34 results about "Pressure-driven flow" patented technology

The invention features devices and methods for enriching a sample in one or more desired particles. An exemplary use of these devices and methods is for the enrichment of cells, e.g., white blood cells in a blood sample. In general, the methods of the invention employ a device that contains at least one sieve through which particles of a given size, shape, or deformability can pass. Devices of the invention have at least two outlets, and the sieve is placed such that a continuous flow of fluid can pass through the device without passing through the sieve. The devices also include a force generator for directing selected particles through the sieve. Such force generators employ, for example, diffusion, electrophoresis, dielectrophoresis, centrifugal force, or pressure-driven flow.

A pressure actuated flow control valve for an infusion catheter permits gravity flow of a liquid through the catheter and into a patient while resisting back flow of blood from the patient and into the catheter. The valve has a hemispherical body with an outstanding circumferential flange and a normally closed, diametric slit. The slit is longer on the convex outer surface than on the concave inner surface. Dome thickness diminishes in the area adjacent the slit, reducing total apical deflection upon collapse of the slit toward the concave surface. An inner orthogonal rib biases the slit closed. Upon application of a predetermined pressure, the slit opens toward the concave surface to permit forward fluid flow. At lower pressures, the slit closes to check fluid flow. Greater reverse pressure is required to collapse the slit toward the concave surface to permit reverse fluid flow.

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.

Microfluidic systems and methods including those that provide control of fluid flow are provided. Such systems and methods can be used, for example, to control pressure-driven flow based on the influence of channel geometry and the viscosity of one or more fluids inside the system. One method includes flowing a plug of a low viscosity fluid and a plug of a high viscosity fluid in a channel including a flow constriction region and a non-constriction region. In one embodiment, the low viscosity fluid flows at a first flow rate in the channel and the flow rate is not substantially affected by the flow constriction region. When the high viscosity fluid flows from the non-constriction region to the flow constriction region, the flow rates of the fluids decrease substantially, since the flow rates, in some systems, are influenced by the highest viscosity fluid flowing in the smallest cross-sectional area of the system (e.g., the flow constriction region). This causes the fluids to flow at the same flow rate at which the high viscosity fluid flows in the flow constriction region. Accordingly, by designing microfluidic systems with flow constriction regions positioned at particular locations and by choosing appropriate viscosities of fluids, a fluid can be made to speed up or slow down at different locations within the system without the use of valves and/or without external control.

Disclosed is a microfluidic assay system and methods that apply flow injection analysis to permit dispersion monitoring. A solution containing a reagent that binds an analyte and a tracer is delivered via pressure-driven flow into the receiving end of the injection channel of the system of the invention. A sample fluid suspected of containing the analyte is delivered into the upstream end of the input channel under conditions permitting flow of the sample fluid toward the downstream end of the assay channel and permitting dispersion of the reagent into the sample fluid. The amount of tracer present in the fluid as it passes over the reference region and the capture region and the amount of binding between the analyte and the capture region are detected. The amount of binding detected between the analyte and the capture region is correlated to the amount of tracer detected in the reference region.

A method for controlling fluid flow at junctions in microchannel systems. Control of fluid flow is accomplished generally by providing increased resistance to electric-field and pressure-driven flow in the form of regions of reduced effective cross-sectional area within the microchannels and proximate a channel junction. By controlling these flows in the region of a microchannel junction it is possible to eliminate sample dispersion and cross contamination and inject well-defined volumes of fluid from one channel to another.

Methods of performing separations in microfluidic devices are provided. The methods include the use of pressure to introduce reagents into the device, mix the reagents or react the reagents, and the use of electrokinetic forces to separate the reagents or products. To achieve improved separation efficiency, the depths of the various microfluidic channels are varied. The pressure driven channels provided are deep in comparison to the separation channels in which flow is electrokinetically driven. Also included are microfluidic devices and integrated systems for performing separations in which pressure driven flow and electrokinetic driven flow are integrated.

Liquid flow devices, particularly microfluidic devices, containing solid porous materials. Flow in the devices can be pressure-driven flow and/or electroosmotic flow. The porous materials are preferably pre-shaped, for example divided from a sheet of porous material, so that they can be assembled with liquid-impermeable barrier materials around them. The devices can for example be prepared by lamination. A wide variety of devices, including mixing devices, is disclosed. A mixing device is illustrated in FIG. 23.

The invention features microfluidic devices that contain structures that impart differential resistance to a fluid flow. The structures are disposed adjacent to intersections of channels. Devices of the invention provide differential resistance, e.g., under electric-field-driven flow and pressure-driven flow.

A described exemplary embodiment of the present invention includes a computational “toolbox” for the a priori design of optimized fluidic components. These components consist of a channel under low-Reynolds number, pressure-driven flow, with an arrangement of grooves cut into the top and/or bottom to generate a tailored cross-channel flow. An advection map for each feature (i.e., groove of a particular shape and orientation) predicts the lateral transport of fluid within the channel due to that feature. We show that applying these maps in sequence generates an excellent representation of the outflow distribution for complex designs that combine these basic features. The effect of the complex three-dimensional flow field can therefore be predicted without solving the governing flow equations through the composite geometry, and the resulting distribution of fluids in the channel is used to evaluate how well a component performs a specified task. The generation and use of advection maps is described, and the toolbox is applied to determine optimal combinations of features for specified mixer sizes and mixing metrics.

Exosomes carry microRNA biomarkers, occur in higher abundance in cancerous patients than in healthy ones, and because they are present in most biofluids, including blood and urine, can be obtained non-invasively. Standard laboratory techniques to isolate exosomes are expensive, time-consuming, provide poor purity, and recover on the order of 25% of the available exosomes. We present a new microfluidic technique to simultaneously isolate exosomes and preconcentrate them by electrophoresis using a high transverse local electric field generated by ion-depleting ion-selective membrane. We use pressure-driven flow to deliver an exosome sample to a microfluidic chip such that the transverse electric field forces them out of the cross flow and into an agarose gel which filters out unwanted cellular debris while the ion-selective membrane concentrates the exosomes through an enrichment effect. We efficiently isolated exosomes from 1×PBS buffer, cell culture media and blood serum. Using flow rates from 150 μL/hr to 200 μL/hr and field strengths of 100 V/cm, we consistently captured between 60% to 80% of exosomes from buffer, cell culture media, and blood serum as confirmed by both fluorescence spectroscopy and nanoparticle tracking analysis. Our microfluidic chip maintained this recovery rate for more than twenty minutes with a concentration factor of 15 for ten minutes of isolation.

A three-dimensional microporous polymer network material, or monolith, cast-to-shape in a microchannel. The polymer monolith, produced by a phase separation process, is capable of trapping and retaining charged protein species from a mixture of charged and uncharged species under the influence of an applied electric field. The retained charged protein species are released from the porous polymer monolith by a pressure driven flow in the substantial absence of the electric field. The pressure driven flow is independent of direction and thus neither means to reverse fluid flow nor a multi-directional flow field is required, a single flow through the porous polymer monolith can be employed, in contrast to prior art systems. The monolithic polymer material produced by the invention can function as a chromatographic medium. Moreover, by virtue of its ability to retain charged protein species and quantitatively release the retained species the porous polymer monolith can serve as a means for concentrating charged protein species from, for example, a dilute solution.

The present invention provides a device and methods of use thereof in concentrating a species of interest and/or controlling liquid flow in a device. The methods, inter-alia, make use of a device comprising a fluidic chip comprising a planar array of channels through which a liquid comprising a species of interest can be made to pass with at least one rigid substrate connected thereto such that at least a portion of a surface of the substrate bounds the channels, and an ion-selective membrane is attached to at least a portion of the surface of the substrate, which bounds said channels, or which bounds a portion of a surface of one of said channels. The device comprises a unit to induce an electric field in the channel and a unit to induce an electrokinetic or pressure driven flow in the channel.

The invention discloses a valve sealing device, which comprises a valve body. A water inlet is opened on the left side of the valve body. The top and the right side of the first fixed block are fixedly connected with a fixed shaft, and the left side of the top of the valve body is fixedly connected with a motor box. The present invention achieves the effect of fixing the second fixed block through the setting of the first support plate, and achieves the fixing of the block through the setting of the groove, and the setting of the sealing pad prevents the leakage of the water flow. The setting achieves the effect that the water flow enters the valve body, and the floating block is moved downward by the pressure of the water flow to drive the fixed sleeve to move. Through the setting of the spring, the floating block is reset by the tension of the spring after the water in the valve body flows out. , At the same time, it solves the problem that the inside of the valve cannot be sealed, resulting in damage to the valve and reducing the use efficiency.

Disclosed are microfluidic devices and systems for the desalination of water. The devices and systems can include an electrode configured to generate an electric field gradient in proximity to an intersection formed by the divergence of two microfluidic channels from an inlet channel. Under an applied bias and in the presence of a pressure driven flow of saltwater, the electric field gradient can preferentially direct ions in saltwater into one of the diverging microfluidic channels, while desalted water flows into second diverging channel. Also provided are methods of using the devices and systems described herein to decrease the salinity of water.

The invention discloses a valve sealing device, which comprises a valve body. A water inlet is opened on the left side of the valve body. The top and the right side of the first fixed block are fixedly connected with a fixed shaft, and the left side of the top of the valve body is fixedly connected with a motor box. The present invention achieves the effect of fixing the second fixed block through the setting of the first support plate, and achieves the fixing of the block through the setting of the groove, and the setting of the sealing pad prevents the leakage of the water flow. The setting achieves the effect that the water flow enters the valve body, and the floating block is moved downward by the pressure of the water flow to drive the fixed sleeve to move. Through the setting of the spring, the floating block is reset by the tension of the spring after the water in the valve body flows out. , At the same time, it solves the problem that the inside of the valve cannot be sealed, resulting in damage to the valve and reducing the use efficiency.

There is disclosed herein a method and apparatus for using rupture pins to selectively open jets on a jet perforating tool. Rupture pins inserted in jets within a jet perforating tool are configured to rupture at pre-designed thresholds, thereby opening the jet to begin a perforating job, or to circulate fluid through the tool. Also disclosed are systems and methods for holding the rupture pins within the tool prior to rupture.