic device incorporates successive capillary traps with retaining members extending into the microchannel opposite the microcavity, designed to capture and retain objects by altering the fluid flow resistance and utilizing secondary microchannels for improved object capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If liquid is introduced into the microchannels via an injection tube that is disconnected after filling, then the device can be filled with fluid, but the liquid suction phenomenon forces objects to leave the capillary traps
Solution Approach 1:
The retaining member is positioned in advance within the microchannel to preemptively counteract the suction force that will occur when the injection tube is disconnected. This preliminary structural arrangement ensures that when liquid suction occurs during injection tube removal, the retaining member is already in place to prevent object escape from capillary traps
Solution Approach 2:
The retaining member provides a counteracting force against the liquid suction phenomenon. By having this structural element in place before the suction occurs, it creates an opposing mechanical resistance that prevents objects from being forced out of the capillary traps during the injection tube disconnection process
2Device complexity
If capillary traps consist of simple cavities without additional retention structures, then the device structure remains simple, but objects escape when fluid flow direction changes
Solution Approach 1:
The capillary trap structure is segmented into two functional parts: the microcavity that initially captures objects and the retaining member that provides secondary retention. This segmentation allows each component to perform its specific function - the cavity for initial trapping and the retaining member for preventing escape during flow direction changes
Solution Approach 2:
The retaining member acts as an intermediary element between the microcavity and the flowing fluid. It provides an additional interface that interacts with both the trapped objects and the fluid flow, mediating the forces acting on objects during flow direction changes to prevent escape
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 significantly reduces object escape during fluid flow changes, enhances the reproducibility of analysis results, and improves the efficiency of object capture within the capillary traps.
Implementation Method 1
At this scale, capillary forces predominate over the forces of gravity
Implementation Method 2
causing a liquid suction phenomenon which tends to force the objects to leave the capillary traps
Data Source
AI summary
A microfluidic device including capillary traps each provided with a microcavity formed on a wall of a microchannel for circulating a fluid and with a retaining member extending in the microchannel opposite the microcavity of the capillary trap so as to retain objects previously trapped in the microcavity when the objects move from the microcavity toward the retaining member, for example due to a change in the flow direction of the fluid in the microchannel.