摘要:
A method and device for fuel cell heat and water management is provided. A thermally and electrically conductive hydrophilic heat and mass transport element is provided to the fuel cell spanning from inside to outside the cell. The transport element is deposited between current collector and gas diffusion layers, where heat is transported along the transport element from an interior portion of the element inside the cell to an exterior portion of the element outside the cell. Liquid water is transported along the element into or out of the cell, and heat is removed from the exterior portion by any combination of radiation, free convection and forced convection, and where the liquid water is removed from the exterior portion by any combination of convection driven evaporation and advection. The water is added to the cell from the exterior to the interior by any combination of advection and capillary wicking.
摘要:
A polymer electrolyte membrane fuel cell water management device is provided. The device includes a hydrophilic water transport element spanning from inside the fuel cell to outside the fuel cell and disposed between a gas diffusion layer and a current collector layer in the cell. The transport element includes an intermediate wick outside the fuel cell that is hydraulically coupled to the transport element, and has a transport element structure integrated with a flow field structure within the fuel cell. The device further includes an electroosmotic pump, where the pump is located outside the fuel cell and is hydraulically coupled to the intermediate wick. The hydraulically coupled pump actively removes excess water from the flow field structure and the gas diffusion layer through the transport element, where a key aspect of the invention is the decoupling of water removal from oxidant delivery and reduced parasitic loads.
摘要:
Water flooding at the cathode of a fuel cell is a common problem in fuel cells. By integrating an electroosmotic (EO) pump to remove product water from the cathode area, fuel cell power can be increased. Integration of EO pumps transforms the designs of air channel and air breathing cathodes, reducing air pumping power loads and increasing oxidant transport. Hydration of gas streams, management of liquid reactants, and oxidant delivery can also be accomplished with integrated electroosmotic pumps. Electroosmotic pumps have no moving parts, can be integrated as a layer of the fuel cell, and scale with centimeter to micron scale fuel cells.
摘要:
Water flooding at the cathode of a fuel cell is a common problem in fuel cells. By integrating an electroosmotic (EO) pump to remove product water from the cathode area, fuel cell power can be increased. Integration of EO pumps transforms the designs of air channel and air breathing cathodes, reducing air pumping power loads and increasing oxidant transport. Hydration of gas streams, management of liquid reactants, and oxidant delivery can also be accomplished with integrated electroosmotic pumps. Electroosmotic pumps have no moving parts, can be integrated as a layer of the fuel cell, and scale with centimeter to micron scale fuel cells.
摘要:
The present invention provides a mechanism for separating or isolating charged particles under the influence of an electric field without metal electrodes being in direct contact with the sample solution. The metal electrodes normally in contact with the sample are replaced with high conductivity fluid electrodes situated parallel and adjacent to the sample. When the fluid electrodes transmit the electric field across the sample, particles within the sample migrate according to their electrophoretic mobility.
摘要:
An electrokinetic pump for pumping a liquid includes a pumping body having a plurality of narrow, short and straight pore apertures for channeling the liquid through the body. A pair of electrodes for applying a voltage differential are formed on opposing surfaces of the pumping body at opposite ends of the pore apertures. The pumping body is formed on a support structure to maintain a mechanical integrity of the pumping body. The pump can be fabricated using conventional semiconductor processing steps. The pores are preferably formed using plasma etching. The structure is oxidized to insulate the structure and also narrow the pores. A support structure is formed by etching a substrate and removing an interface oxide layer. Electrodes are formed to apply a voltage potential across the pumping body. Another method of fabricating an electrokinetic pump includes providing etch stop alignment marks so that the etch step self-terminates.
摘要:
An “in-plane” electroosmotic pump may reduce deterioration of performance due to electrolytic gas generation. By controlling the flow of gas generated at the electrodes, while allowing ionic current, the gas may be prevented from fouling the narrow slots which act as pumping channels.
摘要:
Provided are methods, devices and systems that utilize free-surface fluidics and SERS for analyte detection with high sensitivity and specificity. The molecules can be airborne agents, including but not limited to explosives, narcotics, hazardous chemicals, or other chemical species. The free-surface fluidic architecture is created using an open microchannel, and exhibits a large surface to volume ratio. The free-surface fluidic interface can filter interferent molecules, while concentrating airborne analyte molecules. The microchannel flow enables controlled aggregation of SERS-active probe particles in the flow, thereby enhancing the detector's sensitivity.
摘要:
An electrokinetic pump for pumping a liquid includes a pumping body having a plurality of narrow, short and straight pore apertures for channeling the liquid through the body. A pair of electrodes for applying a voltage differential are formed on opposing surfaces of the pumping body at opposite ends of the pore apertures. The pumping body is formed on a support structure to maintain a mechanical integrity of the pumping body. The pump can be fabricated using conventional semiconductor processing steps. The pores are preferably formed using plasma etching. The structure is oxidized to insulate the structure and also narrow the pores. A support structure is formed by etching a substrate and removing an interface oxide layer. Electrodes are formed to apply a voltage potential across the pumping body. Another method of fabricating an electrokinetic pump includes providing etch stop alignment marks so that the etch step self-terminates.
摘要:
Apparatus and methods according to the present invention preferably utilize electroosmotic pumps in fluid handling and field sampling applications. The electroosmotic pumps used in these applications are capable of generating high pressure and flow without moving mechanical parts and the associated generation of unacceptable electrical and acoustic noise, as well as the associated reduction in reliability. Having multiple small flow channels in parallel provides both a high flow rate and high pressure in liquid handling. These electroosmotic pumps are fabricated with materials and structures that improve performance, efficiency, and reduce weight and manufacturing cost relative to presently available micropumps. These electroosmotic pumps also allow for recapture of evolved gases and deposited materials, which may provide for long-term closed-loop operation. Apparatus and methods according to the present invention also allow active regulation of the fluid handling and field sampling devices through electrical control of the flow through the pump. Electroosmotic pumping enables precise dispensing of samples to form genetic, proteomic, or small molecule arrays. A fluid sensor which can be optical, capacitive or other type of electrical sensor is integrated with the electroosmotic pump for measuring liquid levels in liquid drawing and dispensing operations.