Abstract: Devices and methods are provided for separation of particles of a first selected electrophoretic mobility or isoelectric point from a fluid comprising particles of at least one other selected electrophoretic mobility or isoelectric point. The devices comprise a microchannel; electrodes to either side of the microchannel for applying a selected voltage to produce an electrical field across the microchannel orthogonal to the length of the microchannel; and outlets in said microchannel placed to receive outlet portions of the fluid containing enhanced concentrations of each type of particle. The devices may be used for particle detection, quantification, separation, mixing, dilution and concentration; to release, separate and detect interior particles of cells or organisms, and to separate particles such as proteins and microorganisms from biological fluids such as blood; or to separate and detect airborne contaminants such as bacterial warfare agents from air.

Abstract: This invention provides methods for using liquid junction potentials to control the transport of charged particles in fluid streams that are in laminar flow within microfluidic channels. Applications of the methods of this invention include sample preconditioning (removal of interfering substances), electrophoretic separation (fractionation) of charged particles, enhanced or delayed mixing of charged particles across a fluid interface relative to diffusion only, focusing charged particles in a fluid stream in one or two dimensions, and concentration of charged reactants at a fluid interface.

Abstract: Devices and methods are provided for separation of particles of a first selected electrophoretic mobility or isoelectric point from a fluid comprising particles of at least one other selected electrophoretic mobility or isoelectric point. The devices comprise a microchannel comprising an inlet for introducing the fluid into the microchannel; electrodes to either side of the microchannel for applying a selected voltage to produce an electrical field across the microchannel orthogonal to the length of the microchannel; and outlets in said microchannel placed to receive outlet portions of the fluid containing enhanced concentrations of each type of particle. The devices may be used for particle detection, quantification, separation, mixing, dilution and concentration. Electrophoretic tags may be used to provide particles with altered electrophoretic mobilities and/or isoelectric points. Interior particles of cells or organisms may be released, separated and detected by these devices and methods.

Abstract: This invention provides methods for using liquid junction potentials to control the transport of charged particles in fluid streams that are in laminar flow within microfluidic channels. Applications of the methods of this invention include sample preconditioning (removal of interfering substances), electrophoretic separation (fractionation) of charged particles, enhanced or delayed mixing of charged particles across a fluid interface relative to diffusion only, focusing charged particles in a fluid stream in one or two dimensions, and concentration of charged reactants at a fluid interface.