Abstract: Methods for the formation of liposomes that encapsulate reagents in a continuous 2-phase flow microfluidic network with precision control of size, for example, from 100 nm to 300 nm, by manipulation of liquid flow rates are described. By creating a solvent-aqueous interfacial region in a microfluidic format that is homogenous and controllable on the length scale of a liposome, fine control of liposome size and polydispersity can be achieved.

Abstract: An apparatus to create a homogenous liposome population without post-processing using laminar flow/diffusive mixing, and for reducing waste discharge of the therapeutic or compound to be encapsulated and delivered by the liposomes.

Abstract: A magnetic connector assembly for microfluidic devices comprises a first magnetic connector with at least one orifice extending therethrough and a second magnetic connector. The first and second connectors are configured to magnetically attract each other. In one aspect, the first magnetic connector is configured to sealingly engage a surface of a microfluidic chip with the second magnetic connector disposed on an opposite side of the microfluidic chip. The first magnetic connector is configured to seal with the microfluidic chip about a channel opening in the microfluidic chip and provide flow communication between the channel opening and the orifice in the first magnetic connector. In at least one other aspect, the first magnetic connector and second magnetic connector each have at least one orifice and are configured to change a flow communication therebetween upon a rotation of the first or second magnetic connector with respect to the other magnetic connector.

Abstract: A method for microfabrication of a microfluidic device having sub-millimeter three dimensional relief structures is disclosed. In this method, homogeneous surfaces, which do not exhibit apparent pixel geometry, emerge from the interaction of the overlapping of diffracted light under opaque pixels and the nonlinear polymerization properties of the photoresist material. The method requires a single photolithographic step and allows for the fabrication of microstructures over large areas (centimeters) with topographic modulation of features smaller than 100 micrometers. The method generates topography that is useful in a broad range of microfluidic applications.

Abstract: A microfluidic device is described, capable of generating multiple spatial chemical gradients simultaneously inside a microfluidic chamber. The chemical gradients are generated by diffusion, without convection, and can either be maintained constant over long time periods, or modified dynamically. A representative device is described with a circular chamber in which diffusion occurs, with three access ports for the delivery and removal of solutes. A gradient typically forms in minutes, and can be maintained constant indefinitely. Gradients overlapping with different spatial location, and a controlled rotation of a gradient formed by diffusion are demonstrated. The device can also be used to evaluate chemotactic responses of bacteria or other microorganisms in the absence of convective flow.

Abstract: A magnetic connector assembly for microfluidic devices comprises a first magnetic connector with at least one orifice extending therethrough and a second magnetic connector. The first and second connectors are configured to magnetically attract each other. In one aspect, the first magnetic connector is configured to sealingly engage a surface of a microfluidic chip with the second magnetic connector disposed on an opposite side of the microfluidic chip. The first magnetic connector is configured to seal with the microfluidic chip about a channel opening in the microfluidic chip and provide flow communication between the channel opening and the orifice in the first magnetic connector. In at least one other aspect, the first magnetic connector and second magnetic connector each have at least one orifice and are configured to change a flow communication therebetween upon a rotation of the first or second magnetic connector with respect to the other magnetic connector.

Abstract: Disclosed is an apparatus and method for the mixing of two microfluidic channels wherein several wells are oriented diagonally across the width of a mixing channel. The device effectively mixes the confluent streams with electrokinetic flow, and to a lesser degree, with pressure driven flow. The device and method may be further adapted to split a pair of confluent streams into two or more streams of equal or non-equal concentrations of reactants. Further, under electrokinetic flow, the surfaces of said wells may be specially coated so that the differing electroosmotic mobility between the surfaces of the wells and the surfaces of the channel may increase the mixing efficiency. The device and method are applicable to the steady state mixing as well as the dynamic application of mixing a plug of reagent with a confluent stream.

Abstract: A microfluidic device is described, capable of generating multiple spatial chemical gradients simultaneously inside a microfluidic chamber. The chemical gradients are generated by diffusion, without convection, and can either be maintained constant over long time periods, or modified dynamically. A representative device is described with a circular chamber in which diffusion occurs, with three access ports for the delivery and removal of solutes. A gradient typically forms in minutes, and can be maintained constant indefinitely. Gradients overlapping with different spatial location, and a controlled rotation of a gradient formed by diffusion are demonstrated. The device can also be used to evaluate chemotactic responses of bacteria or other microorganisms in the absence of convective flow.

Abstract: A method for microfabrication of a microfluidic device having sub-millimeter three dimensional relief structures is disclosed. In this method, homogeneous surfaces, which do not exhibit apparent pixel geometry, emerge from the interaction of the overlapping of diffracted light under opaque pixels and the nonlinear polymerization properties of the photoresist material. The method requires a single photolithographic step and allows for the fabrication of microstructures over large areas (centimeters) with topographic modulation of features smaller than 100 micrometers. The method generates topography that is useful in a broad range of microfluidic applications.

Abstract: A three dimensional microfluidic device for passive sorting and storing of liquid plugs is provided with homogeneous surfaces from the exposure of a photopolymer through binary masking motifs, i.e., arrays of opaque pixels on a transparency mask. The device includes sub-millimeter three-dimensional relief microstructures to aid in the channeling of fluids. The microstructures have topographically modulated features smaller than 100 micrometers.

Abstract: Disclosed is an apparatus and method for the mixing of two microfluidic channels wherein several wells are oriented diagonally across the width of a mixing channel. The device effectively mixes the confluent streams with electrokinetic flow, and to a lesser degree, with pressure driven flow. The device and method may be further adapted to split a pair of confluent streams into two or more streams of equal or non-equal concentrations of reactants. Further, under electrokinetic flow, the surfaces of said wells may be specially coated so that the differing electroosmotic mobility between the surfaces of the wells and the surfaces of the channel may increase the mixing efficiency. The device and method are applicable to the steady state mixing as well as the dynamic application of mixing a plug of reagent with a confluent stream.

Abstract: A method and device are provided for concentrating and separating ionic species in solution within a fluidic device having a fluid conduit such as a channel or capillary. The concentration is achieved by balancing the electrophoretic velocity of an analyte against the bulk flow of solution in the presence of a temperature gradient. Using an appropriate buffer, the temperature gradient can generate a corresponding gradient in the electrophoretic velocity so that the electrophoretic and bulk velocities sum to zero at a unique point and the analyte will be focused at that point. The method and device may be adapted for use with a variety of analytes including fluorescent dyes, amino acids, proteins, DNA and to concentrate a dilute analyte.

Abstract: A method is described for modifying performed channels fabricated in a variety of substrate materials including PMMA. The method involves exposing a portion of a fluid flow channel to light at a fluence and wavelength which modifies the surface charge of the substrate at the exposure site. The method can be used to modulate electroosmotic flow in channels or to immobilize chemical compounds or biological species in the fluid flow channels at the modified surfaces.

Abstract: Disclosed is an apparatus and method for the mixing of two microfluidic channels wherein several wells are oriented diagonally across the width of a mixing channel. The device effectively mixes the confluent streams with electrokinetic flow, and to a lesser degree, with pressure driven flow. The device and method may be further adapted to split a pair of confluent streams into two or more streams of equal or non-equal concentrations of reactants. Further, under electrokinetic flow, the surfaces of said wells may be specially coated so that the differing electroosmotic mobility between the surfaces of the wells and the surfaces of the channel may increase the mixing efficiency. The device and method are applicable to the steady state mixing as well as the dynamic application of mixing a plug of reagent with a confluent stream.

Abstract: A microchannel device is provided with a plastic substrate having a microchannel formed therein. Polyelectrolyte multilayers are disposed along selected surfaces of the microchannel. The polyelectrolyte layers comprise alternating net positively charged layers and net negatively charged layers. A microchannel lid has a surface facing the microchannel. In making the microchannel device, selected surfaces of the microchannel are alternatively exposed to solutions comprising positively charged polyelectrolytes and negatively charged polyelectrolytes to form the desired number of polyelectrolyte layers.

Abstract: A method for simultaneously forming microstructures in substrates and altering their chemical character. The method involves exposing a surface portion of a substrate to light source, which is strong enough and of the appropriate wavelength to cause ablation of the substrate. The ablation of the substrate is controlled to form microstructures therein, such as channels. The ablation is conducted under a chemical atmosphere, which causes a change in the chemical functionality of the microstructures. The chemical atmosphere can be a gas, liquid or solid that is provided on the substrate surface. The method can be used to fabricate or modify microfluidic systems.

Abstract: Disclosed is an apparatus and method for the mixing of two microfluidic channels wherein several wells are oriented diagonally across the width of a mixing channel. The device effectively mixes the confluent streams with electrokinetic flow, and to a lesser degree, with pressure driven flow. The device and method may be further adapted to split a pair of confluent streams into two or more streams of equal or non-equal concentrations of reactants. Further, under electrokinetic flow, the surfaces of said wells may be specially coated so that the differing electroosmotic mobility between the surfaces of the wells and the surfaces of the channel may increase the mixing efficiency. The device and method are applicable to the steady state mixing as well as the dynamic application of mixing a plug of reagent with a confluent stream.

Abstract: A method and device are provided for concentrating and separating ionic species in solution within a fluidic device having a fluid conduit such as a channel or capillary. The concentration is achieved by balancing the electrophoretic velocity of an analyte against the bulk flow of solution in the presence of a temperature gradient. Using an appropriate buffer, the temperature gradient can generate a corresponding gradient in the electrophoretic velocity so that the electrophoretic and bulk velocities sum to zero at a unique point and the analyte will be focused at that point. The method and device may be adapted for use with a variety of analytes including fluorescent dyes, amino acids, proteins, DNA and to concentrate a dilute analyte.

Abstract: A microchannel device is provided with a plastic substrate having a microchannel formed therein. Polyelectrolyte multilayers are disposed along selected surfaces of the microchannel. The polyelectrolyte layers comprise alternating net positively charged layers and net negatively charged layers. A microchannel lid has a surface facing the microchannel. In making the microchannel device, selected surfaces of the microchannel are alternatively exposed to solutions comprising positively charged polyelectrolytes and negatively charged polyelectrolytes to form the desired number of polyelectrolyte layers.

Abstract: A method for modifying and controlling fluid flow in channels formed in substrates. The method involves exposing a portion of a fluid flow channel to light at a fluence which modifies the surface charge of the substrate at the exposure site. The method can be used to immobilize chemical compounds or biological species in the fluid flow channels at the modified surfaces.