• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    An array (10) of flow units (100) for controlling a flow of a fluid is disclosed. The flow units (100) are arranged to have a lateral extension in a common lateral plane and such that a downstream side (D) of a first one the flow units is in fluid communication with an upstream side (U) of a second one of the flow units so as to allow a flow of fluid to pass through said flow units. The flow units comprise a first electrode (110) and a second electrode (120) which are connectable to a voltage source. At least a portion of the first electrode has a maximum height (h) in a direction parallel to the direction of the flow and a maximum gauge (w) in a direction orthogonal to the direction of the flow, wherein said maximum height is larger than said maximum gauge so as to improve the pumping efficiency of the device. A method for controlling a fluid flow by means of such device is also disclosed.Figure elected for publication with abstract: 3
    公开号:SE1550716A1
    申请号:SE1550716
    申请日:2015-06-03
    公开日:2016-12-04
    发明作者:Thorslund Robert；Nilsson Peter；Björneklett Are
    申请人:Apr Tech Ab；
    IPC主号:
    专利说明:

    MICROFLUIDIC ARRAY Field of the invention The invention disclosed herein relates to devices for transporting fluids.More precisely, it relates to an electro-hydrodynamic array of flow units forcontrolling a fluid flow, as well as methods for controlling such array.
    Backqround of the invention The performance of electronic systems is to a large extent limited bythe available cooling techniques for keeping the electronics within anappropriate temperature range. Smaller electronic devices having improvedperformance are associated with increased heat dissipation over a relativelysmall area. ln other words, there is a growing need for space and energyefficient cooling of electronic devices.
    As an example, satellites, such as telecommunication satellites, areapproaching the technology limits of existing on-board thermal managementsystems. The power dissipation of these satellites increases to meet thegrowing requirements for broadcasting, broadband multimedia and mobilecommunications services. Micro, nano, or 'cube' satellites, which require low-mass heat removal from electronic components (satellite on a chip) are likelyto need more compact thermal management systems for maintaining a highperformance.
    Cooling is also a crucial factor in the design of other electronic deviceshaving heat-generating components, such as power electronics, powerfulprocessors, light emitting diodes (LEDs), radio frequency amplifiers, lasersetc.
    Bologa et al., ”Multistage electrohydrodynamical pump", proceedings ofthe 2000 Conference on Electrical lnsulation and Dielectric Phenomena,discloses a multistage electrohydrodynamical (EHD) pump with latticedelectrodes of parallel wires embedded in a metal ring. According to Bologa etal., a formation of ions in a working medium, comprising a dielectric liquid,occurs at the emitter electrode, whereas the ions recombine at the collector.
    The ions move under the influence of Coulomb forces, which ions therebyentrain a flow of the working medium.
    Even though such EHD pump may be employed in various coolingapplications, there is still a need for an improved device and method forcontrolling the flow of a fluid and for providing improved pumping efficiency.
    Summarv of the invention lt is an object of the present invention to control the flow of a fluid insuch manner that the efficiency of the transportation of the fluid is improved. ltis a particular object to improve the capacity of an EHD pump for dielectricfluids.
    Accordingly, the invention provides an array of flow units and a controlmethod with the features of the independent claims. The dependent claimsdefine advantageous embodiments. ln a first aspect, an array of flow units is provided, wherein the flowunits are arranged to have a lateral extension in a common lateral plane.Each flow unit is adapted to control a respective flow of a fluid in a directionintersecting the common lateral plane. Each flow unit comprises a firstelectrode and a second electrode, wherein the second electrode is offset fromthe first electrode in a downstream direction of the respective flow of the fluidand wherein the electrodes are connectable to a voltage source. The firstelectrode comprises bridges and joints forming a grid structure, which isarranged to allow the fluid to flow there through. At least a portion of at leastone of the bridges has a maximum height in a direction parallel to thedirection of the flow, and a maximum gauge in a direction orthogonal to thedirection of the flow, wherein the maximum height is larger than the maximumgauge, preferably at least twice the maximum gauge. The maximum heightmay also be three, four, five, or six times the maximum gauge, or larger. Theflow units are arranged in an array such that a downstream side of a first oneof the flow units is in fluid communication with an upstream side of a secondone of the flow units so as to allow a flow of fluid to pass through the first andsecond one of the flow units. ln a second aspect, a method for controlling the flow of a fluid throughan array of flow units is provided. The method comprises providing an array offlow units according to the first aspect, providing a fluid contacting the firstelectrode of at least one of the flow units, and applying an electric potentialdifference between the first electrode and the second electrode of said flowunit.
    By the term “direction of flow of the fluid” or “flow direction” should beunderstood the main direction of the resulting net flow of fluid passing througha flow unit during operation. The term may also be referred to as “intendeddirection of flow”.
    The term “array” may refer to any ordered arrangement of flow units,wherein a plurality of flow units e.g. may be distributed along a line or in atvvo-dimensional matrix. The array may extend in a lateral plane and beformed of flow units arranged side by side, or abreast, in said lateral plane.
    The “upstream side” of a flow unit may also be referred to as a side orportion of the flow unit at which the fluid, during use, enters the flow unit.Hence, this side could be understood as an inlet side, inlet portion or inletopening. The upstream side may in some examples correspond to a portionof the flow unit in which the first electrode is located. Accordingly, the“downstream side” of a flow unit may be referred to as a side or portion atwhich the fluid, during use, exits the flow unit. This side could hence beunderstood as an outlet side, outlet portion or outlet opening. Further, thisside may in some examples correspond to a portion in which the secondelectrode is located.
    The first electrode may also be referred to an “emitter” or “emitterelectrode”, whereas the second electrode may be referred to as “collector” or“collector electrode”. During use, the emitter may be adapted to emitelectrons into the fluid and/or to negatively charge matter, such as particles orimpurities of the fluid, in a close proximity of the emitter.
    By a grid it is understood any structure comprising bridges that arejoined to each other so as to e.g. a grating, net, or honeycomb structure, etc.The bridges and the joints define open areas of the grid which admit a fluidflow. ln one example, the grid may comprise flanges forming a heat sink. The flanges, which e.g. may be formed of sheet metal, may be arranged in alamellar structure wherein their edge portions are joined to a peripheral frameof the grid. Further, it is understood that the grid may comprise severalbridges having the above specified ratio between their height and gauge. Asan example, the whole grid other than its peripheral portions may e.g. beformed of such bridges. ln another example, most of or all of bridges of thegrid may fulfil the maximum height/gauge relation.
    Several advantages are associated with the invention. By arrangingflow units in an array extending in a lateral plane, a relatively flat and/or thinpump may be achieved that may be advantageous over pumps comprisingseveral, stacked stages. Arranging a plurality of flow units abreast instead ofabove each other in a stack allows for the total height to be reduced, therebyallowing for a pump that can be used in applications wherein space is limited.Further, a thinner and/or flatter pump may have a larger surface-to-volumeratio, which may facilitate cooling or dissipation through an outer surface ofthe pump.
    Connecting a downstream side of a first flow unit with an upstream sideof a second or neighbouring flow unit allows for the fluid to be pumped oraccelerated in several steps, which may increase e.g. pumping efficiency,flow velocity, and volumetric flow rate of the array. This arrangement may besimilar to an array of series connected or cascade connected flow units forenhancing, controlling or manipulating a flow of the fluid. Pressure, volumetricflow or velocity of the fluid flow may be increased at each, or at least some of,the flow units in the array.
    The present invention further allows for a flow of fluid to be re-circulated through one or several flow units. ln other words, a given amount offluid may pass through a flow unit several times so as to, in each round,further increase e.g. pressure, volumetric flow rate or flow velocity. By re-circulating the fluid flow, the number of flow units of the array may hence bereduced.
    The flow units of the array may be oriented in the same direction, i.e.,such that the downstream side of each flow unit, respectively, faces in a samedirection. ln other words, the flow units are arranged abreast such that the direction of fluid flow is parallel for each flow unit. Such orientation mayfacilitate manufacturing and assembling of the array. Arranging all flow unitsin a same orientation, e.g. with the upstream side facing a first direction andthe downstream side facing a second, possibly opposing, direction may alsofacilitate electrical connection of the flow units. ln one example, this allows forall first electrodes to be electrically connected on a first side of the arrayand/or the second electrodes to be electrically connected on a second side ofthe array.
    Alternatively, the array may comprise at least one flow unit pointing, orbeing oriented, in an opposite direction as compared to the other flow units ofthe array. This may facilitate or simplify the fluid communication between twooppositely arranged flow units, since the fluid flow may exit the first one of theflow units and enter the second one of the flow units at the same side of thearray. Shifting or alternating the orientation of one or several of the fluid unitsmay further reduce the size of the array, thereby allowing for a smaller andyet relatively efficient array.
    By forming the first electrode of a grid of bridges that have a relativelylarge height in relation to their gauge, the grid may be relatively rigid in termsof its ability to carry loads in the height direction of the bridges, or thedirection of the flow. Thereby, a relatively rigid electrode is enabled, which isless prone to bend or deform, especially in the direction of the flow, andhence the risk for e.g. short-circuiting of the flow unit may be reduced.Further, the relatively rigid and stable grid may still have a relatively largeopen area which may provide a relatively low flow resistance being met by thefluid passing through the grid. Further, the relatively high and narrow bridgesmay reduce the amount of material required for forming a relatively stable andrigid grid, which may reduce both weight and cost of the flow unit and hencethe array. By using a relatively rigid grid, the need for additional supportstructures may be reduced and a relatively well defined and constant spacingbetween the first and second electrodes may be achieved. The spacing maye.g. be within the range of 10-2000 um, and more preferably in the range of50-1000 um.
    With their relatively large height, the bridges also provide a relativelylarge contact surface between the grid structure and the passing fluid, whichmay facilitate any interactions between the electrode and the fluid, such ase.g. diffusion of material and/or injection of ions or electrons.
    The distance, or spacing, between the first and the second electrode ofa flow unit may be varied so as to control the strength of the electric fieldbeing induced between the electrodes. Experiments have shown that asmaller gap, and thus a stronger induced electric field, may enable increasedpump efficiency, or flow rate, as compared to devices having a larger gap andbeing supplied with the same electric power.
    According to an embodiment, at least one of the bridges of the firstelectrode comprises a tapered portion forming an edge or tip that is directedtowards the second electrode. The present embodiment is based on theinsight that by providing the first electrode with beaked or pointed portions,the injection of electrons per unit area of the first electrode into the fluid maybe improved. lncreasing the emitting of electrons may enhance theelectrohydrodynamic effect, increase the flow through the flow unit, and thusimprove its pumping efficiency of the array. Further, increasing the electronemitting efficiency from the first electrode may advantageously allow for areduction of the flow resistance through the grid, since the open area of thegrid, i.e. the grid area through which the fluid may pass, may be reducedwithout necessarily reducing the injected current.
    According to an embodiment, at least one of the bridges comprises atapered portion forming an edge or tip directed away from the secondelectrode. ln other words, the tapered portion is directed anti-parallel to theflow of the fluid, which advantageously may streamline the upstream portionof the grid so as to reduce the flow resistance and enhance the efficiency ofthe flow unit.
    According to an embodiment, the second electrode comprises bridgesand joints forming a grid structure that allows the fluid to flow through thesecond electrode. At least one of the bridges comprises a portion having amaximum height in a direction parallel to the direction of the flow and amaximum gauge in a direction orthogonal to the direction of the flow, wherein the maximum height is larger than the maximum gauge, preferably at leasttwice the maximum gauge. The present embodiment is associated withsimilar advantages and effects as described with reference to the structure ofthe grid of the first electrode.
    According to an embodiment, the second electrode comprises astructured surface portion facing the first electrode. The structured surfaceportion may comprise micro- and/or nanostructures which may increase thearea of the surface portion. The microstructures and/or nanostructures mayfor example include the geometrical form of hills, ridges, paraboloids, pillars,or trenches. lncreasing surface area of the second electrode is advantageousin that it may improve the ability of collecting, or absorbing, electrons andhence improve the efficiency of the electrode. Further, by increasing thesurface area by means of micro- and /or nanostructures, a relatively activesurface area can be achieved on a relatively small surface portion. Thisadvantageously allows for a relatively larger active surface area and arelatively lower flow resistance. A relatively larger active area may alsoincrease the lifetime of the second electrode, since it may then be lesssensitive to contaminants passivating the surface.
    According to an embodiment, the second electrode comprises aconcave surface portion facing the first electrode. A concave surface portionis advantageous in that it may provide an increased surface area ascompared to a flat surface portion, thereby enhancing the ability to collectelectrons, e.g., electrons emitted by the first electrode. The concave surfacemay e.g. conform to an arc of a circle, or a surface of a sphere or of acylinder, having its centre or symmetry axis at an edge or tip of the firstelectrode. Thereby, a homogenous electric field may be achieved betweenthe first electrode and the second electrode.
    According to an embodiment, at least one of the bridges and/orjointsof the second electrode comprises a channel, or a plurality of channels,adapted to allow the fluid to flow through said channel. By arranging apassage through the material of the grid, the flow may be increased and/orthe fluid resistance reduced.
    According to some embodiments, at least one of the flow units maycomprise a first electrode having an open area that is smaller than an openarea of the second electrode, or vice versa. The first (or second) electrodemay e.g. comprise a sparser grid, i.e. a grid having a larger distance betweenits bridges/joints, than a grid of the second (or first) electrode. Further, theopen area of the first electrode may be differently distributed as compared tothe open area of the second electrode. ln one example, the open area of thefirst (second) electrode may be distributed as a plurality of open regions orthrough-holes of a grid, whereas the open area of the second (first) electrodemay be formed of a single through-hole in a plate extending in a planeintersecting the direction of the flow of the fluid. lt will also be appreciated thatthe open area of the first and/or second electrode may be formed of a sum ofopen areas of through-holes having a particular distribution over the surfaceof the electrode, and that the particular distribution is chosen with respect toe.g. desired flow resistance properties and/or desired electrical properties,such as a desired electric field distribution or electric field strength betweenthe first electrode and the second electrode.
    According to an embodiment, a flow unit may comprise a supportstructure arranged to separate the second electrode from the first electrode inthe direction of the flow. The support structure may e.g. be electrically non-conductive and have a well defined thickness so as to maintain a desiredspacing between the first and second electrodes. The support structure maye.g. be formed as a grid or a spacer comprising e.g. ceramics or polymers,and the first and/or second electrode(s) may be connected to or arranged onthe support structure by means of e.g. welding, gluing, soldering, brazing,glazing or sintering. The support structure may comprise an alignmentstructure adapted to align the first electrode with the second electrode, and/orto align or position the flow unit in the array. The alignment structure may e.g.comprise a protruding member and a receiving member, such as adepression or recess, wherein the protruding member is adapted to cooperatewith a corresponding receiving member of another support structure, and viceversa. Thereby the assemblage and alignment of the electrodes and/or theflow unit may be facilitated.
    According to further embodiments, at least one of the first electrode,the second electrode and the support structure comprises a deformationstructure arranged to compensate for, or absorb, e.g. thermally inducedstresses, particularly in a p|ane intersecting the direction of the f|uid flow. Thedeformation structure may e.g. be formed by a bridge being curved in thep|ane orthogonal to the direction of the flow. As the bridge is exposed tostresses or torsional torques in the p|ane orthogonal to its height (i.e. the flowdirection), the bridge may due to its relatively large height and small gaugetend to deform in that p|ane rather than in the flow or height direction. Thisadvantageously allows for a flow unit that is less sensitive to thermallyinduced stresses and thermal expansion. Thereby a flow unit, and possiblyarray, having relatively well defined dimensions and a relatively reliable shapemay be achieved. Furthermore, the deformation structure may allow materialshaving different coefficients of thermal expansion (CTE) to be combined. Asan example, the first and/or the second electrodes may be formed of amaterial having a first CTE whereas the support structure, to which the firstand/or the second electrodes may be attached, may have another CTE. lnsuch case, a deformation structure may be provided in the electrodes and/orthe support structure so as to enable any internal thermal stresses that maybe caused by the difference in CTE to be absorbed by the deformationstructure being deformed in the p|ane orthogonal to the direction of the f|uidflow. Thus, the deformation structure may enable a more reliable flow unithaving a prolonged life.
    According to an embodiment, the first electrode and/or the secondelectrode and/or the support structure is formed of a material that isselectively deposited so as to form the desired structure. The material maye.g. comprise a stacked structure of one or several metals. The depositingmethod may e.g. comprise molding, plating, screen printing, glazing,sputtering, evaporation or sintering.
    Alternatively, or additionally, the manufacturing may comprise removalof material, e.g. by selectively removing material from a substrate. Examplesof suitable techniques may include cutting, milling, etching, and abrasiveblasting. lt will be further appreciated that the first electrode and/or the secondelectrode may be formed as a lamellar structure of flanges oriented in thedirection of the flow and adapted to allow the f|uid to flow through theelectrode. The flanges may e.g. be formed from a planar sheet of anelectrically conducting, and possibly heat conducting, material such ascopper, which may be bent to form a lamellar structure.
    The first and/or second electrodes may advantageously comprise amaterial that has a relatively good ability of emitting electrons and ischemically stable, or inert, in relation to the pumped f|uid. Further, thematerial may have a relatively high temperature resistance. Examples of suchmaterials may include e.g. Pt, Au, and stainless steel.
    According to an embodiment, the applied electric potential differencebetween the first and the second electrodes of a flow unit of the array may bevaried as a function of time. Experiments have shown that by e.g. alternatingthe potential difference between a first, positive value and zero, and/orbetween a positive and a negative value, the f|uid flow per unit area, andhence the pump efficiency, may be improved.
    Examples of fluids, i.e. liquids and gases, that can be pumped bymeans of embodiments of the inventions includes e.g. dielectrics such asacetone, alcohols, helium, nitrogen, carbon dioxide, air, and fluorocarbon-based fluids such as e.g. FluorinertTM or NovecTM. ln the present specification, the term “pump” or “pump assembly” mayinclude any device capable of creating a movement, current or flow of a f|uidwithin and/or through the device. The term may also be understood as a fanor fan assembly, in particular in case the f|uid comprises a gaseous material.
    Further objectives of, features of and advantages with the presentinvention will become apparent when studying the following detaileddisclosure, the drawings and the appended claims. Those skilled in the artrealise that different features of the present invention, even if recited indifferent claims, can be combined into embodiments other than thosedescribed in the following. 11 Brief description of the drawinqs The above, as well as additional objects, features and advantages ofthe present invention, will be better understood through the followingillustrative and non-limiting detailed description of embodiments of the presentinvention. Reference will be made to the appended drawings, on which: figure 1 is a schematic perspective view of an array of flow unitsaccording to an embodiment of the invention; figures 2 shows a cross sectional portion of an array according to anembodiment of the invention; figure 3 is a cross section according to yet an embodiment; figure 4 is a schematic perspective view of a first and a secondelectrode of a flow unit according to an embodiment; figures 5a to d show cross sectional portions of the first and secondelectrode of a flow unit according to an embodiment; figures 6a and b illustrate a flow unit according to an embodiment; figures 7a and b show a cross section according to an embodiment; figures 8a and b are top views of an electrode of a flow unit providedwith a deformation structure according to embodiments of the invention; figure 9 is a cross section of a flow unit according to an embodiment;and figures 10a and b graphically illustrate electric current pulses applied toe.g. the emitter of a flow unit in accordance with an embodiment of theinvenfion.
    All the figures are schematic, generally not to scale, and generally onlyshow parts which are necessary in order to elucidate the invention, whereasother parts may be omitted or merely suggested.
    Detailed description of embodiments Figure 1 shows an array 10, or pump assembly, comprising a pluralityof flow units 100. The flow units 100 may be arranged in a cell structurecomprising a lid part 18 and a bottom part 19. ln figure 1, the outline of eachcell 11 of the cell structure is indicated by a dashed line, whereas a cell 11comprising a flow unit 100 is indicated by diagonal cross-hatching. The array 12 10 may comprise a first opening 12 for supply of fluid to the array 10. The firstopening 12 may e.g. be arranged in the lid part 18. Further, a second opening11 for outputting the fluid may be arranged in the bottom part 19 (indicated bya dashed line). According to the present embodiment, the array 10 maycomprise e.g. five flow units 100 arranged in every second cell 11 of the cellstructure. The flow units 100 may be arranged in a same direction ororientation such that the direction of flow of the fluid is essentially parallel foreach one of the flow units 100. The cells 11 may be in fluid communicationwith one or several other cells 11 so as to allow a fluid to flow between thecells, preferably from one cell 11 to a neighbouring cell 11. During operation,a fluid may enter the cell structure via the first opening 12 and pass through afirst flow unit 100 to a second flow unit 100 via neighbouring or intermediatecell 11.
    Figure 2 is a cross sectional side view of an array 10 that is similarlyconfigured as the array 10 of figure 1. The array 10 of flow units 100a, 100c,100e is arranged in cells 11a, 11c, 11e defined by a lid part 18 and a bottompart 19 comprising cell separating walls 17. The cells 11a, 11b, 11c, 11d, 11eare connected to each other by means of channels 16 adapted to let a flow offluid pass from a downstream side D of a flow unit 100a, via an empty cell11b, to an upstream side U ofa neighbouring flow unit 100c. Each flow unit100a, 100c, 100e comprise a first electrode 110, such as e.g. a grid shapedemitter, and a second electrode 120, such as e.g. a metal plate provided witha through-hole.
    During operation, fluid may be entered through a first opening 12 andbrought in fluid contact with the first electrode 110 of the flow cell 100aarranged in cell 11a. The fluid may be brought to flow by means of an electricfield induced between the first electrode 110 and the second electrode 120,and continue through the channel 16 and the neighbouring, empty cell 11b tothe next flow unit 100c. This process is repeated until the fluid reaches thesecond opening 14, through which it may exit the array 10.
    As indicated in figures 1 and 2, the flow units 100 may be oriented inthe same direction, allowing the fluid to pass through each flow unit 100 in thesame flow direction. Such arrangement of the flow units 100 may require a 13 channel 16 and, according to the present example, an intermediate empty cell11b, 11d for “reversing” the flow exiting at the downstream side D of a firstflow unit 100 before it can enter at the upstream side U of a second flow unit12.
    However, as shown in figure 3, the array described with reference tofigures 1 and 2 may comprise flow units 100 that are arranged in opposingdirections. Figure 3 is a schematic illustration of such principle, wherein a firstflow unit 100a is arranged with its upstream side U facing in a first direction(i.e. upwards in figure 3) and a second flow unit 100b is arranged with itsupstream side U facing a second direction (i.e. downwards in figure 3). As thefluid enters the first cell 11a, it flows downwards through the first flow unit100a, passes under the first cell separating wall 17b into the second cell 11b,continues upwards through the second flow unit 100b, over the second cellseparating 17b wall and into the third cell 11c (the fluid flow indicated byarrows). This process is repeated for the third flow unit 100c, the third cellseparating wall 17c, the fourth cell 11d and the fourth flow unit 100d until thefluid eventually exits through opening 14. As illustrated in figure 3, the array10 may be adapted to let a flow enter and/or exit in a plane parallel to lateralplane of extension of the array 10.
    Figure 4 shows an example of a flow unit 100 according toembodiments similar to the embodiments of figures 1 to 3. The flow unit 100may comprise a first electrode, or emitter 110, comprising bridges 111 andjoints 112 forming a grid that allows a fluid to flow through the emitter110.The emitter 110 may have a lateral extension in a plane perpendicular to theintended flow direction, which is indicated by an arrow in figure 4. Accordingto this embodiment, the second electrode, or collector 120, comprises bridges121 and joints 122 that are arranged in a similar grid the one described withreference to the emitter 110. Consequently, the collector 120 may have alateral extension in a plane perpendicular to the direction of the flow such thatboth the emitter 110 and the collector 120 are parallel to each other.
    The emitter 110 and the collector 120 may be arranged spaced apartfrom each other in the flow direction by a positive distance d. The spacingmay e.g. be maintained by a support arrangement, or grid spacer 130 (not 14 shown in figure 1) being arranged between the emitter 110 and the collector120. A relatively narrow gap d may be desirable since such gap may providea relatively high electric field and thus enhance the electrohydrodynamiceffect affecting the flow rate. The use of a grid spacer 130, which may have awell defined thickness, may advantageously reduce the risk of a shortcut orbreakdown between the emitter 110 and the collector 120. As will bediscussed in more detail below, the grid spacer 130 may e.g. have a similarconfiguration as the emitter 110 and/or the collector 120, i.e. comprising agrid of bridges 111, 121 and joints 112, 122. The grid spacer130 mayhowever have other configurations as well, such as e.g. being formed as aframe supporting the lateral edges of the emitter 110 and/or collector 120. lt will also be realised that the grid may have one of a broad variety ofshapes, wherein the edges and the joints e.g. may form a grating, a net, ahole pattern, a honeycomb structure, or other structures or patterns suitablefor admitting a flow through the emitter 110 and/or collector 120.
    Figure 5 shows a cross section of a portion of the emitter 110 andcollector 120 of a flow unit similarly configured as the flow units describedwith reference to any one of the previous figures. The cross section is takenthrough three pairs of the bridges 111, 121 and along a plane parallel to theflow direction. According to this embodiment, the bridges 111 of the emitter110 is arranged at a constant distance d from the bridges 121 of the collector120, wherein the bridges 111 of the emitter have a maximum height h1 in theflow direction and a maximum gauge w1 in a direction orthogonal to the flowdirection. As shown in figure 2, the maximum height h1 is greater than themaximum gauge w1 so as to enable a relatively stable and rigid grid structurethat can carry a relatively large load in the flow direction without a risk ofdeforming or collapsing, and yet have a relatively large open area allowingthe fluid flow. According to this embodiment, the collector 120 may have asimilar relationship between the maximum height hg and the maximum gaugew2 of the bridges 121. The ratio between the maximum height h1, hg and themaximum gauge w1, w2 may e.g. be larger than 1, and more preferably largerthan 2.
    The cross section of the bridges 111 of the emitter 110 may comprise adownstream portion 113 having a tapered shape forming an edge or a point114 facing the collector 120. The tapered shape may e.g. be manifested asan edge or narrow end 114 extending along the downstream portion 113 ofthe bridge 111, or one or several protrusions having a shape conforming toe.g. a tip, needle, pyramid, dome, etc. As the emitter 110 is subjected to anelectric potential difference, there may be an electric field concentration at theedge 114 of the tapered portion 113 which may facilitate or promote emissionof electrons.
    Correspondingly, the portion of the bridges 121 of the collector 120which face the emitter 110 may be provided with a dedicated shape orsurface structure for enhancing collection of the emitted electrons. Thebridges 121 and/orjoints 122 of the collector 120 may e.g. be provided with aconcave surface portion 123 increasing the surface area, and/or a structuredsurface comprising microscopic protrusions and/or recesses 124 increasingthe active surface area. The structures 124 may e.g. be formed by molding,electroplating, surface treatment or by selectively adding and/or removingmaterial by e.g. abrasive blasting, etching, milling, grinding, etc.
    Figure 5a shows an example embodiment wherein the emitter 110 andthe collector 120 are formed by screen printed Pt paste which has beensintered at about 800°C so as to form a grid of bridges having a maximumheight h1, hg of about 100-200 um and a maximum gauge w1, w2 of about 50um. As shown in figure 2b, the collector 120 has been equipped with a micro-structured surface portion 124, facing the emitter 110, by means of micro-blasting, wherein the surface is bombarded with sharp, micrometer-sizedparticles so as to increase the area of the surface.
    The flow units 100 in figures 5b-d are similar to the flow unit 100described with reference to figure 5a. According to figure 5b, the emitter 110is further provided with a tapered upstream portion 117, forming a relativelysharp edge 118 directed towards the fluid flow so as to reduce the flowresistance and hence enhance the flow through the emitter 110. As indicatedin figures 5c and d, the collector 120 may further define channels 126extending through the bridges 121 and/or the joints 122 (not shown) of the 16 grid in order to decrease the flow resistance. The channels 126 may e.g. beeffected by etching, such as e.g. reactive ion etching, wet etching, etc.
    Figure 6a is a top view indicating the outline or contour of a first orsecond electrode, such as e.g. an emitter 110. As shown in figure 6a, theemitter 110 may comprise alignments structures 119, which also can be usedas electric contact portions for enabling electric connection of the emitter 110.The electric contact portions 119 may e.g. comprise protrusions which areintegrally formed with the emitter 110, and which may be adapted to engagewith a corresponding structure of e.g. a support structure 130 and/or stackingstructure 140 (not shown in figure 6a). ln figure 6b, a perspective view of a portion of an emitter 110 is shown,the emitter 110 being similar to the emitter 110 described with reference tofigure 6a. According to figure 6b, the alignment structure 119 is bent to form acontact portion enabling electric connection of the emitter.
    Even though the embodiments described with reference to figures 6aand b relates to an emitter 110, it will be appreciated that the same featuresand advantages e.g. may apply to a collector 120.
    Figures 7a is a cross section of a flow unit according to an embodimentof the invention. The flow unit may be similarly configured as the flow unitsdescribed with reference to figures 1 to 6, and may comprise a first electrode,or emitter 110, and a second electrode, or collector 120, which are arrangedin a stacking structure 140. The emitter 110 and the collector 120 has alateral extension in a plane perpendicular to the direction of the fluid flow, andare arranged spaced apart from each other by a support structure, or gridspacer 130. According to figure 7a, the emitter 110 and the collector 120comprises a respective contact portion 119, 129 arranged at one of the sidesof the flow unit. The respective contact portions 119, 129 may formed asintegrally formed protrusions of the electrodes and be adapted to engage withan edge of the stacking structure. The protruding contact portions 119, 129may hence act as alignment structures during assemblage of the flow units.and/or enable electric contacting of the electrodes 110, 120.
    The stacking structure 140 may comprise alignment structures 142 forfacilitating alignment of the stacked flow units 100. The alignment structures 17 142 of the stacking structure may 140 e.g. comprise a protruding portion thatis adapted to fit into a recess of a corresponding alignment structure of a cellstructure or bottom part. Correspondingly, the alignment structure 140 maycomprise a recess adapted to receive a protruding portion of an alignmentstructure of a |id part.
    Figure 7b shows a similar flow unit 100 as the one described withreference to figure 7a, wherein the emitter 110 and the co|ector 120 eachhave contacts portions 119, 129 arranged at both sides of the flow unit.According to other embodiments, the contact portions 119, 129 may also bearranged such that the contact portions 119 of the emitter 110 are arranged ata side opposite to the side at which the contact portions 129 of the co|ector120 are arranged. This advantageously allows the emitters 110 and collectors120 to be electrically contacted at separate sides of the flow unit 100, whichmay facilitate assemblage and handling of the flow units 100 and/or the array10.
    Figure 8a shows a deformation structure 115 of a grid acting as e.g. anemitter 110 in a flow unit 100 according to embodiments of the presentinvention. The grid comprises bridges 111 and joints 112 in accordance withthe previously described embodiments. As indicated in figure 8a, thedeformation structure 115 is composed of bridges 111 that are curved in aplane normal to the flow direction. The curved shape may e.g. be formedduring manufacturing of the bridges 111, or induced by e.g. thermal stressesoccurring during use of the flow unit 100. The curved shape may alsocomprise a weakened portion, e.g. a portion having a reduced gauge, so asto make it easier to deform upon heat induced stresses. As the material of thegrid may expand with an increasing temperature, the bridges 111 of thedeformation structure 126 may be compressed by compressive forces actingin the length direction of the bridges 111. By length direction should beunderstood the direction of extension between a first joint and a second joint.Thereby the lateral expansion of the grid may be absorbed by the deformationstructure 115 and thermally induced stresses reduced so that the emitter 110other than the deformation structure 115 may keep its original shape despitethermal expansion. lt should however be understood that the forces acting on 18 the bridges 111 of the deformation structure 115 also, or alternatively, may becaused by e.g. a torsional moment, or torque, acting on the structure.
    Figure 8b shows a similar deformation structure 125 as described withreference to figure 8a, wherein the deformation structure 125 is formed ofbridges 121 of a co|ector 120 of a flow unit 100 according to an embodiment.lt will however be understood that the flow unit 100 may be provided withdeformation structures 115, 125 arranged in any one, or several, of theemitter 110, the co|ector 120, and the support structure 130.
    The deformation structure 115, 125 may be provided in an emitter 110and/or co|ector 120 that is attached to a support structure 130, wherein in thesupport structure 130 may have a coefficient of thermal expansion (CTE) thatdiffers from the CTE(s) of the emitter 110 and/or co|ector 120. ln case theemitter 110 and/or co|ector 120 is/are rigidly attached to the support structure130, the risk for deformations, such as e.g. bending and flexures, anddamages such as fractures, disconnected or loosening joints etc. may bereduced by the deformation structure 115, 125. Thereby, reliability and usefullife of the flow unit 100 may be increased.
    Figure 9 shows a cross section of flow unit 200 comprising a stackedstructure of three first electrodes 110 and three second electrodes 210according to any one of the previously described embodiments. The crosssection is taken along the direction of the flow (indicated by an arrow in figure6) and across a respective bridge 111, 121 of the grids of the electrodes 110,120. A grid spacer 130 is arranged to separate the emitter 110 and theco|ector 120 electrodes from each other in the direction of the flow. Accordingto this embodiment, the emitters 110 and collectors 120 may comprise e.g.Pt, Au, or stainless steel forming e.g. the bulk material or a surface coating.
    The grid spacer 130 may e.g. be formed as a grid supporting theemitters 110 and the collectors 120. As illustrated in figure 9, the grid spacer130 may comprise a peripheral frame of bridges to which the edge portions ofthe emitter 110 and the co|ector 120 are attached by e.g. welding, solderingor gluing. Alternatively, or additionally, the grid spacer 130 may compriseother spacing structures such as pillars or spacers, etc. The grid spacer 130may also comprise one or several spacing members, such as e.g. additional 19 bridges or pillars, supporting the centre portions of the emitter and collector.The grid spacer 130 may also comprise a deformation structure 115, 125 (notshown) similar to the deformation structure described with reference tofigures 8a and b.
    The spacing d of the emitter and collector may be determined by theheight of the bridges of the grid spacer 130, which may hence determine themagnitude of the electric field induced between the emitter 110 and thecollector 120. The distance d between the emitter 110 and the collector 120may e.g. be within the range of 10 um and 1000 um.
    Further, the grid spacer 130 may comprise an alignment structure forfacilitating alignment of the emitters 110 and the collectors 120, and/oralignment of the flow units 100 in the array.
    As shown in figure 9, the emitter(s) 110 and the collector(s) 120 of aflow unit 200 may be connected to an external voltage supply by an electricconnector or terminal 150. ln this manner, an electric potential difference maybe applied between the emitter 110 and collector 120 of the respective flowunits 200. The electric potential difference may induce an electric field whichmay promote the electron emission and impart movement of the fluid betweenand through each of the emitter 110 and collector 120. Further, the electricconnection 150 between the emitters 110 and/or collectors 120 and theexternal power supply may be provided by mechanical features and/or byelectric contact portions 129 (not shown in figure 9). The mechanical featuresmay e.g. be adapted so as to enable the electric connection to be formed bye.g. dispensing or screen printing, followed by e.g. sintering or welding.Advantageously, several or all of the flow units 200 can be connected in thesame manufacturing step.
    Figure 10a and b shows, as a function oftime t, an electric current iprovided to the emitter 110 of a flow unit 100 according to any one of theprevious embodiments. ln figure 10a, a positive current is applied andmaintained for a first time period, and then removed. After a second timeperiod the current supply is switched on again, thus forming a second pulse.Repeating this procedure can reduce the space charges that may be presentin the fluid and may also allow any ionized particles to recombine.
    To further improve relaxation, a pulse-reverse current may beintroduced between the pulses described with reference to figure 10a. Anexample of such process is shown in figure 10b, wherein the positive pulsesare separated by negative pulses. As shown in figure 10b, the negativepulses may have a larger absolute value than the positive pulses, but last fora shorter period of time so as to enable an overall positive flow. Thisprocedure of separating the positive pulses by reverse pulses mayadvantageously improve relaxation, possibly to remove contaminants of theemitter 110 and/or collector 120.
    The above described pulses may be applied simultaneously to severalflow units 100 of the array 10, or selectively over time according to apredetermined schedule.
    From a design point of view, it is an advantage to confine chargedparticles, such as e.g. ions, between a portion of a bridge 111 and/orjoint 112of the emitter 110 and a corresponding portion of a bridge 121 and/orjoint122 of the collector 120. Outside this volume, i.e. between the open portionsof the respective grid, the charged ions may have a limited effect on thepumping action. The time duration of the positive pulses may be selectedsuch that negatively charged ions, created at the emitter, may just reach thecollector 120. Hence, if the time duration is sufficiently short, the spreading ofunwanted ions into the liquid loop may be limited. This time length can becalculated from the ion mobility, where a range from 2><10'8 to 2><10'7 mZ/Vs isknown form the prior art. For a pump having an electrode spacing of 100 um,this may correspond to pulse duration of around 1 ms. The zero or negativepulse may advantageously be sufficiently long to allow recombination of ionsor charged particles.
    As outlined above, the method for controlling the flow of a fluid asillustrated by figures 10a and 10b may be embodied as computer-executableinstructions distributed and used in the form of a computer-program productincluding a computer-readable medium storing such instructions. By way ofexample, computer-readable media may comprise computer storage mediaand communication media. As is well known to a person skilled in the art,computer storage media includes both volatile and non-volatile, removable 21 and non-removable media implemented in any method or technology forstorage of information such as computer readable instructions, datastructures, program modules or other data. Computer storage media (or non-transitory media) includes, but is not limited to, RAM, ROM, EEPROM, flashmemory or other memory technology, CD-ROM, digital versatile disks (DVD)or other optical disk storage, magnetic cassettes, magnetic tape, magneticdisk storage or other magnetic storage devices. Further, it is known to theskilled person that communication media (or transitory media) typicallyembodies computer readable instructions, data structures, program modulesor other data in a modulated data signal such as a carrier wave or othertransport mechanism and includes any information delivery media.
    权利要求:
    Claims (20)
    [1] 1. An array (10) of flow units (100) arranged to have a lateral extension ina common lateral plane, wherein each flow unit is adapted to control arespective flow of a fluid a in a direction intersecting the common lateralplane, each flow unit comprising: a first electrode (110); and a second electrode (120) offset from the first electrode in adownstream direction of the flow of the fluid, the electrodes being connectableto a voltage source; wherein the first electrode comprises bridges (111) and joints (112) forming agrid structure, which is arranged to allow the fluid to flow through the firstelectrode; and at least a portion of at least one of the bridges has a maximum height(h1) in a direction parallel to a direction of the flow and a maximum gauge (w1)in a direction orthogonal to the direction of the flow, wherein said maximumheight is larger than said maximum gauge; and wherein a downstream side (D) of a first one the flow units is influid communication with an upstream side (U) of a second one of the flowunits so as to allow a flow offluid to pass through said first and second one ofthe flow units.
    [2] 2. The array according to claim 1, wherein said at least one of the bridgeshas a portion with a substantially uniform cross section and comprises atapered portion (113) having a cross section forming an edge and/or tip (114)facing the second electrode.
    [3] 3. The array according to claim 1 or 2, wherein said at least one of thebridges comprises a tapered portion (117) having a cross section forming an edge and/or tip (118) facing away from the second electrode.
    [4] 4. The array according to any one of the preceding claims, wherein: 23 the second electrode comprises bridges (121) and joints (122) forming a grid structure, which is arranged to allow the fluid to flow through thesecond electrode, and a least a portion of at least one of the bridges has amaximum height (hg) in a direction parallel to the direction of the flow and amaximum gauge (wg) in a direction orthogonal to the direction of the flow,wherein said maximum height is larger than said maximum gauge.
    [5] 5. The array according to claim 4, wherein the second electrodecomprises a surface portion facing the first electrode and being provided withmicrostructures (124) for increasing the area of the surface portion.
    [6] 6. The array according to claim 4 or 5, wherein the second electrodecomprises a concave surface portion (123) facing the first electrode.
    [7] 7. The array according to any one of claims 4 to 6, wherein at least one ofthe bridges and/orjoints of the second electrode comprise a channel (126)adapted to allow the fluid to flow through said channel.
    [8] 8. The array according to any one of the preceding claims, wherein, for atleast one of the fluid units, an open area of the first electrode is smaller thanan open area of the second electrode.
    [9] 9. The array according to any one of claims 1-7, wherein, for at least oneof the fluid units, an open area of the first electrode is larger than an openarea of the second electrode. 10.least one of the fluid units, an open area of the first and/or second electrode is The array according to any one of the preceding claims, wherein, for at formed of a sum of open areas of a plurality of through holes. 11. The array according to claim 10, wherein said plurality of through holesare arranged in a first surface distribution on the first electrode and a second 24 surface distribution on the second electrode, said first and seconddistributions being different. 12. The array according to any one of claims 1 to 3, wherein: the second electrode is formed as a plate extending in a planeintersecting the direction of the flow of the fluid and comprising a through-holeadapted to allow the fluid to flow through the second electrode. 13.flow unit further comprising a support structure (130) separating the second The array according to any one of the preceding claims, wherein each electrode from the first electrode in the direction of the flow. 14.least one of the first electrode, the second electrode and the support structure The array according to any one of the preceding claims, wherein at comprises a deformation structure (115, 125) arranged to deform in a planeorthogonal to the direction of the flow to absorb thermally induced stress inthe first electrode, the second electrode or the support structure, respectively. 15.least one of the bridges being curved in the plane orthogonal to the direction The array according to claim 14, wherein said structure is formed of at of the flow. 16.downstream side of each flow unit, respectively, is facing the same direction. The array according to any one of the preceding claims, wherein the 17.downstream sides of two neighbouring flow units, respectively, are facing The array according to any one of claims 1 to 15, wherein the opposite directions. 18.least one of the flow units comprises a stack of a plurality of first and/or The array according to any one of the preceding claims, wherein at second electrodes arranged above each other in the direction of the flow ofthe fluid. 19. A method for controlling the a flow of a fluid through an array of flowunits, comprising: providing an array (10) of flow units according to any one of claims 1 to20; providing a fluid contacting the first electrode (110) of at least one ofthe flow units; andapplying an electric potential difference between the first electrode and the second electrode (120) of said flow unit. 21. The method according to claim 19, further comprising the step ofvarying the electric potential difference as a function oftime.
    类似技术:
    公开号 | 公开日 | 专利标题
    SE1550716A1|2016-12-04|Microfluidic array
    US9955611B2|2018-04-24|Pressure structure and pressure unit
    KR20150142797A|2015-12-23|Fuel cell separator, and fuel cell comprising the same
    US10629919B2|2020-04-21|Separating plate, method for manufacturing same, and fuel cell stack comprising same
    TWI662578B|2019-06-11|Microfluidic device
    JP6794456B2|2020-12-02|Electrohydrodynamic control device
    JP6656999B2|2020-03-04|Porous separator for fuel cell
    JP6806320B2|2021-01-06|Separation plate and fuel cell stack including it
    US10930941B2|2021-02-23|Separator, and fuel cell stack comprising the same
    KR101756037B1|2017-07-10|Fuel cell separator, and fuel cell comprising the same
    CN107924895B|2021-05-11|Microfluid fan
    CN107004871B|2020-06-02|Flow member and bipolar plate
    同族专利:
    公开号 | 公开日
    EP3304589A4|2019-08-21|
    WO2016195570A1|2016-12-08|
    ES2862904T3|2021-10-08|
    EP3304589A1|2018-04-11|
    US20180166360A1|2018-06-14|
    US10943849B2|2021-03-09|
    EP3304589B1|2020-12-16|
    SE541352C2|2019-08-13|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    WO2017127017A1|2016-01-20|2017-07-27|Apr Technologies Ab|Electrohydrodynamic control device|JPH0427906B2|1983-12-20|1992-05-13|Nippon Jidosha Buhin Sogo Kenkyusho Kk|
    DE3925749C1|1989-08-03|1990-10-31|Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung Ev, 8000 Muenchen, De|
    US5686789A|1995-03-14|1997-11-11|Osram Sylvania Inc.|Discharge device having cathode with micro hollow array|
    US5632876A|1995-06-06|1997-05-27|David Sarnoff Research Center, Inc.|Apparatus and methods for controlling fluid flow in microchannels|
    AU3181999A|1998-03-30|1999-10-18|Igor Ivakhnenko|Fiber heat sink and fiber heat exchanger|
    JP3941537B2|2001-02-28|2007-07-04|ソニー株式会社|Heat transport equipment|
    US20040091392A1|2002-08-09|2004-05-13|Mcbride Sterling Eduard|Method and apparatus for employing a tunable microfluidic device for optical switching, filtering and assaying of biological samples|
    TW559460U|2002-12-12|2003-10-21|Ind Tech Res Inst|Enhanced heat conductance structure configured with electrodes|
    US7316543B2|2003-05-30|2008-01-08|The Board Of Trustees Of The Leland Stanford Junior University|Electroosmotic micropump with planar features|
    KR20070108880A|2005-01-24|2007-11-13|손 마이크로 테크놀로지스, 인코포레이티드|Electro-hydrodynamic pump and cooling apparatus comprising an electro-hydrodynamic pump|
    JP2006302888A|2005-04-19|2006-11-02|Ngk Insulators Ltd|Power supply member and heating device|
    US7571618B2|2005-05-10|2009-08-11|University Of Maryland|Compact heat exchanging device based on microfabricated heat transfer surfaces|
    US20070188090A1|2006-02-15|2007-08-16|Matsushita Toshiba Picture Display Co., Ltd.|Field-emission electron source apparatus|
    US20080060794A1|2006-09-12|2008-03-13|Neng Tyi Precision Industries Co., Ltd.|Heat sink device generating an ionic wind|
    KR100763934B1|2006-11-20|2007-10-05|삼성전자주식회사|Electrohydrodynamic micropump and method of operating the same|
    KR20090107548A|2007-01-23|2009-10-13|벤티바, 인코포레이티드|Contoured electrodes for an electrostatic gas pump|
    JP5085978B2|2007-05-22|2012-11-28|和幸 三井|Electric response fluid pump|
    US20090321056A1|2008-03-11|2009-12-31|Tessera, Inc.|Multi-stage electrohydrodynamic fluid accelerator apparatus|
    US8522570B2|2008-06-13|2013-09-03|Oracle America, Inc.|Integrated circuit chip cooling using magnetohydrodynamics and recycled power|
    US8466624B2|2008-09-03|2013-06-18|Tessera, Inc.|Electrohydrodynamic fluid accelerator device with collector electrode exhibiting curved leading edge profile|
    US8411435B2|2008-11-10|2013-04-02|Tessera, Inc.|Electrohydrodynamic fluid accelerator with heat transfer surfaces operable as collector electrode|
    US20110116206A1|2009-11-16|2011-05-19|Mentornics, Inc.|Cooling of electronic components using self-propelled ionic wind|
    US20110149252A1|2009-12-21|2011-06-23|Matthew Keith Schwiebert|Electrohydrodynamic Air Mover Performance|
    JP5636555B2|2012-04-02|2014-12-10|株式会社メトラン|Pump unit, breathing assistance device|
    CN103839905B|2014-01-17|2016-10-05|华南理工大学|There is silicon substrate microchannel heat exchanger and the manufacture method thereof of electrohydrodynamic Micropump|JP6190349B2|2013-12-05|2017-08-30|株式会社神戸製鋼所|Heat exchanger|
    CN108461460B|2017-12-15|2020-02-21|天津津航计算技术研究所|Two-phase separation microchannel heat sink|
    US10431524B1|2018-04-23|2019-10-01|Asia Vital Components Co., Ltd.|Water cooling module|
    EP3588667A1|2018-06-25|2020-01-01|APR Technologies AB|Immersion cooling of battery device|
    FR3097094A1|2019-06-06|2020-12-11|Valeo Siemens Eautomotive France Sas|Active cooling circuit for electrical equipment|
    SE1951280A1|2019-11-08|2021-05-09|Apr Tech Ab|Electrohydrodynamics system and method|
    CN111002856A|2019-12-17|2020-04-14|重庆国翰能源发展有限公司|High-power quick-witted liquid cooling circulation system that charges|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1550716A|SE541352C2|2015-06-03|2015-06-03|Microfluidic array|SE1550716A| SE541352C2|2015-06-03|2015-06-03|Microfluidic array|
    US15/579,438| US10943849B2|2015-06-03|2016-05-20|Microfluidic array|
    EP16803850.3A| EP3304589B1|2015-06-03|2016-05-20|Microfluidic array|
    ES16803850T| ES2862904T3|2015-06-03|2016-05-20|Microfluidic matrix|
    PCT/SE2016/050465| WO2016195570A1|2015-06-03|2016-05-20|Microfluidic array|
    [返回顶部]