|Title of Invention||
A FUEL CELL AND POWER CHIP USING MULTIPLE FUEL CELLS
|Abstract||. A fuel cell comprising: a) a substrate; b) first and second channels for admitting fuel into the a first channel and oxidant into the a second channel; c) a membrane coupled to the substrate and having first and second sides separating the first channel from the second channel; d) a first electrode on the first side of the membrane and a second electrode on the second side of the membrane; e) a catalyst in electrical communication with the membrane sides and the electrodes; and f) a cover made from a gas impermeable material which forms a seal with the membrane.|
|Full Text||FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
THE PATENTS RULES, 2003 COMPLETE SPECIFICATION
[See Section 10; rule 13]
"A FUEL CELL AND POWER CHIP USING MULTIPLE FUEL CELLS"
INTEGRATED FUEL CELL TECHNOLOGIES, INC., of 19 Crosby Drive, Bedford, Massachusetts 01730, United States of America,
The following specification particularly describes the invention and the manner in which it is to be performed:
The present invention relates to a fuel cell and power chip using multiple
The electro-chemical fuel cell is not new. Invented in.1839 by Alexander Grove, it has recently been the subject of extensive development. NASA used its principals in their 1960's space program, but the latest push into this technology is being driven largely by the automotive industry. Daimler-Chrysler and Ford Motor Co. together have invested about $750 million in. a partnership to develop fuel cell systems. As environmental concerns mount and legislation toughens, development of "green" energy sources becomes more justified as a course of action, if not required.
The information age has ushered in the necessity for new ways to examine, process, manage, access and control the information. As the basic technologies and equipment evolve to handle these new requirements, there is a growing need for a smaller, lighter and faster (to refuel/recharge) electrical energy source. Portable computing and communications, in particular, would benefit.greatly from a miniature fuel cell based power source.
SUMMARY OF THE INVENTION .
In accordance with the invention, a method and apparatus is provided which uses a combination of polymers/SAMs (self-assembled monolayers), MEMS (micro electrical mechanical systems), "chemistry-on-a-chip" and semiconductor fabrication techniques to create a scalable array of power cells directly on a
substrate, preferably a semiconductor wafer. These wafers may be "stacked" (i.e. electrically connected in series or parallel, as well as individually programmed to achieve various power (V*I) characteristics and application driven configurations.
One preferred embodiment of the invention is formed by fabricating a plurality of individual fuel cells on a planar semiconductor wafer into which flow channels are formed by etching or other well-known semiconductor processes.) Oxygen is admitted into one side of a channel and hydrogen into the other side; with the two gases being separated by a membrane. Electrodes are formed on opposite sides of the membrane and a catalyst is provided in electrical communication with the electrode and membrane on both sides. Lastly, a gas impermeable cover or lid is attached to the cell.
Preferably, the membrane is a PEM (Proton Exchange Membrane) formed by depositing or otherwise layering a column of polymers into etched channels in the substrate to create a gas tight barrier between the oxygen and hydrogen, which is capable of conveying hydrogen ions formed by the catalyst across the barrier to produce electricity across the contacts and water when the H-ions combine with the oxygen in the other channel.
In addition, a number of fuel cells, can be electrically interconnected and coupled to gas sources on a portion of the same wafer to form a "power chip". Traditional electrical circuitry can be integrated on the wafer along with the chips to provide process monitoring and control functions for the individual cells. Wafers
containing multiple chips (power discs) or multiple cells can then be vertically
stacked upon one another.
A further understanding of the nature and advantages of the invention herein
may be realized with respect to the detailed description which, follows .and the
drawings described below.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other
like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
FIG. 1 is a schematic plan view of a semiconductor fuel cell array in accordance with the invention.
FIG. 2 is a simplified schematic cross-sectional view taken along the lines II- of a fuel cell 12 of the invention.
FIGs. 3(a)-(h) is a schematic sectional process view of the major steps in fabricating a PEM barrier structure 30 of the invention.
FIG. 4 is a cross-sectional schematic view illustrating an alternate cast PEM barrier invention.
FIG. 5 is a sectional view of a PEM structure embodiment.
FIG. 6 is a sectional view of an alternate of the PEM structure.
FIG. 7 is a sectional view of another alternate-PEM structure.
FIG. 8 is a block diagram of circuitry which may be integrated onto a fuel
FIG. 9 is a schematic of the wiring for an integrated control system for the
operation of individual cells or groups of cells.
FIG. 10 is a schematic side view of a manifold system for a power cell.
FIG. 11 is a schematic plan view of a plurality of cells arranged side-by-side
on a wafer to form a power chip and stocked on top of each other to form a power disc.
FIG. 12 is a fragmented side-view of FIG. 11.
DETAILED DESCRIPTION OF THE INVENTION
A description of preferred embodiments of invention follows.
Referring now to FIG. 1, there is shown in plan view a conventional-semiconductor wafer 10 upon which a plurality of semiconductor fuel cells 12 have
been fabricated . A plurality of cells may be electrically interconnected on a wafer
and provided with gases to form; a power chip 15. For simplicity, fuel cells 12 and
chips 15 are not shown to scale in as much as it is contemplated that at least 80
million cells may be formed on a 4"wafer. One such cell is shown in fragmented cross-Section in FIG. 2. In its s simplest Form, each cell 12 consists of a substrate 14, contacts 16A and B, and a conductive polymer base 18 formed on both sides of a first layer 20 (a) of non-conductive layered polymer support structure 20 and in intimate contact with the metal electrical contacts.
A conductive polymer 22 with embedded catalyst particles 28 on both sides of the central structure 20 forms a PEM barrier separating the hydrogen gas on the left side from the oxygen gas on the right side. Etched channels 50B and 50A respectively for admittance of the Oz and Hz gas and a heatsink lid 40 over the cell 12 is also shown in FIG. 2.
FIGs. 3a-3h are a series of schematic sectional views showing the relevant fabrication details of the PEM barrier 30 in several steps. FIG. 3a shows the bottom of a power cell channel which has been etched into the semiconductor substrate 14.
It also shows the contacts 16 which are responsible for conveying the electrons out of the power cell 12 to a power distribution routing and the rest of the circuitry.
These contacts are deposited by well-known photolithographic processes in the semiconductor fabrication process.
FIG. 3b shows the conductive polymer base 18 as it has been applied to the structure. Base 18 is in physical/electrical contact with the contacts 16 and has been adapted to attract the conductive polymer 22 of the step shown in FIG. 3a-3h.
FIG. 3c shows the nonconductive polymer base 20 (a) as it has been applied to the structure. It is positioned between the two conductive polymer base sites 18 and is adapted to attract the nonconductive polymer 20.
FIG. 3d shows a polymer resist 21 as applied to the structure. Resist 21 is responsible for repelling the polymers and preventing their growth in unwanted areas.
FIG. 3e shows the first layer 20B of nonconductive polymer as it has been grown on its base 20A. This is the center material of the PEM barrier. It helps support the thinner outer sides 22 when they are constructed.
FIG. 3f shows the subsequent layers of nonconductive polymer 20 which are laid down, in a layer by layer fashion to form a vertical barrier. This vertical orientation allows for area amplification.
FIG. 3g shows the first layer 22a of conductive polymer grown on its base
This is the outside wall material with catalyst of the PEM barrier.
FIG. 3h shows the subsequent layers of conductive polymer 22 laid down, in a layer by layer fashion on to the structure. FIG. 2 shows the completed structure after removal of the polymer resist layer 21 and the addition of lid 40 and the pre-existing sidewalls 52 left out of FIG. 3a-3h for simplicity. This resist removal may not be necessary if layer 21 was originally the passivation layer of the final step in the semiconductor fabrication process.
Referring now to FIG. 2 again further details of the elements forming the fuel cell 12 will be explained. The protein exchange membrane shown generally at 30 forms a barrier between the fuel H2 and the oxidant °2- The PEM barrier 30 is made up of three parts of two materials. There is the first outside wall 22B, then the center 20, and finally the second outside wall 22C. It is constructed with a center piece 20 of the first material in contact with the two outside walls which are both made of the second material.
The material 20 forming the center piece, is preferably an ionic polymer capable of passing the hydrogen ions (protons) through from the hydrogen side to the oxygen side. It is electrically nonconductive so that it does not, effectively, short out the power cell across the two contacts 16A and 16B. It may be made of Nafion (D or of a material of similar characteristics. An external load 5 as shown in dotted lines may be coupled across the contacts to extract power.
The second material 22, forming the two outside walls, is also a similar ionic polymer capable of passing the hydrogen ions. In addition, it is doped with nano catalyst particles 28 (shown by the dots), such as, platinum/alloy catalyst and is also electrically conductive.
By embedding the catalyst particles 28 into the polymer 22, maximum intimate contact is achieved with the PEM 30. This intimate contact provides a readily available path which allows the ions to migrate freely towards the cathode electrode 16B. Catalysis is a surface effect. By suspending the catalytic particles 28 in the polymer 22, effective use of the entire surface area is obtained. This will dramatically increase the system efficiency.
By making the second material 11 electrically conductive, an electrode is produced. The proximity of the electrode to the catalytic reaction affects how well it collects electrons. This method allows the catalytic reaction to occur effectively within the electrode itself. This intimate contact provides a readily
available path which allows the electrons to migrate freely towards the anode 1 6A. This will allow for the successful collection of most of the free electrons. Again, this will dramatically increase the system efficiency.
In addition to the electrical and chemical/functional characteristics of the PEM 30 described above, there are some important physical ones, that are described below: This self assembly process allows for the construction of a more important physical ones, that are described below: This self assembly process allows for the construction of a more optimum PEM harrier. By design it will be more efficient.
First, there is the matter of forming the separate hydrogen and oxygen path ways. This requires that the PEM structure to be grown/formed so that it dissects the etched channel 50 fully into two separate channels 50A, SOB. This means that it must be patterned to grow in the center of the channel and firmly up against the walls of the ends of the power cell. It must also be grown to the height of the channel to allow it to come into contact with an adhesive 42 on the bottom of lid 40.
Second, there is the matter of forming a gas tight seal. This requires that the PEM structure 30 be bonded thoroughly to the base structures 18 and 20A, the substrate 14 and the end walls (not shown) of the power cell and to an adhesive 42 which coats the lid 40. By proper choice of the polymers, a chemical bond is formed between the materials -they contact in the channel. In addition to this chemical bond, there is the physical sealing effect by applying the lid 40 down on top of the PEM barrier. If the height of the PEM 30 is controlled correctly, the pressure of the applied lid forms a mechanical"0 ring"type of self seal. Growing the PEM 30 on the substrate 14 eliminates any fine registration issues when combining it with the lid 40. There are no fine details on the lid that require targeting.
Turning now to FIG. 4, there is shown in simplified perspective an alternate
embodiment of a PEM barrier involving a casting/injecting process and structure.
Using MEMS machining methods three channels 60A, 60B and 60C are
etched into a semiconductor substrate 140. The outside two channels 60A and 60C
are separated from the middle channel 60B by thin walls 70A, 70B. These walls
have a plurality of thin slits S1 — Sn etched into them. The resultant tines T1 — Tn+1
have a catalyst 280 deposited on them in the area of the slits. At the bottom of these
thin walls, 70A, 70B, on the side which makes up a wall, of an outside channel 60A,
60C, a metal electrode 160A, 160Bis deposited. A catalyst 280 is deposited on the
tines after the electrodes 160 are in place. This allows the catalyst to be deposited so
as to come into electrical contact and to cover to some degree, the respective
electrodes 160 at their base. In addition, metal conductors 90 are deposited to
connect to each electrode 160, which then run up and out of the outside channels.
A lid 400 is provided with an adhesive layer 420 which is used to bond the lid to the substrate 140. In this way, three separate channels are formed in the substrate; a hydrogen channel 60A, a reaction channel 60B, and an oxygen channel 60C. In addition, the lid 400 has various strategically placed electrolyte injection ports or holes 500. These holes 500 provide feed pathways that lead to an electrolyte membrane of polymer material (not shown) in the reaction channel 60B only. If holes could be created through the substrate, one or more of these channels could be run vertically through the cell. A manifold could be mated with either holes in the top lid or bottom side of the wafer to control distribution to the channels.
The structure of FIG. 4 is assembled as follows:
First, the semiconductor, fabrication process is formed including substrate
machining and deposition of all electrical circuits.
Next, the lid 400 is machined and prepared with adhesive 420. The lid 400 is
bonded to the substrate 140.-Then, the electrolyte (not shown) is injected into the
The thin walls 70A, 70B of the reaction channel 60B serve to retain the
electrolyte during its casting; The slits S1 — SN allow the hydrogen and oxygen in
the respective channels 60A, 60B access to the catalyst 280 and PEM 300. Coating
the tines T1 — T1+n with a catalyst 280 in the area of the slits provides a point of
reaction when the H2 gas enters the slits! When the electrolyte is poured/injected into the reaction channel 60B, it fills it up completely. The surface tension of the liquid electrolyte keeps it from pushing through the slits and into the gas channels, which would otherwise fill up as well. Because there is some amount of pressure behind the application of the electrolyte, there will be a ballooning effect of the electrolyte's surface as the pressure pushes it into the slits. This will cause the electrolyte to be in contact with the catalyst 280 which coats the sides of the slits S1 --- SN. Once this contact is formed and the membrane (electrolyte) is hydrated, it will expand even further, ensuring good contact with the catalyst. The H2/02 gases are capable of diffusing into the (very thin, i.e. 5 microns) membrane, in the area of the catalyst. Because it can be so thin it will produce a more efficient i.e. less resistance (12R) losses are low. This then puts the three components of the reaction in contact with each other. The electrodes 160A and 160B in electrical contact with the catalyst 280 is the fourth component and provides a path for the free electrons [through an external load (not shown)] while the hydrogen ions pass through the electrolyte membrane to complete the reaction on the other side.
Referring now to the cross-sectional views of FIGs. 5-7, various alternate configurations of the PEM structure 30 of the invention will be described in detail. In FIG. 5, the central PEM structure 20 is formed as a continuous nonconductive vertical element, and the electrode/catalyst 16/28 is a non-continuous element to which lead wires 90 are attached. FIG. 6 is a view of an alternate PEM structure in which the catalyst 28 is embedded in the non-conductive core 20 and the electrodes 16 are formed laterally adjacent the catalyst. Lastly, in FIG. 7, the PEM structure is similar to FIG. 5 but the center core 201 is discontinuous.
FIG. 8 is a schematic block diagram showing some of the possible circuits that
may be integrated along with a plurality of mierocontrollers onto the semiconductor
wafer 10 to monitor and control multiple cells performance. Several sensor circuits
80, 82, 84 and 86 are provided to perform certain functions. Redundancy may be
used to improve yields.
Temperature circuit 80 provides the input to allow the microcontroller 88 to define a thermal profile of the fuel cell 12. Voltage circuit 82 monitors the voltage
at various levels of the configuration hierarchy or group of cells. This provides information regarding changes in the load. With this information, the processor 88 can adjust the system configuration to achieve/maintain the required performance. Current circuit 84 performs a function similar to the voltage monitoring circuit 82 noted above.
Pressure circuit 86 monitors the pressure in the internal gas passages 50A, 50B. Since the system's performance is affected by this pressure, the microprocessor 88 can make adjustments to keep the system running at optimum performance based on these reading. An undefined circuit 81 is made available to provide a few spare inputs for the micro 88 in anticipation of future functions.
In addition, configuration circuit 94 can be used to control at least the V*I switches to be described in connection with FIG. 9. The output voltage and current capability is defined by the configuration of these switches. Local circuitry 92 is provided as necessary to be dynamically programmed, such as the parameters of the monitoring circuits. These outputs can be used to effect that change. Local subsystems 94 are used by the micro 98 to control gas flow rate, defect isolation and product removal. A local power circuit 96 is used to tap off some part of the electricity generated by the fuel cell 12 to power the onboard electronics. This power supply circuit 96 will have its own regulation and conditioning circuits. A two-wire communications I/F device 98 may be integrated onto the chip to provide the electrical interface between communicating devices and a power bus (not shown) that connects them.
The microcontroller 8 is the heart of the integrated electronics subsystem. It is responsible for monitoring and controlling all designated system functions. In addition, it handles the communications protocol of any external communications. It
is capable of "in circuit programming" so that its .executive control program can be
updated as required. It is capable of data storage and processing and is also capable of self/system diagnostics and security features.
Referring now to FIG. 9,'further details of the invention are shown. In this
embodiment, the individual power cells 121; 122 — 12n are formed on a wafer and
wired in parallel across power buses 99A and 99B using transistor switches 97
which can be controlled from the microprocessor 88 of FIG. 8. Switches 97B and
97A are negative and positive bus 'switches respectively, whereas switch 97C is a
series switch and switches 97D and 97E are respective positive and negative parallel
This allows the individual cells or groups of cells (power chip 15) to be wired in various configurations, i.e., parallel or series. Various voltages are created by wiring the cells in series. The current capacity can also be increased by wiring the cells in parallel. In general, the power profile of the power chip can be dynamically controlled to achieve or maintain a "programmed" specification. Conversely, the chip can be configured at the time of fabrication to some static profile and thus, eliminate the need for the power switches. By turning the switches on and off and by changing the polarity of wiring one can produce both AC and DC power output.
To implement a power management subsystem, feedback from the power generation process is required. Circuitry can be formed directly on the chip to constantly measure the efficiencies of the processes. This feedback can be used to modify the control of the system in a closed loop fashion. This permits a maximum level of system efficiency to be dynamically maintained. Some of these circuits are discussed next.
The quality of the power generation process will vary as the demands on the system change over time. A knowledge of the real-time status of several operational parameters can help make decisions which will enable the system to self-adjust, in order to sustain optimum performance. The boundaries of these parameters are defined by the program.
For example, it is possible to measure both the voltage and the current of an individual power cell or group of power cells. The power output can be monitored and if a cell or group is-not per-formingr, it can-be removed if-necessary. This can be accomplished by the power switches 97 previously described. Alternately, integrated MEMS fabricated micro fans may be used to control oxygen or hydrogen
flow between fuel cells or stack of power cells for optimal system performance.
An average power level can also be maintained while moving the active
"loaded" area around on the chip. This should give a better overall performance
level due to no one area being on 100% of the time. This duty cycle approach is especially applicable to surge demands. The concept here is to split the power into pieces for better cell utilization characteristics.
It is expected that the thermal characteristics of the power chip will vary due to electrical loading and that this heat might have an adverse effect on power generation at the power cell level. Adequate temperature sensing and an appropriate response to power cell utilization will minimize the damaging effects of a thermal build up.
The lid 40 is the second piece of a two-piece "power chip" assembly. It is preferably made of metal to provide a mechanically rigid backing for the fragile semiconductor substrate 14. This allows for easy handling and provides a stable foundation upon which to build "power stacks", i.e., a plurality of power chips 15 that are literally stacked on top of each other. The purpose being to build a physical unit with more power.
FIG. 10 illustrates how the fuel 50A and oxidant/product channels 50A (and 50B not shown) may be etched into the surface of the substrate 14. These troughs are three sided and must be closed and sealed on the top side. The lid 40 and adhesive 42 provides this function of forming a hermetic seal when bonded to the substrate 14 and completes the channels. A matrix of fuel supply and oxidant and product water removal channels is thereby formed at the surface of the substrate.
The lid 40 provides a mechanically stable interface on which the input/output ports can be made. These are the gas supply and water removal ports. The design must encompass the size transition from the large outside world to the micrometer sized features on the substrate. This is accomplished by running the micrometer sized channels to a relatively much larger hole H. This larger hold will allow for less registration requirements between the lid and substrate.- The.large..holds in the lid line up with the large holes in the substrate which have micrometer sized
channels also machined into the substrate leading from the large hold to the power
Each wafer may have its own manifolds. This would require external connections for the fuel supply, oxidant and product removal. The external
plumbing may require an automated docking system. Today's MEMS processing allows for etching holes through a wafer. Such vertical through holes may ease the manifold design and improve gas flow.
FIGS. 11 and 12 illustrates one of many ways in which several cells 12 (in this example three cells side-by-side can be formed on a wafer 14 to form a power chip 15. Power disks can be stacked vertically upon each other to form a vertical column with inlet ports, 50HI, 50OI respectfully coupled to sources of hydrogen and oxygen respectively. The vertical column of wafers with power chips formed therein comprise a power stack (93).
FIG. 12 illustrates how stacking of a number of power discs 15 may be used to
form power stacks (93) with appreciable power. The use of the word "stacking" is
reasonable for it suggests the close proximity of the wafers, allowing for short
electrical interconnects and minimal plumbing. In reality, the stacking actually
refers to combining the electrical power of the wafers to form a more powerful unit.
They need only to electrically stacked to effect his combination. However, it is
desirable to produce the most amount of power in the smallest space and with the
highest efficiencies. When considering the shortest electrical interconnect (power
bussing) alternatives, one should also consider the possibility of using two of the
main manifolds as electrical power busses. This can be done by electrically isolating
these manifold/electrical power buss segments and using them to convey the power
from each wafer to the next. This reduces the big power wiring requirements and
permits this function to be done in an automated fashion with the concomitant
increased accuracy and reliability.
A desirable manifold design would allow for power disc stacking. In this
design the actual manifold 95 would be constructed in segments, each segment being
anintegral part ofthe lid-40. --As-the discs-are stacked amanifold (tube) is formed
This type of design would greatly reduce the external plumbing requirements.
Special end caps would complete the manifold at the ends of the power stack.
In summary, one of the primary objects of this invention is to be able to mass produce a power chip 15 comprised of a wafer 10 containing multiple power cells 12 on each chip 15 utilizing quasi standard semiconductor processing methods. This
process inherently supports very small features. These features (power cells), in
turn, are expected to create very small amounts of power per cell. Each cell will be
designed to have the maximum power the material can support. To achieve any real
substantially power, many millions will be fabricated on a single power chip 15 and
many power chips fabricated on a "power disc" (semiconductor wafer 10). This is
why reasonable power output can be obtained from a single wafer. A l0uM X
l0uM power cell would enable one million power cells per square centimeter. The
final power cell topology will be determined by the physical properties of the
constituent materials and their characteristics.
The basic electro-chemical reaction of the solid polymer hydrogen fuel cell is
most efficient at an operating temperature somewhere between 80 to 100°C. This is
within the operating range of a common semiconductor substrate like silicon.
However, if the wafers are stacked additional heatsinking may be required. Since a
cover is needed anyway, making the lid 40 into a heatsink for added margin makes
The fuel and oxidant/product channels are etched into the surface of the
semiconductor substrate. These troughs are three-sided and must be closed and
sealed on the top side. The lid 40 provides this function. It is coated with an
adhesive to form a hermetic seal when bonded to the semiconductor substrate and
completes the channels. This forms a matrix of fuel supply and oxidant and product
water removal channels at the surface of the semiconductor substrate. The power
cells two primary channels are themselves separated by the PEM which is bonded to
this same adhesive. Thus, removing any fine grain critical alignment requirements.
While this invention has-been particularly shown and deseribed-with
references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims. For example, while silicon because of its well-defined electrical and mechanical properties is the material of choice for the substrate 14, other semiconductor
materials may be substituted, therefore, such as Gd, Ge, or III-V compounds such as
GaAs. Alternatively, the substrate for the, cell may be formed of an amorphous
material such as glass or plastic, or phenolic; in which case, the controls for the cells
can be formed on a separate semiconductor die and electrically coupled to the cells
to form a hybrid structure. The interface between the PEM's structure is preferably
an assembled monolayer (SAM) interface formed of gold, however, other metals
such as silver or platinum, may be used in place thereof. Likewise, although the
PEM is formed of many molecular chains, it preferably has a base with an affinity
for gold so that it will bond to the gold SAM feature. Again, other pure metals such
as platinum and silver may be substituted therefore. Alternate catalysts to the SAM
may also be possible. Such catalysts and PEMs might be applied to the substrate
using sacrificial mold casting or depositing and etching.
1. A fuel cell comprising:
a) a substrate;
b) first and second channels for admitting fuel into the a first channel and oxidant into the a second channel;
c) a membrane coupled to the substrate and having first and second sides separating the first channel from the second channel;
d) a first electrode on the first side of the membrane and a second electrode on the second side of the membrane;
e) a catalyst in electrical communication with the membrane sides and the electrodes; and
f) a cover made from a gas impermeable material which forms a seal with the membrane.
2. The fuel cell as claimed in claim 1 wherein:
a) the first and second channels define respective first and second flow paths; and
b) the membrane encloses an area, wherein the enclosed area includes the first flow path;
3. The fuel cell as claimed in claim 1 wherein the catalyst is incorporated in the first and second membrane sides.
4. The fuel cell as claimed in claim 1 wherein the catalyst is incorporated within the electrodes.
5. The fuel cell as claimed in claim 1 wherein the electrodes are formed of an electrically conductive polymer.
6. The fuel cell as claimed in claim 1 wherein the membrane is a proton
7. The fuel cell as claimed in claim 1 wherein the membrane is formed of a polymer.
8. The fuel cell as claimed in claim 7 wherein the polymer is built in layers.
9. The fuel cell as claimed in claim 1 wherein the membrane is cast.
10. The fuel cell as claimed in claim 9 wherein the membrane is cast into a sacrificial mold which is made from standard materials used in IC or MEMS processing.
11. The fuel cell as claimed in claim 1 wherein the membrane is a thin or thick film membrane.
12. The fuel cell as claimed in claim 11 wherein the membrane is then etched to create the first and second sides.
13. The fuel cell as claimed in claim 11 wherein the membrane is applied using a spin coating process such as the Spin on Glass (SOG) technique.
14. The fuel cell as claimed in claim 1 wherein the membrane is corrugated to increase surface area.
15. The fuel cell as claimed in claim 1 wherein the contacts to the electrodes are made using butted or buried contacts.
16. The fuel cell as claimed in claim 15 wherein the buried contacts are made using PtSi, WSi2, TiSi2, Ti:W, TiN.
17. The fuel cell as claimed in claim 15 wherein the butted contacts are made using Al, Cu, Au, Ag, or a metal alloy.
18. The fuel cell as claimed in claim 15 wherein the contacts are made using polysilicon, silicided polysilicon, or the substrate.
19. The fuel cell as claimed in claim 1 further including physical features on the substrate which aid in the registration and/or anchoring of the membrane. •
20. The fuel cell as claimed in claim 1 wherein the substrate has holes through which fuel or oxidant flows perpendicular to a plane of the substrate.
21. The fuel cell as claimed in claim 20 wherein the holes supply fuel or oxidant to inside or outside of fuel cell.
22. The fuel cell as claimed in claim 1 wherein electrically conductive material crosses under the membrane for interconnection to the electrodes.
23. A power chip comprising:
a) an array of fuel cells as claimed in claim 1 electrically interconnected to form the power chip;
b) a plurality of manifolds enclosing the array to distribute fuel and oxidant to the fuel cells; and
c) a plurality of power terminals.
24. The power chip as claimed in claim 23 wherein the substrate is formed of an insulator.
25. The power chip as claimed in claim 24 wherein the insulator is taken from the group consisting of sapphire, glass, and FR4.
26. The power chip as claimed in claim 23 wherein the substrate is formed of semiconductor material.
27. The power chip as claimed in claim 26 wherein the semiconductor is taken from the group consisting of Si, Ge, and GaAs.
28. The power chip as claimed in claim 23 wherein covers of fuel cells in the array are integrated with the manifold.
29. The power chip as claimed in claim 23 wherein a plurality of fuel cells are electrically interconnected via switches, fuses or metal links, in a configurable manner.
30. The power chip as claimed in claim 29 wherein switches are semiconductor transistors integrated onto the substrate.
31. The power chip as claimed in claim 29 wherein the configuration is one time programmable.
32. The power chip as claimed in claim 29 wherein the configuration is under control of a microcontroller.
33. The power chip as claimed in claim 29 wherein switches under
control provide for dynamic active area control to optimize fuel
consumption and operating efficiencies.
34. The power chip as claimed in claim 23 wherein one or more microcontrollers monitor performance parameters such as power output, temperature or fuel consumption.
35. The power chip as claimed in claim 23 wherein one or more microcontrollers are integrated onto the substrate.
36. The power chip as claimed in claim 23 including a plurality of integrated sensors such as temperature, voltage, current and gas pressure and flow sensors.
37. The power chip as claimed in claim 23 which supports internal and external communications.
38. The power chip as claimed in claim 37 wherein the communications interface uses the power terminals.
39. A power disc comprising: ;l
a) a plurality of power chips as claimed in claim 23 :
b) a plurality of manifolds enclosing the array to distribute fuel and oxidant to the power chips; and ..
c) a plurality of power bus terminals.
40. The power disc as claimed in claim 39 wherein the manifolds include
interface ports for interchangable fuel and/or oxidant subsystems.
41. The power disc as claimed in claim 39 wherein the power output is v programmable.
42. A power stack comprising:
a) a plurality of power chips as claimed in claim 23 and/or discs as claimed in claim 39 arranged vertically with respect to each other;
b) an electrical interconnect between the power chips and/or discs; and
c) a manifold to supply fuel and oxidant to the power chips and/or discs.
43. A power stack as claimed in claim 42 wherein the flow paths between power chips or discs are self coupling.
44. A power stack as claimed in claim 42 wherein the power bus between power chips or discs are self-coupling.
Dated this 16th day of May,
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANTS
|Indian Patent Application Number||IN/PCT/2002/00628/MUM|
|PG Journal Number||28/2007|
|Date of Filing||16-May-2002|
|Name of Patentee||INTEGRATED FUEL CELL TECHNOLOGIES INC.|
|Applicant Address||19 CROSBY DRIVE, BEDFORD, MASSACHUSETTS-|
|PCT International Classification Number||H 01 M 8/00|
|PCT International Application Number||PCT/US00/31825|
|PCT International Filing date||2000-11-17|