Abstract: The present invention relates to droplet-based pyrosequencing including a method of identifying a base at a target position in a sample nucleic acid. The method includes: (a) providing a droplet microactuator including a first droplet including a sample nucleic acid immobilized on a bead; and (b) on the droplet microactuator: (i) contacting the first droplet with one or more reagent droplets to yield a second droplet, wherein the one or more reagent droplets include reagents for extending a double stranded portion of the sample nucleic acid by incorporating a nucleotide at the target position; (ii) splitting the second droplet to yield a third droplet including the bead and a fourth droplet lacking the bead; and (iii) assaying the third droplet to determine whether the nucleotide was incorporated at the target position.

Abstract: On-board reagent storage, handling, and dispensing apparatuses and methods for droplet actuator systems are provided. In one embodiment, a fluidic analyzer is provided and includes a droplet actuator including a substrate including a plurality of electrodes configured to actuate a droplet and a reagent storage component in selective fluid communication with the droplet actuator and including a reagent configured to combine with a solvent at a time of use. In another embodiment, a method of conducting fluidic analysis is provided and includes storing a reagent within a reagent storage component in fluid communication with a droplet actuator including a plurality of electrodes configured to actuate a droplet and combining the reagent with a solvent at a time for use within the droplet actuator.

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: The invention provides a method of dispersing or circulating magnetically responsive beads within a droplet in a droplet actuator. The invention, in one embodiment, makes use of a droplet actuator with a plurality of droplet operations electrodes configured to transport the droplet, and a magnetic field present at a portion of the plurality of droplet operations electrodes. A bead-containing droplet is provided on the droplet actuator in the presence of the uniform magnetic field. Beads are circulated in the droplet during incubation by conducting droplet operations on the droplet within a uniform region of the magnetic field. Other embodiments are also provided.

Abstract: A droplet actuator with a droplet formation electrode configuration associated with a droplet operations surface, wherein the electrode configuration comprises one or more electrodes configured to control volume of a droplet during formation of a sub-droplet on the droplet operations surface. Methods of making and using the droplet actuator are also provided.

Abstract: Systems for controlling a droplet microactuator are provided. According to one embodiment, a system is provided and includes a controller, a droplet microactuator electronically coupled to the controller, and a display device displaying a user interface electronically coupled to the controller, wherein the system is programmed and configured to permit a user to effect a droplet manipulation by interacting with the user interface. According to another embodiment, a system is provided and includes a processor, a display device electronically coupled to the processor, and software loaded and/or stored in a storage device electronically coupled to the controller, a memory device electronically coupled to the controller, and/or the controller and programmed to display an interactive map of a droplet microactuator.

Abstract: The present invention relates to a droplet microactuator system. According to one embodiment, the droplet microactuator system includes: (a) a droplet microactuator configured to conduct droplet operations; (b) a magnetic field source arranged to immobilize magnetically responsive beads in a droplet during droplet operations; (c) a sensor configured in a sensing relationship with the droplet microactuator, such that the sensor is capable of sensing a signal from and/or a property of one or more droplets on the droplet microactuator; and (d) one or more processors electronically coupled to the droplet microactuator and programmed to control electrowetting-mediated droplet operations on the droplet actuator and process electronic signals from the sensor.

Abstract: A droplet actuation system is provided including a droplet actuation device including a substrate that includes electrodes for conducting droplet operations; temperature control means for heating and/or cooling a region of the droplet actuation device and arranged such that a droplet can be transported on the electrodes to a region for heating; and a means for effecting a magnetic field in proximity to one or more of the electrodes sufficient to immobilize magnetically responsive beads in a droplet on the substrate during droplet operations. The system further includes a processor for controlling the electrodes and temperature control means, wherein the processor is programmed, and electrodes and magnetic field are arranged, to cause the electrodes to split a droplet including the magnetically responsive beads yielding a first daughter droplet which includes the magnetically responsive beads and a second daughter droplet without a substantial amount of the magnetically responsive beads.

Abstract: The invention provides a method of circulating magnetically responsive beads within a droplet in a droplet actuator. The invention also provides methods for splitting droplets. The invention, in one embodiment, makes use of a droplet actuator with top and bottom substrates, a plurality of magnetic fields respectively present proximate the top and bottom substrates, wherein at least one of the magnet fields is selectively alterable, and a plurality of droplet operations electrodes positioned along at least one of the top and bottom surfaces. A droplet is positioned between the top and bottom surfaces and at least one of the magnetic fields is selectively altered.

Abstract: A droplet actuator with arrays of electrodes electrically coupled to a number of controllable voltage sources that is less than the number of electrodes. A method of defining partitions for pin layouts in a droplet actuator for a specific assay, the method including: defining droplet traces for the assay; and defining a guard ring along the traces. Other methods, systems, droplet actuators, and algorithms are also provided.

Abstract: A droplet actualor having electrodes configured for ejecting droplet operations transporting droplets on a surface, and a sensor arranged in proximity to one or more of the electrodes establishing a detection window on the surface for detection of one or more properties of one or more droplets on the surface, wherein the electrodes establish at least two pathways for transport of droplets into the detection window. Also provided is, A method of detecting a property of a target droplet, including using droplet operations to modulate signals from a droplet set comprising the target droplet, detecting the modulated signals of the droplet set, demodulating the modulated signals to identify the signal produced by one or more individual droplets of the set Related methods and alternative embodiments are also provided.

Abstract: A droplet actuator comprising a substrate comprising an electrode coupled to a voltage source, wherein the droplet actuator is configured such that when voltage is applied to the electrode, an electrostatic energy gradient is established at a surface of the substrate which causes a droplet to be transported in a direction established by the energy gradient. Related methods and other embodiments are also provided.

Abstract: The invention relates to certain novel approaches to reducing or eliminating the movement of contaminants from one droplet to another on a droplet actuator via liquid filler fluid. In one application, droplet actuators are used to conduct genetic analysis using polymerase chain reaction (PCR) techniques. The invention addresses the need for improved methods of performing PCR on a droplet actuator that provide for optimum amplification and detection of a sample target.

Abstract: An apparatus and a method for concentrating a target substance in a liquid has been invented. The apparatus comprises a first reservoir with inlet openings for introducing a fluid comprising a target substance into the first reservoir and a second reservoir separated from the first reservoir by a partition permeable to permit the fluid to traverse the partition while retaining the target substance in the first reservoir.

Abstract: A method, circuit and apparatus for detecting capacitance on a droplet actuator, inter alia, for determining the presence, partial presence or absence of a droplet at an electrode on a droplet actuator by: (a) providing a droplet actuator comprising: (i) a substrate comprising electrodes arranged on the substrate for conducting droplet operations on a surface of the substrate; (ii) a capacitance detection circuit for detecting capacitance at the droplet operations surface at one or more of the electrodes; (b) detecting capacitance at the droplet operations surface at one or more of the electrodes; and (c) determining from the capacitance the presence, partial presence or absence of a droplet at the droplet operations surface at the electrode.

Abstract: The present invention is directed to a droplet actuator and methods of making and using the droplet actuator including one or more substrates configured to form a droplet operations gap and including a physical or chemical feature that may be provided at a predetermined locus within or exposed to the droplet operations gap and configured to retain a bubble in position within the droplet operations gap.

Abstract: Methods of using protein crystallization droplet actuators are provided. Protein sample droplets and reagent droplets are dispensed, transported, and merged to yield an array of crystallization conditions by electrowetting droplet operations in a gap comprising oil filler fluid. The oil filler fluid is doped with a surfactant that enhances droplet operations using the protein sample.

Abstract: A method of conducting a droplet-based enzymatic assay is provided. The method generally makes use of a droplet actuator. A droplet comprising an enzyme of interest is provided on the droplet actuator along with a droplet comprising a substrate which is potentially modified in the presence of the enzyme. The method involves executing droplet operations on the droplet actuator to combine the droplets, thereby yielding an assay droplet, and detecting modification of the substrate by the enzyme in the assay droplet on the droplet actuator. The enzyme of interest may, for example, be a potentially mutated or improperly folded enzyme exhibiting altered enzyme activity as compared to a corresponding normal enzyme.

Abstract: The invention provides a droplet actuator drive. In certain embodiments, the droplet actuator drive may include a detection apparatus for sensing a property of a droplet on a droplet actuator; circuitry for controlling the detection apparatus electronically coupled to the detection apparatus; a droplet actuator cartridge connector; circuitry for controlling a droplet actuator coupled to the droplet actuator connector; and/or a means for coupling the droplet actuator circuitry to a processor. Systems, kits and methods of conducting assays are also provided.

Abstract: The present invention relates to droplet-based surface modification and washing. According to one embodiment, a method of providing a bead-containing droplet with a reduced concentration of a substance is provided, the method including providing a droplet microactuator including a droplet having a starting volume and including one or more beads and a starting concentration and starting quantity of the substance. The method further includes conducting one or more droplet operations to merge a wash droplet with the droplet provided in the above step to yield a combined droplet and including one or more droplet operations to divide the combined droplet to yield a set of droplets including a droplet including substantially all of the one or more beads and having a decreased concentration of the substance relative to the starting concentration and a droplet which is substantially lacking in the beads.