In accordance with an embodiment of the invention, there is provided a method for: a) high-throughput, multiplexed, affinity-based separation of proteins—especially low abundance proteins—from complex biological mixtures such as serum; and b) high-throughput, multiplexed, affinity-based separation of cells—especially rare cells—from complex biological mixtures such as blood or blood fractions. The separation of proteins or cells is achieved based on differential binding to affinity-capture beads of different sizes and then sorting the protein-bound or cell-bound beads using the concept of centrifugal-induced Dean migration in a spiral microfluidic device. This method enables continuous-flow, high throughput affinity-separation of milligram-scale protein samples or millions of cells in minutes after binding. This is particularly applicable to the isolation of antigen-specific antibodies from polyclonal sera and antigen-specific immune cells or circulating tumor cells from blood, both of which are otherwise highly labor-intensive and expensive to perform.

A method for determining a biological response of a target (41, 42) to a soluble candidate substance includes the steps: introducing a soluble candidate substance into a laminar flow of a buffer liquid (2) to form a candidate substance solute (3) having an initial concentration profile (31); dispersing the initial concentration profile (31) to form a dispersed concentration profile (32); directing the dispersed concentration profile (32) into a detection channel (12) to form a final symmetrical concentration profile (33) therein; introducing a target into the detection channel (12) to obtain a combined concentration profile including a constant target concentration profile overlying the final symmetrical concentration profile (33); holding in the detection channel (12) at least one half of the combined concentration profile; and optically scanning the combined concentration profile to detect an optical signal representative of the biological response of the target to the soluble candidate substance.

A system and method are provided for harvesting target biological substances. The system includes a substrate and a first and second channel formed in the substrate. The channels longitudinally extending substantially parallel to each other. A series of gaps extend from the first channel to the second channel to create a fluid communication path passing between a series of columns with the columns being longitudinally separated by a predetermined separation distance. The system also includes a first source configured to selectively introduce into the first channel a first biological composition at a first channel flow rate and a second source configured to selectively introduce into the second channel a second biological composition at a second channel flow rate. The sources are configured to create a differential between the first and second channel flow rates to generate physiological shear rates along the second channel that are bounded within a predetermined range.

In a method for hydrodynamic focusing of a laminar and planar sample fluid flow, a system is provided for analysis and/or sorting of microscopic objects in the sample fluid comprising an optical objective for optical inspection of the microscopic objects. Microscopic objects are conveyed in the laminar flow of the sample fluid, and two laminar and planar flow of sheath fluids are provided. The flow of the sample fluid is hydrodynamically focused at an optical inspection zone of the system by the sheath fluids. Focusing of the flow of the sample fluid is controlled such that all of the microscopic objects in the sample fluid are caused to be conveyed in a common flow direction in one single plane at the inspection zone of the system, and the microscopic objects in the fluid are optically inspected through the optical objective.

Various aspects of the present invention relate to the control and manipulation of fluidic species, for example, in microfluidic systems. In one aspect, the invention relates to systems and methods for making droplets of fluid surrounded by a liquid, using, for example, electric fields, mechanical alterations, the addition of an intervening fluid, etc. In another aspect, the invention relates to systems and methods for dividing a fluidic droplet into two droplets, for example, through charge and/or dipole interactions with an electric field. The invention also relates to systems and methods for fusing droplets, according to another aspect of the invention, for example, through charge and/or dipole interactions. Another aspect of the invention provides the ability to determine droplets, or a component thereof, for example, using fluorescence and/or other optical techniques (e.g., microscopy), or electric sensing techniques such as dielectric sensing.

There is provided a microparticle sorting method including a procedure of collecting a microparticle in a fluid that flows through a main channel in a branch channel that is in communication with the main channel by generating a negative pressure in the branch channel. In the procedure, a flow of a fluid is formed that flows toward a side of the main channel from a side of the branch channel at a communication opening between the main channel and the branch channel.

This document provides methods and devices for metering fluids. In some cases, the methods and devices include intersecting channels that include capillary-stop geometries at each intersection point that guides the fluids on a desired path, which is controlled by the opening and closing of valves. For example, a metering channel can intersect a loading channel and intersect an outflow channel and a metering portion can be defined by the geometry of the metering channel between the intersection points.

The invention describes a method for isolating one or more genetic elements encoding a gene product having a desired activity, comprising the steps of: (a) compartmentalising genetic elements into microcapsules; and (b) sorting the genetic elements which express the gene product having the desired activity; wherein at least one step is under microfluidic control. The invention enables the in vitro evolution of nucleic acids and proteins by repeated mutagenesis and iterative applications of the method of the invention.

Nozzle Assemblies and methods of use for producing a liquid jet are disclosed that may be permit adjustable time delays between mixing of fluids and observation of reactions. An example nozzle assembly includes: a housing having an inlet and an outlet and a first channel defined therebetween, where the housing includes a gas focusing aperture defining the housing outlet; an intermediate tube disposed within the first channel of the housing, where the intermediate tube has an inlet and an outlet and defines a second channel therebetween; and a central tube disposed within the second channel of the intermediate tube, where the central tube has an inlet and an outlet and defines a third channel therebetween, where the central tube outlet is longitudinally spaced apart from the intermediate tube outlet such that the intermediate tube outlet is disposed between the central tube outlet and the gas focusing aperture's inlet.

The present invention generally relates to the manipulation of fluids using acoustic waves such as surface acoustic waves. In some aspects, one fluid may be introduced into another fluid via application of suitable acoustic waves. For example, a fluid may be added or injected into another fluid by applying acoustic waves where, in the absence of the acoustic waves, the fluid cannot be added or injected, e.g., due to the interface or surface tension between the fluids. Thus, for example, a fluid may be injected into a droplet of another fluid. Other embodiments of the invention are generally directed to systems and methods for making or using such systems, kits involving such systems, or the like.