Manipulation of fluids and reactions in microfluidic systems

• US 9,440,232 B2
• Filed: 12/19/2014
• Issued: 09/13/2016
• Est. Priority Date: 02/06/2007
• Status: Active Grant

• Current Assignee: Brandeis University
• Original Assignee: Raindance Technologies Incorporated (Bio-Rad Laboratories Incorporated)
• Inventors: Fraden, Seth, Cristobal-Azkarate, Galder
• Primary Examiner(s): Hyun, Paul
• Application Number:
  US14/577,652
• Publication Number:
  US 20150118761A1
• Time in Patent Office: 634 Days
• US Class Current: 1/1
• CPC Class Codes: B01L 2200/0621 Control of the sequence of chambers filled or emptied
• CPC Class Codes: B01L 2200/0642 Filling fluids into wells by specific techniques
• CPC Class Codes: B01L 2200/0668 Trapping microscopic beads
• CPC Class Codes: B01L 2200/0673 Handling of plugs of fluid surrounded by immiscible fluid
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/0864 comprising only one inlet and multiple receiving wells, e.g. for separation, splitting
• CPC Class Codes: B01L 2300/0867 Multiple inlets and one sample wells, e.g. mixing, dilution
• CPC Class Codes: B01L 2300/1822 using Peltier elements
• CPC Class Codes: B01L 2400/0406 capillary forces
• CPC Class Codes: B01L 2400/0655 pinch valves
• CPC Class Codes: B01L 3/06 Crystallising dishes
• CPC Class Codes: B01L 3/5027 by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip B01L3/5023 takes precedence; micromixers B01F33/30; microreactors for synthesis B01J19/0093; microcapillary devices in general B81B1/00
• CPC Class Codes: B01L 3/502715 characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces
• CPC Class Codes: B01L 3/50273 characterised by the means or forces applied to move the fluids micropumps F04B19/006, of the membrane type F04B43/043
• CPC Class Codes: B01L 3/502746 characterised by the means for controlling flow resistance, e.g. flow controllers, baffles B01L3/502738 takes precedence
• CPC Class Codes: B01L 3/502784 specially adapted for droplet or plug flow, e.g. digital microfluidics automatic analysis using a stream of discrete samples in a tube system G01N35/08
• CPC Class Codes: B01L 7/54 using spatial temperature gradients
• CPC Class Codes: C30B 29/58 Macromolecular compounds
• CPC Class Codes: C30B 7/00 Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions from molten solvents C30B9/00; by normal or gradient freezing C30B11/00; under a protective fluid C30B27/00
• CPC Class Codes: G01N 1/38 Diluting, dispersing or mixing samples
• CPC Class Codes: G01N 2001/386 : Other diluting or mixing processes
• CPC Class Codes: Y10T 137/0318 : Processes
• CPC Class Codes: Y10T 436/2575 : Volumetric liquid transfer

Abstract

Microfluidic structures and methods for manipulating fluids and reactions are provided. Such structures and methods may involve positioning fluid samples, e.g., in the form of droplets, in a carrier fluid (e.g., an oil, which may be immiscible with the fluid sample) in predetermined regions in a microfluidic network. In some embodiments, positioning of the droplets can take place in the order in which they are introduced into the microfluidic network (e.g., sequentially) without significant physical contact between the droplets. Because of the little or no contact between the droplets, there may be little or no coalescence between the droplets. Accordingly, in some such embodiments, surfactants are not required in either the fluid sample or the carrier fluid to prevent coalescence of the droplets. Structures and methods described herein also enable droplets to be removed sequentially from the predetermined regions.

Claims

1. A method, comprising:

providing a microfluidic network comprising five or more sections in a serial arrangement, each section comprising a first microchannel, a second microchannel, a microwell, and a junction, wherein the junction is fluidicly coupled to the first and second microchannels and the microwell, and the microwell comprises a constricted fluidic path that exits the microwell;

flowing an oil in the microfluidic network;

flowing a plurality of aqueous droplets in the microfluidic network;

positioning each of the plurality of aqueous droplets in the microwells of a plurality of the sections, wherein each microwell has at most one positioned aqueous droplet; and

maintaining the positioned aqueous droplets in the microwells while the oil is flowing in the microfluidic network.

2. The method of claim 1, wherein the oil does not comprise a surfactant.

3. The method of claim 1, wherein the aqueous droplets do not come into physical contact with each other during the positioning or maintaining steps.

4. The method of claim 1, wherein positioning or maintaining at least one aqueous droplet is independent of a flow rate of the oil in the microfluidic channel.

5. The method of claim 1, wherein the aqueous droplets are sequentially positioned.

6. The method of claim 1, wherein the aqueous droplets comprise different aqueous fluids.

7. The method of claim 1, wherein the first and second microfluidic channels have a maximum cross sectional dimension of 500 microns or smaller.

8. The method of claim 1, wherein the first and second microfluidic channels have a maximum cross sectional dimension of 100 microns or smaller.

9. The method of claim 1, wherein the aqueous droplets have a volume of less than 1 nL.

10. The method of claim 1, wherein the oil is a fluorinated oil.