Capillary Barriers for Bubble-Free Staged Microfluidic Loading
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Solution Overview
Problem
Loading multiple liquids into microfluidic chips is challenging due to limited access, hydrophobic channels, and the risk of fluid loss and bubble trapping, especially when dealing with rare samples like DNA or RNA.
Innovation Solution
A capillary barrier system is used to position a liquid meniscus at a fluid-interface region using capillary forces, with an escape path for the second liquid and a fluid-flow limiter to control volume flow rate, allowing liquids to interact without loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple liquids are loaded into microfluidic channels from multiple directions, then the liquid interface can be created, but bubbles can be trapped in the channels
Solution Approach 1:
The microfluidic device is divided into separate loading channels (first channel for first liquid, second channel for second liquid) that converge at a fluid interface region. This segmentation allows independent control of each liquid loading path, enabling bubble-free interface creation by preventing bubble interference between channels while maintaining multiple loading directions.
2Ease of operation
If aqueous liquids are driven into hydrophobic channels using external pressure, then the channels can be loaded, but fluid loss occurs
Solution Approach 1:
A hydrophilic coating is applied to the inner surfaces of the microfluidic channels to act as an intermediary between the aqueous liquids and the hydrophobic channel material. This coating enables aqueous liquids to advance through the channels without requiring high external pressure, thereby reducing fluid loss while maintaining ease of loading operation.
3Quantity of substance
If limited volumes of rare samples are used for creating liquid interfaces, then sample availability is optimized, but fluid loss becomes critical
Solution Approach 1:
The microfluidic device incorporates integrated fluid management features including capillary wicking structures and pressure-regulated valves that automatically control fluid flow and prevent loss. These self-regulating mechanisms ensure that limited volumes of rare samples are retained within the device during interface creation, eliminating the need for external monitoring and adjustment while minimizing sample loss.
Data Source
AI summary
Various aspects of the present disclosure are directed toward methods and apparatuses for interacting a first liquid and a second liquid in one or more fluidic channels of a capillary structure. The methods and apparatuses can include providing at least one capillary barrier that positions a meniscus of the first liquid at a fluid-interface region using capillary forces within the capillary structure. Additionally, a path is provided along one of the channels for the second liquid to flow toward the fluid-interface region. Additionally, gas pressure is released, via a gas-outflow port, from the fluid-interface region while flow of the first liquid is arrested. Further, the first liquid and the second liquid contact in the fluid-interface region with the capillary barrier holding the first liquid at the fluid-interface region.