Abstract: An electrochemical system with reduced limiting-current behavior is disclosed. The electrochemical system is useful for fuel cells and bio-sensors. In part, the invention relates a method of reducing or eliminating limiting-current behavior in the operation electrochemical systems, in particular those with ion-selective membrane or electrochemical electrodes, by spatially reducing the convection near the membrane or the electrode. The invention further relates to electrochemical systems in which micropores, microarrays or pillar arrays are used to reduce convection in comparison to conventional systems without microarrays, micropores or pillar arrays.

Abstract: The invention in some aspects relates to methods, devices and compositions for evaluating material properties, such as mechanical and rheological properties of substances, particularly biological substances, such as cells, tissues, and biological fluids. In some aspects, the invention relates to methods, devices and compositions for evaluating material properties of deformable objects, such as cells. In further aspects, the invention relates to methods, devices and compositions for diagnosing and/or characterizing disease based on material properties of biological cells.

Abstract: A neural prosthetic device is provided that includes one or more ion-selective membranes enabling electrically-controlled local modulation of ion concentrations around a nerve so as to achieve different excitability states of the nerve for electrical stimulation or inhibition of nerve signal propagation.

Abstract: A multiplexed concentration interface that can connect with a plurality of microchannels, conventional 96 well plates or other microarrays is disclosed. The interface can be used in biosensing platforms and can be designed to detect single or multiple targets such as DNA/RNA, proteins and carbohydrates/oligosaccharides. The multiplexed concentration device will provide a set of volume-matched sample preparation and detection strategies directly applicable by ordinary researchers. Furthermore, a multiplexed microfluidic concentrator without buffer channels is disclosed.

Abstract: The present invention provides a device and methods of use thereof for desalting a solution. The methods, inter-alia, make use of a device comprising microchannels, which are linked to conduits, whereby induction of an electric field in the conduit results in the formation of a space charge layer within the microchannel. The space charge layer provides an energy barrier for salt ions and generates an ion depletion zone proximal to the linkage region between the microchannel and the conduit. The method thus enables the removal of salt ions from the region proximal to the conduit and their accumulation in a region distant from the conduit, within the microchannel.

Abstract: This invention provides a method and an apparatus for quickly continuously fractionating biomolecules, such as DNAs, proteins and carbohydrates by taking advantage of differential bidirectional transport of biomolecules with varying physico-chemical characteristics, for example size, charge, hydrophobicity, or combinations thereof, through periodic arrays of microfabricated nanofilters. The passage of biomolecules through the nanofilter is a function of both steric and electrostatic interactions between charged macromolecules and charged nanofilter walls, Continuous-flow separation through the devices of this invention are applicable for molecules varying in terms of any molecular properties (e.g., size, charge density or hydrophobicity) that can lead to differential transport across the nanofilters.

Abstract: This invention provides methods utilizing a microfluidic device that can quickly and accurately discern differences in deformability between individual cells and sets of cells and continuously fractionate populations of cells based on their deformability. This information may be important in disease diagnosis and treatment efficacy monitoring. For example such a device may be able to determine the stage of malarial infection by using red blood cell deformability. Additionally, methods of the invention may be used as a tool to screen drugs that can make cells more flexible in diseases such as sickle cell anemia that causes sickle cell crises. The relatively low manufacturing and operation costs of methods of the invention enable this device to be used in resource-limited settings to diagnose and monitor disease.

Abstract: Nanofluidic entropic traps, comprising alternating thin and thick regions, sieve small molecules such as DNA or protein polymers and other molecules. The thick region is comparable or substantially larger than the molecule to be separated, while the thin region is substantially smaller than the size of the molecules to be separated. Due to the molecular size dependence of the entropic trapping effect, separation of molecules may be achieved. In addition, entropic traps are used to collect, trap and control many molecules in the nanofluidic channel. A fabrication method is disclosed to provide an efficient way to make nanofluidic constrictions in any fluidic devices.

Abstract: This invention provides a device and methods for increasing the concentration of a charged species in solution, wherein the solution containing the concentrated species is exposed to the environment. Such solution can be formed on a surface or on a tip of a measurement device. The open-environment concentration technique overcomes the disadvantages of in-channel concentration devices, especially by eliminating flow-induced delivery processes that lead to concentration losses. Combined with direct contact dispensing, methods of this invention can be used for various applications such as immunoassay and MALDI-MS.

Abstract: 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 microchannels, which are linked to nanochannels, whereby induction of an electric field in the nanochannel results in ion depletion in the linkage region between the microchannel and nanochannel, and a space charge layer is formed within the microchannel, which provides an energy barrier for said species of interest which enables its concentration in a region in the microchannel.

Abstract: 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 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 a high aspect ratio ion-selective membrane is embedded within the chip, attached to at least a portion of the 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.

Abstract: This invention is directed to methods and devices for separating molecules in a sample, based on differences in their isoelectric point (pI). The methods and devices make use of a diffusion potential created in a microfluidic chamber when a buffered solution comprising molecules, which differ in terms of their isoelectric point (pI) values and a second buffer, which differs from the buffered solution in terms of its pH or salt concentration are introduced in the chamber. The diffusion potential, in turn, enables charge-based separation of the molecules. Applications and permutations of the methods and devices are described.

Abstract: The present invention provides a device/kit and methods of use thereof in rapid detection of target molecule binding to a cognate binding partner. The methods, inter-alia, make use of a device comprising channels or reservoirs, which are linked to nanochannels, whereby upon application of the cognate binding partner to the nanochannel comprising the target molecule under flow, a detectable change in conductance, capacitance or fluorescence or surface potential occurs.

Abstract: 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.

Abstract: Nanofluidic entropic traps, comprising alternating thin and thick regions, sieve small molecules such as DNA or protein polymers and other molecules. The thick region is comparable or substantially larger than the molecule to be separated, while the thin region is substantially smaller than the size of the molecules to be separated. Due to the molecular size dependence of the entropic trapping effect, separation of molecules may be achieved. In addition, entropic traps are used to collect, trap and control many molecules in the nanofluidic channel. A fabrication method is disclosed to provide an efficient way to make nanofluidic constrictions in any fluidic devices.

Abstract: Nanofluidic entropic traps, comprising alternating thin and thick regions, sieve small molecules such as DNA or protein polymers and other molecules. The thick region is comparable or substantially larger than the molecule to be separated, while the thin region is substantially smaller than the size of the molecules to be separated. Due to the molecular size dependence of the entropic trapping effect, separation of molecules may be achieved. In addition, entropic traps are used to collect, trap and control many molecules in the nanofluidic channel. A fabrication method is disclosed to provide an efficient way to make nanofluidic constrictions in any fluidic devices.

Abstract: This invention provides a method and an apparatus for quickly continuously fractionating biomolecules, such as DNAs, proteins and carbohydrates by taking advantage of differential bidirectional transport of biomolecules with varying physico-chemical characteristics, for example size, charge, hydrophobicity, or combinations thereof, through periodic arrays of microfabricated nanofilters. The passage of biomolecules through the nanofilter is a function of both steric and electrostatic interactions between charged macromolecules and charged nanofilter walls, Continuous-flow separation through the devices of this invention are applicable for molecules varying in terms of any molecular properties (e.g., size, charge density or hydrophobicity) that can lead to differential transport across the nanofilters.

Abstract: 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 microchannels, which are linked to nanochannels, whereby induction of an electric field in the nanochannel results in ion depletion in the linkage region between the microchannel and nanochannel, and a space charge layer is formed within the microchannel, which provides an energy barrier for said species of interest which enables its concentration in a region in the microchannel.

Abstract: Disclosed herein are multidimensional electrophoresis devices and methods of using thereof. The multidimensional electrophoresis devices comprise short microchannels having lengths of less than about 1 millimeter to about 5 centimeters. The microchannels may comprise solid sieving medium having different sieving characteristics. IEF and PAGE, including SDS-PAGE and native PAGE, using the multidimensional electrophoresis devices takes only a few minutes or less to perform.

Abstract: Nanofluidic entropic traps, comprising alternating thin and thick regions, sieve small molecules such as DNA or protein polymers and other molecules. The thick region is comparable or substantially larger than the molecule to be separated, while the thin region is substantially smaller than the size of the molecules to be separated. Due to the molecular size dependence of the entropic trapping effect, separation of molecules may be achieved. In addition, entropic traps are used to collect, trap and control many molecules in the nanofluidic channel. A fabrication method is disclosed to provide an efficient way to make nanofluidic constrictions in any fluidic devices.