Microfluidic Device with Varying Dwell Times for Gradient Generation
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Solution Overview
Problem
Existing microfluidic technologies face challenges in producing and delivering a mobile phase with a concentration gradient at low flow rates, often resulting in high waste, complexity, low repeatability, and long delay times, particularly in microfluidic applications where precise control over fluid flow is required for separation processes.
Innovation Solution
A fluidic device with multiple fluid-transporting features of varying dwell times, allowing for the merging of fluids to produce an output stream with desired characteristics such as concentration gradients, utilizing a common inlet and outlet, and incorporating a switching valve for alternating fluid communication from multiple sources to achieve a linear or stepped concentration profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional LC pumps are used to deliver mobile phase at low flow rates, then the pump operates outside its optimum flow-rate range, but this enables gradient LC to be performed. However, this results in poor pump performance and potential waste of diverted fluid
Solution Approach 1:
The system segments the mobile phase delivery into multiple parallel pathways, each with its own pump operating at optimum flow rates. This allows the overall system to achieve low flow rates for microfluidic applications while individual pumps operate efficiently within their optimal ranges, eliminating the need to divert fluid and waste resources.
2Productivity
If mixing equipment with large volume is used to generate concentration gradient, then the gradient can be produced, but the delay time becomes excessively high at low flow rates
Solution Approach 1:
The mixing chambers are nested within the microfluidic circuitry itself, utilizing the flow paths and residence times of the microfluidic device for mixing purposes. This eliminates the need for separate external mixing equipment with large volumes, thereby reducing delay time while maintaining gradient generation capability at low flow rates.
Solution Approach 2:
The system transitions from external mixing equipment to on-chip mixing within the microfluidic device, utilizing the third dimension of space within the microfluidic channels. This allows mixing to occur within the existing device volume rather than requiring additional external equipment, reducing overall system delay time.
3Adaptability or versatility
If multiple pumps are used to deliver fluids independently for gradient generation, then the concentration gradient can be controlled, but the device complexity increases
Solution Approach 1:
The microfluidic device serves multiple functions: it acts as both the separation channel and the mixing chamber for gradient generation. The same device structure that performs chromatographic separation also facilitates fluid mixing through controlled residence times and flow paths, eliminating the need for separate mixing equipment and reducing overall system 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 efficient generation of concentration gradients with reduced waste, improved repeatability, and shorter delay times, facilitating high-resolution microfluidic separations by using a single pump and switching valve to manage fluid flow, even at low flow rates, thereby optimizing microfluidic separation processes.
Implementation Method 1
a plurality of fluid-transporting features extending from a common inlet to a common outlet, each fluid-transporting feature being associated with a different fluid dwell time
Implementation Method 2
The features are associated with differing fluid dwell times. The means for effecting fluid flow cooperates with the fluid-transporting features to merge fluids from the fluid-transporting features
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3D
AI summary
A fluidic device (10) is provided that includes a plurality of fluid-transporting features (19) extending from a common inlet (46) to a common outlet (48) and a means for effecting fluid flow through the fluid-transporting features (19). The features (19) are associated with differing fluid dwell times. The means for effecting fluid flow cooperates with the fluid-transporting features (19) to merge fluids from the fluid-transporting features (19) in a manner effective to produce an output stream from the common outlet (48) that exhibits at least one desired characteristic generated as a result of the differing dwell times. Also provided is a method for producing a fluid stream exhibiting at least one desired characteristic. Optionally, the device (10) and/or method are used in microfluidic applications.