Variable-Depth Microfluidic Channel for Reliable Capillary Triggering
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Solution Overview
Problem
Conventional microfluidic channels and capillary trigger valves face reliability issues due to the risk of trigger fluid stopping at transitions between channels of different depths, leading to unreliable fluid control in microfluidic systems.
Innovation Solution
A channel design with a portion of variable depth that gradually transitions between two different depths, preventing the air-liquid interface from stopping at the transition, allowing for a smooth capillary flow from a first depth to a second, deeper depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the trigger channel has an extended depth at the central portion, then the main fluid stops flowing before entering the central portion, but the channel complexity increases
Solution Approach 1:
The solution addresses the flow control problem by modifying the cross-sectional dimensions of the channel. The trigger channel's second section has increased cross-sectional area compared to the first section, creating a gradual expansion that prevents fluid stoppage. This dimensional change provides a geometric solution to the flow reliability issue.
2Area of stationary object
If the channel has a smaller cross-sectional dimension, then the footprint on the microfluidic chip is reduced, but the fluid flow resistance increases significantly
Solution Approach 1:
The channel system is segmented into different sections with optimized cross-sectional dimensions for their specific functions. The trigger channel uses a smaller cross-section in its first section for compactness and a larger cross-section in its second section for reliable fluid transport, while the main channel uses an abrupt transition to control flow stopping.
Solution Approach 2:
Different sections of the channel system are assigned different cross-sectional properties locally. The trigger channel's second section has a larger cross-section to reduce flow resistance and ensure reliable trigger fluid delivery, while other portions maintain smaller dimensions for compact chip footprint.
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 channel design minimizes the risk of fluid stoppage at transitions, ensuring reliable fluid flow and control in microfluidic systems by maintaining a gradual capillary pressure transition, enhancing the functionality of capillary trigger valves.
Implementation Method 1
Microfluidics deals with the behavior, precise control and manipulation of fluids that are geometrically constrained to a small, typically sub-millimeter, scale... utilizing the capillary forces that arise within sub-millimeter channels
Implementation Method 2
For a channel of constant cross-section of a given length, a smaller cross-section will generally result in a longer time to traverse the length of the channel than a larger cross-sectional dimension. This is because, at least for a circular cross-section channel of dimension D, the driving force behind the capillary flow, the capillary pressure, scales as D1 while the channel resistance scales as D4
Data Source
Figure 1
Figure 2a~2c
Figure 3~4
AI summary
The disclosure relates to a channel (100) for a microfluidic system, comprising: a portion (112) of a first depth (D1) and a portion (114) of a second, deeper, depth (D2) along a direction of flow (L) of the channel; a portion of variable depth located between the portion (112) of a first depth and the portion (114) of a second depth along the direction of flow (L), wherein, in the portion (116) of variable depth, each cross-section of the channel (110) that is orthogonal to the direction of flow (L) has at least two different depths, being equal to at least the first depth (D1) and the second depth (D2), at different portions thereof, thereby allowing for a gradual transition in capillary pressure as a capillary flow in the channel (110) transitions from the portion (112) of a first depth (D1) to the portion (114) of a second depth (D2).