A microfluidic device for forming droplets includes at least one ferrofluid reservoir disposed in the microfluidic device and containing a ferrofluid therein. The microfluidic device includes a continuous-phase reservoir disposed in the microfluidic device and containing an oil phase therein and one or more microfluidic channels connecting between the at least one ferrofluid reservoir and the continuous-phase reservoir, the continuous-phase reservoir comprising a step region having an increased height as compared to a height of the one or more microfluidic channels. To form droplets an externally applied magnetic field is applied to the device to pull the ferrofluid into the continuous-phase reservoir, whereby droplets are formed at step region.

System for performing a flow-based assay. The system may comprise a droplet generator to produce an emulsion including droplets in a carrier fluid. The system also may comprise a thermocycler including two or more temperature-controlled zones and also including a channel connected to the droplet generator for receiving the emulsion. The channel may form a single-pass continuous fluid route traversing the temperature-controlled zones multiple times, such that droplets passing through the channel are thermally cycled. The system further may comprise a detection station downstream from the thermocycler and configured to detect a signal from the droplets after such droplets have been thermally cycled by passing through the channel.

Integrated devices that include a sample preparation component integrated with a detection component are disclosed. The sample preparation component may be a digital microfluidics module or a surface acoustic wave module which modules are used for combing a sample droplet with a reagent droplet and for performing additional sample preparation step leading to a droplet that contains beads/particles/labels that indicate presence or absence of an analyte of interest in the sample. The beads/particles/labels may be detected by moving the droplet to the detection component of the device, which detection component includes an array of wells.

The present invention relates to an emulsion, preferably a water-in-oil emulsion. comprising: a continuous phase comprising a conductivity improving compound, a dispersed phase suspended in the continuous phase, and a surfactant. The present invention also relates to a population of droplets comprising an aqueous phase, dispersed in a continuous oily phase comprising an oil and a conductivity-improving compound. The present invention also relates to a microfluidic chip comprising a hydrophobic composition comprising an oil, a surfactant and a conductivity improving compound in an injection chamber configured so that injecting a hydroplilic composition through said injection means will generate an emulsion in the injection chamber; and to a kit comprising a microfluidic chip and a container comprising an aqueous composition. The present invention also relates to a process for manufacturing an emulsion according to the invention. The present invention also provides methods for analyzing biological material, for example for analyzing biological material within the emulsion of the invention.

Examples herein involve sorting a droplet including a biologic sample. In a particular example, sorting a droplet including a biologic sample includes generating a droplet including a biologic sample and a pH sensitive surfactant, and heating a nucleic acid molecule in the biologic sample. The pH sensitive surfactant may change the surface tension of the droplet responsive to amplification of the nucleic acid molecule. The droplet may be sorted into one of a plurality of sorting lanes based on the surface tension of the droplet, where a sorting lane among the plurality of sorting lanes is associated with droplets including the amplified nucleic acid molecule. A determination of whether the droplet includes the amplified nucleic acid molecule may be performed by detecting passage of the droplet in one of the plurality of sorting lanes.

A cartridge includes: a first reservoir capable of accommodating a sample liquid; a sheath liquid conduit; a sterilization filter; a mixer; a nozzle; a droplet collection member; and a check valve. The sterilization filter is provided at the sheath liquid conduit. The check valve is connected to a waste-droplet collection member. A sample liquid flow path and a sheath liquid flow path are isolated from a surrounding environment around the cartridge and are maintained in a sterile state. The sample liquid flow path extends from the first reservoir to the droplet collection member. The sheath liquid flow path extends from the sterilization filter to the droplet collection member.

A high-throughput optofluidic device for detecting fluorescent droplets is disclosed. The device uses time-domain encoded optofluidics to detect a high rate of droplets passing through parallel microfluidic channels. A light source modulated with a minimally correlating maximum length sequences is used to illuminate the droplets as they pass through the microfluidic device. By correlating the resulting signal with the expected pattern, each pattern formed by passing droplets can be resolved to identify individual droplets.

Methods and systems for sorting particles are provided. Methods and systems for sorting cell beads are provided. In some cases, cell beads may be sorted from particles unoccupied with cell derivatives. In some cases, singularly occupied cell beads may be sorted from unoccupied particles and multiply occupied cell beads.

The present invention discloses a microstructured discrimination device for separating hydrophobic-hydrophilic fluidic composites comprising particulate and/or fluids in a fluid flow. The discrimination is the result of surface energy gradients obtained by physically varying a textured surface and/or by varying surface chemical properties, both of which are spatially graded. Such surfaces discriminate and spatially separate particulate and/or fluids without external energy input. The device of the present invention comprises a platform having bifurcating microchannels arranged radially. The lumenal surfaces of the microchannels may have a surface energy gradient created by varying the periodicity of hierarchically arranged microstructures along a dimension. The surface energy gradient is varied in two regions. In one pre-bifurcation region the surface energy gradient generates a fluid flow. In the other post-bifurcation region, there is a difference in surface energy proximal to the bifurcation such that different flow fractions are divided into separate channels in response to different surface energy gradients in each of the post-bifurcation channels. Accordingly, fluids of different hydrophobicity and/or particulate of different hydrophobicity are driven into separate channels by a global minimization of the fluid system energy.

We describe a microfluidic structure for spacing out droplets, the structure comprising: a main channel for guiding droplets in a spacing fluid; a first inlet for introducing droplets into the main channel; and a second inlet for introducing a spacing fluid into the main channel, wherein a cross-sectional area of the main channel decreases downstream from the first inlet. We also describe a method of spacing out droplets using a microfluidic structure.