US20050252543A1 - Low power thermoelectric generator - Google Patents
Low power thermoelectric generator Download PDFInfo
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- US20050252543A1 US20050252543A1 US11/185,312 US18531205A US2005252543A1 US 20050252543 A1 US20050252543 A1 US 20050252543A1 US 18531205 A US18531205 A US 18531205A US 2005252543 A1 US2005252543 A1 US 2005252543A1
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
- H10N10/80—Constructional details
- H10N10/85—Thermoelectric active materials
- H10N10/851—Thermoelectric active materials comprising inorganic compositions
- H10N10/852—Thermoelectric active materials comprising inorganic compositions comprising tellurium, selenium or sulfur
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
- H10N10/10—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects
- H10N10/17—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects characterised by the structure or configuration of the cell or thermocouple forming the device
Definitions
- the present invention pertains generally to thermoelectric devices and, more particularly, to a self-sufficient, low power thermoelectric generator having a compact size and a relatively high voltage output which is specifically adapted to be compatible with microelectronic devices.
- Thermoelectric generators are self-sufficient energy sources that convert thermal energy into electrical energy under established physics principles.
- the Seebeck effect is a transport phenomenon underlying the generation of power from thermal energy utilizing solid state electrical components with no moving parts.
- the Seebeck effect utilizes a pair of dissimilar metals (n-type and p-type), called thermocouples, which are joined at one end. N-type and p-type respectively stand for the negative and positive types of charge carriers within the material. If the joined end of the thermocouple is heated while the unjoined end is kept cold, an electromotive force (emf) or voltage potential is generated across the unjoined end.
- emf electromotive force
- the forces acting on the electrons at the junction of the two dissimilar metals tend to pull the electrons from the metal having a higher electron density toward the metal having a lower electron density.
- the metal that gains electrons acquires negative electrical potential while the metal that loses electrons acquires positive potential.
- thermoelectric generator may be incorporated into the wristwatch to take advantage of the waste heat and generate a supply of power sufficient to operate the wristwatch as a self contained unit.
- many microelectronic devices that are similar in size to a typical wristwatch require only a small amount of power and are therefore compatible for powering by thermoelectric generators.
- thermoelectric generator The operating parameters of a thermoelectric generator may be mathematically characterized in several ways. For example, the voltage measured across unjoined ends of a thermocouple is directly proportional to the temperature difference across the two ends.
- thermoelectric figure of merit Z
- S 2 ⁇ / ⁇ ⁇ and ⁇ are the electrical conductivity and thermal conductivity, respectively.
- Z the thermal and electrical properties of a thermoelectric material that may be utilized in a thermoelectric generator.
- thermoelectric generators Another key in improving thermoelectric generators lies in increasing the integration density of the thermocouples. Often with waste heat sources, only a small temperature difference exists between the heat source and the heat sink. Because of this small temperature difference, a large number of thermocouples must be connected in series in order to generate a sufficient thermoelectric voltage. Consequently, the thermocouples must have extreme aspect ratios of length to width of the cross-section.
- the prior art includes a number of devices that attempt to improve the efficiency and operating characteristics of thermoelectric generators.
- One prior art device includes a heat-conducting substrate disposed in thermal contact with a high-temperature region opposite a low-temperature region. Heat flows from the high-temperature region into the heat-conducting substrate and into a number of alternating n-type and p-type thermoelectric legs cut from crystal material. The n-type and p-type thermoelectric legs are electrically connected in series and thermally connected in parallel. The n-type and p-type thermoelectric legs are formed on the substrate in a two-dimensional checkerboard pattern.
- thermoelectric generator Because total voltage is the sum of the individual voltages across each n-type and p-type pair, and because each thermocouple of n-type and p-type thermoelectric legs may produce only a few millivolts for a given temperature differential, a very large area is required in order to encompass the checkerboard pattern of alternating n-type and p-type thermoelectric legs. Such a large area requirement prevents the miniaturizing of the thermoelectric generator.
- thermoelectric module having a gapless insulating eggcrate for providing insulated spaces for a number of n-type and p-type thermoelectric legs.
- the absence of gaps eliminates the possibility of interwall electrical shorts between the thermoelectric legs.
- the thermoelectric legs are electrically connected in series and thermally connected in parallel between hot and cold sides of the module. Electrical connections are comprised of a layer of aluminum over a layer of molybdenum. The surfaces are ground down to expose the eggcrate walls except in the areas where the thermoelectric legs are interconnected.
- thermoelectric generators have increased the integration density of thermocouples by miniaturizing the individual monolithic structures of the thermocouples. Although such devices succeeded in reducing the cross section of these bulk material bismuth telluride thermocouples to a sufficiently small size, the extreme difficulty in handling and fabricating these bismuth telluride-type thermocouples from bulk material translates into extremely high production costs leading to a very high cost of the final product.
- thermoelectric generator that is compatible with the requirements of microelectronic devices. More specifically, there exists a need for a thermoelectric generator for producing low power that is of compact size, and that is specifically adapted for producing a high output voltage while being mass-producible at a relatively low cost.
- the present invention specifically addresses and alleviates the above referenced deficiencies associated with thermoelectric generators. More particularly, the present invention is an improved foil segment for a self-sufficient, low power thermoelectric generator having a compact size and that is specifically adapted to be compatible with microelectronic devices.
- the thermoelectric generator takes advantage of a thermal gradient to generate useful power according to the Seebeck effect.
- the thermoelectric generator is comprised of a bottom plate, a top plate, and an array of foil segments.
- the array of foil segments are interposed between the bottom plate and the top plate in side-by-side arrangement.
- Each of the foil segments is perpendicularly disposed between and in thermal contact with the bottom and top plates.
- a series of alternating n-type and p-type thermoelectric legs is disposed on a substrate of each one of the foil segments.
- the thermoelectric legs are generally fabricated from a bismuth telluride-type thermoelectric material.
- the top plate is disposed in spaced relation above the bottom plate.
- the bottom and top plates may have a generally orthogonal configuration and may be fabricated from any rigid material such as ceramic material.
- the bottom plate and top plate are configured to provide thermal contact between a heat sink and a heat source such that a temperature gradient may be developed across the alternating n-type and p-type thermoelectric legs.
- Each one of the foil segments has a front substrate surface and a back substrate surface opposing the front substrate surface.
- the foil segments are arranged such that the back substrate surface of a foil segment faces the front substrate surface of an adjacent foil segment.
- the spaced, alternating n-type and p-type thermoelectric legs are disposed in parallel arrangement to each other on the front substrate surface.
- Each of the n-type and p-type thermoelectric legs are formed of the thermoelectric material generally having a thickness in the range of from about 5 microns ( ⁇ m) to about 100 ⁇ m, with a preferable thickness of about 7 ⁇ m.
- the front substrate surface may have a surface roughness that is smoother than that of the back substrate surface in order to enhance the repeatability of forming the n-type and p-type thermoelectric legs on the front substrate surface.
- a p-type and n-type thermoelectric leg pair makes up a thermocouple of the thermoelectric generator.
- the width of the thermoelectric legs may be in the range of from about 10 ⁇ m to about 100 ⁇ m, the length thereof being in the range of from about 100 ⁇ m to about 500 ⁇ m.
- a preferred length of the n-type and p-type thermoelectric legs is about 500 ⁇ m.
- a preferred width of the n-type thermoelectric leg is about 60 ⁇ m while a preferred width of the p-type thermoelectric leg is about 40 ⁇ m.
- the geometry of the respective n-type and p-type thermoelectric legs may be adjusted to a certain extent depending on differences in electrical conductivities of each n-type and p-type thermoelectric leg.
- Each one of the p-type thermoelectric legs is electrically connected to adjacent n-type thermoelectric legs at opposite ends of the p-type thermoelectric legs by a hot side metal bridge and a cold side metal bridge such that electrical current may flow through the thermoelectric legs from a bottom to a top of a p-type thermoelectric leg and from a top to a bottom of an n-type thermoelectric leg.
- the plurality of foil segments may preferably include a total of about 5000 thermocouples connected together and substantially evenly distributed on the array of foil segments and forming a thermocouple chain.
- Each of the thermocouples includes one n-type and one p-type thermoelectric leg.
- thermoelectric generator having 5000 thermocouples will include 5000 n-type thermoelectric legs and 5000 p-type thermoelectric legs.
- the thermoelectric generator may preferably include about 120 foil segments with each of the respective ones of the foil segments including about 40 thermocouples although any number of foil segments may be included.
- a contact pad may be disposed at each of extreme ends of the thermocouple chain.
- Each one of the hot side metal bridges and cold side metal bridges is configured to electrically connect an n-type thermoelectric leg to a p-type thermoelectric leg.
- Each one of the hot side and cold side metal bridges is also configured to act as a diffusion barrier in order to impede the diffusion of unwanted elements into the n-type and p-type thermoelectric legs which may be easily contaminated with foreign material.
- each one of the hot side and cold side metal bridges is configured to impede the diffusion of unwanted elements out of the n-type and p-type thermoelectric legs.
- each one of the hot side and cold side metal bridges is configured to conduct heat into and out of the p-type and n-type thermoelectric legs.
- the hot side and cold side metal bridges may be fabricated of a highly thermally conductive material such as gold-plated nickel.
- the substrate may have a thickness in the range of from about 7.5 ⁇ m to about 50 ⁇ m, although the thickness of the substrate is preferably about 25 ⁇ m. Because of the desire to reduce the thermal heat flux through the substrate in order to increase the efficiency of energy conversion, it is desirable to decrease the thickness of the substrate upon which the thermoelectric legs are disposed.
- An electrically insulating material with a low thermal conductivity such as polyimide film may be utilized for the substrate.
- the thermoelectric film that makes up the n-type and p-type thermoelectric legs may be comprised of a semiconductor compound of the bismuth telluride (Bi 2 Te 3 ) type. However, specific compositions of the semiconductor compound may be altered to enhance the thermoelectric performance of the n-type and p-type thermoelectric legs.
- the composition of the n-type thermoelectric legs may include selenium (Se).
- the composition of the p-type thermoelectric legs may include antimony (Sb).
- the excess of tellurium (Te) in respective ones of the p-type and n-type thermoelectric legs may be altered in order to enhance the fabrication thereof.
- Magnetron sputtering may be utilized for deposition of a relatively thick bismuth telluride-based thermoelectric film onto the thinner substrate at an optimal sputtering deposition rate of about 2.7 nanometers per second.
- FIG. 1 is a perspective view of a thermoelectric generator illustrating the arrangement of a plurality of foil segments of the present invention
- FIG. 2 is a cross-sectional side view of the thermoelectric generator taken along line 2 - 2 of FIG. 1 illustrating the arrangement of alternating n-type and p-type thermoelectric legs disposed on a substrate film of each of the foil segments;
- FIG. 3 is a schematic illustration of p-type and n-type thermoelectric leg pair that makes up a thermocouple of the thermoelectric generator.
- FIG. 1 is a perspective view of the thermoelectric generator 10 within which a foil segment 16 of the present invention may be utilized.
- the thermoelectric generator 10 takes advantage of a thermal gradient to generate useful power according to the Seebeck effect.
- the thermoelectric generator 10 is typically comprised of a bottom plate 12 , a top plate 14 , and an array of foil segments 16 .
- the array of foil segments 16 are interposed between the bottom plate 12 and the top plate 14 in side-by-side arrangement, with each one of the foil segments 16 being perpendicularly disposed between and in thermal contact with the bottom and top plates 12 , 14 .
- thermoelectric legs 32 , 34 A series of generally elongate, alternating n-type and p-type thermoelectric legs 32 , 34 is disposed on a substrate 18 of each one of the foil segments 16 . As will be discussed in more detail below, the thermoelectric legs 32 , 34 are generally fabricated from a bismuth telluride-type thermoelectric material 44 . As may be seen in FIG. 1 , the top plate 14 is disposed in spaced relation above the bottom plate 12 .
- the bottom and top plates 12 , 14 may have a generally orthogonal configuration of rectangular shape. However, it will be recognized that the bottom and top plates 12 , 14 , which generally define the overall size of the thermoelectric generator 10 , may be of any shape or configuration. In this regard, although the generally rectangular shape of the bottom and top plates 12 , 14 as seen in FIG. 1 , may be easily adaptable for integrating the array of generally same-sized ones of the foil segments 16 , the bottom plate 12 and the top plate 14 may optionally have a circular-like shape that may be adapted for use in a wearable microelectronic device, such as in a wrist-watch or a device generally shaped liked a wristwatch.
- the bottom plate 12 and the top plate 14 may be fabricated from any material that is both substantially rigid and highly thermally conductive. In this regard, it is contemplated that ceramic material may be utilized to fabricate the bottom and top plates 12 , 14 .
- the bottom plate 12 and top plate 14 may be configured to substantially provide thermal contact between a heat sink 22 and a heat source 20 , respectively, as can be seen in FIG. 1 .
- the bottom and top plates 12 , 14 may also be configured to provide a protective housing for the thermoelectric device 10 such that the foil segments 16 are protected from mechanical contact and chemical influences that may damage the foil segments 16 .
- FIG. 2 Shown in FIG. 2 is a cross-sectional side view of the thermoelectric generator 10 taken along line 2 - 2 of FIG. 1 illustrating the arrangement of the alternating n-type and p-type thermoelectric legs 32 , 34 disposed on a substrate 18 film of each of the foil segments 16 .
- Each one of the foil segments 16 has a front substrate surface 40 and a back substrate surface 42 (not shown) opposing the front substrate surface 40 .
- the foil segments 16 may be arranged such that the back substrate surface 42 of a foil segment 16 faces the front substrate surface 40 of an adjacent foil segment 16 .
- the spaced, alternating n-type and p-type thermoelectric legs 32 , 34 are disposed parallel to each other on the front substrate surface 40 .
- thermoelectric material 44 is formed of the thermoelectric material 44 .
- the thermoelectric material 44 may have a thickness in the range of from about 5 microns ( ⁇ m) to about 100 ⁇ m, a preferable thickness of the thermoelectric material 44 is about 7 ⁇ m.
- FIG. 3 shown is a schematic representation of the n-type and p-type thermoelectric leg 32 , 34 pair that makes up a thermocouple 46 of the thermoelectric generator 10 .
- the n-type and p-type thermoelectric legs 32 , 34 have a respective width.
- the n-type thermoelectric leg width is denoted as a 1 .
- the p-type thermoelectric leg 34 width is denoted as a 2.
- the thermoelectric leg 32 , 34 length for both the n-type thermoelectric leg 32 and the p-type thermoelectric leg 34 is denoted as b.
- thermoelectric generator 10 may be configured wherein the n-type and p-type thermoelectric legs 32 , 34 are of differing lengths.
- the extreme aspect ratio of the length to the width allows the generation of relatively high thermoelectric voltages in the miniaturized thermoelectric generator 10 .
- the geometry of the respective ones of the n-type and p-type thermoelectric legs 32 , 34 may be adjusted to a certain extent depending on differences in electrical conductivities of each one of the n-type and p-type thermoelectric legs 32 , 34 .
- the width of the thermoelectric legs 32 , 34 may be in the range of from about 10 ⁇ m to about 100 ⁇ m.
- the lengths of the thermoelectric legs 32 , 34 may be in the range of from about 100 ⁇ m to about 500 ⁇ m.
- a preferred length b of the n-type and p-type thermoelectric legs 32 , 34 is about 500 ⁇ m.
- thermoelectric leg 32 A preferred width a 1 of the n-type thermoelectric leg 32 is about 60 ⁇ m while a preferred width a 2 of the p-type thermoelectric leg 34 is about 40 ⁇ m.
- the thermoelectric properties of the p-type thermoelectric leg 34 are typically superior to those of the n-type thermoelectric leg 32 . Therefore the width of the p-type thermoelectric legs 34 can be narrower than that of the n-type thermoelectric legs 32 .
- the thermoelectric legs 32 , 34 are shown in FIG. 2 as having an elongate configuration, it is contemplated that the thermoelectric legs 32 , 34 may configured in numerous other configurations such as, for example, an L-shaped or S-shaped configuration.
- thermoelectric legs 32 , 34 are connected thermally in parallel and electrically in series. As illustrated in FIG. 1 and schematically in FIG. 2 , each one of the p-type thermoelectric legs 34 is electrically connected to an adjacent one of the n-type thermoelectric legs 32 at opposite ends of the p-type thermoelectric legs 34 by a hot side metal bridge 26 and a cold side metal bridge 28 . In this manner, electrical current may flow through the thermoelectric legs 32 , 34 from a bottom to a top of a p-type thermoelectric leg 34 and from a top to a bottom of an n-type thermoelectric leg 32 . Each alternating one of the thermoelectric legs 32 , 34 is connected to an adjacent one of the thermoelectric legs 32 , 34 of opposite conductivity type, forming a thermocouple 46 .
- the representative n-type thermoelectric leg 32 is connected at a respective upper end thereof to a respective upper end of the p-type thermoelectric leg 34 .
- a plurality of n-type and p-type thermoelectric legs 32 , 34 are connected at opposite ends thereof forming a plurality of thermocouples 46 leaving a free p-type thermoelectric leg 34 and a free n-type thermoelectric leg 32 end on respective extreme opposite end of the series.
- thermoelectric generator 10 may further comprise a first electrical lead 24 and a second electrical lead 30 respectively connected to opposite ends of the series of n-type and p-type thermoelectric legs 32 , 34 at contact pads 38 .
- Each one of the hot side metal bridges 26 and cold side metal bridges 28 is configured to electrically connect an n-type thermoelectric leg 32 to a p-type thermoelectric leg 34 .
- Each one of the hot side metal bridges 26 and cold side metal bridges 28 is also configured to act as a diffusion barrier in order to impede the diffusion of unwanted elements into the n-type and p-type thermoelectric legs 32 , 34 which may be easily contaminated with foreign material.
- each one of the hot side metal bridges 26 and cold side metal bridges 28 is configured to impede the diffusion of unwanted elements out of the n-type and p-type thermoelectric legs 32 , 34 .
- each one of the hot side metal bridges 26 and cold side metal bridges 28 is configured to conduct heat into and out of the p-type and n-type thermoelectric legs 32 , 34 .
- the hot side metal bridges 26 and cold side metal bridges 28 may be fabricated of a highly thermally conductive material such as gold-plated nickel.
- the first electrical lead 24 is connected to a free end of the n-type thermoelectric leg 32 while the second electrical lead 30 is connected to a free end of the p-type thermoelectric leg 34 .
- the foil segments 16 are electrically connected in series such that a free one of the n-type thermoelectric legs 32 on an extreme end of the foil segment 16 is electrically connected to a free one of the p-type thermoelectric legs 34 of an adjacent one of the foil segments 16 , and vice versa.
- the first electrical lead 24 is connected to a free end of the n-type thermoelectric leg 32 of a forward-most foil segment 16 of the array while the second electrical lead 30 is connected to a free end of the p-type thermoelectric leg 34 of the aft-most foil segment 16 of the array.
- the plurality of foil segments 16 may preferably include a total of about 5000 thermocouples 46 substantially evenly distributed on the array of foil segments 16 although it is contemplated that the thermoelectric generator 10 may comprise any number of thermocouples 46 from about 1000 to about 20,000.
- the thermoelectric generator 10 may preferably include about 120 foil segments 16 with each of the respective ones of the foil segments 16 including about forty thermocouples 46 .
- the thermoelectric generator 10 may include any number of foil segments 16 sufficient to integrate the total number of thermocouples 46 needed for producing the required power at the given operating temperatures. Assuming that all the thermocouples 46 are electrically connected in series, the total voltage output of the thermoelectric generator 10 is simply calculated as the sum of the individual voltages generated across each thermocouple 46 .
- the substrate 18 of the typical one of the foil segments 16 of the present invention has a thickness in the range of from about 7.5 ⁇ m to about 50 ⁇ m, although the thickness of the substrate 18 is preferably about 25 ⁇ m. Because of the desire to reduce the thermal heat flux 48 through the substrate 18 in order to increase the efficiency of energy conversion, it is desirable to decrease the thickness of the substrate 18 upon which the thermoelectric legs 32 , 34 are disposed. Regarding the material that may comprise the substrate 18 , an electrically insulating material may be utilized such that the adjacent ones of the thermoelectric legs 32 , 34 disposed on the substrate 18 may be electrically insulated from one another.
- the substrate 18 material may also have a low thermal conductivity and may be a polyimide film such as Kapton film made by DuPont. Due to its low thermal conductivity, polyimide film is an excellent substrate 18 for thermoelectric generators 10 .
- polyimide film has a coefficient of thermal expansion that is within the same order of magnitude as that of the bismuth telluride-type material utilized in the thermoelectric legs 32 , 34 in the room temperature range of about 70° F. Therefore, by utilizing polyimide film, the residual mechanical stresses that may occur at the substrate 18 /thermoelectric material 44 interface may be minimized or eliminated. In this regard, the overall durability and useful life of the thermoelectric generator 10 may be enhanced.
- thermoelectric material 44 that makes up the n-type and p-type thermoelectric legs 32 , 34 may be comprised of a semiconductor compound of the bismuth telluride (Bi 2 Te 3 ) type, as was mentioned above.
- the specific compositions of the semiconductor compound may be altered to enhance the thermoelectric performance of the n-type and p-type thermoelectric leg 32 , 34 .
- the semiconductor compound utilized in fabricating the p-type thermoelectric legs 32 may comprise a material having the formula: (Bi 0.15 Sb 0.85 ) 2 Te 3 plus 18 at. % Te excess. although the excess may be in the range of from about 10 at. % Te excess to about 30 at. % Te excess.
- the thermoelectric generator 10 may include the plurality of n-type and p-type thermoelectric legs 32 , 34 wherein each one of the p-type thermoelectric legs 34 is formed of the semiconductor compound having the formula (Bi 0.15 Sb 0.85 ) 2 Te 3 plus about 10 at. % Te excess to about 30 at. % Te excess.
- thermoelectric material 44 may be utilized onto the substrate 18 .
- the method of sputtering such as magnetron sputtering, may be utilized with the aid of high vacuum deposition equipment.
- Sputtering may be utilized for deposition of relatively thick bismuth telluride-based thermoelectric material 44 onto the thin substrates 18 .
- the rate of deposition of the thermoelectric material 44 onto the substrate 18 has been increased, resulting in a lower overall cost of the thermoelectric generator 10 .
- the optimal sputtering deposition rate may be about 2.7 nanometers per second.
- the sputtering deposition rate may be in the range of from about 2 nanometers per second to about 10 nanometers per second.
Abstract
Disclosed is a foil segment for a thermoelectric generator comprising a top plate disposed in spaced relation above a bottom plate. An array of the foil segments is perpendicularly disposed in side-by-side arrangement between and in thermal contact with the bottom and top plates. Each foil segment comprises a substrate having a thickness of about 7.5-50 microns, opposing front and back substrate surfaces and a series of spaced alternating n-type and p-type thermoelectric legs disposed in parallel arrangement on the front substrate surface. Each of the n-type and p-type legs is formed of a bismuth telluride-based thermoelectric material having a thickness of about 5-100 microns, a width of about 10-100 microns and a length of about 100-500 microns. The alternating n-type and p-type thermoelectric legs are electrically connected in series and thermally connected in parallel such that a temperature differential between the bottom and top plates results in the generation of power.
Description
- (Not Applicable)
- (Not Applicable)
- The present invention pertains generally to thermoelectric devices and, more particularly, to a self-sufficient, low power thermoelectric generator having a compact size and a relatively high voltage output which is specifically adapted to be compatible with microelectronic devices.
- The increasing trend toward miniaturization of microelectronic devices necessitates the development of miniaturized power supplies. Batteries and solar cells are traditional power sources for such microelectronic devices. However, the power that is supplied by batteries dissipates over time requiring that the batteries be periodically replaced. Solar cells, although having an effectively unlimited useful life, may only provide a transient source of power as the sun or other light sources may not always be available.
- Thermoelectric generators are self-sufficient energy sources that convert thermal energy into electrical energy under established physics principles. The Seebeck effect is a transport phenomenon underlying the generation of power from thermal energy utilizing solid state electrical components with no moving parts. The Seebeck effect utilizes a pair of dissimilar metals (n-type and p-type), called thermocouples, which are joined at one end. N-type and p-type respectively stand for the negative and positive types of charge carriers within the material. If the joined end of the thermocouple is heated while the unjoined end is kept cold, an electromotive force (emf) or voltage potential is generated across the unjoined end. Based on free electron theory of metals, the forces acting on the electrons at the junction of the two dissimilar metals tend to pull the electrons from the metal having a higher electron density toward the metal having a lower electron density. The metal that gains electrons acquires negative electrical potential while the metal that loses electrons acquires positive potential.
- The temperature gradient across the thermocouple may be artificially applied or it may be natural, occurring as “waste heat” such as the heat that is constantly rejected by the human body. In a wristwatch, one side is exposed to air at ambient temperature while the opposite side is exposed to the higher temperature of the wearer's skin. Thus, a small temperature gradient is present across the thickness of the wristwatch. A thermoelectric generator may be incorporated into the wristwatch to take advantage of the waste heat and generate a supply of power sufficient to operate the wristwatch as a self contained unit. Advantageously, many microelectronic devices that are similar in size to a typical wristwatch require only a small amount of power and are therefore compatible for powering by thermoelectric generators.
- The operating parameters of a thermoelectric generator may be mathematically characterized in several ways. For example, the voltage measured across unjoined ends of a thermocouple is directly proportional to the temperature difference across the two ends. When n-type thermoelectric legs and p-type thermoelectric legs that make up a thermocouple are electrically connected in series but thermally connected in parallel with a temperature differential T1 and T2 maintained thereacross, the open circuit voltage V under the Seebeck effect may be mathematically expressed by the following formula:
V=S(T 1 −T 2)
where S is the Seebeck coefficient expressed in microvolts per degree (μV/K). - The efficiency of thermoelectric generators may be characterized by a thermoelectric figure of merit (Z), traditionally defined by the following formula:
Z=S 2σ/κ
where σ and κ are the electrical conductivity and thermal conductivity, respectively. The figure of merit Z, expressed in reciprocal K, represents the thermal and electrical properties of a thermoelectric material that may be utilized in a thermoelectric generator. One of the keys to improve the efficiency of thermoelectric generators lies in the development of highly effective thermoelectric films having low electrical resistance, high Seebeck coefficient and low thermal conductivity. - Another key in improving thermoelectric generators lies in increasing the integration density of the thermocouples. Often with waste heat sources, only a small temperature difference exists between the heat source and the heat sink. Because of this small temperature difference, a large number of thermocouples must be connected in series in order to generate a sufficient thermoelectric voltage. Consequently, the thermocouples must have extreme aspect ratios of length to width of the cross-section.
- The prior art includes a number of devices that attempt to improve the efficiency and operating characteristics of thermoelectric generators. One prior art device includes a heat-conducting substrate disposed in thermal contact with a high-temperature region opposite a low-temperature region. Heat flows from the high-temperature region into the heat-conducting substrate and into a number of alternating n-type and p-type thermoelectric legs cut from crystal material. The n-type and p-type thermoelectric legs are electrically connected in series and thermally connected in parallel. The n-type and p-type thermoelectric legs are formed on the substrate in a two-dimensional checkerboard pattern. Because total voltage is the sum of the individual voltages across each n-type and p-type pair, and because each thermocouple of n-type and p-type thermoelectric legs may produce only a few millivolts for a given temperature differential, a very large area is required in order to encompass the checkerboard pattern of alternating n-type and p-type thermoelectric legs. Such a large area requirement prevents the miniaturizing of the thermoelectric generator.
- Another prior art device provides a thermoelectric module having a gapless insulating eggcrate for providing insulated spaces for a number of n-type and p-type thermoelectric legs. The absence of gaps eliminates the possibility of interwall electrical shorts between the thermoelectric legs. The thermoelectric legs are electrically connected in series and thermally connected in parallel between hot and cold sides of the module. Electrical connections are comprised of a layer of aluminum over a layer of molybdenum. The surfaces are ground down to expose the eggcrate walls except in the areas where the thermoelectric legs are interconnected. Although the module of the reference overcomes the problems of electrical shorts between adjacent thermoelectric legs, the device of the reference requires numerous manufacturing steps and is therefore costly.
- Other prior art devices attempting to miniaturize thermoelectric generators have increased the integration density of thermocouples by miniaturizing the individual monolithic structures of the thermocouples. Although such devices succeeded in reducing the cross section of these bulk material bismuth telluride thermocouples to a sufficiently small size, the extreme difficulty in handling and fabricating these bismuth telluride-type thermocouples from bulk material translates into extremely high production costs leading to a very high cost of the final product.
- In view of the above-described shortcomings of conventional thermoelectric generators, there exists a need in the art for a thermoelectric generator that is compatible with the requirements of microelectronic devices. More specifically, there exists a need for a thermoelectric generator for producing low power that is of compact size, and that is specifically adapted for producing a high output voltage while being mass-producible at a relatively low cost.
- The present invention specifically addresses and alleviates the above referenced deficiencies associated with thermoelectric generators. More particularly, the present invention is an improved foil segment for a self-sufficient, low power thermoelectric generator having a compact size and that is specifically adapted to be compatible with microelectronic devices.
- The thermoelectric generator takes advantage of a thermal gradient to generate useful power according to the Seebeck effect. The thermoelectric generator is comprised of a bottom plate, a top plate, and an array of foil segments. The array of foil segments are interposed between the bottom plate and the top plate in side-by-side arrangement. Each of the foil segments is perpendicularly disposed between and in thermal contact with the bottom and top plates. A series of alternating n-type and p-type thermoelectric legs is disposed on a substrate of each one of the foil segments. The thermoelectric legs are generally fabricated from a bismuth telluride-type thermoelectric material. The top plate is disposed in spaced relation above the bottom plate.
- The bottom and top plates may have a generally orthogonal configuration and may be fabricated from any rigid material such as ceramic material. The bottom plate and top plate are configured to provide thermal contact between a heat sink and a heat source such that a temperature gradient may be developed across the alternating n-type and p-type thermoelectric legs.
- Each one of the foil segments has a front substrate surface and a back substrate surface opposing the front substrate surface. The foil segments are arranged such that the back substrate surface of a foil segment faces the front substrate surface of an adjacent foil segment. The spaced, alternating n-type and p-type thermoelectric legs are disposed in parallel arrangement to each other on the front substrate surface. Each of the n-type and p-type thermoelectric legs are formed of the thermoelectric material generally having a thickness in the range of from about 5 microns (μm) to about 100 μm, with a preferable thickness of about 7 μm. The front substrate surface may have a surface roughness that is smoother than that of the back substrate surface in order to enhance the repeatability of forming the n-type and p-type thermoelectric legs on the front substrate surface.
- A p-type and n-type thermoelectric leg pair makes up a thermocouple of the thermoelectric generator. The width of the thermoelectric legs may be in the range of from about 10 μm to about 100 μm, the length thereof being in the range of from about 100 μm to about 500 μm. A preferred length of the n-type and p-type thermoelectric legs is about 500 μm. A preferred width of the n-type thermoelectric leg is about 60 μm while a preferred width of the p-type thermoelectric leg is about 40 μm. The geometry of the respective n-type and p-type thermoelectric legs may be adjusted to a certain extent depending on differences in electrical conductivities of each n-type and p-type thermoelectric leg.
- Each one of the p-type thermoelectric legs is electrically connected to adjacent n-type thermoelectric legs at opposite ends of the p-type thermoelectric legs by a hot side metal bridge and a cold side metal bridge such that electrical current may flow through the thermoelectric legs from a bottom to a top of a p-type thermoelectric leg and from a top to a bottom of an n-type thermoelectric leg. The plurality of foil segments may preferably include a total of about 5000 thermocouples connected together and substantially evenly distributed on the array of foil segments and forming a thermocouple chain. Each of the thermocouples includes one n-type and one p-type thermoelectric leg. Thus, a thermoelectric generator having 5000 thermocouples will include 5000 n-type thermoelectric legs and 5000 p-type thermoelectric legs. The thermoelectric generator may preferably include about 120 foil segments with each of the respective ones of the foil segments including about 40 thermocouples although any number of foil segments may be included. A contact pad may be disposed at each of extreme ends of the thermocouple chain.
- Each one of the hot side metal bridges and cold side metal bridges is configured to electrically connect an n-type thermoelectric leg to a p-type thermoelectric leg. Each one of the hot side and cold side metal bridges is also configured to act as a diffusion barrier in order to impede the diffusion of unwanted elements into the n-type and p-type thermoelectric legs which may be easily contaminated with foreign material. Additionally, each one of the hot side and cold side metal bridges is configured to impede the diffusion of unwanted elements out of the n-type and p-type thermoelectric legs. Finally, each one of the hot side and cold side metal bridges is configured to conduct heat into and out of the p-type and n-type thermoelectric legs. In this regard, the hot side and cold side metal bridges may be fabricated of a highly thermally conductive material such as gold-plated nickel.
- The substrate may have a thickness in the range of from about 7.5 μm to about 50 μm, although the thickness of the substrate is preferably about 25 μm. Because of the desire to reduce the thermal heat flux through the substrate in order to increase the efficiency of energy conversion, it is desirable to decrease the thickness of the substrate upon which the thermoelectric legs are disposed. An electrically insulating material with a low thermal conductivity such as polyimide film may be utilized for the substrate. The thermoelectric film that makes up the n-type and p-type thermoelectric legs may be comprised of a semiconductor compound of the bismuth telluride (Bi2Te3) type. However, specific compositions of the semiconductor compound may be altered to enhance the thermoelectric performance of the n-type and p-type thermoelectric legs. Specifically, the composition of the n-type thermoelectric legs may include selenium (Se). The composition of the p-type thermoelectric legs may include antimony (Sb). Furthermore, the excess of tellurium (Te) in respective ones of the p-type and n-type thermoelectric legs may be altered in order to enhance the fabrication thereof.
- Magnetron sputtering may be utilized for deposition of a relatively thick bismuth telluride-based thermoelectric film onto the thinner substrate at an optimal sputtering deposition rate of about 2.7 nanometers per second.
- These as well as other features of the present invention will become more apparent upon reference to the drawings wherein:
-
FIG. 1 is a perspective view of a thermoelectric generator illustrating the arrangement of a plurality of foil segments of the present invention; -
FIG. 2 is a cross-sectional side view of the thermoelectric generator taken along line 2-2 ofFIG. 1 illustrating the arrangement of alternating n-type and p-type thermoelectric legs disposed on a substrate film of each of the foil segments; and -
FIG. 3 is a schematic illustration of p-type and n-type thermoelectric leg pair that makes up a thermocouple of the thermoelectric generator. - Referring now to the drawings wherein the showings are for purposes of illustrating preferred embodiments of the present invention and not for purposes of limiting the same,
FIG. 1 is a perspective view of thethermoelectric generator 10 within which afoil segment 16 of the present invention may be utilized. As mentioned above, thethermoelectric generator 10 takes advantage of a thermal gradient to generate useful power according to the Seebeck effect. Thethermoelectric generator 10 is typically comprised of abottom plate 12, atop plate 14, and an array offoil segments 16. The array offoil segments 16 are interposed between thebottom plate 12 and thetop plate 14 in side-by-side arrangement, with each one of thefoil segments 16 being perpendicularly disposed between and in thermal contact with the bottom andtop plates thermoelectric legs substrate 18 of each one of thefoil segments 16. As will be discussed in more detail below, thethermoelectric legs thermoelectric material 44. As may be seen inFIG. 1 , thetop plate 14 is disposed in spaced relation above thebottom plate 12. - The bottom and
top plates top plates thermoelectric generator 10, may be of any shape or configuration. In this regard, although the generally rectangular shape of the bottom andtop plates FIG. 1 , may be easily adaptable for integrating the array of generally same-sized ones of thefoil segments 16, thebottom plate 12 and thetop plate 14 may optionally have a circular-like shape that may be adapted for use in a wearable microelectronic device, such as in a wrist-watch or a device generally shaped liked a wristwatch. - The
bottom plate 12 and thetop plate 14 may be fabricated from any material that is both substantially rigid and highly thermally conductive. In this regard, it is contemplated that ceramic material may be utilized to fabricate the bottom andtop plates bottom plate 12 andtop plate 14 may be configured to substantially provide thermal contact between aheat sink 22 and aheat source 20, respectively, as can be seen inFIG. 1 . The bottom andtop plates thermoelectric device 10 such that thefoil segments 16 are protected from mechanical contact and chemical influences that may damage thefoil segments 16. - Shown in
FIG. 2 is a cross-sectional side view of thethermoelectric generator 10 taken along line 2-2 ofFIG. 1 illustrating the arrangement of the alternating n-type and p-typethermoelectric legs substrate 18 film of each of thefoil segments 16. Each one of thefoil segments 16 has afront substrate surface 40 and a back substrate surface 42 (not shown) opposing thefront substrate surface 40. Thefoil segments 16 may be arranged such that theback substrate surface 42 of afoil segment 16 faces thefront substrate surface 40 of anadjacent foil segment 16. The spaced, alternating n-type and p-typethermoelectric legs front substrate surface 40. Each of the n-type and p-typethermoelectric legs thermoelectric material 44. Although thethermoelectric material 44 may have a thickness in the range of from about 5 microns (μm) to about 100 μm, a preferable thickness of thethermoelectric material 44 is about 7 μm. - Turning briefly now to
FIG. 3 , shown is a schematic representation of the n-type and p-typethermoelectric leg thermocouple 46 of thethermoelectric generator 10. As can be seen inFIG. 3 , the n-type and p-typethermoelectric legs thermoelectric leg 34 width is denoted as a2. Thethermoelectric leg thermoelectric leg 32 and the p-typethermoelectric leg 34 is denoted as b. Although the n-type and p-typethermoelectric legs thermoelectric generator 10 may be configured wherein the n-type and p-typethermoelectric legs thermoelectric generator 10. - The geometry of the respective ones of the n-type and p-type
thermoelectric legs thermoelectric legs thermoelectric legs thermoelectric legs thermoelectric legs thermoelectric leg 32 is about 60 μm while a preferred width a2 of the p-typethermoelectric leg 34 is about 40 μm. The thermoelectric properties of the p-typethermoelectric leg 34 are typically superior to those of the n-typethermoelectric leg 32. Therefore the width of the p-typethermoelectric legs 34 can be narrower than that of the n-typethermoelectric legs 32. Although thethermoelectric legs FIG. 2 as having an elongate configuration, it is contemplated that thethermoelectric legs - The n-type and p-type
thermoelectric legs FIG. 1 and schematically inFIG. 2 , each one of the p-typethermoelectric legs 34 is electrically connected to an adjacent one of the n-typethermoelectric legs 32 at opposite ends of the p-typethermoelectric legs 34 by a hotside metal bridge 26 and a coldside metal bridge 28. In this manner, electrical current may flow through thethermoelectric legs thermoelectric leg 34 and from a top to a bottom of an n-typethermoelectric leg 32. Each alternating one of thethermoelectric legs thermoelectric legs thermocouple 46. - In
FIG. 3 , the representative n-typethermoelectric leg 32 is connected at a respective upper end thereof to a respective upper end of the p-typethermoelectric leg 34. InFIG. 2 , a plurality of n-type and p-typethermoelectric legs thermocouples 46 leaving a free p-typethermoelectric leg 34 and a free n-typethermoelectric leg 32 end on respective extreme opposite end of the series. Whenever heat is applied by theheat source 20 through thetop plate 14 at the hotside metal bridge 26, a temperature gradient, indicated by the symbol ΔT, is created with respect to the coldside metal bridge 28 of thethermocouple 46 at thebottom plate 12 andheat sink 22 such that aheat flux 48 flows through thethermoelectric generator 10. Current then flows through a load in theelectrical circuit 36 in the direction indicated by the symbol A. Thethermoelectric generator 10 may further comprise a firstelectrical lead 24 and a secondelectrical lead 30 respectively connected to opposite ends of the series of n-type and p-typethermoelectric legs contact pads 38. - Each one of the hot side metal bridges 26 and cold side metal bridges 28 is configured to electrically connect an n-type
thermoelectric leg 32 to a p-typethermoelectric leg 34. Each one of the hot side metal bridges 26 and cold side metal bridges 28 is also configured to act as a diffusion barrier in order to impede the diffusion of unwanted elements into the n-type and p-typethermoelectric legs thermoelectric legs thermoelectric legs - In the illustration shown in
FIG. 2 , the firstelectrical lead 24 is connected to a free end of the n-typethermoelectric leg 32 while the secondelectrical lead 30 is connected to a free end of the p-typethermoelectric leg 34. However, for thethermoelectric generator 10 having an array offoil segments 16 disposed in side-by-side arrangement as shown inFIG. 1 , thefoil segments 16 are electrically connected in series such that a free one of the n-typethermoelectric legs 32 on an extreme end of thefoil segment 16 is electrically connected to a free one of the p-typethermoelectric legs 34 of an adjacent one of thefoil segments 16, and vice versa. In such a configuration, the firstelectrical lead 24 is connected to a free end of the n-typethermoelectric leg 32 of aforward-most foil segment 16 of the array while the secondelectrical lead 30 is connected to a free end of the p-typethermoelectric leg 34 of theaft-most foil segment 16 of the array. - It is contemplated that the plurality of
foil segments 16 may preferably include a total of about 5000thermocouples 46 substantially evenly distributed on the array offoil segments 16 although it is contemplated that thethermoelectric generator 10 may comprise any number ofthermocouples 46 from about 1000 to about 20,000. Thethermoelectric generator 10 may preferably include about 120foil segments 16 with each of the respective ones of thefoil segments 16 including about fortythermocouples 46. Alternatively, however, thethermoelectric generator 10 may include any number offoil segments 16 sufficient to integrate the total number ofthermocouples 46 needed for producing the required power at the given operating temperatures. Assuming that all thethermocouples 46 are electrically connected in series, the total voltage output of thethermoelectric generator 10 is simply calculated as the sum of the individual voltages generated across eachthermocouple 46. - Referring to
FIG. 2 , shown is thesubstrate 18 of the typical one of thefoil segments 16 of the present invention. Thesubstrate 18 has a thickness in the range of from about 7.5 μm to about 50 μm, although the thickness of thesubstrate 18 is preferably about 25 μm. Because of the desire to reduce thethermal heat flux 48 through thesubstrate 18 in order to increase the efficiency of energy conversion, it is desirable to decrease the thickness of thesubstrate 18 upon which thethermoelectric legs substrate 18, an electrically insulating material may be utilized such that the adjacent ones of thethermoelectric legs substrate 18 may be electrically insulated from one another. - The
substrate 18 material may also have a low thermal conductivity and may be a polyimide film such as Kapton film made by DuPont. Due to its low thermal conductivity, polyimide film is anexcellent substrate 18 forthermoelectric generators 10. In addition, polyimide film has a coefficient of thermal expansion that is within the same order of magnitude as that of the bismuth telluride-type material utilized in thethermoelectric legs substrate 18/thermoelectric material 44 interface may be minimized or eliminated. In this regard, the overall durability and useful life of thethermoelectric generator 10 may be enhanced. - The
thermoelectric material 44 that makes up the n-type and p-typethermoelectric legs thermoelectric leg thermoelectric legs 32 may comprise a material having the formula:
(Bi0.15Sb0.85)2Te3 plus 18 at. % Te excess.
although the excess may be in the range of from about 10 at. % Te excess to about 30 at. % Te excess. As a separate embodiment of the semiconductor compound, thethermoelectric generator 10 may include the plurality of n-type and p-typethermoelectric legs thermoelectric legs 34 is formed of the semiconductor compound having the formula (Bi0.15Sb0.85)2Te3 plus about 10 at. % Te excess to about 30 at. % Te excess. - Although a number of microfabrication techniques may be utilized in depositing the
thermoelectric material 44 onto thesubstrate 18, the method of sputtering, such as magnetron sputtering, may be utilized with the aid of high vacuum deposition equipment. Sputtering may be utilized for deposition of relatively thick bismuth telluride-basedthermoelectric material 44 onto thethin substrates 18. - Advantageously, the rate of deposition of the
thermoelectric material 44 onto thesubstrate 18 has been increased, resulting in a lower overall cost of thethermoelectric generator 10. In forming thethermoelectric material 44, the optimal sputtering deposition rate may be about 2.7 nanometers per second. However, because the sputtering deposition rate is dependent on the specific composition to be deposited as well as the intendedthermoelectric material 44 properties, the sputtering deposition rate may be in the range of from about 2 nanometers per second to about 10 nanometers per second. - Additional modifications and improvements of the present invention may also be apparent to those of ordinary skill in the art. Thus, the particular combination of parts described and illustrated herein is intended to represent only certain embodiments of the present invention, and is not intended to serve as limitations of alternative devices within the spirit and scope of the invention.
Claims (17)
1. A foil segment for a thermoelectric generator, the foil segment comprising:
a substrate having opposing front and back substrate surfaces; and
a series of elongate alternating n-type and p-type thermoelectric legs disposed in spaced parallel arrangement on the front substrate surface, each of the n-type and p-type legs being formed of a thermoelectric material having a thickness in the range of from about 5 microns to about 100 microns, each n-type and p-type thermoelectric leg having a width and a length, the width being in the range of from about 10 microns to about 100 microns, the length being in the range of from about 100 microns to about 500 microns;
wherein each one of the p-type thermoelectric legs is electrically connected to an adjacent one of the n-type thermoelectric legs at opposite ends of the p-type thermoelectric legs such that the series of n-type and p-type thermoelectric legs are electrically connected in series and thermally connected in parallel.
2. The foil segment of claim 1 wherein the substrate has a thickness in the range of from about 7.5 microns to about 50 microns.
3. The foil segment of claim 1 wherein the substrate has a thickness of about 25 microns.
4. The foil segment of claim 1 wherein the thickness of the thermoelectric material is about 7 microns.
5. The foil segment of claim 1 wherein the thermoelectric material for the p-type thermoelectric legs is a semiconductor compound having the following formula:
(Bi0.15Sb0.85)2Te3 plus about 10 at. % Te excess to about 30 at. % Te excess.
6. The foil segment of claim 5 wherein the semiconductor compound has about 18 at. % excess.
7. The foil segment of claim 5 wherein each one of the p-type thermoelectric legs has a width of about 40 microns.
8. The foil segment of claim 1 wherein each one of the n-type thermoelectric legs has a width of about 60 microns.
9. The foil segment of claim 1 wherein the length of the n-type and p-type thermoelectric legs is about 500 microns.
10. The foil segment of claim 1 wherein the semiconductor compound is deposited on the substrate by sputtering.
11. The foil segment of claim 10 wherein the sputtering deposition rate is in the range of from about 2 nanometers per second to about 10 nanometers per second.
12. The foil segment of claim 11 wherein the sputtering deposition rate is about 2.7 nanometers per second.
13. An array of foil segments for a thermoelectric generator, each one of the foil segments being configured as defined in claim 1 wherein:
each one of the p-type thermoelectric legs and an adjacent one of the n-type thermoelectric legs collectively defines a thermocouple; and
the array of foil segments includes a total of from about 1000 to about 20,000 thermocouples substantially evenly distributed upon the array of foil segments.
14. A foil segment for a thermoelectric generator, the foil segment including a plurality of n-type and p-type thermoelectric legs, each one of the p-type thermoelectric legs being formed of a semiconductor compound having the following formula:
(Bi0.15Sb0.85)2Te3 plus about 10 at. % Te excess to about 30 at. % Te excess.
15. The foil segment of claim 14 wherein the semiconductor compound has about 18 at. % excess.
16. A foil segment for a thermoelectric generator, the foil segment comprising:
a substrate having a thickness in the range of from about 7.5 microns to about 50 microns and including opposing front and back substrate surfaces, the substrate formed of an electrically insulating material having a low thermal conductivity; and
a series of spaced alternating n-type and p-type thermoelectric legs disposed in parallel arrangement on each one of the front substrate surfaces, each of the n-type and p-type legs being formed of a thermoelectric material and having a thickness in the range of from about 5 microns to about 100 microns, each n-type and p-type thermoelectric leg having a width and a length, the width being in the range of from about 10 microns to about 100 microns and the length being in the range of from about 100 microns to about 500 microns;
wherein each one of the p-type thermoelectric legs is electrically connected to adjacent n-type thermoelectric legs at opposite ends of the p-type thermoelectric legs such that the series of n-type and p-type thermoelectric legs are electrically connected in series and thermally connected in parallel.
17. The foil segment of claim 16 wherein each one of the p-type thermoelectric legs is formed of a semiconductor compound having the following formula:
(Bi0.15Sb0.85)2Te3 plus about 18 at. % excess.
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US12/242,810 US8269096B2 (en) | 2003-05-19 | 2008-09-30 | Low power thermoelectric generator |
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- 2004-05-13 CN CNB2004800173908A patent/CN100499192C/en not_active Expired - Fee Related
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US20090025771A1 (en) * | 2003-05-19 | 2009-01-29 | Digital Angel Corporation | low power thermoelectric generator |
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US20090260667A1 (en) * | 2006-11-13 | 2009-10-22 | Massachusetts Institute Of Technology | Solar Thermoelectric Conversion |
US20100186794A1 (en) * | 2007-05-21 | 2010-07-29 | Gmz Energy ,Inc. | Solar thermoelectric and thermal cogeneration |
WO2008153686A2 (en) * | 2007-05-21 | 2008-12-18 | Gmz Energy, Inc. | Solar thermoelectric and thermal cogeneration |
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US20100139291A1 (en) * | 2008-12-08 | 2010-06-10 | Hofmeister R Jon | Field-deployable electronics platform having thermoelectric power source and interchangeable power management electronics and application modules |
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US20110253126A1 (en) * | 2010-04-15 | 2011-10-20 | Huiming Yin | Net Zero Energy Building System |
RU2546830C2 (en) * | 2010-06-04 | 2015-04-10 | О-Флекс Технологиз Гмбх | Thermoelectric element |
US20120085382A1 (en) * | 2010-10-04 | 2012-04-12 | King Fahd University Of Petroleum And Minerals | Energy conversion efficient thermoelectric power generator |
US20130252366A1 (en) * | 2010-10-04 | 2013-09-26 | King Fahd University Of Petroleum And Minerals | Energy conversion efficient thermoelectric power generator |
US20220199884A1 (en) * | 2019-04-15 | 2022-06-23 | Agency For Science, Technology And Research | Thermoelectric device |
Also Published As
Publication number | Publication date |
---|---|
CN100499192C (en) | 2009-06-10 |
CN1836340A (en) | 2006-09-20 |
AU2004241965A1 (en) | 2004-12-02 |
US20040231714A1 (en) | 2004-11-25 |
EP1625629A4 (en) | 2006-12-13 |
MXPA05012477A (en) | 2006-07-03 |
WO2004105143A1 (en) | 2004-12-02 |
EP1625629A1 (en) | 2006-02-15 |
CA2526270A1 (en) | 2004-12-02 |
AU2004241965B2 (en) | 2009-11-19 |
JP2007500951A (en) | 2007-01-18 |
US6958443B2 (en) | 2005-10-25 |
JP4290197B2 (en) | 2009-07-01 |
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