Electronic control of fluidic species

• US 20070003442A1
• Filed: 02/23/2006
• Published: 01/04/2007
• Est. Priority Date: 08/27/2003
• Status: Active Grant

• Current Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Original Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Inventors: Link, Darren, Weitz, David, Ahn, Keunho, Cristobal-Azkarate, Galder, Cheng, Zhengdong
• Granted Patent: US 8,765,485 B2
• Time in Patent Office: Days
• US Class Current: 422/99
• CPC Class Codes: B01F 25/23 Mixing by intersecting jets
• CPC Class Codes: B01F 25/433 Mixing tubes wherein the shape of the tube influences the mixing, e.g. mixing tubes with varying cross-section or provided with inwardly extending profiles
• CPC Class Codes: B01F 25/4338 Mixers with a succession of converging-diverging cross-sections, i.e. undulating cross-section
• CPC Class Codes: B01F 25/45 Mixers in which the materials to be mixed are pressed together through orifices or interstitial spaces, e.g. between beads B01F25/44 takes precedence
• CPC Class Codes: B01F 25/45211 the elements being cylinders or cones which obstruct the whole diameter of the tube, the flow changing from axial in radial and again in axial
• CPC Class Codes: B01F 33/302 the materials to be mixed flowing in the form of droplets
• CPC Class Codes: B01F 33/3021 the components to be mixed being combined in a single independent droplet, e.g. these droplets being divided by a non-miscible fluid or consisting of independent droplets
• CPC Class Codes: B01F 33/3031 using electro-hydrodynamic [EHD] or electro-kinetic [EKI] phenomena to mix or move the fluids
• CPC Class Codes: B01F 33/305 using mixing means not otherwise provided for B01F25/00, B01F27/00, B01F29/00, B01F31/00, B01F33/301 - B01F33/3045, B01F33/40 and B01F33/45 take precedence
• CPC Class Codes: B01J 19/0093 Microreactors, e.g. miniaturised or microfabricated reactors laboratory containers with capillary fluid transport in microfabricated channels or chambers B01L3/5027
• CPC Class Codes: B01J 2219/00783 Laminate assemblies, i.e. the reactor comprising a stack of plates
• CPC Class Codes: B01J 2219/00862 Dimensions of the reaction cavity itself
• CPC Class Codes: B01L 2200/0636 Focussing flows, e.g. to laminate flows
• CPC Class Codes: B01L 2200/0652 Sorting or classification of particles or molecules
• CPC Class Codes: B01L 2200/0673 Handling of plugs of fluid surrounded by immiscible fluid
• 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 2300/161 Control and use of surface tension forces, e.g. hydrophobic, hydrophilic
• CPC Class Codes: B01L 2400/0415 electrical forces, e.g. electrokinetic
• CPC Class Codes: B01L 2400/0439 ultrasonic vibrations, vibrating piezo elements
• CPC Class Codes: B01L 2400/0487 : fluid pressure, pneumatics
• CPC Class Codes: B01L 3/0241 : Drop counters; Drop formers making arrays for combinatorial libraries B01J19/0046; automation of dispensing for analysis G01N35/10
• 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 3/502761 : 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 3/502776 : specially adapted for focusing or laminating flows
• 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 3/502792 : for moving individual droplets on a plate, e.g. by locally altering surface tension
• CPC Class Codes: B01L 3/5088 : confining liquids at a location by surface tension, e.g. virtual wells on plates, wires B01L3/50857 takes precedence
• CPC Class Codes: C12Q 2563/159 : Microreactors, e.g. emulsion PCR or sequencing, droplet PCR, microcapsules, i.e. non-liquid containers with a range of different permeability's for different reaction components
• CPC Class Codes: C12Q 2565/629 : being a microfluidic device
• CPC Class Codes: G01N 15/10 : Investigating individual particles
• CPC Class Codes: G01N 15/14 : Optical investigation techniques, e.g. flow cytometry
• CPC Class Codes: G01N 15/1459 : the analysis being performed on a sample stream
• CPC Class Codes: G01N 15/1484 : microstructural devices
• CPC Class Codes: G01N 15/149 : specially adapted for sorting particles, e.g. by their size or optical properties
• CPC Class Codes: G01N 2015/1006 : for cytology
• CPC Class Codes: G01N 2015/1028 : Sorting particles
• CPC Class Codes: Y10S 436/807 : Apparatus included in process claim, e.g. physical support structures
• CPC Class Codes: Y10T 436/118339 : with formation of a segmented stream
• CPC Class Codes: Y10T 436/2525 : Stabilizing or preserving
• CPC Class Codes: Y10T 436/2575 : Volumetric liquid transfer

Abstract

Various aspects of the present invention relate to the control and manipulation of fluidic species, for example, in microfluidic systems. In one aspect, the invention relates to systems and methods for making droplets of fluid surrounded by a liquid, using, for example, electric fields, mechanical alterations, the addition of an intervening fluid, etc. In some cases, the droplets may each have a substantially uniform number of entities therein. For example, 95% or more of the droplets may each contain the same number of entities of a particular species. In another aspect, the invention relates to systems and methods for dividing a fluidic droplet into two droplets, for example, through charge and/or dipole interactions with an electric field. The invention also relates to systems and methods for fusing droplets according to another aspect of the invention, for example, through charge and/or dipole interactions. In some cases, the fusion of the droplets may initiate or determine a reaction. In a related aspect of the invention, systems and methods for allowing fluid mixing within droplets to occur are also provided. In still another aspect, the invention relates to systems and methods for sorting droplets, e.g., by causing droplets to move to certain regions within a fluidic system. Examples include using electrical interactions (e.g., charges, dipoles, etc.) or mechanical systems (e.g., fluid displacement) to sort the droplets. In some cases, the fluidic droplets can be sorted at relatively high rates, e.g., at about 10 droplets per second or more. Another aspect of the invention provides the ability to determine droplets, or a component thereof, for example, using fluorescence and/or other optical techniques (e.g., microscopy), or electric sensing techniques such as dielectric sensing.

Claims

1. A method of combining at least two species in a controlled manner in a microfluidic system, comprising:

providing a series of droplets flowing in a microfluidic system;

selecting a first droplet from the series of droplets and separating the first droplet from at least some other droplets in the series of droplets, wherein the first droplet has a maximum cross-sectional dimension of less than about 100 microns and contains a first chemical, biological, or biochemical species;

providing a second droplet separate from the series of droplets, wherein the second droplet has a maximum cross-sectional dimension of less than about 100 microns and contains a second chemical, biological, or biochemical species;

selectively urging the first droplet and/or the second droplet toward a location where coalescence can occur, and allowing the first droplet and the second droplet to coalesce into one combined droplet; and

determining a reaction involving at least the first species in the first droplet and the second species in the second droplet.

274. A method as in claim 1, wherein at least about 90% of the series of droplets each consists of the same number of entities of the first chemical, biological, or biochemical species therein.

275. The method of claim 1, wherein the series of droplets have an average diameter that is less than about 200 micrometers.

276. A method as in claim 1, wherein the act of allowing the first droplet and the second droplet to coalesce into one combined droplet comprises inducing a positive charge on the first droplet and a negative charge on the second droplet.

277. A method as in claim 276, wherein the positive charge on the first droplet is at least about 10⁻

16 C.

2. A method of sorting droplets in a controlled manner in a microfluidic system, comprising:

providing a series of droplets flowing in a microfluidic system; and

selecting a first droplet from the series of droplets and separating the first droplet from at least some other droplets in the series of droplets, wherein the first droplet has a maximum cross-sectional dimension of less than about 100 microns.

3. A method as in claim 2, further comprising selecting a second droplet from the series of droplets and separating the second droplet from at least some other droplets in the series of droplets, wherein the second droplet has a maximum cross-sectional dimension of less than about 100 microns.

4. A method as in claim 2, wherein the first droplet contains a chemical, biological, or biochemical species other than the fluid defining the droplet.

5. A method as in claim 2, wherein the first droplet does not contain a chemical, biological, or biochemical species other than the fluid defining the droplet.

6. A method as in claim 2, comprising sorting a plurality of the droplets flowing in the microfluidic system by determining, for each of the plurality of droplets, an amount or lack of a contained specific chemical, biological, or biochemical species and if the droplet contains a first amount of or does not contain the species directing the droplet into a first channel and if the droplet contains a second amount of the species directing the droplet into a second channel.

278. A method as in claim 2, wherein the act of selecting occurs at a rate of at least about 10 droplets/s.

279. A method as in claim 278, wherein the act of selecting occurs at a rate of at least about 1000 droplets/s.

280. A method as in claim 279, wherein the act of selecting occurs at a rate of at least about 100,000 droplets/s.

281. A method as in claim 2, comprising selecting the first droplet based on a characteristic of the first droplet.

282. A method as in claim 2, wherein the first droplet comprises a cell.

7-10. -10. (canceled)

11. A method of combining at least two droplets in a microfluidic system, comprising:

providing at least two droplets in a microfluidic system;

exposing the droplets to an electric field thereby inducing, in the droplets, dipole moments; and

coalescing the at least two droplets into a single droplet at least in part via droplet-droplet attraction due to the induced dipole moments.

12. A method as in claim 11, comprising coalescing the droplets under conditions in which, in the absence of the field-induced dipole moments, the droplets would not coalesce.

283. A method as in claim 11, wherein the electric field has an intensity of at least about 0.01 V/micrometer.

284. A method as in claim 11, wherein the at least two droplets have substantially the same volume.

285. A method as in claim 11, wherein each of the at least two droplets have an average diameter that is less than about 200 micrometers.

13-273. -273. (canceled)