Abstract: A method of modifying the concentration of reactants and carrying out a chemical reaction on a microfluidic device in which first and second reactants are delivered into a reaction channel combined, the second reactant different from the first reactant and capable of reacting with the first reactant. The first reactant is subjected to a stacking process, thereby producing a first stacked reactant. The second reactant is subjected to the stacking process, thereby producing a second stacked reactant. The first stacked reactant is exposed to the second stacked reactant so that the first stacked reactant and the second stacked reactant undergo a chemical reaction.

Abstract: A method of modifying the concentration of reactants and carrying out a chemical reaction on a microfluidic device in which first and second reactants are delivered into a reaction channel combined, the second reactant different from the first reactant and capable of reacting with the first reactant. The first reactant is subjected to a stacking process, thereby producing a first stacked reactant. The second reactant is subjected to the stacking process, thereby producing a second stacked reactant. The first stacked reactant is exposed to the second stacked reactant so that the first stacked reactant and the second stacked reactant undergo a chemical reaction.

Abstract: A method of carrying out a chemical reaction on a microfluidic device in which a first reactant at a first concentration is delivered into a reaction channel; within the reaction channel the concentration of the first reactant is changed from the first concentration to a second concentration; and while at the second concentration the first reactant is exposed to a second reactant.

Abstract: A method of carrying out a chemical reaction on a microfluidic device in which a first reactant at a first concentration is delivered into a reaction channel; within the reaction channel the concentration of the first reactant is changed from the first concentration to a second concentration; and while at the second concentration the first reactant is exposed to a second reactant.

Abstract: This invention provides methods and compositions, e.g., to reduce interference from non-specific binding sample constituents in a migration shift assay. Interference due to non-specific binding of sample constituents to an affinity substance (e.g., an affinity molecule or a conjugate of an affinity molecule and a charged carrier molecule) is prevented by, e.g., binding the constituents to charged polymers such as heparin sulfate. The present invention also provides methods to concentrate an analyte of interest with high concentration and to detect the analyte with high sensitivity, and further to optimize the reaction conditions for easily concentrating the analyte. Such objects of the present invention are attained, for example, by concentrating a complex of the analyte and a conjugate which is formed by contacting the analyte in a sample with an affinity molecule bound to a charged carrier molecule such as DNA.

Abstract: This invention provides methods and devices for spatially separating at least first and second components in a sample which in one exemplary embodiment comprises introducing the first and second components into a first microfluidic channel of a microfluidic device in a carrier fluid comprising a spacer electrolyte solution and stacking the first and second components by isotachophoresis between a leading electrolyte solution and a trailing electrolyte solution, wherein the spacer electrolyte solution comprises ions which have an intermediate mobility in an electric field between the mobility of the ions present in the leading and trailing electrolyte solutions and wherein the spacer electrolyte solution comprises at least one of the following spacer ions MOPS, MES, Nonanoic acid, D-Glucuronic acid, Acetylsalicyclic acid, 4-Ethoxybenzoic acid, Glutaric acid, 3-Phenylpropionic acid, Phenoxyacetic acid, Cysteine, hippuric acid, p-hydroxyphenylacetic acid, isopropylmalonic acid, itaconic acid, citraconic acid, 3,

Abstract: This invention provides methods and systems for injection of analytes into a separation channel for resolution and detection. Samples can be preconditioned and concentrated by isotachophoresis (ITP) before the injection is triggered by a detected voltage event. Separation of analytes from other sample constituents can be enhanced using skewing channel ITP.

Abstract: Methods of measuring widths of illumination spots and distances between two points, and predicting detected signal widths are provided. Systems, software, and kits for performing the methods of the invention are also provided.