KR20080091783A - Closely spaced electrodes with a uniform gap - Google Patents

Abstract

An improved design for maintaining separation between electrodes in tunneling, diode, thermionic, thermophotovoltaic and other devices is disclosed. At least one electrode is made from flexible material. A magnetic field is present to combine with the current flowing in the flexible electrode and generate a force that counterbalances the electrostatic force or other attracting forces between the electrodes. The balancing of forces allows the separation and parallelism between the electrodes to be maintained at a very small spacing without requiring the use of multiple control systems, actuators, or other manipulating means, or spacers. The shape of one or both electrodes is designed to maintain a constant separation over the entire overlapping area of the electrodes. The end result is an electronic device that maintains two closely spaced parallel electrodes in stable equilibrium with a uniform gap therebetween over a large area in a simple configuration for simplified manufacturability and use to convert heat to electricity or electricity to cooling.

Description

CLOSELY SPACED ELECTRODES WITH A UNIFORM GAP

The present invention relates to diodes, thermoionic, tunneling, thermophotovoltaic and other devices that are designed to have very small gaps between electrodes and in some cases require thermal isolation between electrodes. The present invention can be applied to heat-tunneling and heat-photovoltaic generators and heat pumps, and to similar systems using thermal ion and thermoelectric methods. These heat-tunneling generators and heat pumps can be operated in reverse to convert thermal energy into electrical energy and provide cooling. In addition, the present invention can be applied to any device requiring close and parallel spacing of two electrodes through which current flows.

The phenomenon that high energy electrons flow from one conductor (emitter) to another conductor (collector) has been used for various purposes in many electronic devices. For example, a tube diode was implemented in this way, and its physical phenomenon was called heat ion release. Due to the limitations imposed by the relatively large physical available space, these diodes needed to operate at very high temperatures (above 1000 Kelvin). The hot electrode needed to be very hot so that the electrons had enough energy to travel a long distance to the collector and enough energy to overcome the high quantum barrier. Nevertheless, vacuum tubes have enabled electronic diodes and amplifiers made thereafter. Over time, in an effort to reduce the operating temperature, these devices have been optimized by coating the electrode with an oxide, or an alkali metal such as cesium. Although the temperature for generating heat ions is still much higher than room temperature, this method of power generation has utility for thermal conversion from combustion or solar concentrator to electricity.

Later, it was found that if the emitter and collector were very closely to each other at approximately atomic distances, such as 2 to 20 nanometers, the electrons could flow at much lower temperatures, even at room temperature. In this small gap, the electron cloud of the atoms of the two electrodes is so close that hot electrons actually flow from the emitter cloud to the collector cloud without physical conduction. This type of current flow in the case where the electron clouds intersect but the electrodes are not in physical contact is called tunneling. Scanning tunneling microscopes, for example, use a pointed conductive stylus placed in close proximity to the conductive surface, and the atomic contour of this surface allows the electrical current to flow when the needle is scanned across the surface. It can be mapped by plotting. US Patent 4343993 (Binnig et al.) Teaches such a method applied to scanning tunneling microscopes.

If such atomic spacing can be maintained over a large area (eg, one square centimeter), a significant amount of heat can be converted to electricity by a single diode type device, which device can be used as a cooler, or from various sources. It is known in the art that it will have utility in recovering spent heat energy. Efficiency of Refrigeration using Thermotunneling and Thermionic Emission in a Vacuum: Use of Nanometer Scale Design, Applied Physics Letters, Vol. 78, No. 17, by Y. Hishinuna, TH Geballe, BY Moyzhes, and TW Kenny, April 23, 2001. ; Vacuum Thermionic Refrigeration with a Semiconductor Heterojunction Structure, Applied Physics Letters, Vol. 81, No. 22, by Y. Hishinuna, T. H. Geballe, B. Y. Moyzhes, November 25, 2002; And Measurements of Cooling by Room Temperature Thermionic Emission Across a Nanometer Gap, Journal of Applied Physics, Vol. 94, no. 7, October 1, 2003, by Y. Hishinuma, TH Geballe, BY Moyzhes, and TW Kenny. . The spacing between the electrodes must be small enough to allow the "hot" electrons (which have higher energy than the Fermi level) to flow, but the normal conduction (flow of electrons at or below the Fermi level) Should not be too close to allow. There is a viable range of separation distances of 2 to 20 nanometers that allows thousands of watts per square centimeter of conversion from electricity to cooling. See Hishinuna et al., Above, for Efficiency of Refrigeration using Thermotunneling and Thermionic Emission in a Vacuum: Use of Nanometer Scale Design. This reference also presents the advantage of a single layer or coating of alkali metal or other material on the emitting electrode to obtain a low work function in the transfer of electrons from one electrode to another. Such coatings or monolayers further reduce operating temperature and increase conversion efficiency.

Mahan showed that the theoretical efficiency of a thermal ion cooler using an electrode with a work function of 0.7 eV and a cold temperature of 500 K is higher than 80% of Carnot efficiency. See Thermionic Refrigeration, Journal of Applied Physics, Vol. 76, No. 7, by G. D. Mahan, October 1, 1994. By similarity, it is expected that the conversion efficiency of the electron tunneling process will also be a high ratio of Carnot efficiency. Carnot efficiency sets an upper limit on the attainable efficiency of thermal energy conversion.

Maintaining the separation of electrodes at atomic size over a large area was the only and most important issue in making devices capable of removing heat from conductors. Scanning tunneling microscopes, for example, require a special laboratory environment free of vibration, and their operation is limited to an area of several square nanometers. Even very recently, all measurements of cooling in the working apparatus have been limited to an area of several square nanometers. See Hishinuma et al., Measurements of Cooling by Room Temperature Thermionic Emission Across a Nanometer Gap.

The spacing of electrodes of size greater than approximately 100 nanometers can support the conversion of heat to electricity using the thermo-photovoltaic method. In a thermo-photovoltaic system, photons tunnel across the gap. The heat source causes one light-emitting electrode to emit, and up to ten times the conversion power for a standard photovoltaic system if the second photosensitive electrode is positioned very short of the radiation wavelength. The heat source may be concentrated by sunlight, fossil fuel combustion or other means. The light emitting electrode may for example be made of tungsten. The photosensitive electrode may be made of silicon, selenium, or indium gallium arsenide. For more information on the thermo-photovoltaic method, see R. DiMatteo, P. Greiff, D. Seltzer, D. Meulenberg, E. Brown, E. Carlen, K. Kaiser, S. finberg, H. Nguyen, J. Azarkevich, P. Baldasaro, J. Beausang, L. Danielson, M. Dashiell, D. DePoy, H. Ehsani, W. Topper, K. Rahner, R. Siergie, Micron-gap ThermoPhotoVoltaics (MTPV), Thermophotovoltaic See Generation of Electricity Sixth Conference, American Institute of Physics, 2004.

Accordingly, there is a need for a device that efficiently converts thermal energy into electrical energy and is cost effective in a package that is easy to use for both the heat source as input and the electrical circuit requiring power as output. Abundant heat sources, including wasted heat, will easily become a source of electricity. Examples of using such a device to benefit the environment, save money, or meet both include:

(1) Converting solar heat and light into electricity, which is more cost effective than photovoltaic devices currently in use. Many papers describe the use of high temperature heat ion release to regenerate thermal energy from a solar collector by using such heat conversion devices. Thermionic Refrigeration, by G. D. Mahan, supra; And Multilayer Thermionic Refrigerator, Journal of Applied Physics, vol. 83, no. 9 by G. D. Mahan, J. A. Sofao and M. Bartkoiwak, May 1, 1998. However, if tunneling occurs at a naturally occurring temperature, this conversion will be less expensive and more widespread.

(2) Recovering heat generated by internal combustion engines such as those used in motor vehicles to useful operation. Some currently available cars, called hybrid gas-electric vehicles, can use either power or internal combustion to produce motion. Approximately 75% of the energy in gasoline is converted to heat that is not available in current internal combustion engines. The tunneling conversion device may recover much of this heat energy from the engine of the hybrid vehicle and put it in a battery for future use. U. S. Patent 6651760 (Cox et al.) Teaches a method of converting heat from a combustion chamber and storing or converting energy into operation.

(3) Reduce the need for toxic gases to enter the atmosphere. Higher energy-efficient hybrid vehicles are a clear example of the reduction of toxic emissions into the atmosphere. Devices that convert and store exhaust heat from engines and hybrid engines, or produce electricity in hybrid batteries, will further increase the efficiency of hybrid vehicles and reduce the need to emit toxic gases. The coolant used for cooling is another example of the toxic gases required to remove heat, and the tunneling conversion device may reduce the need for the release of toxic gases.

(4) Recovering thermal energy at a time available, storing it as chemical energy in the battery, and re-using it at a time when it is not available. Tunneling conversion devices can convert solar energy into electricity during the day and store it in batteries. During the night, stored battery power may be used to produce electricity.

(5) Power generation from geothermal energy. Heat is present in many places on the earth's surface, and is virtually unlimited in the deep interiors of the earth. An efficient tunneling conversion device will be able to develop this supply of energy.

(6) Generation of cooling by compact, quiet and static solid state devices. This tunneling device may here provide cooling for an air conditioner or refrigeration to replace the need for bulky pneumatic machines and compressors.

(7) Power generation from body heat. The human body produces approximately 100 watts of heat, which can be converted into useful power for portable products such as cell phones, cordless phones, music players, personal digital asistants (PDAs) and flashlights. The heat conversion device presented herein can produce sufficient power to operate or charge a battery for such a portable product from heat applied through partial contact with the human body.

(8) power from raw material combustion. Wood stoves produce tens of thousands of watts of heat. Such a tunneling device would be able to produce enough heat from one or two kilowatts to power a typical household electrical appliance from this heat. Similar applications are possible by burning other raw materials such as natural gas, coal and the like. Homes in remote areas may then not need a connection to the power grid or noisy generators for modern convenience.

The challenge of putting two parallel electrodes together in a spacing gap smaller than 20.0 nanometers requires attention to two parameters. One is the roughness of the surface and the other is the flatness of the surface. The roughness of the surface is a deviation from smoothness in small, localized areas. Holes and scratches are examples of misalignments that affect the roughness of the surface. The flatness of the surface is apparent from parallelism over a large area. Warping, bending, and creeping are examples of misalignments that affect the flatness of the surface.

In the case where two rigid materials are polished flat using the best technology currently available for integrated circuits, the flatness of the surface is approximately several micrometers for the square centimeter area. In addition, heat or other stresses can cause changes in bending and bending over time, presenting additional problems in maintaining uniform spacing once achieved. Polished metal or semiconductor surfaces using current technology can easily achieve roughness less than 0.5 nanometers.

The state of the art of tunneling energy conversion devices suffers from one or more of the following limitations: (1) too large separation for tunneling, (2) areas too small for sufficient energy conversion, and (3) thermal isolation. Layers of solid material that cannot be made resulting in low conversion efficiency, and (4) an overly complex design to manufacture at an efficient cost.

Spaces of more than 10 micrometers have been achieved by many thermal ion systems, but these systems operate only at very high temperatures and require expensive designs for safety and are limited to the environment in which these temperatures are achieved.

A spacing of approximately 20 to 20.0 nanometers was achieved by the method taught in US Pat. No. 4343993 (Binnig et al.) In the design of a scanning tunneling microscope, but the effective area is approximately several square nanometers. These areas are too small (relative to the desired area of approximately one square centimeter or more) to allow sufficient current to flow, and do not convert enough energy even for the best material.

The semiconductor industry teaches and uses many methods of controlling physical parameters, such as film thickness, which are approximately several nanometers. Thermoelectric devices are examples of integrated circuits that convert energy into a stack of stacked materials. See Chris LaBounty, Ali Shakouri, and John E. Bowers, Design and Characterization of Thin Film Microcoolers, Journal of Applied Physics, Vol. 89, No. 1, April 1, 2001. However, all of these methods require the solid materials to contact each other in layers. Heat easily flows from layer to layer, limiting temperature differences and conversion efficiency. Since the two electrodes are in contact, the design depends on the thermoelectrically sensitive material available, and the energy barrier across the electrons, which is possible by setting the width of the vacuum gap, cannot be arbitrarily constructed. Materials with the necessary properties are rare and expensive elements such as bismuth and telluride. For this reason, thermoelectric devices are limited to high cost per watt of cooling power and low efficiency of approximately 7%.

Techniques for separating two conductors from approximately 2.0 to 20.0 nanometers in the square centimeter area have been advanced by the use of an array of very precise feedback control systems for this length. The control system includes feedback means for measuring the actual separation compared to the desired separation and moving means for bringing the components closer or further away to maintain the desired separation. The feedback means can measure the capacitance between the two electrodes, which capacitance increases as the separation decreases. Means of movement for these dimensions in the art are actuators which generate motion through piezoelectric, magnetostriction or electrostriction phenomena. US Pat. No. 6720704 (Tavkhelidze et al.) Discloses a design that includes using a feedback control system to complete parallelism before use after shaping one surface using another surface. This design approach is problematic for low cost manufacturing due to the use of multiple feedback control systems to maintain parallelism and complex processes associated with forming one surface relative to another.

Other methods are documented in US Pat. No. 6,774,003 (Tavkhelidze et al.), US patent applications 2002/0170172 (Tavkhelidze et al.) And 2001/0046749 (Tavkhelidze et al.), Which describe a "sacrificial layer" between the electrodes during manufacture. "Is about inserting. Thereafter, the sacrificial layer is evaporated to create a gap between the electrodes close to the desired spacing of 2-20 nanometers. These three methods are prone to instability after fabrication due to differences in warpage or thermal expansion between the electrodes or require an actuator arrangement to compensate for this instability.

Another way to achieve the desired spacing and maintain it over time is the use of dielectric spacers that maintain the spacing of the flexible electrodes in a manner very similar to the poles holding the tent. Documented in US Pat. No. 6,876,123 (Martinovsky et al.) And US patent application 2004/0050415. One disadvantage of such dielectric spacers is that they conduct heat from one electrode to another, reducing the efficiency of the conversion process. Another disadvantage of this method is that the flexible metal electrode can elongate or deform between spacers over time in the presence of large electrostatic forces and slowly move towards the conducting gap rather than tunneling or thermal ion release.

Another method for achieving the desired vacuum spacing between the electrodes is disclosed in US patent application 2004/0195934, where a small void is created at the interface of two bonded wafers. This gap is small enough to allow heat-tunneling of electrons across a gap of several nanometers. Such gaps may support heat-tunneling, but unwanted thermal conduction occurs around the gaps, and the nonuniformity of electrode spacing is difficult to control.

 Another way to achieve the heat-tunneling gap is to use an actuator that allows the facing surfaces of the two wafers to contact and then pull them apart by a few nanometers, as described in US Patent Application 2006/0000226. . Although this method can create a thermal-tunneling gap, this method suffers from the cost of multiple actuators and the thermal conduction between wafers outside the gap area.

Despite efforts to date, there are ongoing and difficult problems in meeting the requirements for achieving and maintaining the positioning of electrodes with a spacing gap of less than 20.0 nanometers and in mass production of low cost thermal-tunneling devices. This remains.

In addition to providing direct cooling, a further use for devices capable of moving electrons across a vacuum gap is to place this gap on top of the thermoelectric stack. In this combination, the hot and cold sides of the thermoelectric gap are thermally isolated and thus more efficient. Devices having a combination of thermoelectric materials and vacuum gaps can provide cooling or thermal conversion through thermoelectric methods, thermo-tunneling methods, thermoion methods, or a combination of these methods.

Thus, there is a need for an improved design for maintaining vacuum separation between electrodes in tunneling diodes and other devices that are more efficient and cheaper than conventional designs. In particular, there is a need for a design with closely located electrodes having a uniform vacuum gap. More specifically, as long as they are self-positioned and aligned themselves with closely spaced gaps between the electrodes to enable the transfer of electrons across the gap by tunneling, thermal ions, or possibly other emission coupled with thermoelectric elements. There is a need for designs with paired electrodes.

 This specification is directed to overcoming the above and other problems and disadvantages of the prior art. Devices and processes are disclosed that use electron flow in a manner not considered by the prior art. In conventional designs, the flow of electrons in the tunneling device was used for two purposes: (1) as a thermodynamic fluid for transferring heat from one conductor to another, and (2) to a battery or electrical circuit / It was used to directly transfer the energy converted from. In the present invention, device configurations and processes are provided wherein the electron flow is also used to generate restoring force to balance static electricity and other attractive forces at the desired spacing of the electrodes.

A device and process for providing electrodes with closely spaced, uniformly spaced gaps are disclosed. More specifically, the specification provides self-positioning in gaps with close spacing between electrodes to enable the transfer of electrons across the gap by tunneling, thermal ions, or possibly other emission coupled with thermoelectric elements. And a pair of electrodes that are self-aligning.

The present invention uses a flexible material for one of the electrodes and includes a magnetic field that balances electrostatic or other attractive forces with magnetostatic repulsive forces, which essentially and simultaneously act on the flexible electrode over a large area. The electrodes are positioned, aligned and held in a stable equilibrium position at a desired distance from the other electrode surface, and are adapted for continuous gap deviation in flatness at either electrode.

Surface roughness smaller than 0.5 nanometers is achieved by polishing the facing surface of the electrodes prior to assembly. Polishing techniques for achieving surface roughness of less than 0.5 nanometers on metals, semiconductors and other materials are readily available in the industry.

In order to achieve a spacing of less than 20.0 nanometers over a large area of more than one square centimeter, a combination of non-contacting forces is created to keep the electrode materials at the desired spacing. In stable equilibrium, one force already present in such diode devices is the electrostatic force between the emitter and the collector. When a voltage is applied, opposite charges accumulate in each of the electrodes, and the presence of these charges results in attraction between the electrodes. Although electrostatic forces are considered to be the main attraction for closely located electrodes, there are also other attractive forces such as gravity, surface tension, Van der Waals force, Casimir force and static frictional force.

One aspect of the present invention creates a second equivalent but opposite force, which acts on the flexible electrode to balance electrostatic attraction and other attraction at all points, such that the flexible electrodes provide the desired spacing and alignment. Keep it. This second force is due to the physical phenomenon in which a force is generated when current flows through the conductor in the presence of a magnetic field. This force acts in a direction perpendicular to the plane defined by the direction of current flow and the magnetic field direction.

Magnetic fields can be added to embodiments of the present invention by having permanent magnets in or near the electrodes. Permanent magnet materials such as iron, cobalt, nickel and their alloys are also metals of very high conductivity, both thermally and electrically. Thus, such magnetic materials are compatible with the thermal and electrical conducting properties of the electrodes. Although it is necessary to use a non-conductive magnetic material to provide a magnetic field, such a magnet may be coated with a conductor or simply have a flat conductor mounted thereon to produce an emitting electrode.

Since the magnetic material loses its magnetism at the Curie temperature level, which is typically between 600 and 1400 Kelvin, the temperature of the surface on which the permanent magnet is placed can affect its operating parameters. However, in the present invention, it can be seen that the magnet can be located on the low temperature side or the high temperature side of the conversion device, and thus the magnet is prevented from reaching its Curie temperature.

The present invention provides a way to put the electrode materials together in a new and nonobvious way to produce a simple and inexpensive thermal-tunneling, thermal voltage, or thermal ion device, which has the following advantages: (1) in the prior art Simplicity by eliminating the need for actuators and control systems required by (2) using technologies and manufacturing processes already developed in the electric incandescent bulb and semiconductor industries to achieve low cost and mass production, (3) Allows tunneling of hot electrons from one electrode to another to achieve a narrow gap gap between the electrodes without the use of spacers to cool the first electrode, and (4) a uniform gap gap over a wide electrode gap such as one square centimeter To keep it.

Other systems, devices and features and advantages of the disclosed devices and processes will become or become apparent to those skilled in the art upon reviewing the following figures and detailed description. All additional systems, devices, features and advantages are intended to be included in this description, to fall within the scope of the invention and to be covered by the appended claims.

Many aspects of the disclosed devices and processes may be better understood by reference to the accompanying Figures 1-14. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention. In addition, in the drawings, like reference numerals do not necessarily require corresponding parts in some drawings. Although illustrative embodiments are described in conjunction with the drawings, there is no intention to limit this description to the embodiments disclosed herein. On the contrary, the intention is to include all alternatives, modifications, and equivalents.

1 illustrates one embodiment of a self-positioning electrode device herein.

FIG. 1A illustrates the directional state of the current, magnetic field, and static magnetic force of the device of FIG. 1.

FIG. 1B shows an alternative embodiment of the electrode 2 of the device of FIG. 1.

FIG. 2 is a schematic plan view of the electrode 1 of the device of FIG. 1.

FIG. 2A is a rear perspective view showing a cut portion of the embodiment of the electrode of FIG. 2. FIG.

3 illustrates an alternative embodiment of the device of FIG. 1.

4 shows another embodiment of the device of FIG. 1.

5 is a graph qualitatively illustrating the interaction force in the device of FIGS.

FIG. 6 is a graph quantitatively illustrating interaction forces in the devices of FIGS. 1, 3 and 4 using polished metal electrodes. FIG.

7 is a graph quantitatively illustrating the interaction forces in the devices of FIGS. 1, 3 and 4 using polished silicon electrodes.

FIG. 8 is a diagram illustrating how electrodes can be fabricated from silicon wafer material.

9A shows an alternative embodiment with a larger gap suitable for thermo-photovoltaic applications.

FIG. 9B is a graph similar to FIG. 5 showing the interaction force in the device of FIG. 9A.

10A-10C illustrate how the plurality of electrode pairs of FIG. 8 can be assembled simultaneously for mass production using process techniques conventional in the semiconductor industry.

11A and 11B illustrate how the plurality of electrode pairs of FIGS. 8, 9A or 10C may be packaged into a larger heat exchanger to achieve higher density and capacity of device functionality.

12A and 12B illustrate that the electrode pairs of FIG. 8 may be packaged using silicon, glass, glass-frit vacuum sealing and other standard micro-electro-mechanical (MEMs) packaging techniques conventional in the industry. Show the way.

FIG. 13 shows an arrangement of permanent magnets attached to a magnetically permeable grating to make larger devices from the smaller devices of FIGS. 8, 9A, 10C, 11A or 12B.

FIG. 14 is an example of a start-up electronic circuit that may be used to form a gap in the device of FIG. 8, 10c, 11a or 12b before applying high energy for embodiments where electricity is generated.

Exemplary embodiments of devices and processes herein are shown in FIGS. 1 through 14 with reference to the drawings in which like reference numerals refer to like elements in some of the drawings.

Generally, devices and processes are disclosed that use facing electrodes and involve two force distributions. The main electrostatic attraction distribution between the electrodes is created by the charge in the electrodes. The equivalent but opposite repulsive force distribution is produced by the current distribution in the electrodes, combined with the applied magnetic field distribution. The two force distributions work simultaneously to establish stable and equilibrium spacing of the electrodes across their facing surfaces.

1 illustrates one embodiment of the present specification. The electrode 1 is a flexible metal foil or metal foil mounted on a plastic film or substrate such as polyimide. The plastic substrate helps to prevent the foil from cracking, cresing or breaking after repeated operations created by electrostatic and electromagnetic forces. The plastic substrate or the electrode 1 of electrical nature can also act to prevent vibration or instability of its operation during equilibrium. The electrode 2 is a permanent magnet made of or coated with a conductive material. In an exemplary form, the electrode 2 is a rectangular block. The two electrodes are polished on the surfaces facing each other. The heat source 30 is present when the device is used for the conversion of thermal energy and is the object to be cooled when the device is used as a cooler. The power source 10 is present when the device is used as a cooler and is additionally an electrical load when the device is used as a heat conversion generator. The insulating layer 4 is present to allow a non-conductive resting point for the tip 6 of the electrode 1 when the device is not in operation (ie while the device is off). Additionally, one of the electrodes may have a coating of nonconductive material that is thinner than the desired equilibrium spacing between the electrodes on which the other one of the electrodes lies when the device is not in operation. The layer or coating 5 on the electrode 2 is designed to have a low work function to facilitate electron tunneling between the electrode 2 and the electrode 1. The connectors 9a and 9b and the wires 8a and 8b complete the circuit. The chamber 20 seals the area between the facing electrodes 1, 2 with a vacuum or inert gas to minimize heat transfer from one electrode to the other. Suitable gases include argon and helium. The wider end of the flexible electrode 1 is fixedly mounted to the support structure in the chamber 20, with the electrode 1 having its tip 6 placed on the insulating layer or film 4 when the power is off. .

FIG. 1A shows the direction state of the current I flowing in electrode 1, the magnetic field B generated by the presence of a permanent magnet in electrode 2, and the force F created from the interaction of I and B. FIG. . The force F acts vertically upward at all points of the electrode 1 and opposes and balances the electrostatic attraction that pulls the electrode 1 down towards the electrode 2.

1b shows an alternative arrangement for the electrode 2. Here, the surface of the material is patterned in an array of peaks 5. The geometry of these peaks allows for an improvement in electron emission from the electrode 2 due to the enlarged electric field in the region of the peak. In addition, such peaks may naturally occur due to the intended or unintended roughness of the surface of the electrode 2 after polishing.

In addition, the device of FIG. 1 has the additional power to create or change a mechanism or system to support its operation during power-off, balance, or transition from power-off to equilibrium or from balance to power-off. Can be. For example, such a mechanism may damp the system to prevent vibration or oscillation of the electrode 1 around its equilibrium resting position. This additional force can be generated mechanically, magnetically, electromechanically, electromagnetically, or in other ways to offset the lack or excess in the magnitude of the main electrostatic and magnetic offset forces.

The material of the flexible electrode 1 may be a conductive metal, a semiconductor material, laminated glass / metal or laminated metal / plastic. Exemplary conductive metals include gold, silver, aluminum and copper. Exemplary semiconductor materials include silicon, germanium, and gallium arsenide. The conductive metal or semiconductor material may optionally be mounted on or with a material that adds flexibility to the metal when the metal is not sufficiently flexible by itself, such as glass, polyamide, polyester, polyimide, polyacrylic or polyolefin. Can be combined into layers.

The permanent magnet of the electrode 2 may be included in or part of an electrode. In an exemplary embodiment, the permanent magnet can include a conductive ferromagnetic material in any combination of iron, cobalt, nickel, neodymium, or aluminum. Alternatively, the permanent magnet may include one or more nonconductive ferromagnetic materials coated with a conductive material. Exemplary non-conductive ferromagnetic materials include ferrite, barium ferrite, and iron oxide particles sealed with a binder.

The layer or coating 5 on the electrode 2 may be a low work function material, a thermoelectrically sensitive material, a resonant tunneling material, a field enhancement texture or a combination thereof. Exemplary embodiments of low work function materials include alkali metals, alloys of alkali metals, diamonds such as oxides or diamond films, or any stacked or other combination of nanotubes. The collection of peaks and valleys resulting from surface roughness or patterning (eg, as shown in FIG. 1B) can enhance the electric field to enhance electron emission from the electrode 2. Finally, semiconductor layers arranged to achieve resonant tunneling can also improve electron emission. Exemplary semiconductor materials include silicon, germanium, and gallium arsenide. Exemplary thermoelectrically sensitive materials include various doped bismuth tellurium compounds.

The low work function material in layer 5 of FIG. 1, or the reinforcing material 5 ′ of FIG. 1B, may be, for example, cesium (Cs), barium (Ba), strontium (Sr), rubidium (Rb), germanium ( Ge), sodium (Na), potassium (K), calcium (Ca), lithium (Li) and combinations thereof or oxides. This material is shown to reduce the work function of the emitting electrode 2 from 4-5 eV to as low as 1.1 eV or less. Additional low work function materials include thorium (Th), metal coated oxides, and silicon. Other materials not mentioned herein can also achieve a low work function, and the addition of such material layers is an obvious scope of the present invention. For example, different types of layers, wide gap semiconductor layers, which facilitate electron tunneling have been proposed by Korotkov. See A. N. Korotkov and K. K. Likharev, Possible Cooling by Resonant Fowler-Nordheim Emission, Applied Physics Letter, Vol. 75, 16, August 23, 1999. Here, a thin oxide layer whose thickness is carefully controlled excites the electrons in a resonant state to help hot electrons escape into the vacuum. In addition, layer 5 of FIG. 1 and 5 'of FIG. 1B may be an arrangement or configuration of carbon nanotubes to maximize emission and minimize work function. The insulating layer 4 material may comprise glass, polyimide or other plastics.

The flow of electrons in FIG. 1 and the uniqueness of the present invention can be explained as follows. Free electrons flow from the power supply or electrical load 10 to the emitting electrode 2. The free electrons emitted from the electrode 2 to the electrode 1 are selected to be high temperature electrons capable of removing heat from the electrode 2 by this design. One aspect of the present invention is that free electrons flow in the electrode 1 from left to right in FIG. 1 in the presence of the magnetic field B in which the direction is shown in FIG. 1A. This free electron flow direction, associated with the applied magnetic field, creates a repulsive force in the direction shown in FIG. 1A, balancing the electrostatic attraction and maintaining a constant and desired separation between the electrode 1 and the electrode 2 over a large area. To achieve.

FIG. 2 is a schematic plan view of an exemplary embodiment of the electrode 1 of FIG. 1 showing the cross section 7, with arrows pointing in the direction of electron flow. The cross section 7 has a current density equal to the total tunneling current picked up by the entirety of the electrode surface to the left, rather than divided by the length of the cross section 7. Since the tunneling current is expected to be proportional to the area of tunneling activity for the left side of 7, the length of the cross section 7 will optimally increase in proportion to the increase in the area of the electrode surface on its left side. Thus, the boundary 3 of the electrode 1 follows an exponential function. Thus, the width of the surface of the flexible electrode 1 increases exponentially from its tip 6 to its opposite end. The exponential function is mathematically equivalent to the area bounded by the exponential function and the X-axis up to its integration point. In addition, the function plotted by the boundary 3 can compensate for other variations in current density, such as electrical resistance due to the path length inside the electrode 1. Also, in some cases, the design may be in a suboptimal state with the electrodes 1 formed in a triangle for ease of manufacture.

FIG. 2A is a schematic rear view of the cut portion of the electrode 1 shown in FIG. 2. This figure shows how the electrode 1 can be patterned on its bottom face facing the electrode 2. This pattern allows the tunneling region (defined by the entire region X of the rising surface x) to be different from the total region Y available for the current to flow through. Patterning electrode 1 in this manner allows a larger total area Y, thus allowing lower electrical resistive losses and heat generating losses for the total current to flow. At the same time, the area in close contact with the electrode 2 is minimized, which reduces the electrostatic force that must be overcome to place the electrodes in their desired position. In addition, by intentional or unintentional surface roughness after polishing, the same effect as that of patterning the electrode 1 can be achieved. The intermittently raised segment 4 is a thin insulating layer, which can support the electrode 1, and when the device is turned on the foil material of the electrode 1 drape towards the electrode 2. To prevent electrical short circuit.

3 schematically illustrates another embodiment of the present disclosure that may achieve a more compact package. Here, the electrode 2 is a cylindrical permanent magnet having a magnetization direction radially outward from the center. The electrode 1 takes the form of an exponential helix whose width increases exponentially every turn. Alternatively, the electrode 1 may have a spiral shape that increases linearly as a simpler approximation to the exponential spiral shape for ease of manufacture. Since the electrode 1 has a spiral shape, the current flow is in a tangential direction. The force on the electrode 1 acts in the vertical direction, providing a repulsive force that balances the electrostatic attraction similar to that achieved in FIG. 1. The helical electrode 1 allows this embodiment to have a more compact design, since the entire tunneling area does not have to spread over one long dimension shown in FIG. Cylindrical magnets with radial magnetization (representing a magnetic field in the radial direction from the center of the device) are routinely available in the industry because they are popular in building loudspeakers. The remaining components of this embodiment are the same as in FIG.

In addition to the embodiment of FIGS. 1 and 3, which use a special form of one electrode to achieve uniform repulsive force, there are a number of other apparent embodiments of the present invention. 4 is a schematic diagram of one such other exemplary embodiment. It uses a changing magnetic field instead of a changing electrode width. For example, in FIG. 4, the current density of the electrode 1 increases from left to right as more current is made available from the tunneling region. In order to achieve a uniform force throughout the electrode 1, the magnetic field decreases from left to right, because more current density is produced and therefore weaker magnetic field strength is required. Therefore, the strength of the magnetic field in the flexible electrode 1 changes in inverse proportion to the current density in order to achieve a constant force. One way of decreasing the magnetic field from left to right is to change the depth of the permanent magnet material 23 included in the electrode 2 and to increase the amount of unmagnetized material 24 such as copper or aluminum.

FIG. 5 is a graph illustrating how the forces in FIGS. 1-4 interact to create a constant spacing between two electrodes across a tunneling region. Y axis 40 is the force, X axis 41 is the gap gap width or separation distance between the electrodes. Curve 43 shows the electrostatic attraction between electrode 1 and electrode 2. The force shown in curve 43 is inversely proportional to the square of the gap gap 41. Curve 46 shows the repulsive force between the two electrodes generated by the tunneling current flowing in the presence of the magnetic field. This current is close to zero until the separation is narrow enough to cause tunneling. This increases rapidly as the spacing further decreases. The location of the spacing point 42 where tunneling begins and the spacing point 44 for complete challenge depends on the process conditions used. For example, according to Hishinuma, the spacing point 42 at which tunneling begins is approximately 20 nanometers for devices with an applied potential of 0.1 to 2.0 volts, and essentially a point of complete conductivity is approximately 1 nanometer. Y. Hishinuna et al., Efficiency of Refrigeration using Thermotunneling and Thermionic Emission in a Vacuum: Use of Nanometer Scale Design; And Measurements of Cooling by Room Temperature Thermionic Emission Across a Nanometer Gap by Y. Hishinuma et al., Supra. The attraction and repulsion are the same at point 45. This is the separation at which the device is placed in its stable equilibrium position. If any disturbance to the device results in a separation greater than the point 45, the attraction force 43 becomes greater than the repulsive force 46, resulting in a tendency to move behind the equilibrium point 45. Similarly, if any disturbance makes the spacing smaller than the point 45, the repulsive force 46 is greater than the attractive force 43, returning the device back to its equilibrium point 45.

In addition to the electrode arrangement described above, the electrodes can also be arranged in multiple layers at periodic intervals. In addition, multiple units of the device can be combined in series, in parallel, or in parallel and in series to achieve higher levels of energy conversion.

In operation, the strength of the current distribution or density in the flexible electrode 1 and the magnetic field of the electrode 2 are adjusted to place the electrode in a spaced apart stable equilibrium position. In one exemplary embodiment, using an electron tunneling or heat ion electron transfer, or a combination of electron tunneling and heat ion principles, an electrode as used herein to convert heat into cooling or electrical energy, the electrode The intensity of the current density or distribution in (1) and the magnetic field of the electrode (2) are directed to spaced apart stable equilibrium positions in the range of 1 nanometer to 20 nanometers with a flexible metal foil for one electrode. Can be adjusted to locate them. In yet another exemplary embodiment, when the device of the present disclosure is used for cooling by heat ion electron transfer or heat conversion to power generation, the intensity of the current density or distribution at electrode 1 and the strength of electrode 2 The magnetic field can be adjusted to position the electrodes facing a stable equilibrium spaced apart in the range of 1 nanometer to 20 nanometers using a silicon wafer as the substrate relative to one or two electrodes.

The devices herein can be used in the process of converting heat into cooling or electrical energy. The heat source may be a radiation source, such as heat generated from an animal's metabolism or organs, such as, but not limited to, solar radiation, heat from the environment, geothermal energy, or heat from a living human body. The heat source may also come from running electricity, steam or an internal combustion engine, burning fuel in a stove such as a wood stove or coal stove or other stove type, or from their exhaust gases. If the heat source comes from, for example, operating an internal combustion engine or from its exhaust, the device can be integrated into the engine or gas exhaust line as a heat sink. The fuel for combustion may be wood, natural gas, coal or other combustible fuel. The converted energy may be stored somewhere such as a battery or may power a portable electrical device such as a cell phone, a cordless phone or other product described above.

In the case where the device operates as a cooler, the operation of the device herein will be described. Again in FIG. 1, a voltage increasing at zero is applied between the electrode 1 and the electrode 2 by the power supply 10. This voltage causes an electrostatic force to pull the tip 6 of the electrode 1 towards the surface of the electrode 2. As the voltage gradually increases, the flexible electrode 1 bends down towards the surface of the electrode 2 in a rolling form starting at the tip 6. This bending continues until the electrode 1 is very close to the electrode 2 and the tunneling current begins to flow upward from the electrode 2 to the electrode 1. This tunneling current flows horizontally to the right in the electrode 1 toward the connector 9 once it reaches the electrode 1. This current flows in the I direction of FIG. 1A, and the magnetic field generated by the permanent magnet near the electrode 2 is the B direction, so the force will act to raise the electrode 1 upwards. While the voltage from the power source 10 continues to increase, the electrode 1 will flatten and match the surface and contour of the electrode 2. The electrostatic force will act to pull the two electrode surfaces together and the opposite force from the current flowing in the electrode 1 will prevent the two electrodes from being placed more closely than the desired spacing.

The operation of the device of the present invention as a generator device is similar except that the heat source 30 generates a "hot electron" transfer from the high temperature high energy state at the electrode 2 to the low temperature low energy state at the electrode 1. . This movement of electrons from one energy state to another creates a current flow between the electrodes. The electrical load 10 becomes a sink for the electrical energy generated thereby.

In the cooling operation, electrical energy is used from the power source to cool it by drawing hot electrons from the electrode 2. When operating as a generator, heat source 30 is used to insert electrons into a power source.

<Examples>

The invention will be further illustrated by the following examples based on the fundamental laws of physics in conjunction with experimental data and measurements obtained by the inventors and academic scientists as described herein. These examples show the following: (1) The devices herein can be designed and manufactured using dimensions and processes common in the industry. (2) The generated quantified force will achieve the desired electrode spacing. (3) The electrical characteristics of the device of the present invention can efficiently transport and transmit the converted electrical energy. Examples describe the three attributes described above of the device of the present invention for a heat-tunneling converter with an electrode spacing less than 20 nanometers and for a thermo-photovoltaic converter with an electrode spacing of approximately 100 nanometers.

<Example 1>

For the heat-tunneling converter, consider the following dimensions in FIG. 1, 2 or 3.

The overall overlapping tunneling area Y of the facing electrodes is 1 square centimeter, or 10 ⁻⁴ square meters. The length L of the flexible electrode 1 is 2 centimeters and the maximum width W is 1 centimeter. The length L and the width W are defined similarly to that of FIG. 3, but the electrode 1 is wound in a spiral form compared to the linear form for FIG. 1. The facing surface of the electrode 1 is a surface having a surface roughness or patterned such that the entire tunneling region X (sum of all x) is one tenth of the total surface region Y, that is, 10 ⁻⁵ square meters. The permanent magnet material used for the electrode 2 has a magnetic field strength B of 1.2 Tesla. The voltage V between the electrodes is 0.15 volts. The dielectric constant epsilon of the vacuum or lean inert gas between the electrodes 1, 2 is equal to 8.8 × 10 ⁻¹² farads per meter. The resistivity r of the flexible electrode 1 is assumed to be close to the resistivity of copper or 1.7 × 10 ⁻⁸ ohm-meters. The resistance of the path of electrons from the upper connector 9a to the other lower connector 9b is assumed to be fully concentrated in the electrode 1 due to the need to be thinner and more flexible than the rest of the circuit. The thickness t of the flexible electrode 1 is 20 micrometers and is thus a foil material.

, 여기에서 d는 전극들간의 이격이다. 자기적인 척력에 대한 공식 F_m은 ILB이며, 여기에서 I는 전류이고, L은 전극(1)에서의 전류 흐름의 유효 평균 길이이다.The formula for electrostatic attraction F _e is

Where d is the spacing between the electrodes. The formula F _m for magnetic repulsion is ILB, where I is the current and L is the effective average length of the current flow in the electrode 1.

The tunneling current I, which is a function of the spacing, is taken from Hishinuma's graph and is assumed to have an operating temperature of 1.0 eV and 300 Kelvin, the work function of the coating 5 of FIG. Y. Hishinuma et al., Efficiency of Refrigeration using Thermotunneling and Thermionic Emission in a Vacuum: Use of Nanometer Scale Design; And the above-described Measurements of Cooling by Room Temperature Thermionic Emission Across a Nanometer Gap by Y. Hishinuma et al.

In FIG. 6, the functions F _m and F _e of the forces for the values described above are plotted on the Y axis according to the logarithmic scale, and on the X axis the electrode spacing gap d is plotted on an arithmetic scale. This plot produces a graph like FIG. 5 and is only now fully quantified. The stable equilibrium point 45 is 2.0 nanometers, which, according to Hishimuna, is within the necessary spacing range to achieve 20 amperes of tunneling current. See, for example, Measurements of Cooling by Room Temperature Thermionic Emission Across a Nanometer Gap by Y. Hishinuma et al. If the disturbance tries to shift the gap gap away in either direction from a stable equilibrium, the restoring force is greater than 0.2 Newtons, which is sufficient to overcome the bending resistance of the flexible electrode and return it back to its equilibrium position. Do.

With an emitting electrode at room temperature, a current of 20 amps and a voltage of 0.15 volts, the device can achieve either 16 watts of power production capacity or cooling capacity, which is described by Y. Hishinuma et al. Calculated by multiplying the current (I) by the Peltier coefficient of 0.8 used in this example as described in by Room Temperature Thermionic Emission Across a Nanometer Gap. The resistive power lost in this flow of current through the flexible electrode 1 is I ² rL / tw. With the above values, the ohmic power loss is calculated at 1.0 watt, which is believed to be manageable as both the power loss and the source of the heating electrode 1. In addition, heat transfer from electrode 2 to electrode 1 can occur by radiation, convection, and conduction, but when the chamber of the device of the present invention is emptied to an argon gas level of 0.06 mm Hg, it becomes 1.3 watts or less. It is estimated. Finally, as described in Y. Hishinuma et al., Measurements of Cooling by Room Temperature Thermionic Emission Across a Nanometer Gap, there is an electrical heat generated on the electrode 2, which is the voltage V multiplied by the current I. Value, or in this example, approximately equal to 3.0 watts. The remaining energy available from the 16 watts of converted energy is 10.7 watts. This corresponds to a calculated efficiency of 67%.

Thus, based on the established electromagnetic theory, it can be seen that the system level characteristics of the device support an operable design and reduction means implemented for heat-tunneling converters with high efficiency.

<Example 2>

Another example of the variety of the invention lies in the choice of materials. As described in Example 1, a preferred embodiment includes a metal foil as one of the electrodes. In another embodiment, single crystal silicon may be used as the flexible metal. Silicon is not usually regarded as a flexible material, but is routinely manufactured in industry with a roughness of 0.5 nanometers and a flatness of 1 micrometer over a square centimeter surface. As measured by Young's Modulus, silicon is much stiff than metal foil, but its flatness indicates that very small warpage is required to approach the ideal flatness. It will be seen that the force generated by the present invention can bend the silicon wafer by 1 micron, which is necessary to completely flatten the silicon wafer. Overall, using silicon as a base material for flexible electrodes or two electrodes has several advantages: (1) Silicon wafers are readily available at low cost. (2) The silicon wafer has desirable roughness and flatness characteristics. (3) Adding a low work function material or pattern of materials on silicon is frequently performed easily in the industry. (4) The resistance of silicon prevents the flexible electrode from reacting too quickly while in contact with or near contact with the other electrode of the present invention. (5) The desired resistance of silicon can be arbitrarily controlled through doping, which is also a common practice in the industry. In total, the designs of the present invention can be made of materials and processes routinely available in the semiconductor industry.

Consider FIG. 8 to illustrate an example of the invention using silicon for a flexible electrode. Here, the electrode 1 consists of a foil backing 62 and a silicon substrate 65. The shape of the electrode 1 in FIG. 8 is a triangle approximating the optimum exponential shape described in Example 1. FIG. The silicon substrate 65 may be cut from a standard wafer and then bonded to the foil backing 62 of the electrode 1 using a conductive adhesive. The electrode 2 'of FIG. 8 is made like the electrode 2 of FIG. 1, and only magnets are not shown and are considered to be spaced apart. By separating the magnet from the electrode 2 ', the electrode 2' of FIG. 8 can be manufactured using the same material and process as the electrode 1 of FIG. Arrow 61 shows the direction of flow of electrons. Since foil backing is much more conductive than silicon, electrons will follow the path of least resistance. Thus, the electrons flow through the conductive, from right to left through the foil backing of the electrode 2 'and then vertically through the silicon substrate of the electrode 2' as indicated by some arrows 67, As indicated by some arrows 66, it flows through the tunneling or heat ion release from the surface 64 of the electrode 2 ′ to the electrode 1 in a vacuum. Once the electrons reach the electrode 1, it flows vertically through the silicon substrate as indicated by some arrows 65 and finally reaches the foil backing 62 of the electrode 1. The electrons then follow a very low resistance path from left to right through the foil backing 62 of the electrode 1. As in the direction indicated by arrow 61, the flow of electrons interacts with the magnetic field of a nearby permanent magnet, not shown in FIG. 8.

In this example, the total thickness t _s of silicon is 0.5 millimeters or 0.25 millimeters per wafer, which is the industry standard thickness. The silicon material is doped to have a resistivity r _s of 0.02 ohm-cm, which is also commonly practiced. The Young's modulus E _s for silicon is known to be 47 Giga Pascals, or 4.7 × 10 ¹⁰ Pascals. Silicon wafers are routinely polished in the industry with surface roughness up to 0.5 nanometers, achieving a surface flatness d _x of 1.0 micrometers for wafers of one centimeter transverse dimension.

FIG. 7 shows the effect of silicon on force as compared to FIG. 6. Since the gap becomes very small, the magnetostatic force is limited to 0.6 Newtons. The resistance of the silicon limits the current flow and thus the magnetostatic repulsion. In addition, a very narrow gap will cause both the supply voltage to drop in the silicon resistance, with zero voltage across the gap, which means that the electrostatic attraction is zero for very small gap spacings.

To quantify this effect, we consider the maximum current that can flow in this system, which is the supply voltage V divided by the silicon resistance, which is equal to r _s t _s / Lw. For the applied voltage, length and width of the electrode in Example 1, the maximum current flow when silicon is present is approximately 50 amps. In addition, when the current approaches this 50 ampere level, the supply voltage drops across both silicon and there can be no voltage difference across the facing surface of the electrodes.

The restoring differential force in FIG. 7 is relatively large. According to the figure, a deviation of 0.1 nanometers from the desired separation produces a restoring force greater than 0.05 Newtons. This restoring force is much larger than the bending force required to flatten the electrode 1 and much greater than the bending force required to achieve parallelism with the electrode 2 as will be calculated below.

In order to flatten the corrugation of 1 micrometer in the electrode 1, a force of 40d _x E _s wt _s ³ / 12L ³ is required. This force is calculated as 0.003 Newtons. If electrode 1 and electrode 2 have opposite valleys, the force required is twice this amount, or 0.006 Newtons, which is greater than the 0.05 Newtons restorative force available to keep the gap at the desired gap of 0.1 nanometers. Much smaller.

The property of the force in FIG. 7 with the silicon electrode material is more desirable for the following reasons than the property of the force in FIG. 6 with the metal foil material: (1) The force with respect to the silicon may be It is not large enough to cause vibrations or sudden movements that can damage or destabilize. (2) The larger flatness of the silicon wafer relative to the metal foil allows the system to start much closer to the desired operating point. (3) The resistance of silicon prevents the formation of large currents in very localized areas, which can cause high temperatures and cause evaporative damage to the electrode material. (4) The hardness of the silicone reduces the amount of material movement to maintain the gap over time, thereby reducing the risk of fatigue, cracking or deformation. (5) The higher hardness and flatness of the silicon ensure that the gap can be maintained in the presence of local fluctuations, thereby providing precision in exponential shape, electrode thickness uniformity and other parameter variations in materials and designs. The need for is reduced.

<Example 3>

9A shows another example of how this device can be used for a different type of energy conversion called thermo-photovoltaic. In this example, the heat source 71 causes the light-emitting material 73 to begin to emit light, shown by 72 across the gap 74, to the photosensitive material 75, which gap is described above. Less than the wavelength of light, this photosensitive material then produces a current shown by arrow 76. In this example, the light-emitting material 73 can be tungsten or the like. The photosensitive material 75 may be silicon, selenium, gallium, arsenic, indium or any combination or alloy thereof. The length required for the gap 74 is typically less than or approximately 100 nanometers below the minimum wavelength emitted by the light-emitting material 73 to achieve near-field optical conditions. The light-emitting electrode 73 is in this case hard, flat and polished on the gap side. Photosensitive electrode 75 has sufficient flexibility to flatten into a generally uniform gap of approximately 100 nanometers.

9B shows a graph of forces that can create a stable gap in the thermal-photovoltaic implementation of the present invention. Since the electrostatic force is too small to be meaningful at this distance, a spring force or similar external force can be replaced to cause a pull between the two electrodes. The spring force has a linear magnitude as a function of gap separation. The balancing repulsive force is generated as in the previous example by the current shown by the arrow 76 flowing in the presence of a magnetic field, which is not shown in FIG. 9. This current is generated by the photosensitive material that receives the photons from the emission of the electrode 73 but on the one hand helps to create and maintain a uniform gap spacing as described in the previous examples. The repulsive force 46 ′ in FIG. 9B is proportional to the thermal-photovoltaic current derived from Micron-gap ThermoPhotoVoltaics (MTPV) by R. DiMatteo et al.

<Example 4>

10A-10C show how the design of FIG. 8 or 9 can be assembled, where a plurality of devices are electrically connected in series and thermally connected in parallel. Also, FIGS. 10A-10C show how to increase to these multiple devices using fabrication techniques widely used in the semiconductor industry. 10A shows a base substrate 82 holding one side of a plurality of devices. The substrate 82 is cooled when the device is operating as a heat-tunneling cooler, heated when it is operating as heat for an electrical converter, or radiates when the device is operating as a thermal-photovoltaic converter. FIG. 10B shows a side view of a film stack that may be created to fabricate a plurality of devices on one substrate 82. Substrate 82 is made of silicon, silicon carbide, aluminum, gallium arsenide or similar substrate materials commonly used in the industry. Layer 88 is an oxide or similar film that electrically insulates first metal layer 83 from substrate layer 82 but still allows thermal conduction. The first metal layer 83 is a relatively thick highly conductive layer for carrying current for heat-tunneling operations, or for carrying heat for thermal-photovoltaic operations. Metal layer 83 may be copper, for example, or may be a less expensive metal, such as aluminum. Gap layer 84 is a metal or other film that is most suitable for the interface with the gap. In the case of heat-tunneling, this layer 84 may be gold to protect it from oxidation and contamination, since gold is an inert metal. In the case of thermal-photovoltaic operation, the gap layer 84 may be tungsten or other material that is highly light-emitting to maximize the conversion of heat to photons across the gap. Layer 85 is a sacrificial layer that is removed after the film stack of layers 83, 84, 84 ′ and 83 ′ has been created. The sacrificial layer provides a structure for placing additional films comprising the second electrode. After removal of the sacrificial layer 85, a gap is formed between the layers 84, 84 ′ by the force balance described above in FIGS. 5, 6, 7 or 9b. Layer 84 'is optimized to receive energy from the gap and to protect layer 83' from contamination or oxidation. In the case of a heat-tunneling operation, layer 84 'may be made of gold. In the case of thermo-photovoltaic operation, layer 84 'may be a photosensitive material described as material 75 in FIG. 9A. Layer 83 'is a current carrying layer that carries current from the device, and the material may be copper or aluminum. Once the film stack shown in FIG. 10B is created using semiconductor processing, serial electrical connections are made as shown in FIG. 10C. In this case, wires and wire junctions 86 are used to make electrical connections from the top electrode to the neighboring substrate electrodes. Wire 89 represents electrical inputs and outputs for a plurality of devices. The sacrificial layer 85 may be made of any material that may be removed with a processing liquid, gas, or melted or evaporated with heat.

Once a pair of devices are created as shown in Figures 8, 9A, or 10C, they can be inserted into the heat exchanger package shown in Figure 11A, for example. Here, electrode pairs or array of electrode pairs 92 transfer heat from one fin 93 to the corresponding fin 93 ′. The fins 93 are all physically connected to the first row plate 90, and the corresponding fins 93 ′ are all physically connected to the second row plate 90 ′. The heat plates 90, 90 'show the hot side and cold side for heat-tunneling or thermo-photovoltaic operation by bringing together the smaller hot side 93 and the smaller cold side 93' together. The thermal plates 90, 90 'are made of a material having high thermal conductivity such as copper, aluminum or silicon. The rectangular tube 91 provides a wall for the sealable container and is made of a material having low thermal conductivity, such as glass, teflon, polyimide or similar material with sufficient compressive strength. Low thermal conductivity allows for thermal isolation of the hot and cold plates 90, 90 ', thereby improving the efficiency of the system. If the plates 90, 90 ′ have mismatched thermal expansion properties to the tube wall 91, the interface material 95 is vacuum-compatible with a viton such as Viton. ) Soft rubber, or Teflon, polyimide or similar materials used to make o-rings in the industry for this type of sealing. If the thermal expansion properties of the thermal plate material 90, 90 ′ and tube wall material 91 are approximately the same, the interfacial material 95 may be a strong bonding material, such as glass frit, epoxy, solder, or welding. FIG. 11B illustrates a manner of creating a magnet structure surrounding the heat exchanger package 11a and providing the magnetic field needed to form a gap in the electrode pair 92 of FIG. 11A. The permanent magnet 101 is secured to a rectangular ring of magnetically permeable material 100. The permanent magnet 101 may be made of standard materials used for magnets such as alloys of iron, cobalt, nickel, neodymium, boron, and aluminum. Typically, the alloy is sintered into small particles to achieve high residual magnetism when magnetized and then repacked into the desired shape using a binder material. The rectangular ring 100 may be made of the same steel used in the transformer to maximize the magnetic field and magnetic permeability generated by the permanent magnet 101. Such materials may be iron-rich steel or some other alloy, for example iron, cobalt, nickel, chromium and platinum.

Figure 13 shows how the magnet assembly can be enlarged to accommodate the heat exchanger arrangement. Magnetically permeable material 110 is arranged in a lattice structure with an array of voids for inserting the devices shown in FIGS. 8, 9A, 10C or 11A. Permanent magnet 101 is inserted into each cell to generate a magnetic field between the magnets.

In a very miniaturized manufacturing process, the magnet arrangement of FIG. 13 may be fabricated on top of the substrate of FIG. 10C and arranged such that the electrode pairs of FIG. 10C are received in the gaps of the magnet arrangement of FIG. 13. In the case of minimization, the permanent magnet 101 and the permeable material 110 are the materials mentioned using standard processes such as evaporation, sputtering or plating directly on a substrate similar to that of the electrode films of FIG. 10B. Can be grown as a metal film.

FIG. 14 illustrates additional electrical circuitry that may be required when the device of FIGS. 8, 10C or 11A operates as a heat-tunneling converter that converts heat into electricity. Since the device 120 of the present invention requires current to flow to achieve gap formation, the gap does not exist before the flow of current. In FIG. 14, an external power source 122 provides a flow of current that can be used to form a gap in the device 120. Once the gap is formed and heat is applied to one electrode, a temperature difference is generated for the other electrode. Once this temperature difference is present, heat-tunneling of the hot electrons will begin to flow, creating an additional current flow. Once the heat-tunneling current flows, as previously described, this alone can maintain a gap in device 120. Now, the external power source 122 is no longer needed and can be switched off by the switch 123. Thus, the circuit of FIG. 14 is a startup circuit for thermal-tunneling conversion that converts heat into a power source for electrical load 126. Each time the heat source is removed and subsequently reset, the switch 123 may reapply the external power source 122.

<Example 5>

12A shows another example of packaging the electrodes of such a device, similar to the way micro-eletromechanical systems (MEMs) are packaged when a vacuum environment is needed. Top and bottom row plates 130 may be made of silicon and may be cut from standard silicon wafers. Silicon has a high thermal conductivity and will therefore be well suited for the thermal path of this device. The wall of the package 132 is made of glass, which has a low thermal conductivity but has a coefficient of thermal expansion close to that of the silicon thermal plate 130. Since glass and silicon have similar thermal expansion properties, known glass frit bonding methods between 130 and 131 can be used. Glass frit bonding is commonly used to bond two pieces of glass together, but glass can also be bonded to silicon because a naturally formed layer of glass silicon dioxide is formed on the silicon surface exposed to air. The result is a very strong and tight seal between glass and silicon that can easily withstand vacuum pressure. Similar vacuum packages are used in the MEMs industry for accelerometers, oscillators and high frequency switches. In addition, the base layer 131 may be made of silicon and bonded to the heat plate 134. The metal layers 134 on the top and bottom heat plates 130 are used to make electrical connections to the electrodes in the package without the need for through holes or other mechanisms that limit the life of incandescent bulbs and other vacuum products.

FIG. 12B illustrates how the electrodes can be accommodated in the vacuum package of FIG. 12A. Electrode pair 145 corresponds to FIGS. 8, 9A or 10C. Thermal interface material 141 conducts heat to / from each electrode to the exterior of the package and also provides a soft layer to reverse the electrodes during operation. Examples of thermal interface material 141 are gap pads from Bergquist Corporation, vacuum greases from Apiezon or Dow Chemical, carbon nanotube compounds and mixtures from MER Corporation, or other soft materials mixed with thermally conductive particles. Bonding material 143 bonds the glass wall to the silicon thermal plate, examples of which are epoxy and glass frit. Wire 144 connects the base of the electrodes to the top and bottom plates. Exemplary materials for the wires are flat foils or cylindrical wires of copper, aluminum, or other electrically conductive material. The copper layer 134 allows a wide current to flow through the resistive silicon plate 130. The silicon plate may be doped with boron, arsenic or similar elements to increase electrical conductivity and minimize resistive loss of current flow into the package. Getter filament 140 is heated much like a filament in an incandescent bulb when a voltage is applied to its copper pad 134. A suitable material, such as cesium chromate, is coated on the filament 140 to allow the release of cesium vapor into the vacuum package. When cesium vapor is released, it achieves the following functions: (1) Exhaust the gases inside the package after sealing by reacting with residual air and other gases to produce a solid. (2) Similarly react to remove gas leaking into the chamber during the lifetime of the device. (3) By naturally forming a cesium monolayer or sub monolayer on the gap-facing surface of the electrode 145, it produces a low work function to aid in the emission of electrons across the gap.

<Other examples>

The above-described basic examples illustrate how an operating heat-tunneling system can be designed to achieve cooling or power conversion. Other examples are easily designed by changing one or more parameters used in Examples 1 and 2. The gap distance can be increased by one or more of the following changes: (1) increasing the magnetic field, (2) decreasing the voltage, (3) increasing the current flow, (4) increasing the length of the flexible electrode, or ( 5) reduction of the area of flexible electrodes. The gap distance can be reduced by making the opposite change.

Some of the features described herein need not necessarily be present and can be achieved without additional manufacturing complexity. Since the industry could not produce a working thermal-tunneling converter larger than the nanometer dimension, the actual operation at the larger size is unknown. For example, referring again to FIGS. 1A and 1B, a low work function layer 5 may not be necessary if the gap can be slightly smaller. The reinforcing material 5 'can only be easily obtained by surface roughness after polishing, which naturally produces peaks and valleys that are known to improve electron emission. In addition, the resting tip 6 may not be necessary given the choice of resistive material for the electrode 1 or 2. The electrode patterning in FIG. 2A, which also provides peaks and valleys to reduce electrostatic forces, can also be achieved by natural surface roughness after polishing. Finally, the vacuum chamber 20 may not be necessary if the tunneling process has been experimentally demonstrated in the air gap. Also, the exponential form of the electrode 1 can be approximated more easily by making a triangular form. All of these complex features (tip 6, layer 5, reinforcing material 5 ', patterning, curved shape of electrode 1, and vacuum chamber 20 of FIG. 2A) are needed for final production. It is included herein for completeness in describing what may be.

The devices disclosed herein have many uses in the manufacture of various types of electronic bonds for the electronics industry that require uniform gaps between the electrodes. For example, a thermoelectric device having poor thermal insulation between the hot side and the cold side may use this specification. The vacuum spacing at the top of the thermoelectric stack may provide better insulation, and the present disclosure provides a means for obtaining such a gap in accordance with or in connection with a thermal ion or heat-tunneling method.

The final description of the ease of manufacture of the devices disclosed herein relates to the mention of other natural forces that occur when two very smooth surfaces are placed together. Two attraction forces known to bring together smooth planes are the Casimir forces and the Van der Waals forces. These forces are strong enough to bring the two electrodes of the invention together before applying a voltage, but during the operation of the invention so as to affect the desired interaction and predominance of electrostatic and magnetostatic forces as described. It is not expected to be strong. However, this Kashmir and Van der Waals forces can ensure that the two electrodes are in full surface contact before turning the device on with the applied voltage. In this case, the operation of the present invention only needs to space the two electrodes by a few nanometers. This Kashmir and van der Waals forces also help to eliminate the need for the insulating layer 4 of FIG. 1 and further simplify the design of the present invention.

Multiple units of the device may be connected together in parallel and in series to achieve higher levels of energy conversion, or to match voltage to a power source, or both.

Experiment and Simulation Results

The electrode configuration of FIG. 8 was assembled in a microelectronic laboratory using copper as the foil backing, and these electrode pairs were placed inside the magnet structure as shown in FIG. 11B. Thermocouples were attached to each electrode to produce a voltage proportional to temperature, and the entire instrument was placed in a vacuum chamber pumped to a vacuum pressure of 1E-3 Torr. When the electrode pair was excited by an external power source having 1.1 amps, a relative temperature difference of 3.0 degrees was observed between the two electrodes, and the lower side was the side emitting electrons. It was observed that this same relative temperature difference was lost when any of the following actions were taken: (1) replacing the vacuum with nitrogen at atmospheric pressure, (2) deactivating the chip by disconnecting the external power source, or ( 3) reversing the current flow to increase the contact attraction between the electrodes instead of forming a gap. Each of these three operations is believed to eliminate the heat-tunneling effect. In addition to the observed electrical properties of the electrodes, computer simulations of the electromechanical system of the instrument have also been successful in creating a thermal-tunneling gap consistent with this design.

It should be emphasized that the above-described embodiments of the present device and process, in particular the "preferred" embodiments, are merely possible examples of implementation and are merely presented for a clear understanding of the principles of the present invention. Many different embodiments of the self-positioning electrode device described herein can be designed and / or manufactured without departing from the spirit and scope of the invention. All such modifications and variations are intended to be included herein within the scope of this specification and should be protected by the following claims. Accordingly, the scope of the invention is not intended to be limited except as indicated in the appended claims.

Claims (75)

A device comprising facing electrodes or electrode assemblies, the device comprising: The attraction force distribution in the electrodes or electrode assemblies, and the opposite repulsive force distribution generated by the current distribution in the electrodes or electrode assemblies in the presence of an applied magnetic field distribution, are two And a device that simultaneously acts to establish a stable equilibrium separation of the two electrodes across the facing surfaces of the electrodes. The method of claim 1, One or two of the facing electrodes is a flexible device. The method of claim 2, The flexible electrode (s) comprises a base material selected from the group consisting of conductive metal, laminated metal / glass, laminated metal / plastic composite, and semiconductor material. The method of claim 3, The base material is in the group consisting of gold, silver, aluminum, copper and nickel optionally bonded with layers having silicon, germanium, or gallium arsenide, or glass, polyimide, polyester, polyamide, polyacrylic or polyolefin. A device comprising a selected conductive metal. The method of claim 1, The surface of the one or more electrodes consists of a low work function material, a thermoelectrically sensitive material, a plurality of peaks and valleys, a semiconductor resonator, a stacked material having a resistive lower layer and a lower work function upper layer, or a combination thereof. Devices that are fabricated, coated, or evaporated thereon. The method of claim 5, The low work function material includes a stack of alkali metals, alloys of alkali metals, oxides, diamonds or nanotubes or other bonds. The method of claim 6, The low work function material is a device selected from the group consisting of cesium, sodium, potassium, thorium, metal-coated oxides, diamond films, silicon, germanium, an array of carbon nanotubes and a collection of nanometer-sized oxide particles. . The method of claim 1, And a permanent magnet mounted on or near one of the electrodes. The method of claim 8, The permanent magnet is received in one of the facing electrodes or is part of one of the facing electrodes. The method of claim 8, And the permanent magnet comprises conductive ferromagnetic magnetic materials in any combination of iron, cobalt, nickel, neodymium and aluminum. The method of claim 8, One of the electrodes formed of a permanent magnet comprising non-conductive ferromagnetic materials coated with a conductive material. The method of claim 1, The device further comprising a force generated mechanically, magnetically, electrostatically, electromechanically, or electromagnetically to offset the lack and excess in the magnitude of the attraction and magnetic repulsive forces. The method of claim 1, And a damping system for preventing oscillation or oscillation of one of the electrodes in the vicinity of the equilibrium resting position. The method of claim 2, And wherein the flexible electrode is shaped to produce a current density distribution that generates, in conjunction with the magnetic field distribution, a repulsive force distribution equal to the attractive force distribution at or near a desired separation distance distribution between the electrodes. The method of claim 14, The width of the surface of the flexible electrode increases exponentially from one end to the other end. The method of claim 1, At least one of the electrodes is patterned or roughened into raised and unlifted regions to simultaneously reduce electrostatic force and electrode resistance loss. The method of claim 2, The flexible electrode (s) are wider at one end and the wider end is fixedly mounted on the support structure. The method of claim 2, The flexible electrode (s) are narrower at one end, with the narrower end lying on an insulating support while the device is turned off. The method of claim 1, Wherein a portion of one electrode has a coating of non-conductive material, while another electrode can lie on the non-conductive material while the device is turned off. The method of claim 2, And said flexible electrode comprises a metal foil mounted on a flexible plastic film. The method of claim 1, And the electrodes are sealed in a vacuum chamber. The method of claim 1, And the electrodes are enclosed in a chamber filled with an inert gas. The method of claim 22, The inert gas comprises argon or nitrogen. The method of claim 2, The strength of the magnetic field varies inversely with the current density in the flexible electrode to obtain a constant force. The method of claim 1, One of the facing electrodes is formed in the form of a spiral and the magnetic field is developed radially from the center of the device. The method of claim 25, And wherein the helix form has a linearly increasing width. The device of claim 25, wherein the spiral shape has an exponentially increasing width. The method of claim 1, And a heat source connected to the electrodes. The method of claim 1, And a power source connected to the electrodes. As a process of converting thermal energy into electrical current, or electrical energy into regulation, Providing the device of claim 1; And Adjusting the current distribution and the strength of the magnetic field to place the facing electrodes in a spaced apart stable equilibrium position Conversion process comprising. The method of claim 30, And the facing electrodes are spaced within a range of approximately 20 nanometers or less. The method of claim 30, The current distribution and the strength of the magnetic field are adjusted to place the facing electrodes in a spaced apart stable equilibrium position within a range of 1 nanometer to 20 nanometers. The method of claim 30, The intensity is adjusted to produce electrode spacing in the range of 6 nanometers to 20 nanometers. The method of claim 30, The intensity is adjusted to produce electrode spacing in the range of 1 to 6 nanometers. A process for converting heat into cooling or electrical energy using the device of claim 1. 36. The method of claim 35 wherein A heat source is a conversion process that is a radiation source, heat from the environment, geothermal energy, or heat generated from metabolism in organs or animals. 36. The method of claim 35 wherein A heat source is a transformation process that is a living human body. 36. The method of claim 35 wherein The heat source is a living human body and the device is a portable device. 36. The method of claim 35 wherein The heat source is a conversion process that is an operating electricity, steam or internal combustion engine, combustion fuel, or exhaust gases thereof. 36. The method of claim 35 wherein The heat source is an internal combustion engine or exhaust gas thereof and the device is integrated as a heat sink in the engine or gas exhaust line. The method of claim 1, The magnetic field strength decreases in the same direction as the current density increases in the one or two electrodes to achieve a uniform force distribution acting between the electrodes. The method of claim 41, wherein The proximity of the magnetic material is reduced in the direction of increasing the current density at the one electrode or two electrodes. The method of claim 1, And the electrodes are arranged in a plurality of layers at periodic intervals. A device comprising a plurality of units of the device of claim 1 assembled in series. A device comprising a plurality of units of the device of claim 1 assembled in parallel. A device comprising a plurality of units of the device of claim 1 assembled in parallel and in series. 36. The method of claim 35 wherein The process is performed at a naturally occurring temperature. 36. The method of claim 35 wherein The device is used in a cooler, an air conditioner, a cooling blanket, a cooling garment, or a cooling device attached to or contained within a human or animal body. A device comprising a plurality of devices of the device of claim 1, comprising: A device fabricated on a wafer or stack of wafers to achieve a production efficiency or packaging density, or a combination of production efficiency and packaging density. The method according to any one of claims 43 to 46 or 49, The electrodes are located on smaller heat sinks that are all connected to a larger heat sink that accumulates heat flow to or from the plurality of devices. 51. The method of claim 50, The smaller heat sinks are connected to the larger heat sink and include fins running in a different planar direction than the connection. 52. The compound of any one of claims 1, 43-46 or 49-51, And a permeable ferromagnetic material and a plurality of permanent magnets arranged to have a void comprising a magnetic field that causes gaps to form in each device when the devices are turned on and have current flow. The method of claim 52, wherein And the permanent magnets are placed inside a grating formed from an investment magnetic material to form an array of the devices having a side through which heat flows into the array of devices and a side through which heat flows out of the array of devices. 55. The compound of any one of claims 1, 43-46 or 49-53, The device is created by a microelectromechanical systmes (MEMs) process and design technique. The method of claim 54, One or two of the electrodes are produced from an array of cantilevered structures made from a combination of film growth and sacrificial layer removal on an industry standard substrate. The method of claim 52, wherein The permanent magnet and / or permeable magnetic material is one of iron, cobalt, nickel, chromium, platinum, aluminum or neodymium, alloys thereof, or recombined sintering. The method of claim 1, And further comprising an electrical circuit that generates a gap-forming starting current in the device that creates a gap that can support a temperature difference between two electrodes or electrode assemblies until electron tunneling can be predominant as a gap generating current. device. The method of claim 1, By including cesium or barium or a combination of cesium and barium in a vacuum package to produce a vapor forming a single layer, a submonolayer, or a plurality of single layers on one or two of the facing electrodes. A device in which a low work function layer is formed. The method of any one of claims 1 or 49 to 56, A device comprising a material that acts as a getter to remove unwanted gases during or after production. The method of claim 59, The getter material is selected from the group consisting of titanium, cesium, barium, sodium, potassium, and combinations thereof. The method of claim 1 or claim 49 to claim 56, The electrodes or electrode assemblies are housed in an evacuated container, the container having two thermal paths entering and exiting the container. 62. The method of claim 61, Wherein the separating material of the two thermal paths is glass, ceramic or other material with low thermal conductivity. 62. The method of claim 61, The thermal path material is made of silicon, copper, aluminum, or another material having high thermal conductivity. The method of claim 62 or 63, wherein The walls of the container are glass, the thermal paths are silicon, and they are bonded together using a glass frit process to form a vacuum seal. The method of claim 63 or 64, The silicon material is heavily doped to allow electrical connection to the electrodes to penetrate the silicon and eliminate the need for wire holes, feed-throughs or similar connections inside the container. Device that allows you to remove it. The method of any one of claims 62 to 65, A device in which soft thermal material with sufficient thermal conductivity is used to conduct heat to or from the electrodes and at the same time allow some movement of the electrodes. The method of claim 66, The thermal material is one of a liquid metal, a polymer free of silicon, a mixture containing carbon nanotubes, a vacuum compatible grease, or a suspension of thermally conductive particles in a soft or liquid material. The method of any one of claims 62 to 65, The connecting wire to the electrode or electrode assembly is attached by solder, solder bump, ultrasonic wire bonding, conductive epoxy, solder paste or contact pressure. The method of claim 58, A compound of alkali metal is attached to a filament that generates the presence of an alkali metal inside the container through heating, vaporization, and condensation. The method of claim 69, wherein Wherein said alkali metal is cesium and said compound is cesium chromate. The method of claim 65 or 69, wherein A device having an electrical path through a filamented connector's doped silicon thermal side to remove wire holes and feed-throughs. The method of claim 69, wherein The filament is electrically connected in parallel with the device and is designed to open the circuit after the alkali metal is vaporized. The method of claim 12, The additional force is a device derived from the distribution of a spring or a porous material. The method of claim 30, The intensity produces electrode spacing in the range of 20 nanometers to 1000 nanometers, and one electrode is mainly used to convert radiation into electrical power by photon heat-tunneling from the radiating electrode to another photosensitive electrode. Conversion process with a photosensitive material. The method of claim 74, wherein Wherein said intensity produces an electrode spacing in the range of 20 nanometers to 100 nanometers.

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