Abstract: Methods and apparatus for mixing fluids are provided. The devices and methods operate without moving parts, and generate well-mixed fluids over a broad dynamic range of flow rates. Preferred embodiments include junction-type mixers, bundled mixers, and co-axial mixers. The devices and methods are optimized to produce rapid, accurate gradients to improve associated system throughput and reproducibility.

Abstract: Microfluidic systems including a principal microfluidic conduit (24), an adjacent dead volume (1) and a drain conduit (70) which mitigates the adverse effects of the dead volume on the operation of the system.

Abstract: An electrochemical cell for processing a sample fluid, has a body with a flow path, the flow path having an inlet and an outlet; a reference electrode in fluid communication with the flow path; a counter electrode in fluid communication with the flow path; a porous working electrode in fluid communication with the flow path, the working electrode having a working electrode material; an electrical connection for the working electrode in electrical contact with the working electrode; and a working electrode section in the flow path. The working electrode is positioned inside the working electrode section. The working electrode section has a volume of from about 1 pL to about 1 ?L.

Abstract: A microfluidic detection device provides reduced dispersion of axial concentration gradients in a flowing sample. The microfluidic detection device includes a cell body and a flow path through the cell body. The flow path has an inlet segment, an outlet segment, and a central segment, which forms a detection cell. The central segment is located between and at an angle with both the inlet segment and the outlet segment. The central segment has a first junction with the inlet segment and a second junction with the outlet segment. The cell body contains two arms that can transmit light to and from the detection cell. At least a portion of a first arm is located in the first junction and at least a portion of a second arm is located in the second junction. The portions of the arms located in the junctions are situated so that fluid entering or exiting the central segment of the flow path flows around the outer surface of one of the portions.

Abstract: Electroosmotic flow controllers and methods of fluid flow control are described. The invention uses an electroosmotically generated flow component in conjunction with a pressure driven flow component to modulate fluid flow. The devices and methods of the invention may include salt bridges for making electrical connection between a power supply and a channel filled with a porous dielectric material and a fluid. Embodiments including flow controllers and flow splitters are described as is their use in a variety of fluid handling applications.

Abstract: A method for providing a stop-off material on a workpiece is provided, as is an associated assembly. A maskant is provided on the workpiece such that a first portion of the workpiece is exposed and a second portion of the workpiece is covered by the maskant. The stop-off is then disposed, with the maskant on the workpiece preventing the stop-off from being applied to the second portion of the workpiece. The maskant is removed from the workpiece leaving the stop-off disposed on a select portion of the workpiece. The removal of the maskant can leave the workpiece substantially free of debris. Thereafter, the workpiece can be further processed, e.g., by diffusion bonding, with the stop-off preventing diffusion bonding of part of the workpiece.

Abstract: Methods and apparatus for mixing fluids are provided. The devices and methods operate without moving parts, and generate well-mixed fluids over a broad dynamic range of flow rates. Preferred embodiments include junction-type mixers, bundled mixers, and co-axial mixers. The devices and methods are optimized to produce rapid, accurate gradients to improve associated system throughput and reproducibility.

Abstract: A fuel cell system having a fuel cell, the fuel cell having a membrane-electrode assembly; a fuel reservoir containing a liquid fuel; a conduit coupling the fuel reservoir to the fuel cell; and an electrokinetic fuel pump coupled to the conduit, the electrokinetic fuel pump having a plurality of electrodes; wherein the electrokinetic fuel pump moves fuel from the fuel reservoir through the conduit to the fuel cell; and wherein the electrokinetic fuel pump electrodes do not deleteriously affect the performance of the membrane-electrode assembly.

Abstract: A heat transfer system comprising a primary heat exchanger for receiving heat from a heat source; a secondary heat exchanger for exhausting heat to a heat sink; a conduit connecting the primary heat exchanger and the secondary heat exchanger; and an electrokinetic pump for pumping a heat exchange fluid between the primary heat exchanger and the secondary heat exchanger through the conduit.