Abstract: Provided herein, among other aspects, are methods and apparatuses for analyzing particles in a sample. In some aspects, the particles can be analytes, cells, nucleic acids, or proteins and can be contacted with a tag, partitioned into aliquots, detected by a ranking device, and isolated. The methods and apparatuses provided herein may include a microfluidic chip. In some aspects, the methods and apparatuses may be used to quantify rare particles in a sample, such as cancer cells and other rare cells for disease diagnosis, prognosis, or treatment.

Abstract: A method of encapsulating a solid sample in a droplet, the method including flowing a continuous phase through a first fluid channel at a first flow rate; flowing a dispersed phase through a second fluid channel at a second flow rate, the dispersed phase including a plurality of particles, cells or beads; trapping the plurality of particles, cells or beads in a mixing region that receives the dispersed phase and the continuous phase; and reducing the first flow rate to encapsulate the trapped particles, cells or beads in droplets of the dispersed phase generated when the dispersed phase and the continuous phase exit the mixing region through an orifice.

Abstract: A microfluidic device and a microfluidic chip are provided. The microfluidic device includes the microfluidic chip, a pouring element, a flow adjustment element and a processor. The microfluidic chip includes a sorting assembly, a sample outlet channel, a pouring channel, a collection channel and a waste channel. The sorting assembly includes a sample inlet channel and a sorting chamber. The pouring element is connected to the pouring channel. The flow adjustment element is connected to a distal end of the sample outlet channel. The processor is configured to control the pouring element to pour a guiding fluid into the pouring channel entering the sample outlet channel and control the flow adjustment element to adjust a flow resistance of a drain section of the sample outlet channel.

Abstract: In accordance with some embodiments, a fluid sample collection and retrieval apparatus including a microfluidic chip, a retrieval tube, a first switch, a second switch and a processor is provided. The microfluidic chip includes a first sample channel, a first fluid directing channel assembly, a first confluence chamber, a first collection channel, a first waste channel, and a retrieval hole. The retrieval hole passes through an outer surface of the microfluidic chip. The retrieval tube is connected to the retrieval hole. The first switch is connected to the microfluidic chip. The second switch is attached to the retrieval tube. The processor is configured to activate the first switch to operate the flow adjustment of the first fluid directing channel assembly and activate the second switch to operate a sample collection in the first collection channel within duration of operating the flow adjustment of the first fluid directing channel assembly.

Abstract: Provided herein, among other aspects, are methods and apparatuses for analyzing particles in a sample. In some aspects, the particles can be analytes, cells, nucleic acids, or proteins and can be contacted with a tag, partitioned into aliquots, detected by a ranking device, and isolated. The methods and apparatuses provided herein may include a microfluidic chip. In some aspects, the methods and apparatuses may be used to quantify rare particles in a sample, such as cancer cells and other rare cells for disease diagnosis, prognosis, or treatment.

Abstract: In accordance with some embodiments, a fluid sample collection and retrieval apparatus including a microfluidic chip, a retrieval tube, a first switch, a second switch and a processor is provided. The microfluidic chip includes a first sample channel, a first fluid directing channel assembly, a first confluence chamber, a first collection channel, a first waste channel, and a retrieval hole. The retrieval hole passes through an outer surface of the microfluidic chip. The retrieval tube is connected to the retrieval hole. The first switch is connected to the microfluidic chip. The second switch is attached to the retrieval tube. The processor is configured to activate the first switch to operate the flow adjustment of the first fluid directing channel assembly and activate the second switch to operate a sample collection in the first collection channel within duration of operating the flow adjustment of the first fluid directing channel assembly.

Abstract: A method of encapsulating a solid sample in a droplet, the method including flowing a continuous phase through a first fluid channel at a first flow rate; flowing a dispersed phase through a second fluid channel at a second flow rate, the dispersed phase including a plurality of particles, cells or beads; trapping the plurality of particles, cells or beads in a mixing region that receives the dispersed phase and the continuous phase; and reducing the first flow rate to encapsulate the trapped particles, cells or beads in droplets of the dispersed phase generated when the dispersed phase and the continuous phase exit the mixing region through an orifice.

Abstract: A microfluidic droplet system that employs flow-focusing methods to generate droplets of desired sizes for encapsulating particles, cells or beads. The microfluidic droplet system can comprise an air cavity that can be vibrated to reduce trapping of cells or beads in flow-focusing regions of the microfluidic droplet systems thereby increasing the encapsulation efficiency of the cells/beads.

Abstract: The present invention discloses a vortex-modulation based micromixer for enforced mass exchange. The micromixer of the present invention comprises a mixing chamber with grooves on one wall thereof and a special-shape barrier on another wall. As different fluids are injected into the mixing chamber respectively from two inlets of the micromixer, the grooves and barriers of the micromixer of the present invention create the constructive interferences to form the active-like agitation of the fluid. For every groove, the flux passed by can be increased via its high pressure gradient. Understandably, the mixing efficiency of the fluids can be greatly improved within a very short distance. At last, the outlet of the micromixer is located in the downstream of the mixing chamber and further is able to connect with other elements. The present invention is entirely a passive micromixer and no additional energy is required.

Abstract: The present invention discloses a vortex-modulation based micromixer for enforced mass exchange. The micromixer of the present invention comprises a mixing chamber with grooves on one wall thereof and a special-shape barrier on another wall. As different fluids are injected into the mixing chamber respectively from two inlets of the micromixer, the grooves and barriers of the micromixer of the present invention create the constructive interferences to form the active-like agitation of the fluid. For every groove, the flux passed by can be increased via its high pressure gradient. Understandably, the mixing efficiency of the fluids can be greatly improved within a very short distance. At last, the outlet of the micromixer is located in the downstream of the mixing chamber and further is able to connect with other elements. The present invention is entirely a passive micromixer and no additional energy is required.