A microfabricated sheath flow structure for producing a sheath flow includes a primary sheath flow channel for conveying a sheath fluid, a sample inlet for injecting a sample into the sheath fluid in the primary sheath flow channel, a primary focusing region for focusing the sample within the sheath fluid and a secondary focusing region for providing additional focusing of the sample within the sheath fluid. The secondary focusing region may be formed by a flow channel intersecting the primary sheath flow channel to inject additional sheath fluid into the primary sheath flow channel from a selected direction. A sheath flow system may comprise a plurality of sheath flow structures operating in parallel on a microfluidic chip.

A microfabricated sheath flow structure for producing a sheath flow includes a primary sheath flow channel for conveying a sheath fluid, a sample inlet for injecting a sample into the sheath fluid in the primary sheath flow channel, a primary focusing region for focusing the sample within the sheath fluid and a secondary focusing region for providing additional focusing of the sample within the sheath fluid. The secondary focusing region may be formed by a flow channel intersecting the primary sheath flow channel to inject additional sheath fluid into the primary sheath flow channel from a selected direction. A sheath flow system may comprise a plurality of sheath flow structures operating in parallel on a microfluidic chip.

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.

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.

The invention generally relates to performing sandwich assays in droplets. In certain embodiments, the invention provides methods for detecting a target analyte that involve forming a compartmentalized portion of fluid including a portion of a sample suspected of containing a target analyte and a sample identifier, a first binding agent having a target identifier, and a second binding agent specific to the target analyte under conditions that produce a complex of the first and second binding agents with the target analyte, separating the complexes, and detecting the complexes, thereby detecting the target analyte.

The invention generally relates to performing sandwich assays in droplets. In certain embodiments, the invention provides methods for detecting a target analyte that involve forming a compartmentalized portion of fluid including a portion of a sample suspected of containing a target analyte and a sample identifier, a first binding agent having a target identifier, and a second binding agent specific to the target analyte under conditions that produce a complex of the first and second binding agents with the target analyte, separating the complexes, and detecting the complexes, thereby detecting the target analyte.

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 relates to a microfluidic device and method for providing emulsion droplets. The device comprising: a microfluidic section comprising one or more microfluidic units; and a well section comprising one or more groups of wells comprising one group of wells for each microfluidic unit; the well section and the microfluidic section forming a fixedly connected unit such that each group of wells forms a fixedly connected unit with a respective corresponding microfluidic unit, each microfluidic unit comprising a fluid conduit network comprising: a plurality of supply conduits comprising a secondary supply conduit and a primary supply conduit comprising a capillary structure having a volume of at least 2 μL; a transfer conduit; and a first fluid junction providing fluid communication between the primary supply conduit, the secondary supply conduit, and the transfer conduit; each group of wells comprising a plurality of wells comprising a collection well and one or more supply wells comprising a primary supply well, the collection well being in fluid communication with the transfer conduit of the corresponding microfluidic unit, the primary supply well being in fluid communication with the primary supply conduit and the secondary supply conduit of the corresponding microfluidic unit.

The present invention relates to a microfluidic device and method for providing emulsion droplets. The device comprising: a microfluidic section comprising one or more microfluidic units; and a well section comprising one or more groups of wells comprising one group of wells for each microfluidic unit; the well section and the microfluidic section forming a fixedly connected unit such that each group of wells forms a fixedly connected unit with a respective corresponding microfluidic unit, each microfluidic unit comprising a fluid conduit network comprising: a plurality of supply conduits comprising a secondary supply conduit and a primary supply conduit comprising a capillary structure having a volume of at least 2 μL; a transfer conduit; and a first fluid junction providing fluid communication between the primary supply conduit, the secondary supply conduit, and the transfer conduit; each group of wells comprising a plurality of wells comprising a collection well and one or more supply wells comprising a primary supply well, the collection well being in fluid communication with the transfer conduit of the corresponding microfluidic unit, the primary supply well being in fluid communication with the primary supply conduit and the secondary supply conduit of the corresponding microfluidic unit.

A microdroplet/bubble-generating device comprising a slit and a row of a plurality of microflow paths is constructed, in such a manner that either a continuous phase or dispersion phase is supplied to the slit, and so that the end of the slit, the other supply port for the continuous phase or dispersion phase and the liquid recovery port are connected. The plurality of microflow paths each have a narrow part where the cross-sectional area of the flow channel is locally narrowed adjacent to or near the connection point between the slit and the microflow path. The continuous phase and dispersion phase that have met at the connection points flow into the narrow parts, and the dispersion phase is sheared at the narrow parts with the continuous phase flow as the driving force, forming droplets or gas bubbles of the dispersion phase. The product is recovered from the liquid recovery port.