# US 9,038,919 B2 · Formation and control of fluidic species > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,038,919 B2 - Document ID: US9038919B2 - Status: Granted - Kind: B2 - Application number: 11/246,911 - Filed: 2005-10-07 - Published: 2006-07-27 - Granted: 2015-05-26 - Earliest claimed: 2003-04-10 - Assignees: President and Fellows of Harvard College - Applicants: Darren Roy Link; David A. Weitz; Manuel Marquez-Sanchez; Zhengdong Cheng - Inventors: Darren Roy Link; David A. Weitz; Manuel Marquez-Sanchez; Zhengdong Cheng - Web page: https://patentgrep.com/patent/US9038919B2 ## CPC - B01L 3/502784: {specially adapted for droplet or plug flow, e.g. digital microfluidics} - 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) - 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 - 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} - B01F 33/3031: using electro-hydrodynamic [EHD] or electro-kinetic [EKI] phenomena to mix or move the fluids - B01J 2/04: in a gaseous medium {(if combined with suspending the material in a gas, e.g. fluidised beds B01J2/16)} - B01L 3/502715: {characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces} - B01L 3/50273: {characterised by the means or forces applied to move the fluids} - B05B 5/03: characterised by the use of gas {, e.g. electrostatically assisted pneumatic spraying (B05B5/04, B05B5/043, B05B5/047 take precedence)} - B05B 7/061: {with several liquid outlets discharging one or several liquids} - B29B 9/10: by moulding the material, i.e. treating it in the molten state - B01F 2215/0431: Numerical size values, e.g. diameter of a hole or conduit, area, volume, length, width, or ratios thereof - B01L 2200/0673: Handling of plugs of fluid surrounded by immiscible fluid - B01L 2300/0867: Multiple inlets and one sample wells, e.g. mixing, dilution - B01L 2400/02: Drop detachment mechanisms of single droplets from nozzles or pins - B01L 2400/0415: electrical forces, e.g. electrokinetic - B01L 2400/0424: Dielectrophoretic forces - B29B 2009/125: {Micropellets, microgranules, microparticles} - B01L: CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE - B01F: MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING (mixing paints B44D3/06) - B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS - B05B: SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES (spray-mixers with nozzles B01F25/72; processes for applying liquids or other fluent materials to surfaces by spraying B05D) - B29B: PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS ## Abstract This invention generally relates to systems and methods for the formation and/or control of fluidic species, and articles produced by such systems and methods. In some cases, the invention involves unique fluid channels, systems, controls, and/or restrictions, and combinations thereof. In certain embodiments, the invention allows fluidic streams (which can be continuous or discontinuous, i.e., droplets) to be formed and/or combined, at a variety of scales, including microfluidic scales. In one set of embodiments, a fluidic stream may be produced from a channel, where a cross-sectional dimension of the fluidic stream is smaller than that of the channel, for example, through the use of structural elements, other fluids, and/or applied external fields, etc. In some cases, a Taylor cone may be produced. In another set of embodiments, a fluidic stream may be manipulated in some fashion, for example, to create tubes (which may be hollow or solid), droplets, nested tubes or droplets, arrays of tubes or droplets, meshes of tubes, etc. In some cases, droplets produced using certain embodiments of the invention may be charged or substantially charged, which may allow their further manipulation, for instance, using applied external fields. Non-limiting examples of such manipulations include producing charged droplets, coalescing droplets (especially at the microscale), synchronizing droplet formation, aligning molecules within the droplet, etc. In some cases, the droplets and/or the fluidic streams may include colloids, cells, therapeutic agents, and the like. ## Claims ### Claim 1 A method of producing a plurality of droplets, comprising: flowing a first liquid in a first microfluidic channel and a second liquid in a second microfluidic channel such that the first and the second liquids meet at a junction of the first and second microfluidic channels; and producing a plurality of regularly-spaced, single-file droplets comprising the first liquid at the junction by applying an electric field to the first and second liquids as they meet at the junction, wherein the droplets are surrounded by the second liquid and flow within at least one of the microfluidic channels. ### Claim 2 (depends on 1) The method of claim 1, wherein said first liquid is an aqueous liquid and said second liquid is a liquid that is immiscible in said aqueous liquid. ### Claim 3 (depends on 1) The method of claim 1, wherein said droplets have an average diameter of less than about 60 microns. ### Claim 4 (depends on 1) The method of claim 1, wherein said first microfluidic channel and said second microfluidic channel are contained on a device comprising a location for expelling said droplets. ### Claim 5 (depends on 1) The method of claim 1, further comprising the step of conducting a reaction in said droplets. ### Claim 6 (depends on 1) The method of claim 1, wherein said first liquid forms a Taylor cone when expelled from an outlet in said first microfluidic channel. ### Claim 7 (depends on 6) The method of claim 6, wherein the first and second liquids flow through a dimensional restriction that stabilizes the Taylor cone. ### Claim 8 (depends on 1) The method of claim 1, wherein the droplets comprise a homogeneous distribution of diameters.