Flow control in microfluidic systems
First Claim
1. A method, comprising:
- flowing a first fluid from a first channel portion to a second channel portion in a microfluidic system, wherein a fluid path defined by the first channel portion has a larger cross-sectional area than a cross-sectional area of a fluid path defined by the second channel portion;
flowing a second fluid in a third channel portion in the microfluidic system in fluid communication with the first and second channel portions, wherein the viscosity of the first fluid is different than the viscosity of the second fluid, and wherein the first and second fluids are substantially incompressible;
without stopping the first or second fluids, causing a volumetric flow rate of the first and second fluids to decrease by a factor of at least 3 in the microfluidic system as a result of the first fluid flowing from the first channel portion to the second channel portion, compared to the absence of flowing the first fluid from the first channel portion to the second channel portion, wherein the volumetric flow rate of the first and second fluids is determined by Poiseuille'"'"'s law; and
effecting a chemical and/or biological interaction involving a component of the first or second fluids at a first analysis region in fluid communication with the channel portions while the first and second fluids are flowing at the decreased flow rate.
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Accused Products
Abstract
Microfluidic systems and methods including those that provide control of fluid flow are provided. Such systems and methods can be used, for example, to control pressure-driven flow based on the influence of channel geometry and the viscosity of one or more fluids inside the system. One method includes flowing a plug of a low viscosity fluid and a plug of a high viscosity fluid in a channel including a flow constriction region and a non-constriction region. In one embodiment, the low viscosity fluid flows at a first flow rate in the channel and the flow rate is not substantially affected by the flow constriction region. When the high viscosity fluid flows from the non-constriction region to the flow constriction region, the flow rates of the fluids decrease substantially, since the flow rates, in some systems, are influenced by the highest viscosity fluid flowing in the smallest cross-sectional area of the system (e.g., the flow constriction region). This causes the fluids to flow at the same flow rate at which the high viscosity fluid flows in the flow constriction region. Accordingly, by designing microfluidic systems with flow constriction regions positioned at particular locations and by choosing appropriate viscosities of fluids, a fluid can be made to speed up or slow down at different locations within the system without the use of valves and/or without external control.
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Citations
35 Claims
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1. A method, comprising:
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flowing a first fluid from a first channel portion to a second channel portion in a microfluidic system, wherein a fluid path defined by the first channel portion has a larger cross-sectional area than a cross-sectional area of a fluid path defined by the second channel portion; flowing a second fluid in a third channel portion in the microfluidic system in fluid communication with the first and second channel portions, wherein the viscosity of the first fluid is different than the viscosity of the second fluid, and wherein the first and second fluids are substantially incompressible; without stopping the first or second fluids, causing a volumetric flow rate of the first and second fluids to decrease by a factor of at least 3 in the microfluidic system as a result of the first fluid flowing from the first channel portion to the second channel portion, compared to the absence of flowing the first fluid from the first channel portion to the second channel portion, wherein the volumetric flow rate of the first and second fluids is determined by Poiseuille'"'"'s law; and effecting a chemical and/or biological interaction involving a component of the first or second fluids at a first analysis region in fluid communication with the channel portions while the first and second fluids are flowing at the decreased flow rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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Specification