Abstract:
The present invention is directed to methods for forming a catalytic coating on a substrate. The method comprises preparing a catalytic fluid and dispensing the catalytic fluid onto a substrate by using a direct writing instrument. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that is will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 10/201,828, filed Jul. 24, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates generally to fuel cells and particularly, to methods for forming a catalytic coating on a substrate.  
         SUMMARY OF THE INVENTION  
         [0003]    According to the present invention, methods for forming a catalytic coating on a substrate are provided.  
           [0004]    In one embodiment, a method of forming a catalytic coating on a substrate is provided. According to the method, a catalytic fluid is prepared and dispensed onto a substrate using a direct writing instrument that has been programmed to dispense the catalytic fluid onto the substrate in a pattern that forms a catalytic coating on the first side of the substrate.  
           [0005]    In another embodiment, a method of forming a catalytic coating on a substrate is provided. According to the method, a catalytic fluid is dispensed onto a substrate using a direct writing instrument that has been programmed to dispense the catalytic fluid onto the substrate in a pattern that forms a first coating on a first side of the substrate. A noncatalytic fluid is also dispensed onto the first side of the substrate using the same direct writing instrument in a shadow pattern of the first coating to form a second coating on the first side of the substrate.  
           [0006]    In still another embodiment, a method of preparing an electrolyte membrane for use in a membrane electrode assembly is provided. According to the method a catalytic fluid is dispensed onto an intermediate material using a direct writing instrument that has been programmed to dispense the catalytic fluid in a pattern that forms a catalytic coating on the intermediate material. The catalytic coating is then transferred from the intermediate material to an electrolyte membrane.  
           [0007]    In still yet another embodiment, a method of preparing an electrolyte membrane for use in a membrane electrode assembly is provided. According to the method, a catalytic fluid is dispensed onto an electrolyte material using a direct writing instrument.  
           [0008]    In still another embodiment, a method of preparing a diffusion media for use in a fuel cell is provided. According to the method, a catalytic fluid is dispensed onto a diffusion media using a direct writing instrument.  
           [0009]    In yet another embodiment, a system for preparing a membrane electrode assembly is provided. The system comprises first and second coating stations, first and second drying stations, a cutting station and a carrier device. The first coating station comprises a first substrate holding device, and at least one coating head for applying a coating to a first side of a substrate. The second coating station comprises a second substrate holding device, and at least one coating head for applying a coating to a second side of a substrate. The carrier device is configured to carry the substrate from station to station.  
           [0010]    These and other features and advantages of the invention will be more fully understood from the following description of the invention taken together with the accompanying drawings. It is noted that the scope of the claims is defined by the recitations therein and not by the specific discussion of features and advantages set forth in the present description. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The following detailed description can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:  
         [0012]    [0012]FIG. 1 is a schematic illustration of a fuel cell system.  
         [0013]    [0013]FIG. 2 is a schematic illustration of a vehicle including a fuel cell system.  
         [0014]    [0014]FIG. 3 is a schematic illustration of a fuel cell stack employing two fuel cells.  
         [0015]    [0015]FIG. 4 is an exploded view of a membrane electrode assembly.  
         [0016]    [0016]FIG. 5 is a block diagram of a direct writing instrument according to one embodiment of the present invention.  
         [0017]    [0017]FIG. 6 is an illustration of the nozzle and nozzle tip of a direct writing instrument forming a pattern on a substrate according to one embodiment of the present invention.  
         [0018]    [0018]FIG. 7 is an illustration of a pattern according to one embodiment of the present invention.  
         [0019]    [0019]FIG. 8 is an illustration of a pattern according to one embodiment of the present invention.  
         [0020]    [0020]FIG. 9 is an illustration of a membrane electrode assembly according to one embodiment of the present invention.  
         [0021]    [0021]FIG. 10 is an illustration of one side of a membrane electrode assembly having a first and a second coating according to one embodiment of the present invention.  
         [0022]    [0022]FIG. 11 is an illustration of a membrane electrode assembly system according to one embodiment of the present invention.  
         [0023]    [0023]FIG. 12 a  is an illustration of an ultrasonic probe applied above to a substrate.  
         [0024]    [0024]FIG. 12 b  is an illustration of an ultrasonic probe applied below a substrate. 
     
    
       [0025]    Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.  
       DETAILED DESCRIPTION  
       [0026]    Referring to FIG. 1, a fuel cell system  2  for automotive applications is shown. It is to be appreciated, however, that other fuel cell system applications, such as for example, in the area of residential systems, may benefit from the present invention. As illustrated, the fuel cell system  2  includes a primary reactor  4 , a water-gas shift reactor  6 , a preferential oxidation (PrOx) reactor  7 , at least one heat exchanger  8 , a tail gas combustor  9 , and a fuel cell  10 . An explanation of these components and the operation of the fuel cell system  2  follows. It is to be appreciated that while one particular fuel cell system design is described, the present invention may be applicable to any fuel cell system design where catalytic coatings are utilized.  
         [0027]    In the primary reactor  4  a hydrocarbon fuel, such as gasoline or methane, air and steam are mixed, heated, and delivered to a catalyzed substrate. Here, the mixture is split into hydrogen, carbon monoxide, and other process gases, as the mixture flows over and reacts with the catalyst, forming a hydrogen-rich stream. Suitable catalyst materials include platinum group metals and base metals. This reaction occurs at temperatures in the range between about 700° C. and about 800° C.  
         [0028]    The hydrogen-rich stream leaving the primary reactor  4  enters the water-gas shift reactor  6 . Oxygen from water is used to convert carbon monoxide to carbon dioxide leaving additional hydrogen and increasing system efficiency. Operating temperatures of the shift reactor  6  range from about 250° C. to about 450° C. The hydrogen-rich stream leaving the shift reactor  6  then enters into the PrOx reactor  7 , where the final cleanup of carbon monoxide takes place before the hydrogen-rich stream enters the fuel cell stack. Air is added to supply the oxygen needed to convert most of the remaining carbon monoxide to carbon dioxide, leaving additional hydrogen behind. Operating temperatures in the PrOx reactor  7  range from about 80° C. to about 200° C. Combined, the three reactors extract hydrogen from the fuel, and reduce or eliminate harmful emissions.  
         [0029]    The three reactors are quickly heated to their operating temperatures before the fuel is introduced. The heat exchanger  8  is therefore used to regulate the various temperatures throughout the fuel cell system  2 . Typically, the heat exchanger  8  preheats the steam and air streams before entering into the primary reactor  4 . The waste heat from the hydrogen-rich stream exits the primary reactor  4 .  
         [0030]    The hydrogen-rich stream then is supplied to the fuel cell  10 , which may comprise a stack of fuel cells, and reacted with oxygen from a source, such as air, to produce electricity, which can be used to power a load  11 . The small quantities of unused hydrogen that leave the fuel cell  10  are consumed in the tail gas combustor  9  which operates at a temperature between about 300° C. to about 800° C. It is to be appreciated that while a series of reactors is described as being the hydrogen source, any hydrogen source is applicable to the present invention.  
         [0031]    Referring to FIG. 2, a vehicle is shown having a vehicle body  90 , and a fuel cell system having a fuel cell processor  4  and a fuel cell stack  15 . A discussion of the present invention as embodied in a fuel cell stack and a fuel cell, is provided hereafter in reference to FIGS.  3 - 9 .  
         [0032]    [0032]FIG. 3 depicts a fuel cell stack  15  having a pair of membrane-electrode-assemblies (MEAs)  20  and  22  separated from each other by an electrically conductive fluid distribution plate  30 . Plate  30  serves as a bi-polar plate having a plurality of fluid flow channels  35 ,  37  for distributing fuel and oxidant gases to the MEAs  20  and  22 . By “fluid flow channel” we mean a path, region, area, or any domain on the plate that is used to transport fluid in, out, along, or through at least a portion of the plate. The MEAs  20  and  22 , and plate  30 , are stacked together between clamping plates  40  and  42 , and electrically conductive fluid distribution plates  32  and  34 . Plates  32  and  34  serve as end plates having only one side containing channels  36  and  38 , respectively, for distributing fuel and oxidant gases to the MEAs  20  and  22 , as opposed to both sides of the plate.  
         [0033]    Nonconductive gaskets  50 ,  52 ,  54 , and  56  provide seals and electrical insulation between the several components of the fuel cell stack. Gas permeable diffusion media material  60 ,  62 ,  64 , and  66  press up against the electrode faces of the MEAs  20  and  22 . Plates  32  and  34  press up against the diffusion media material  60  and  66  respectively, while the plate  30  presses up against the diffusion media material  62  on the anode face of MEA  20 , and against diffusion media material  64  on the cathode face of MEA  22 .  
         [0034]    An oxidizing fluid, such as O 2 , is supplied to the cathode side of the fuel cell stack from storage tank  70  via appropriate supply plumbing  86 . While the oxidizing fluid is being supplied to the cathode side, a reducing fluid, such as H 2 , is supplied to the anode side of the fuel cell from storage tank  72 , via appropriate supply plumbing  88 . The reducing fluid may be derived from a mixture of methane or gasoline, air, and water according to a reforming process in the presence of a catalyst. Exhaust plumbing (not shown) for both the H 2  and O 2 /air sides of the MEAs will also be provided. Additional plumbing  80 ,  82 , and  84  is provided for supplying liquid coolant to the plate  30  and plates  32  and  34 . Appropriate plumbing for exhausting coolant from the plates  30 ,  32 , and  34  is also provided, but not shown.  
         [0035]    Referring to FIG. 4, an exploded view of membrane electrode assembly  20  is shown comprising an anode layer  102 , a cathode layer  106 , and an electrolyte  104  separating the anode layer  102  and the cathode layer  106 . Membrane electrode assembly  20  and membrane electrode assembly  22  are identical. For simplicity purposes, the present invention is being described in relation to membrane electrode assembly  20 , it is to be appreciated that the present invention can be applied to membrane electrode assembly  22  and membrane electrode assemblies in general.  
         [0036]    Generally, the anode layer  102  and the cathode layer  106  are coatings formed in such a manner that they are in intimate contact with the electrolyte material once the fuel cell  10  (FIG. 1) is assembled. Methods of forming a catalytic coating on a substrate will now be explained. The first step in the method is to prepare a catalytic fluid. Generally, the catalytic fluid is a solution of ionomer, precious metal catalyst, solvent and water. A solution of ionomer and precious metal catalyst istypically prepared on a support in a mixture of the solvent and water. Different amounts maybe used depending on the desired viscosity of the catalytic fluid and the carbon to ionomer ratio desired. Generally, between about 30 grams and about 250 grams of solvent is mixed with between about 130 grams and about 200 grams of water and between about 5 grams and about 30 grams of ionomer and between about 5 grams and about 20 grams of precious metal catalyst are mixed together to form a solution. The support used for the solution of the ionomer and precious metal catalyst is typically carbon having a high surface area. The amount of carbon is generally between about 5 grams and about 20 grams. More specifically, the catalytic solution comprises about 4% by wt. of precious metal, about 4% by wt. of ionomer, about 4% by wt. of carbon, about 28% by wt. of water and about 60% by wt. of solvent.  
         [0037]    The precious metal catalyst can be selected from platinum, platinum alloys and combinations thereof. The solvent can be selected from isopropyl alcohol, ethanol, butanol, and combinations thereof. The catalytic fluid can be prepared to exhibit a viscosity between about 70 cp and about 2000 cp, and more specifically, a viscosity of about 300 cp. The catalytic fluid can be prepared to exhibit an ionomer to carbon ratio of about 0.8 to about 2.0. The amount of solid in the solution is between about 8% by wt. and about 20% by wt., and more specifically about 12% by wt.  
         [0038]    Once the catalytic fluid is prepared, it is dispensed onto a substrate  110  using a direct writing instrument. By “direct writing,” we mean depositing fluid directly onto a surface of a substrate in a pattern defined by the motion of the instrument, the motion of the substrate, or both. In direct writing, the deposited fluid forms a relatively well-defined line or area of deposition, relative to the overall dimensions of the deposition surface or the deposited pattern. Relative motion between the fluid source and the deposition substrate increases the extent of the well-defined line or area of deposition to create a more extensive deposited pattern.  
         [0039]    [0039]FIG. 5 shows one embodiment of a direct writing instrument according to the present invention. The direct writing instrument  150  comprises a design system  152 , a writing system controller  154  and a writing system  160 . The writing system  160  further comprises a fluid dispensing system  168 , a nozzle  166 , a nozzle tip  167 , and a substrate holding device  162 . The design system  152  stores a pattern that is drawn on a graphic display. The design system  152  electronically communicates with the writing system controller  154  such that the writing system controller  154  knows the pattern and controls the writing system  160  in a manner that allows the writing system  160  to draw the pattern stored in the design system  152  on the substrate  110 .  
         [0040]    Referring to FIGS. 5 and 6, the writing system controller  154  electronically communicates with the fluid dispensing system  168  and the substrate holding device  162 . Therefore, the writing system controller  154  allows the fluid dispensing system  168  to deliver the catalytic fluid to the nozzle  166 . The catalytic fluid is dispensed through the nozzle tip  167  onto the substrate  110 . The catalytic fluid may be carried to the fluid dispensing system  168  by any suitable means.  
         [0041]    The writing system controller  154  allows the substrate holding device  162  to move in a variety of positions that form the pattern  170  stored in the design system. By moving the substrate holding device  167  in various positions, the substrate  110  is accurately placed under the nozzle tip  167  while the catalytic fluid is being dispensed onto the substrate  110 . In this manner, the nozzle  166  and the nozzle tip  167  do not move, but remain stationary while dispensing the catalytic fluid. Also, the pressure of the nozzle tip  167  is controlled such that no direct surface contact with the substrate  110  occurs. In another embodiment, the substrate holding device  162  remains stationary while the nozzle  166  and nozzle tip  167  move over the substrate  110  while dispensing the catalytic fluid.  
         [0042]    The design system  152  may be any computer-aided-design (CAD) interface that allows the design of a pattern via a graphics editor, digitizing tablet, or interface through a generic photo plotter interface. The nozzle  166  may be heated to allow the catalytic fluid to remain in a molten state so that it will easily dispense through the nozzle tip  167 . The width and thickness of the line, or lines,  169  forming the pattern  170  depend upon the nozzle tip diameter, the volumetric flowrate of the fluid to the nozzle tip, and the writing speed. The writing speed may vary depending upon the movement of the substrate  110  relative to the nozzle tip  167  or the movement of the nozzle tip  167  the substrate. Thus, the line thickness can be determined by the following equation: t=Q/(Vw), wherein Q=volumetric flow rate, w=line width, V=writing speed, and t=the line thickness. Viscosity of the fluid determines how close the line width is to the nozzle tip diameter, i.e. a low viscosity fluid will flow, therefore the line width is greater than the nozzle tip diameter while a high viscosity fluid does not flow as well, therefore, the line width is about equivalent to the nozzle tip diameter.  
         [0043]    The nozzle tip  167  can produce at least one line having a width between about 0.002 inches to about 0.25 inches. If more than one line is desired, a space up to about 0.0005 inches can be made between the lines. The line thickness can be up to 0.010 inches per pass with the nozzle. The line can have tolerances of about +/−0.000025 inches. The instrument writes at a speed between about 0.05 inches per second to about 5.0 inches per second. The instrument  150  operates on a minimum grid pitch of 0.0005 inches.  
         [0044]    The pattern  170  formed on the substrate  110  can be selected from a rectangular spiral, a straight line, a series of lines, or any suitable geometric pattern. An example of a pattern  170  having a line, or series of lines,  169  forming a rectangular spiral is shown in FIG. 7. The spacing between adjacent lines can be adjusted. For the case of no spacing between adjacent lines, the pattern  170  would form a single continuous coating over the entire substrate  110 . FIG. 8 shows a pattern  170  having a series of lines  169  formed by a direct writing instrument according to one embodiment of the present invention.  
         [0045]    Typically, after the pattern is formed on the substrate  110 , the substrate  110  is dried by a heat source having a temperature between about 70° C. and about 100 ° C. The pattern, once dried, forms a coating on the substrate  110 . The heat source is selected from an infrared heater, convective oven, heated jets, or any other suitable heating device for removing solvent from the catalytic fluid. The substrate  110  is subjected to the heat for a time sufficient to evaporate primarily all of the solvent in the coating, more specifically between about 2 minutes to about 10 minutes.  
         [0046]    The method of making the membrane electrode assembly may vary depending upon the substrate upon which the catalytic fluid is dispensed. The substrate is generally selected from an intermediate material, a diffusion media material, or electrolyte membrane material.  
         [0047]    If the substrate is an intermediate material then the catalytic solution is deposited in the programmed pattern onto the intermediate material by a direct writing instrument. The coated substrate is then dried at a temperature between about 70° C. to about 100° C., typically in an oven. After the substrate is dry, a secondary ionomer solution may be applied to the substrate and dried. The application of the ionomer solution is typically performed by spraying. The coating formed on the intermediate material is then transferred to an electrolyte membrane material typically using a hot-press transfer. In one embodiment of the present invention, a second fluid that is nonreactive may be applied onto the intermediate material after the deposition of catalytic fluid or simultaneously with the catalytic fluid. The coating formed on the intermediate material is then transferred to an electrolyte membrane material. The intermediate material is typically selected from polytetrafluoroethlyene, ethylene tetrafluoroethylene, or variations thereof. The noncatalytic fluid is described in detail below.  
         [0048]    A second substrate that can be used in the present invention is a diffusion media material. If the diffusion media material is used, the catalytic fluid is prepared as described above and then deposited onto the diffusion media material using a direct writing instrument as described above in any of the patterns described above. The coated diffusion media material is then subjected to drying. The diffusion media material can be any suitable diffusion media material used in fuel cells. In one embodiment of the present invention, a second fluid that is noncatalytic fluid may be applied onto the diffusion media material after the deposition of catalytic fluid or simultaneously with the catalytic fluid.  
         [0049]    As an alternative, the substrate can be the electrolyte membrane material. Therefore, the catalytic fluid is deposited directly onto the electrolyte membrane material. The coated electrolyte membrane material is then subjected to drying. The electrolyte membrane material may be a proton conducting membrane, such as perfluorinated sulfonic acid, or some variation thereof.  
         [0050]    In one embodiment of the present invention, a second fluid that is noncatalytic may be applied onto the electrolyte membrane material after the deposition of catalytic fluid or simultaneously with the catalytic fluid, thereby forming a catalytic coating and a noncatalytic coating on one side of the electrolyte membrane material. Referring to FIG. 9, an MEA  180  having both the catalytic coating  182  and the noncatalytic coating  184  is shown. The noncatalytic fluid forms a noncatalytic coating  184  when dried. The noncatalytic fluid is deposited in such a manner that it “shadows” the catalytic fluid. By “shadow” we mean that one fluid follows the outline of the other fluid such that one fluid is not deposited directly over the other fluid. When used, the noncatalytic fluid fills in the spaces between the lines of catalytic fluid on the substrate  202 .  
         [0051]    The noncatalytic fluid comprises a material that exhibits a high electrical conductivity, a high thermal conductivity, and low porosity. The noncatalytic fluid may be a carbonaceous material, carbon black, graphite, or combinations thereof. The carbonaeous material may also comprise a polymeric binder such as polyimide, polyethylene terephthalate, and combinations thereof. The viscosity of the noncatalytic fluid can be adjusted as appropriate to readily fill regions between catalytic coatings illustrated in FIG. 9. Generally, the noncatalytic fluid exhibits a viscosity between about 300 cp and about 10,000 cp. The noncatalytic fluid can be dispensed such that it is thicker on the substrate than the catalytic fluid.  
         [0052]    Referring to FIG. 10, one embodiment of an MEA  180  having a catalytic coating  182  and a noncatalytic coating  184  is shown. The catalytic fluid can be deposited in a pattern that allows the lines of the catalytic coating  182  to align with channels in a flow field plate. The noncatalytic fluid can then be deposited in pattern that allows the lines of the noncatalytic coating  184  to align with the lands  186  in the flow field plate. This can be accomplished on both sides of the substrate  202  such that the catalytic fluid forming the catalytic anode coating  182   a  is aligned with the channels  185  of the anode flow field plate. Therefore, the noncatalytic coating  184  lies between the spaces of the catalytic fluid or catalytic anode coating  182   a , forming a noncatalytic coating  184  on the lands  186  of the anode flow field plate. Similarly on the cathode side of the MEA  180 , the catalytic fluid forming the catalytic cathode coating  182   b  is aligned with the channels  187  of the cathode flow field plate. Thus, the noncatalytic fluid is deposited between the spaces of the catalytic fluid or catalytic cathode coating  182   b , forming a noncatalytic coating  184  on the lands  186  of the cathode flow field plate. The catalytic anode coating  182   a  and catalytic cathode coating  182   b  are shown to be narrower than the opening of the channels  185 ,  187 , respectively. It is to be appreciated that the catalytic anode coating  182   a  and the catalytic cathode coating  182   b  may be formed such that the coating is as wide as channels  185 ,  817  or wider. This concept is explained in more detail in application Ser. No. 10/201,828.  
         [0053]    When the noncatalytic fluid is used, to form a noncatalytic coating  184  on the substrate  202  and the substrate is an electrolyte membrane material, the fuel cell may eliminate the use of the diffusion media material in a fuel cell. Thus, the resulting fuel cell would be identical to the fuel cell  10  shown in FIG. 3, however, the diffusion media  60 ,  62 ,  64 , and  66  would not be present.  
         [0054]    Referring to FIG. 11, an MEA fabrication system  200  according to one embodiment of the present invention is shown. The system has three primary stations: a first coating station, a second coating station, and a die cutting station. The substrate  202  is placed on a feed roll  212  where the substrate  202  is pulled from station to station by rollers  216 ,  218 ,  224 , and  226 . At the first coating station the substrate  202  is pulled over a first substrate holding device  214 . Once over the first substrate holding device  214 , a nozzle  210   a  dispenses catalytic fluid directly onto the first side  202   a  of the substrate  202 . The catalytic fluid is typically dispensed in the form of a pattern, as described above. The substrate  202  is then pulled to first drying area  215 . The first drying area  215  can be an array of heated jets, an infrared heater, convection oven, or any other suitable device for removing a majority of solvent from the catalytic fluid. The first drying area  215  typically maintains a temperature between about 70° C. and about 100° C. While in first drying area  215  the catalytic fluid dries to the substrate  202  and forms a catalytic coating on the substrate  202 . The catalytic coating may be either an anode coating or a cathode coating.  
         [0055]    Next, the substrate  202  is pulled to a second coating station. In the second coating station, the substrate  202  is pulled over a second substrate holding device  228 . A catalytic fluid is deposited onto the second side  202   b  of the substrate  202 . The catalytic fluid may be dispensed onto the substrate  202  in a manner that forms a pattern as discussed above. While being pulled through first drying area  215 , the substrate  202  is turned in a manner that allows the first side  202   a  of the substrate  202  to face the opposite side such that nozzle  220   a  is placing catalytic fluid on the second side  202   b  of the substrate  202 . After the catalytic fluid is placed onto the second side  202   b  of the substrate  202 , the substrate  202  is pulled to a second drying area  222 . The second drying area  222  can be an array of heated jets, an infrared heater, convection oven, or any other suitable device for removing a majority of solvent from the catalytic fluid. The second drying area  222  typically maintains a temperature between about 70° C. to about 100° C. While in second drying area  222 , the catalytic fluid deposited on the second side  202   b  of the substrate  202  forms a catalytic coating over the substrate  202 . The catalytic coating may be either an anode coating or a cathode coating.  
         [0056]    The substrate  202  is then pulled to a cutting station  230  where the substrate  202  is cut into separate pieces such that each piece of substrate  202  has both an anode coating and a cathode coating. The substrate  202  may be further cut in such a manner as to not interrupt a pattern that may have been formed on the substrate  202  by the fluid.  
         [0057]    As FIG. 11 shows, more than one nozzle  210   a ,  210   b ,  220   a , and  220   b  can be used at each station to deposit more than one fluid onto the substrate  202  at a time. While only two nozzles are shown at each station, it is to be appreciated that an array of nozzles can be present. When more than one fluid is deposited at a time, one fluid may shadow the other fluid. Although the noncatalytic fluid is described above as being the second fluid, it is to be appreciated that the second fluid can be any desired fluid. For example, the second fluid can be a fluid containing a high amount of precious metal that is deposited near the inlet and exit of the MEA. Then a fluid have a lower amount of precious metal can be deposited in the center of the MEA, thereby, alleviating a portion of the durability and mass transfer losses.  
         [0058]    The nozzles  210   a ,  210   b ,  220   a , and  220   b  are typically attached to a direct writing instrument as described above. The fluid is typically dispensed onto the substrate  202  in the form of one of the patterns as described above. The catalytic fluid is prepared as described above. The first and second substrate holding devices  214  and  228  can be vacuum tables or any other suitable device for holding the substrate in place.  
         [0059]    Referring to FIGS. 12 a  and  12   b , an additional step to the method of applying more than one fluid to the substrate is shown. Ultrasonic energy can be applied to assist with coating of the substrate  202 . An ultrasonic probe  250  can be placed over the catalytic fluid  240  and the noncatalytic fluid  242  as the fluids are dispensed from nozzles  210   a  and  210   b  onto the substrate  202 . The ultrasonic probe  250  transmits acoustic energy  251  through the air above the contact line  241  of the catalytic fluid  240  and the noncatalytic fluid  242  as shown in FIG. 12 a . Referring specifically to FIG. 12 b , the ultrasonic probe  250  can be placed below the substrate  202  to transmit acoustic energy  251  through the substrate  202  as the catalytic fluid  240  and the noncatalytic fluid  242  are dispensed from nozzles  210   a  and  210   b . The acoustic energy  251  is transmitted at the contact line  241  of the catalytic fluid  240  and the noncatalytic fluid  242 .  
         [0060]    The acoustic energy  251  is applied continuously to the contact line  241 , such that surface tension at the liquid-liquid interface is continuously lowered at the point of application, thereby enabling better fluid flow and creating a smooth interface between fluids  240  and  242 . It is to be appreciated that while FIGS. 12 a  and  12   b  are shown using nozzles  210   a  and  210   b  which operate at the first coating station, it is to be appreciated that FIGS. 12 a  and  12   b  also show nozzles  220   a  and  220   b  which operate at the second coating station. It is also to be appreciated that the acoustic energy  251  can be used in any suitable method system for making the MEA having two fluids, comprising both a catalytic and noncatalytic fluid, dispensed onto a substrate both a catalytic fluid and a noncatalytic fluid. It is further to be appreciated that while this step is explained using acoustic energy from an ultrasonic probe, any instrument or energy that can relieve surface tension at the liquid-liquid interface can be used.  
         [0061]    While the invention has been described by reference to certain preferred embodiments, it should be understood that numerous changes could be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the disclosed embodiments, but that it have the full scope permitted by the language of the following claims.