Abstract: The invention provides a method of redistributing magnetically responsive beads in a droplet. The method may include providing a droplet including magnetically responsive beads. The droplet may be provided within a region of a magnetic field having sufficient strength to attract the magnetically responsive beads to an edge of the droplet or towards an edge of the droplet, or otherwise regionalize or aggregate beads within the droplet. The method may also include conducting on a droplet operations surface one or more droplet operations using the droplet without removing the magnetically responsive beads from the region of the magnetic field. The droplet operations may in some cases be electrode-mediated. The droplet operations may redistribute and/or circulate the magnetically responsive beads within the droplet. In some cases, the droplet may include a sample droplet may include a target analyte.

Abstract: Methods comprising measuring the impedance of the electrode produced by the excitation signal, wherein the impedance indicates presence of liquid at the electrode are disclosed. Computer readable mediums storing processor executable instructions for performing the method, and systems are also disclosed. The systems comprise a processor, memory and code stored in the memory that when executed cause the processor at least to: receive an output voltage signal, superimpose an excitation signal onto the output voltage signal to produce a superimposed signal, connect the superimposed signal to an electrode in a droplet actuator, suppress the output voltage signal, when detecting an impedance of the electrode, and measure the impedance of the electrode produced by the excitation signal, wherein the impedance indicates presence of liquid at the electrode.

Abstract: A droplet actuator comprising: (a) a base substrate comprising electrodes configured for conducting droplet operations on a droplet operations surface thereof; (b) a droplet comprising one or more beads situated on the droplet operations surface; (c) a barrier arranged in relation to the droplet and the electrodes such that a droplet may be transported away from the beads using one or more droplet operations mediated by one or more of the electrodes while transport of the beads is restrained by a barrier.

Abstract: A method of mixing a droplet, the method comprising providing a droplet on a surface, forming the droplet into a first “U” shape having a bottom region and two terminal ends, and simultaneously merging the terminal ends and splitting the droplet at the bottom region to form a second “U” shape which is substantially opposite the first “U” shape.

Abstract: Microfluidic system including a droplet actuator having an interior cavity and a series of electrodes arranged along the interior cavity for forming a droplet-operation path therethrough. The droplet actuator has a module-engaging side including an opening that is in flow communication with the interior cavity. The microfluidic system also includes a reservoir module configured to be coupled to the droplet actuator. The reservoir module includes a plurality of liquid compartments having respective outlets and at least one seal positioned along the outlets to retain liquid within the liquid compartments. The reservoir module is movable along the module-engaging side of the droplet actuator to position the outlets relative to the opening. The microfluidic system also includes a piercer having a tip configured to penetrate the seal thereby permitting the liquid within the corresponding liquid compartment to flow into the opening.

Abstract: A series of microactuators for manipulating small quantities of liquids, and methods of using these for manipulating liquids, are disclosed. The microactuators are based on the phenomenon of electrowetting and contain no moving parts. The force acting on the liquid is a potential-dependent gradient of adhesion energy between the liquid and a solid insulating surface.

Abstract: The invention is directed to droplet actuator devices and assay methods. The invention includes assay methods of conducting an assay comprising combining a sample with an umbelliferyl derivative, wherein the sample potentially comprises an enzyme capable of cleaving the umbelliferyl derivative and where the umbelliferyl derivative comprises an umbelliferyl core modified with one or more modifying moieties.

Abstract: A method of providing a droplet comprising one or more reagents, the method comprising, depositing a first aqueous droplet comprising the one or more reagents on a surface; drying the droplet to yield a dried composition on the surface comprising the one or more reagents; covering the dried composition with oil; and causing a second aqueous droplet in the oil to contact the dried composition and thereby resuspend one or more reagents.

Abstract: The invention relates to methods of manipulating a droplet in a droplet actuator. Methods of the invention utilize light alone or light in combination with droplet operations to, for example, pin droplets, split droplets, pattern surfaces, and/or sort droplets, particles, and/or cells.

Abstract: A method of inoculating a culture medium including providing a droplet including a single cell type on a droplet actuator and inoculating a culture medium with the droplet. A method of providing a metabolically useful substance to a cell culture, including providing a droplet actuator including a cell culture droplet loaded thereon, the sample droplet including cells and a cell culture medium, and a second droplet comprising a metabolically useful substance. The method also includes conducting one or more droplet operations to combine the cell culture droplet with the second droplet on the droplet actuator. Related methods, droplet actuators, and systems are also provided.

Abstract: The invention provides a droplet actuator comprising a base substrate and a top substrate separated to form a gap, wherein: (a) the base substrate comprises electrodes configured for conducting droplet operations in the gap; and (b) the top substrate comprises a first portion coupled to second portion, where the second portion comprises one or more openings establishing a fluid path extending from an exterior of the droplet actuator and into the gap. The invention also provides related methods of manufacturing the droplet actuator, methods of using the droplet actuator, and methods of loading the droplet actuator.

Abstract: Droplet actuator devices and methods for immunoassays and washing are provided. According to one embodiment, a method of providing a droplet in contact with a surface of a super paramagnetic bead with a reduced concentration of a substance is provided and includes: (a) providing a super paramagnetic bead in contact with a droplet comprising a starting concentration and starting quantity of the substance and having a starting volume; (b) conducting one or more droplet operations to merge a wash droplet with the droplet provided in step (a) to yield a combined droplet; and (c) conducting one or more droplet operations to divide the combined droplet to yield a set of droplets. The set of droplets includes: (i) a droplet in contact with the super paramagnetic bead having a decreased concentration of the substance relative to the starting concentration; and (ii) a droplet which is separated from the super paramagnetic bead.

Abstract: The present invention relates to surface assisted fluid loading and droplet dispensing on a droplet micro actuator. A droplet actuator is provided and includes one or more electrodes configured for conducting one or more droplet operations on a droplet operations surface of the substrate. The droplet actuator further includes a wettable surface defining a path from a fluid reservoir into a locus which is sufficiently near to one or more of the electrodes that activation of the one or more electrodes results in a droplet operation. Methods and systems are also provided.

Abstract: The present invention relates to bead incubating and washing on a droplet actuator. Methods for incubating magnetically responsive beads that are labeled with primary antibody, a sample (i.e., analyte), and secondary reporter antibodies on a magnet, on and off a magnet, and completely off a magnet are provided. Also provided are methods for washing magnetically responsive beads using shape-assisted merging of droplets. Also provided are methods for shape-mediated splitting, transporting, and dispensing of a sample droplet that contains magnetically responsive beads. The apparatuses and methods of the invention provide for rapid time to result and optimum detection of an analyte in an immunoassay.

Abstract: The invention provides droplet actuators and droplet actuator techniques. Among other things, the droplet actuators and methods are useful for manipulating beads on a droplet actuator, such as conducting droplet operations using bead-containing droplets on a droplet actuator. For example, beads may be manipulated on a droplet actuator in the context of executing a sample preparation protocol and/or an assay protocol. An output of the methods of the invention may be beads prepared for execution of an assay protocol. Another output of the methods of the invention may be results of an assay protocol executed using beads.

Abstract: The present invention provides droplet actuators, modified fluids and methods relating to droplet operations. An aspect includes a droplet actuator including a droplet operations substrate; an oil based filler fluid on the droplet operations substrate comprising an oil soluble additive in the filler fluid; and a droplet in contact with the oil based filler fluid. Still other aspects are provided.

Abstract: The invention provides a method of redistributing magnetically responsive beads in a droplet. The method may include providing a droplet including magnetically responsive beads. The droplet may be provided within a region of a magnetic field having sufficient strength to attract the magnetically responsive beads to an edge of the droplet or towards an edge of the droplet, or otherwise regionalize or aggregate beads within the droplet. The method may also include conducting on a droplet operations surface one or more droplet operations using the droplet without removing the magnetically responsive beads from the region of the magnetic field. The droplet operations may in some cases be electrode-mediated. The droplet operations may redistribute and/or circulate the magnetically responsive beads within the droplet. In some cases, the droplet may include a sample droplet may include a target analyte.

Abstract: The present invention relates to bead incubating and washing on a droplet actuator. Methods for incubating magnetically responsive beads that are labeled with primary antibody, a sample (i.e., analyte), and secondary reporter antibodies on a magnet, on and off a magnet, and completely off a magnet are provided. Also provided are methods for washing magnetically responsive beads using shape-assisted merging of droplets. Also provided are methods for shape-mediated splitting, transporting, and dispensing of a sample droplet that contains magnetically responsive beads. The apparatuses and methods of the invention provide for rapid time to result and optimum detection of an analyte in an immunoassay.

Abstract: Droplet actuator for conducting droplet operations, such as droplet transport and droplet dispensing, is provided. In one embodiment, the droplet actuator may include an electrode that is rotationally but not reflectively symmetrical.

Abstract: A method of loading a droplet actuator is provided. In one embodiment, the method may include, providing: a droplet actuator loaded with a filler fluid; a reservoir comprising a droplet fluid; and a fluid path extending from the reservoir into the droplet actuator; and forcing filler fluid from one locus in the droplet actuator to another locus in the droplet actuator; or out of the droplet actuator; thereby causing droplet fluid to flow through the fluid path and into the droplet actuator.