In situ-generated microfluidic isolation structures incorporating a solidified polymer network, methods of preparation and use, compositions and kits therefor are described. The ability to introduce in real time, a variety of isolating structures including pens and barriers offers improved methods of micro-object manipulation in microfluidic devices. The in situ-generated isolation structures may be permanently or temporarily installed.

A micro-fluidic device includes at least one inlet and a curvilinear microchannel having a trapezoidal cross section defined by a radially inner side, a radially outer side, a bottom side, and a top side, the cross section having a) the radially inner side and the radially outer side unequal in height, or b) the radially inner side equal in height to the radially outer side, and wherein the top side has at least two continuous straight sections, each unequal in width to the bottom side.

The invention generally provides a sieve valve including: a substrate defining a channel; a flexible membrane adapted and configured for deployment at an intersection with the channel; and one or more protrusions extending into the channel from the substrate or the flexible membrane. The one or more protrusions define a plurality of recesses extending beyond the intersection between the channel and the flexible membrane; A microfluidic circuit including one or more sieve valves. In particular embodiments, the circuit comprises one or more input/output valves. The one or one or more input/output valves can include one or more input valves and one or more output valves. The microfluidic circuit can further include a mixing circuit. At least one of the sieve valves can be positioned between the one or more input/output valves and the mixing circuit. The invention further provides methods of using the device for the analysis of samples comprising cells.

An example system includes an input channel to flow nucleic segments therethrough, a mixing portion coupled to the input channel, a separation chamber in fluid communication with the second end of the input channel, at least two output channels coupled to the chamber, and an integrated pump to facilitate flow through the separation chamber. The mixing portion is to include at least two different categories of beads having different sizes from each other and having a probe to attach to a corresponding nucleic acid segment. The separation chamber has a passive separation structure including an array of columns spaced apart to facilitate separation of the different categories of beads and attached corresponding nucleic acid segment into at least two flow paths based on a size of the category of the beads. Each output channel is to receive separated categories of beads and attached nucleic acid segments.

The subject invention pertains to a microfluidic apparatus and methods for screening and isolating a target cell from a population of cells. The apparatus comprises a first microfluidic layer comprising microfluidic channels; a second microfluidic layer comprising microfluidic channels; and a microfluidic cell analysis layer comprising a top hanging blocking structure located directly below each location where the first layer microfluidic channels overlap with the second layer microfluidic channels and a cell trap juxtaposed to each of the top hanging blocking structures. The top hanging blocking structures can close or open the juxtaposed cell trap when either or both the first or second layer microfluidic channels located directly above the top hanging blocking structure are sufficiently pressurized and/or sufficiently depressurized. The methods for screening and isolating a target cell from a population of cells comprise screening the population of cells using the apparatus and isolating the target cell interest therefrom.

A microfluidic system for cell retention for a perfusion bioreactor is provided. The system comprises at least one inlet configured to receive a bioreaction mixture to be processed. At least one curvilinear microchannel is in fluid flow connection with the at least one inlet, the at least one curvilinear microchannel being adapted to isolate cells in the bioreaction mixture, based on cell size, along at least one portion of a cross-section of the at least one curvilinear microchannel. At least two outlets are in fluid flow connection with the at least one curvilinear microchannel. At least one outlet of the at least two outlets is configured to flow the isolated cells to be recycled to the perfusion bioreactor.

Methods and devices for isolating microbial cells from a sample, extracting eukaryotic DNA from a sample, and identifying the microbial species in the sample are disclosed herein.

A sample extraction chip and a biological reaction device are disclosed according to the present disclosure. The sample extraction chip includes a chip body and a sample extraction module provided on the chip body, the sample extraction module includes a sample-loading lysis unit, a liquid release-control unit, an extraction unit, a liquid switch-control unit, a liquid collection unit and a sample collection unit, which are connected through flow channels in a sequence of extraction. The liquid release-control unit is configured to store and release liquid reagents, and the liquid switch-control unit is configured to switch between communication of the liquid collection unit and the extraction unit and communication of the sample collection unit and the extraction unit. The sample collection unit includes a front collection portion and a rear collection portion which are both in communication with the liquid switch-control unit.

A microfluidic device includes: a microchannel defining a flow path; a Brownian motor structure comprising two or more sorting channels having distinct ratchet topographies, the Brownian motor structure in fluid communication with the microchannel; and a filter extending transversely to the microchannel, the filter configured to filter particles, subject to sizes thereof, in a liquid advancing along the flow path, whereby smaller particles of the liquid can pass downstream of the filter in the flow path, and larger particles of the liquid are directed to the Brownian motor structure to be sorted out according to sizes thereof via the sorting channels.

An analyte selection device can include: a body defining a fluid channel having a channel inlet and channel outlet; a bipolar electrode (BPE) between the inlet and outlet; one of an anode or cathode electrically coupled with the BPE on a channel inlet side of the BPE and the other of the anode or cathode electrically coupled with the BPE on a channel outlet side of the BPE; and an electronic system operably coupled with the anode and cathode so as to polarize the BPE. The fluid channel can have any shape or dimension. The channel inlet and channel outlet can be longitudinal or lateral with respect to the longitudinal axis of the channel. The BPE can be any metallic member, such as a flat plate on a wall or mesh as a barrier BPE. The anode and cathode can be located at a position that polarizes the BPE.