Abstract: A liquid sample is prepared at a preparation site and then processed, e.g. in an HPLC column. The sample is prepared and conveyed to the device at a flow rate which is substantially less than the flow rate through the device. The different flow rates are preferably provided by variable rate working fluid supplies which drive the sample from the preparation site and through the device.

Abstract: A liquid sample is prepared at a preparation site and then processed, e.g. in an HPLC column. The sample is prepared and conveyed to the device at a flow rate which is substantially less than the flow rate through the device. The different flow rates are preferably provided by variable rate working fluid supplies which drive the sample from the preparation site and through the device.

Abstract: A liquid sample is prepared at a preparation site and then processed, e.g. in an HPLC column. The sample is prepared and conveyed to the device at a flow rate which is substantially less than the flow rate through the device. The different flow rates are preferably provided by variable rate working fluid supplies which drive the sample from the preparation site and through the device.

Abstract: Variable potential electrokinetic devices and electrokinetic multipliers used for pumping and flow control are disclosed that offer improvements in safety and design flexibility. The devices of the present invention take advantage of combinations of pumping conduits and conducting conduits to permit the use of lower operating voltages in pumps, pressure multipliers, and flow controllers. Devices having N pumping stages and 2N+1 electrodes permit the use of arbitrary voltages at the fluid connection points between the devices and other system components, further improving device safety and flexibility.

Abstract: A system for simultaneously processing a plurality of particles, e.g. beads or cells. A liquid sample containing the particles is delivered to a processing chamber in which the particles are positioned on particle retainers which lie in a plane. The particle retainers are sized to receive only one particle, so that the particles do not overlap. The system can make use of positioning fluid for forcing the particles into the particle retainers. The positioned particles can, for example, be processed by interrogating the particles with a light of a preselected wavelength, and analyzing signals received from the particles.

Abstract: Particles dispersed in a liquid are assembled in a configuration in which all the particles lie in the same plane, and the assembled particles are processed while in that configuration. The assembled particles can for example be simultaneously exposed to electromagnetic radiation which elicits from the particles a response which provides information about the particles. The particles can for example be cells, cell fragments, or analyte-bearing beads of the type conventionally analyzed in a cytometer.

Abstract: A variable flow rate injector provides accurate, precise, and reproducible injection volumes that have low dispersion. The invention is particularly well-suited for HPLC injection volumes <500 nL but can be used to inject larger volumes and in different applications as well. Injections are performed at a first flow rate and separations are performed at a second flow rate. For improved HPLC system performance, the first flow rate is less than the second flow rate. The injector uses a variable flow rate fluid supply that allows rapid switching between flow rates desired for injection and flow rates desired for separations.

Abstract: A variable flow rate injector provides accurate, precise, and reproducible injection volumes that have low dispersion. The invention is particularly well-suited for HPLC injection volumes <500 nL but can be used to inject larger volumes and in different applications as well. Injections are performed at a first flow rate and separations are performed at a second flow rate. For improved IIPLC system performance, the first flow rate is less than the second flow rate. The injector uses a variable flow rate fluid supply that allows rapid switching between flow rates desired for injection and flow rates desired for separations.

Abstract: Particles dispersed in a liquid are assembled in a configuration in which all the particles lie in the same plane, and the assembled particles are processed while in that configuration. The assembled particles can for example be simultaneously exposed to electromagnetic radiation which elicits from the particles a response which provides information about the particles. The particles can for example be cells, cell fragments, or analyte-bearing beads of the type conventionally analyzed in a cytometer.

Abstract: A check valve for a fluidic system includes a fluidic conduit having an inlet with a first particle barrier, an outlet with a second particle barrier and a fluid chamber between the inlet and the outlet; and at least one particle disposed in the fluid chamber, the particle or particles aggregating at the first particle barrier to form a first hydrodynamic resistance when a first fluid pressure at the inlet is less than a second fluid pressure at the outlet, the particle or particles aggregating at the second particle barrier to form a second hydrodynamic resistance when the first fluid pressure is greater than the second fluid pressure.

Abstract: Variable potential electrokinetic devices and electrokinetic multipliers used for pumping and flow control are disclosed that offer improvements in safety and design flexibility. The devices of the present invention take advantage of combinations of pumping conduits and conducting conduits to permit the use of lower operating voltages in pumps, pressure multipliers, and flow controllers. Devices having N pumping stages and 2N+1 electrodes permit the use of arbitrary voltages at the fluid connection points between the devices and other system components, further improving device safety and flexibility.

Abstract: A system for simultaneously processing a plurality of particles such as beads or cells utilizes a unique processor. The processor has a body, a process section in the body, and a feed stream inlet conduit and a feed stream outlet conduits into and from the processor section, respectively. The process section comprises a positioning means for positioning the particles in the process section so that the particles do not overlap. The positioning means can be a plurality of pockets that are sized to receive only one particle. The system also includes positioning fluid or the like for forcing the particles into the pockets for processing. Particles can be processed by such techniques as in interrogating the particles with light of a pre-selected wavelength, and analyzing light received from the particles.

Abstract: Variable potential electrokinetic devices and electrokinetic multipliers used for pumping and flow control are disclosed that offer improvements in safety and design flexibility. The devices of the present invention take advantage of combinations of pumping conduits and conducting conduits to permit the use of lower operating voltages in pumps, pressure multipliers, and flow controllers. Devices having N pumping stages and 2N+1 electrodes permit the use of arbitrary voltages at the fluid connection points between the devices and other system components, further improving device safety and flexibility.

Abstract: A check valve for a fluidic system includes a fluidic conduit having an inlet with a first particle barrier, an outlet with a second particle barrier and a fluid chamber between the inlet and the outlet; and at least one particle disposed in the fluid chamber, the particle or particles aggregating at the first particle barrier to form a first hydrodynamic resistance when a first fluid pressure at the inlet is less than a second fluid pressure at the outlet, the particle or particles aggregating at the second particle barrier to form a second hydrodynamic resistance when the first fluid pressure is greater than the second fluid pressure.

Abstract: Variable potential electrokinetic devices and electrokinetic multipliers used for pumping and flow control are disclosed that offer improvements in safety and design flexibility. The devices of the present invention take advantage of combinations of pumping conduits and conducting conduits to permit the use of lower operating voltages in pumps, pressure multipliers, and flow controllers. Devices having N pumping stages and 2N+1 electrodes permit the use of arbitrary voltages at the fluid connection points between the devices and other system components, further improving device safety and flexibility.

Abstract: An electrokinetic high pressure hydraulic pump for manipulating fluids in capillary-based system. The pump uses electro-osmotic flow to provide a high pressure hydraulic system, having no moving mechanical parts, for pumping and/or compressing fluids, for providing valve means and means for opening and closing valves, for controlling fluid flow rate, and manipulating fluid flow generally and in capillary-based systems (microsystems), in particular. The compact nature of the inventive high pressure hydraulic pump provides the ability to construct a micro-scale or capillary-based HPLC system that fulfills the desire for small sample quantity, low solvent consumption, improved efficiency, the ability to run samples in parallel, and field portability. Control of pressure and solvent flow rate is achieved by controlling the voltage applied to an electrokinetic pump.

Abstract: Apparatus and method for improving the resolution of non-pressure driven capillary chromatographic systems, and particularly for capillary electrochromatography (CEC) systems. By reducing the cross-sectional area of a packed capillary column by means of a second open capillary contiguous with the outlet end of a packed capillary column, where the packed capillary column has a cross sectional area of between about 2 and 5 times that of the open capillary column, the phenomenon of band broadening in the transition region between the open capillary and the packed capillary column, where the individual components of the mixture are analyzed, can be eliminated, thereby providing for a significant improvement in resolution and more accurate detection and analysis.

Abstract: An electrokinetic high pressure hydraulic pump for manipulating fluids in capillary-based systems. The pump uses electro-osmotic flow to provide a high pressure hydraulic system, having no moving mechanical parts, for pumping and/or compressing fluids, for providing valve means and means for opening and closing valves, for controlling fluid flow rate, and manipulating fluid flow generally and in capillary-based systems (Microsystems), in particular. The compact nature of the inventive high pressure hydraulic pump provides the ability to construct a micro-scale or capillary-based HPLC system that fulfills the desire for small sample quantity, low solvent consumption, improved efficiency, the ability to run samples in parallel, and field portability. Control of pressure and solvent flow rate is achieved by controlling the voltage applied to an electrokinetic pump.

Abstract: A method and apparatus for efficiently and rapidly mixing liquids in a system operating in the creeping flow regime such as would be encountered in capillary-based systems. By applying an electric field to each liquid, the present invention is capable of mixing together fluid streams in capillary-based systems, where mechanical or turbulent stirring cannot be used, to produce a homogeneous liquid.

Abstract: Apparatus and method for improving the resolution of non-pressure driven capillary chromatographic systems, and particularly for capillary electrochromatography (CEC) systems. By reducing the cross-sectional area of a packed capillary column by means of a second open capillary contiguous with the outlet end of a packed capillary column, where the packed capillary column has a cross sectional area of between about 2 and 5 times that of the open capillary column, the phenomenon of band broadening in the transition region between the open capillary and the packed capillary column, where the individual components of the mixture are analyzed, can be eliminated, thereby providing for a significant improvement in resolution and more accurate detection and analysis.