SYSTEM FOR FORMING EMULSIONS

• US 20120152369A1
• Filed: 11/01/2011
• Published: 06/21/2012
• Est. Priority Date: 11/01/2010
• Status: Active Grant

• Current Assignee: Bio-Rad Laboratories Incorporated
• Original Assignee: Bio-Rad Laboratories Incorporated
• Inventors: Hiddessen, Amy L., Masquelier, Donald A., Hindson, Benjamin J., Makarewicz, Anthony J. Jr., Ness, Kevin D., Steenblock, Erin R.
• Granted Patent: US 9,089,844 B2
• Time in Patent Office: Days
• US Class Current: 137/14
• CPC Class Codes: B01F 23/41 Emulsifying
• CPC Class Codes: B01F 33/3011 using a sheathing stream of a fluid surrounding a central stream of a different fluid, e.g. for reducing the cross-section of the central stream or to produce droplets from the central stream
• CPC Class Codes: B01F 33/813 mixing simultaneously in two or more mixing receptacles
• CPC Class Codes: B01L 2200/0605 Metering of fluids
• CPC Class Codes: B01L 2200/0673 Handling of plugs of fluid surrounded by immiscible fluid
• CPC Class Codes: B01L 2300/0867 Multiple inlets and one sample wells, e.g. mixing, dilution
• CPC Class Codes: B01L 2400/0487 fluid pressure, pneumatics
• CPC Class Codes: B01L 3/502761 specially adapted for handling suspended solids or molecules independently from the bulk fluid flow, e.g. for trapping or sorting beads, for physically stretching molecules investigating characteristics of particles G01N15/00
• 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: G01N 1/38 Diluting, dispersing or mixing samples
• CPC Class Codes: G01N 2035/1046 Levitated, suspended drops
• CPC Class Codes: Y10T 137/0396 Involving pressure control
• CPC Class Codes: Y10T 137/8593 Systems

Abstract

System, including methods, apparatus, and kits, for forming emulsions. The system may include an instrument and a microfluidic chip received by the instrument. The instrument may apply pressure to prospective emulsion phases held by the chip, to drive formation and collection of emulsions in the chip. In some embodiments, the instrument may stop applying pressure to the chip when a change in pressure meeting a predefined condition is detected by the instrument. The change may indicate that an endpoint of droplet generation has been reached.

Claims

1. A method of emulsion formation, comprising:

applying pressure to a microfluidic chip holding prospective emulsion phases, to drive droplet formation and collection of emulsions in the chip;

monitoring the pressure for a change that meets a predefined condition; and

stopping application of the pressure when the change is detected.

2. The method of claim 1, wherein the chip includes output containers that collect the emulsions, and wherein the pressure includes negative pressure applied to the output containers.

3. The method of claim 1, wherein the chip includes input containers that hold the prospective emulsion phases, and wherein the pressure includes positive pressure applied to the input containers.

4. The method of claim 1, wherein the chip includes input containers that hold the prospective emulsion phases and output containers that collect the emulsions, and wherein the pressure includes positive pressure applied to at least a subset of the input containers and negative pressure applied to the output containers.

5. The method of claim 1, wherein the chip provides input wells for holding the prospective emulsion phases and output wells for collecting the emulsions.

6. The method of claim 1, wherein the pressure is applied with a gas phase that contacts liquid contained completely by the chip.

7. The method of claim 6, wherein the gas phase is composed of air.

8. The method of claim 1, wherein the pressure is a first pressure applied with an instrument having a pressure sensor, and wherein the pressure sensor monitors the first pressure by detecting a second pressure corresponding to the first pressure.

9. The method of claim 8, wherein the instrument includes a fluidics assembly with a manifold providing a plurality of ports through which the first pressure is applied to the chip, wherein the second pressure is detected in a region of the fluidics assembly that is fluidically connected to the ports, and wherein the ports provide a resistance to fluid flow that reduces a magnitude of the first pressure relative to the second pressure.

10. The method of claim 9, wherein the manifold includes a main channel and a plurality of side channels that branch from the main channel, wherein the side channels form the ports, and wherein the second pressure corresponds more closely to pressure in the main channel than the side channels.

11. The method of claim 1, wherein air following liquid into one or more channels of the chip leads to the change in the pressure.

12. The method of claim 11, wherein the prospective emulsion phases are held by a plurality of input wells of the chip, and wherein the change in the pressure occurs if only one of the input wells is empty.

13. The method of claim 1, wherein the prospective emulsion phases are held by input containers, wherein application of the pressure drives the phases through channels of the chip for droplet formation and collection as emulsions in output containers of the chip, and wherein application of the pressure is stopped after air has followed liquid into one or more of the channels from one or more of the input containers and before the air has reached all of the emulsions collected in the output containers.

14. The method of claim 1, wherein the prospective emulsion phases include a plurality of samples, and wherein application of the pressure is stopped when at least about 80% by volume of each of the samples has been converted to droplets.

21. The method of claim 1, wherein the emulsions are collected in output containers of the chip, further comprising a step of concentrating the emulsions by selectively driving a continuous phase of an emulsion from each of the output containers.

15. A system for emulsion formation, comprising:

a microfluidic chip configured to hold prospective emulsion phases; and

an instrument including a fluidics assembly having a pressure sensor, the instrument being configured to apply pressure to the chip with the fluidics assembly to drive droplet generation and collection of emulsions in the chip, to monitor the pressure with the pressure sensor for a change indicating an endpoint of droplet generation has been reached, and to stop application of the pressure when the change is detected by the pressure sensor.

16. The system of claim 15, further comprising a gasket defining a plurality of orifices configured to provide fluid communication between the chip and the fluidics assembly such that the pressure can be applied by the fluidics assembly.

17. The system of claim 16, wherein the chip has a plurality of wells, and wherein the gasket is configured to be engaged with the chip such that an orifice of the gasket overlaps each well.

18. The system of claim 15, wherein the chip includes input wells interconnected with output wells by channels, and wherein the instrument is configured to stop application of the pressure after air has followed liquid into one or more of channels from one or more of the input wells and before the air has reached all of the emulsions collected in the output wells.

19. The system of claim 15, wherein the instrument is configured to receive an actuation signal from a user after the chip holding the emulsion phases is received by the instrument, and wherein the actuation signal causes the instrument, without any further user input or participation, to apply the pressure, to monitor the pressure, and to stop application of the pressure.

20. The system of claim 15, wherein the fluidics assembly includes a pump that functions as a source of the pressure, and wherein the pressure is applied by the instrument while the pump is fluidically isolated from the chip, not pumping fluid, or both fluidically isolated and not pumping fluid.