JP2021061440A - Thermoelectric transducer and manufacturing method thereof - Google Patents

Abstract

To provide a thermoelectric transducer with which a plurality of thermoelectric conversion units are formed in series connection on a substrate, and which has a height difference equal to or greater than thickness of a thermoelectric conversion layer between a heat absorption side and a heat radiation side, is capable of obtaining a high power generation performance even if used without being stood, and can be stably installed on a planar heating device only with a substrate on which the thermoelectric conversion units are formed.SOLUTION: A thermoelectric transducer 1 comprises a substrate 2 and a plurality of thermoelectric conversion units 10. A cross-sectional shape of a unit formed part 21 is formed from a projection 211, a first low surface part 212 and a second low surface part 213 at both sides of the projection. A non-formed part 22 in which no thermoelectric conversion unit is formed is located at a position lower than an apex 211a of the projection 211. The thermoelectric conversion unit 10 includes a first layer 31 from the first low surface part 212 of the unit formed part 21 to the apex 211a, and a second layer 32 from the apex 211a to the second low surface part 213. At least one of the first layer 31 and the second layer 32 are formed from a thermoelectric conversion material.SELECTED DRAWING: Figure 1

Description

The present invention relates to a thermoelectric conversion element and a method for manufacturing the same.

A thermoelectric conversion element is an element capable of converting thermal energy and electric energy into each other. By installing the thermoelectric conversion element in an environment where a temperature difference occurs at both ends thereof, electric power can be taken out from the thermoelectric conversion element without the need for a moving part. For example, electrical energy can be generated from waste heat. Therefore, power generation technology using a thermoelectric conversion element is highly expected as an energy harvesting technology for recovering and utilizing unused energy around us.
If the thermoelectric conversion element can be used as, for example, a distributed self-sustaining power source, it can be used as a power source for large-scale sensor networks, wearable electronics, and the like. In particular, when a thermoelectric conversion material made of an organic substance is used, the thermoelectric conversion layer can be formed by a printing pattern, so that weight reduction, cost reduction, and high output due to a large area can be achieved. In this case, in order to maintain the flatness of the thermoelectric conversion element unit, the temperature difference is generally given in the direction perpendicular to the substrate of the unit.

An example of a thermoelectric conversion element having a thermoelectric conversion layer as a print pattern is a thermoelectric power generation element disclosed in Patent Document 1. In the thermoelectric conversion element (thermoelectric power generation element) of Patent Document 1, a plurality of thermoelectric conversion layers (thermoelectric conversion units) composed of printed patterns are formed on a corrugated substrate (base material) in which the bottom and the top are alternately repeated. , Multiple thermoelectric conversion layers are connected in series. Each thermoelectric conversion layer is formed on one of a pair of slopes having one convex or concave portion constituting the waveform of the substrate, and is not formed on the other.
In the thermoelectric conversion element of Patent Document 1, the bottom is the endothermic side and the top is the heat dissipation side, and power generation is performed by the temperature difference between the bottom side and the top side. Further, since the substrate is formed in a corrugated shape, a large temperature difference can be obtained because the distance between the endothermic side and the heat radiating side is increased. On the other hand, in a thermoelectric conversion element having a substrate having no unevenness, a sufficient temperature difference cannot be obtained when the substrate is held horizontally.

International Publication 2013/114854 Pamphlet

In the thermoelectric conversion element of Patent Document 1, the cross-sectional shape of the entire substrate is corrugated, including not only the portion where the thermoelectric conversion layer is formed but also the portion where the thermoelectric conversion element is not formed. Therefore, when a large height difference is formed between the bottom and the top, it is necessary to provide a reinforcing material for maintaining the shape in the space below the convex portion of the substrate. Further, in order to stably install it on a flat heating device such as a hot plate, a supporting base material on which a plurality of bottom portions of the substrate are placed and fixed is further required.
The problem of the present invention is that a plurality of thermoelectric conversion units are formed in series on a substrate, and the heat absorbing side and the heat radiating side have a height difference equal to or larger than the thickness of the thermoelectric conversion layer, and even if they are used without standing up, they are high. It is an object of the present invention to provide a thermoelectric conversion element capable of stably installing on a flat heating device only with a substrate on which power generation performance is obtained and a thermoelectric conversion unit is formed.

In order to solve the above problems, the first aspect of the present invention provides a thermoelectric conversion element having the following configurations (1) to (4).
(1) It has a substrate and a plurality of thermoelectric conversion units formed on the upper surface or the lower surface of the substrate.
(2) The cross-sectional shape of the unit forming portion on which the thermoelectric conversion unit is formed of the substrate is composed of a convex portion and a first low surface portion and a second low surface portion lower than the convex portions on both sides thereof. The non-formed portion of the substrate on which the thermoelectric conversion unit is not formed is located at a position lower than the top of the convex portion.
(3) The thermoelectric conversion unit has a first layer extending from the first low surface portion of the unit forming portion to the top of the convex portion, and a second layer extending from the top to the second low surface portion. At least one of the first layer and the second layer is made of a thermoelectric conversion material.
(4) The plurality of thermoelectric conversion units are connected in series by wiring connecting the first layer and the second layer of the adjacent thermoelectric conversion units formed on the first low surface portion and the second low surface portion. It is connected. It has connection terminals at both ends of the series connection.

The second aspect of the present invention is a method for manufacturing a thermoelectric conversion element having the above configurations (1) to (4), and is characterized by having each step of the following configurations (11) to (13).
(11) A first printing step of forming a thermoelectric conversion pattern including the first layer and the second layer constituting the plurality of thermoelectric conversion units on a substrate.
(12) A second printing step of forming a conductive layer pattern composed of the wiring and the connection terminals on the thermoelectric conversion pattern.
(13) A convex portion forming step of forming the convex portion by stretching and deforming the first layer and the second layer and the portion of the substrate on which the first layer and the second layer are formed.

The thermoelectric conversion element manufactured by the method of the second aspect has the above configurations (1) to (4) and the following configurations (21) and (22).
(21) The plurality of thermoelectric conversion unit substrates are composed of a printed pattern.
(22) The wiring and the connection terminal are made of a print pattern.

According to the present invention, a plurality of thermoelectric conversion units are formed in series on a substrate, and the heat absorbing side and the heat radiating side have a height difference equal to or larger than the thickness of the thermoelectric conversion layer, and it is high even if it is used without standing. Provided is a thermoelectric conversion element which can obtain power generation performance and can be stably installed on a flat heating device only with a substrate on which a thermoelectric conversion unit is formed.

It is a partial cross-sectional view which shows the thermoelectric conversion element of 1st Embodiment, and shows the unit forming part of the substrate corresponding to one thermoelectric conversion unit, and the non-forming part on both sides thereof. It is a top view explaining the pre-stage process of the 1st printing process which constitutes the manufacturing method of the thermoelectric conversion element shown in FIG. It is a top view explaining the post-stage process of the 1st printing process which constitutes the manufacturing method of the thermoelectric conversion element shown in FIG. It is a top view explaining the 2nd printing process which comprises the manufacturing method of the thermoelectric conversion element shown in FIG. It is a top view explaining the through hole forming process which constitutes the manufacturing method of the thermoelectric conversion element shown in FIG. FIG. 5 is a cross-sectional view taken along the line AA of FIG. It is a partial cross-sectional view which shows the thermoelectric conversion element of the 2nd Embodiment, and shows the unit forming part of the substrate corresponding to one thermoelectric conversion unit in the substrate surface, and the non-forming part on both sides thereof. FIG. 7 is a plan view showing a state before the convex portion forming step of the thermoelectric conversion element shown in FIG. 7, and a cross-sectional view taken along the line A'-A'after forming the convex portion corresponds to FIG. It is a partial cross-sectional view which shows the thermoelectric conversion element of 3rd Embodiment, and shows the unit forming part of the substrate corresponding to one thermoelectric conversion unit in the substrate surface, and the non-forming part on both sides thereof. It is a top view explaining the insulation layer forming process which comprises the manufacturing method of the thermoelectric conversion element shown in FIG. It is a top view explaining the coating layer forming process which comprises the manufacturing method of the thermoelectric conversion element shown in FIG. 11 is a cross-sectional view taken along the line AA of FIG. It is a perspective view explaining an example of the wireless sensor transmission device using the thermoelectric conversion element of 1st Embodiment. It is a front view explaining the cow collar which is an example of the power source for a wearable device using the thermoelectric conversion element of 3rd Embodiment. It is a schematic diagram which shows the state which the cow collar of FIG. 14 is wrapped around a cow. It is a schematic diagram corresponding to the BB cross section of FIG. It is a front view which shows the example of the shape different from 1st and 2nd Embodiment about the convex part of the substrate which comprises the thermoelectric conversion element of embodiment.

Hereinafter, embodiments of the present invention will be described. In the embodiments shown below, technically preferable limitations are made for carrying out the present invention, but the present invention is not limited to the embodiments shown below.

[First Embodiment]
The thermoelectric conversion element of this embodiment is a thermoelectric conversion element manufactured by performing each step shown in FIGS. 2 to 5. FIG. 1 shows a cross section of one thermoelectric conversion unit 10 constituting the thermoelectric conversion element 1 of this embodiment.
The thermoelectric conversion element 1 includes a first-stage step of the first printing process shown in FIG. 2, a second-stage process of the first printing process shown in FIG. 3, a second printing process shown in FIG. 4, and a through-hole forming step shown in FIG. And the convex portion forming step of changing from the state of FIG. 6 to the state of FIG. 1 is performed.

The thermoelectric conversion element 1 has a flexible substrate 2 and a plurality of thermoelectric conversion units 10 composed of a printed pattern formed on the upper surface of the substrate 2. The cross-sectional shape of the unit forming portion 21 on which the thermoelectric conversion unit 10 of the substrate 2 is formed includes a convex portion 211, a first low surface portion 212, and a second low surface portion 213. The first low surface portion 212 and the second low surface portion 213 are lower than the convex portions on both sides of the convex portion 211, and have the same height as the non-formed portion 22 in which the thermoelectric conversion unit 10 is not formed.
The thermoelectric conversion unit 10 has a first layer 31 extending from the first low surface portion 212 of the unit forming portion 21 to the top portion 211a of the convex portion 211, and a second layer 32 extending from the top portion 211a to the second low surface portion 213. The first layer 31 is made of a p-type conductive polymer (thermoelectric conversion material), and the second layer 32 is made of a cured product of silver paste (conductive material). A layer made of an n-type conductive polymer (thermoelectric conversion material) may be provided as the second layer 32, but since there is no one having stable performance at present, in this embodiment, a silver paste is used as an alternative. A second layer 32 made of a cured product is provided.

As shown in FIG. 5, 14 thermoelectric conversion units 10 are formed in 2 columns and 7 rows on the upper surface of the substrate 2. A rectangular through hole 25 is formed in the entire range of the convex portion 211 between the thermoelectric conversion units 10 adjacent to each other between the rows of the substrate 2. That is, the thermoelectric conversion units 10 adjacent to each other between the rows of the substrate 2 are separated within the range of the convex portion 211.
Then, the lower wiring 41 connecting the first layer 31 and the second layer 32 of the thermoelectric conversion units 10 adjacent to each other between the rows and columns is placed on the first low surface portion 212 and the second low surface portion 213, and the first layer 31 And is formed via the second layer 32.

Further, since the first layer 31 and the second layer 32 are made of different materials, the upper wiring 42 connecting the first layer 31 and the second layer 32 in the thermoelectric conversion unit 10 is provided at the position of the top portion 211a of the convex portion 211. It is formed. Further, both ends of the series connection are present on one edge of the upper surface of the substrate 2, and connection terminals 43 with the outside are formed at each position.
In the method for manufacturing the thermoelectric conversion element 1 of this embodiment, first, as a pre-process of the first printing process, one first layer 31 is provided in one thermoelectric conversion unit 10 in a rectangular planar shape in the arrangement shown in FIG. Formed with. That is, the adjacent first layers 31 are arranged in the rows of 14 thermoelectric conversion units 10 in two rows and between the rows at positions opposite to each other in the long side direction of the rectangle.

Next, as a subsequent step of the first printing step, as shown in FIG. 3, one second layer 32 is placed in one thermoelectric conversion unit 10 in contact with the first layer 31 next to the first layer 31. Form with the same planar shape and thickness.
In this way, a thermoelectric conversion pattern composed of all the first layer 31 and the second layer 32 constituting the 14 thermoelectric conversion units 10 in two rows is formed on the upper surface of the substrate 2. In the state of FIG. 3, the portion of the substrate 2 where the first layer 31 and the second layer 32 exist is the unit forming portion.
Next, as a second printing step, as shown in FIG. 4, a conductive layer pattern including the lower wiring 41, the connection terminal 43, and the upper wiring 42 is formed on the thermoelectric conversion pattern shown in FIG.

Next, as shown in FIG. 5, a through hole 25 is formed by a punching method or a cutting method in a portion of the entire range where the convex portion 211 is formed in the subsequent process, which is between the adjacent thermoelectric conversion units 10 between the rows of the substrate 2. To form. In this state, the thermoelectric conversion unit 10 is formed in a flat plate shape on the flat plate-shaped substrate 2 as shown in FIG.
Next, as a convex portion forming step, a mold having a male portion and a female portion corresponding to the convex portion 211 of FIG. 1 is prepared, and the male portion is pressed against the back surface side of the substrate 2 and the female portion is pressed against the front surface side. Pressurize while heating (heat pressurization molding is performed). As a result, the first layer 31 and the second layer 32 and the portion of the substrate 2 on which the first layer 31 and the second layer 32 are formed are stretched and deformed to form the convex portion 211. At that time, by using a mold having a male portion and a female portion corresponding to the convex portions 211 of all the unit forming portions 21, the convex portions 211 are formed in all the thermoelectric conversion units 10 at once.

The thermoelectric conversion element 1 manufactured in this manner has a low portion 31a which is a portion on the first low surface portion 212 of the first layer 31 and a second low surface portion 213 of the second layer 32 in all the thermoelectric conversion units 10. Between the lower portion 32a, which is the upper portion, and the high portions 31b, 32b, which are the portions on the tops 211a of the first layer 31 and the second layer 32, the thickness of the first layer 31 and the second layer 32 or more. Has a height difference of.
Therefore, the thermoelectric conversion element 1 is placed horizontally on the non-formed portion 22 of the substrate 2 and placed on, for example, a hot plate, and the low portion 31a of the first layer 31 and the low portion 31a of the second layer 32 are placed via the substrate 2. High power generation performance can be obtained even when the portion 32a is heated and used. Further, it can be stably installed on the hot plate only by the substrate 2 on which the printed pattern is formed.

Further, by forming the through hole 25, the thermoelectric conversion units 10 adjacent to each other between the rows of the substrate 2 are separated from each other in the entire range of the convex portion 211 in all the unit forming portions 21. That is, as shown in FIG. 1, all the unit forming portions 21 have cut surfaces 214 that are independently separated for each thermoelectric conversion unit 10 over the entire range of the convex portions 211, and the cut surfaces 214 that are adjacent to each other between the rows. The space (through hole 25) and the space K below the convex portion 211 communicate with each other. Therefore, every 10 thermoelectric conversion units, the atmosphere comes into contact with the surroundings.
Therefore, when the above-mentioned hot plate is used for heating, if the atmosphere is circulated in the flow path formed by the lower space K to cool the top portion 211a, the low portions 31a and 32a and the high portions 31b and 32b of the thermoelectric conversion unit 10 are formed. It can be expected that a larger temperature difference will occur between them.
In the method for manufacturing the thermoelectric conversion element 1 of this embodiment, the printing process is performed in the order of the first layer 31, the second layer 32, and the conductive layer pattern (lower wiring 41, connection terminal 43, and upper wiring 42). However, the printing order of these layers can be changed arbitrarily.

[Second Embodiment]
As shown in FIG. 7, the thermoelectric conversion element 101 of the second embodiment not only has the thermoelectric conversion unit 10 of 2 columns and 7 rows on the upper surface of the substrate 2 like the thermoelectric conversion element 1 of the first embodiment. A thermoelectric conversion unit 10A having 2 columns and 7 rows is provided on the lower surface of the substrate 2.
Each thermoelectric conversion unit 10A is arranged at a position overlapping each thermoelectric conversion unit 10 with the substrate 2 interposed therebetween. The first layer 31 of the thermoelectric conversion unit 10A is formed so as to overlap the second layer 32 of the thermoelectric conversion unit 10, and the second layer 32 of the thermoelectric conversion unit 10A is formed so as to overlap the first layer 31 of the thermoelectric conversion unit 10. Has been done. Further, all the unit forming portions 21 have cut surfaces 214 that are independently separated for each thermoelectric conversion unit 10 and 10 A over the entire range of the convex portions 211, and are convex with the space between the cut surfaces 214 adjacent to each other between the rows. It communicates with the lower space K of the portion 211.

Further, as shown in FIG. 8, the connection terminal 43a on the upper surface and the connection terminal 43a on the lower surface that overlaps the connection terminal 43a that sandwiches the substrate 2 are connected by, for example, an electrode provided on the end surface of the substrate 2. As a result, the thermoelectric conversion unit 10 having 2 columns and 7 rows on the upper surface and the thermoelectric conversion unit 10A having 2 columns and 7 rows on the lower surface are connected in series. In this case, the connection terminals 43b on the upper surface and the lower surface serve as connection terminals to the outside.
The first layer 31 of the thermoelectric conversion unit 10A is formed so as to overlap the first layer 31 of the thermoelectric conversion unit 10, and the second layer 32 of the thermoelectric conversion unit 10A overlaps with the second layer 32 of the thermoelectric conversion unit 10. The connection terminals 43a on the upper surface and the connection terminals 43b on the lower surface may be connected to each other. In this case, the thermoelectric conversion unit 10 in 2 columns and 7 rows on the upper surface and the thermoelectric conversion unit 10A in 2 columns and 7 rows on the lower surface are connected in parallel, and the connection terminals 43a and the connection terminals 43b connected vertically are connected to the outside. It becomes a terminal.

The thermoelectric conversion element 101 is subjected to the first printing step and the second printing step on the upper surface and the lower surface of the substrate 2 by the same method as the manufacturing method of the thermoelectric conversion element 1 of the first embodiment, and then the thermoelectric conversion element 101 of the first embodiment is performed. It can be manufactured by performing a through hole forming step and a convex portion forming step on the substrate 2 in the same manner as the manufacturing method of the conversion element 1.
According to the thermoelectric conversion element 101 of this embodiment, in addition to the effect of the thermoelectric conversion element 1 of the first embodiment, by having thermoelectric conversion units on both sides of the substrate 2, a high electromotive force can be obtained with one substrate. It also has the effect of being obtained.

That is, the thermoelectric conversion element 101 of the second embodiment has the same area of the thermoelectric conversion element 1 and the substrate 2 of the first embodiment, but the thermoelectric conversion units 10 and 10A having the same pattern are arranged in the thickness direction of the substrate 2. Since it has two layers, the output voltage is twice that of the thermoelectric conversion element 1 in the case of series connection, and the output current is twice that of the thermoelectric conversion element 1 in the case of parallel connection.
Further, by increasing the number of thermoelectric conversion units 10 in the thickness direction of the substrate 2 to three layers, four layers, or more, the output current of the thermoelectric conversion element can be increased without changing the area of the substrate 2. ..
Further, in the thermoelectric conversion element 101 of the second embodiment, it is preferable that all the thermoelectric conversion units 10, the lower wiring 41 and the upper wiring 42 are covered with a weather resistant material. In that case, the coating layer made of the weather-resistant material may be formed at either timing before or after the formation of the convex portion 211.

[Third Embodiment]
As shown in FIG. 9, the thermoelectric conversion element 102 of the third embodiment only has the thermoelectric conversion unit 10 of 2 columns and 7 rows in the plane of the substrate 2, similarly to the thermoelectric conversion element 1 of the first embodiment. Instead, the same two columns and seven rows of thermoelectric conversion units 10 are provided on the upper surface of the substrate 2 in two layers. FIG. 9 shows a cross section of a portion where the thermoelectric conversion units 10 and 10B of the thermoelectric conversion element 102 overlap. As shown in FIG. 9, the thermoelectric conversion element 102 has an insulating layer 44 between two layers of thermoelectric conversion units 10 and 10B, and a coating layer 45 made of a weather resistant material on a surface opposite to the substrate 2.
The thermoelectric conversion element 102 is manufactured by the following method.

First, each step shown in FIGS. 2 to 5 is performed in the same manner as in the thermoelectric conversion element 1 of the first embodiment, and a pattern of the thermoelectric conversion unit 10 of the first layer (thermoelectric conversion pattern and conductive layer pattern) is performed on the substrate 2. And a through hole 25 is formed. Next, the insulating layer 44 is formed on the entire surface excluding the portion of the connection terminal 43 on the substrate 2 in the state shown in FIG. FIG. 10 shows this state. Next, each step shown in FIGS. 2 to 4 is performed in the same manner, and a pattern (thermoelectric conversion pattern and conductive layer pattern) of the second layer thermoelectric conversion unit 10B is formed on the substrate 2 in the state shown in FIG. After the formation, the coating layer 45 is formed on the entire surface of the substrate 2 to be in the state shown in FIG.

The thermoelectric conversion element 102 in this state has a flat plate shape, and as shown in FIG. 12, the thermoelectric conversion units 10 and 10B also have a flat plate shape. Next, by performing the same convex portion forming step as in the first embodiment, the convex portions 211 are formed in all the thermoelectric conversion units 10 and 10B.
The thermoelectric conversion element 102 manufactured in this manner has a low portion 31a which is a portion on the first low surface portion 212 of the first layer 31 and a second low of the second layer 32 in all the thermoelectric conversion units 10 and 10B. The thickness of the first layer 31 and the second layer 32 is between the lower portion 32a, which is a portion on the surface portion 213, and the high portions 31b, 32b, which are portions on the top portions 211a of the first layer 31 and the second layer 32. It has a height difference of more than that.

Therefore, the thermoelectric conversion element 102 is placed horizontally on the non-formed portion 22 of the substrate 2 and placed on, for example, a hot plate, and the low portion 31a of the first layer 31 and the low portion 31a of the second layer 32 are placed via the substrate 2. High power generation performance can be obtained even when the portion 32a is heated and used. Further, it can be stably installed on the hot plate only by the substrate 2 on which the printed pattern is formed.
Further, by forming the through hole 25, the thermoelectric conversion units 10 and 10B adjacent to each other between the rows of the substrate 2 are separated from each other in the entire range of the convex portion 211 in all the unit forming portions 21. That is, as shown in FIG. 9, all the unit forming portions 21 have cut surfaces 214 that are independently separated for each thermoelectric conversion unit 10 and 10B over the entire range of the convex portion 211, and the cutting is adjacent between the rows. The space between the surfaces 214 and the space K below the convex portion 211 communicate with each other.

Therefore, when the above-mentioned hot plate is used for heating, if the atmosphere is circulated in the flow path formed by the lower space K to cool the top portion 211a, the lower portions 31a and 32a and the high portions 31b and 32b of the thermoelectric conversion units 10 and 10B are cooled. It can be expected that a larger temperature difference will be generated between the two.
Further, the thermoelectric conversion element 102 of the third embodiment has the same area of the thermoelectric conversion element 1 and the substrate 2 of the first embodiment, but the thermoelectric conversion units 10 and 10B having the same pattern are arranged in the thickness direction of the substrate 2. Since it has two layers, the output current is larger than that of the thermoelectric conversion element 1.
The thermoelectric conversion element 102 of the third embodiment has the same conductive layer pattern (lower wiring 41, upper wiring 42, and connection terminal 43) of the two layers of thermoelectric conversion units 10 and 10B, and is the second layer. When the conductive layer pattern is formed, the second layer connection terminal 43 is printed on top of the first layer connection terminal 43, so that the two layers of thermoelectric conversion units 10 and 10B are connected in parallel.

Further, by setting the printing patterns of the conductive layer and the insulating layer, the output voltage of the thermoelectric conversion element 102 can be increased by connecting the two layers of thermoelectric conversion units 10 and 10B in series. Further, the output of the thermoelectric conversion element 102 can be freely adjusted by connecting the two layers of thermoelectric conversion units 10 and 10B in combination of parallel connection and series connection in each layer and between layers.
Further, by increasing the number of thermoelectric conversion units 10 in the thickness direction of the substrate 2 to three layers, four layers, or more, the output current of the thermoelectric conversion element can be increased without changing the area of the substrate 2. ..
Further, in the third embodiment, the convex portion 211 is formed after the coating layer 45 is formed, but the convex portion 211 is formed after the thermoelectric conversion unit 10B of the uppermost layer is formed, and then the coating is formed. Layer 45 may be formed.

[application]
Examples of applications of the thermoelectric conversion element 1 of the first embodiment and the thermoelectric conversion element 101 of the second embodiment include an independent power supply of a wireless sensor transmitter.
The wireless sensor transmission device 5 shown in FIG. 13 includes an antenna circuit 52 and a sensor terminal 53 formed on a circuit board 51, an independent power supply including a thermoelectric conversion element 1, a signal processing / transmission circuit 54, and a voltage amplification unit / battery. It is composed of 55 and.
As described above, the thermoelectric conversion element 1 of the embodiment is composed of low portions (heat absorbing portions) 31a and 32a and high portions (heat radiating portions) 31b and 32b of the thermoelectric conversion unit 10 and has thermoelectric conversion layers (first layer 31 and). Since it has a height difference equal to or larger than the thickness of the second layer 32), sufficient power can be supplied to drive the wireless sensor even when the heat energy applied to the endothermic portion is small. Therefore, the wireless sensor transmitting device 5 using the thermoelectric conversion element 1 of the embodiment as a power source can be used as a self-supporting wireless sensor transmitting device that can always operate even in a place without lighting where a solar cell cannot be used.
An application example of the thermoelectric conversion element 102 of the third embodiment is an independent power supply of a wearable wireless sensor transmitter.

The cow collar 6 shown in FIG. 14 has a self-sustaining power supply composed of a thermoelectric conversion element 102 fixed to the inner surface of the collar body (attachment) 61. The coating layer 45 side of the thermoelectric conversion element 102 is attached to the collar body 61, and the substrate 2 side is exposed.
As shown in FIG. 15, the cow collar 6 is wound around the neck 71 of a cow (warm-blooded animal) 7 with the thermoelectric conversion element 102 side inside, and a wearable wireless sensor transmitter is attached to the connection terminal 43 of the thermoelectric conversion element 102. Used by connecting. As shown in FIG. 16, in a state where the cow collar 6 is wound around the cow 7, the lower space K of the thermoelectric conversion element 102 exists on the neck 71 side of the cow 7. That is, between the neck 71 of the cow 7 and the collar body 61, there is an atmospheric flow path in which the lower space K for each row of the thermoelectric conversion units 10 and 10B is connected.

Since the substrate 2 of the thermoelectric conversion element 102 has flexibility, the cow collar 6 can be easily attached to the neck 71 of the cow 7 and has the thermoelectric conversion element 102 thinly formed as an independent power source. It does not interfere with the behavior of cow 7 when worn. Further, the thermoelectric conversion element 102 can supply electric power capable of driving the wearable wireless sensor transmitter by the temperature difference between the body surface of the cow 7 and the environment in which the cow 7 exists.
Further, since the atmosphere passes through the flow path of the atmosphere accompanying the lower space K, the temperature between the low portions 31a and 32a and the high portions 31b and 32b of the thermoelectric conversion units 10 and 10B is not used. The difference can be secured. As a result, the thickness of the cow collar 6 can be reduced by the amount of the heat radiating plate.

Further, since the thermoelectric conversion element 102 has a coating layer 45 made of a weather resistant material, the thermoelectric conversion element 102 can be used for a long period of time even when used outdoors. If it is used indoors or for a short period of time, the thermoelectric conversion element 1 of the first embodiment without the coating layer 45 may be used instead of the thermoelectric conversion element 102 of the third embodiment.
The cow collar 6 shown in FIG. 14 is an example of a power source for a wearable device, but the shape and material of the attachment of the power source for a wearable device are not limited, and the body surface of a homeothermic animal such as a limb, neck, or body is not limited. It is sufficient that it can be mounted on a part of the thermoelectric conversion element without significantly obstructing the flow of air around the thermoelectric conversion element and not easily falling off from the mounting position.

[About the shape of the convex part]
FIG. 17 shows a plurality of examples of the shapes of the convex portions forming the cross-sectional shape of the unit forming portion 21 of the substrate 2.
The convex portion of FIG. 17A is a pair of inclined surfaces connecting the top 27 formed of an arc surface facing the same plane 26 as the back surface of the substrate 2 and both ends of the straight line forming the plane 26 and both ends of the arc forming the top 27. 28 and. The boundary between the top 27 and the inclined surface 28 is formed to be round.
The convex portion of FIG. 17B is a pair of inclinations connecting a top portion 27 formed of a plane facing parallel to the same plane surface 26 as the back surface of the substrate 2 and both ends of the straight line forming the plane 26 and both ends of the straight line forming the top 27. It has a surface 28 and. The boundary between the top 27 and the inclined surface 28 is formed to be round.

The convex portion of FIG. 17C connects a top portion 27 formed of a plane facing parallel to the same plane surface 26 as the back surface of the substrate 2, both ends of the straight line forming the plane 26, and both ends of the straight line forming the top 27, and both straight lines. It has a pair of vertical planes 29 that are perpendicular to it. The boundary between the top 27 and the vertical surface 29 is rounded.
The convex portion of FIG. 17D is composed of an arc surface 27A facing the same plane 26 as the back surface of the substrate 2 and being connected to both ends of a straight line forming the plane 26. The position farthest from the plane 26 of the arc surface 27A is the top.

[About materials]
<Thermoelectric conversion material>
As the thermoelectric conversion material, a conductive polymer or CNT (carbon nanotube) can be preferably used, and depending on the type of the conductive polymer, a binder such as a thermosetting resin required for molding and conductivity A CNT (carbon nanotube) dispersion or a polar high boiling solvent such as ethylene glycol, dimethylsulfoxide, n-methylpyrrolidone or dimethylformamide, polyethylene glycol, or diethylene glycol monomethyl ether can be added.
The thermoelectric conversion material is not limited in type as long as it can follow the deformation of the substrate, and an inorganic material or a mixed material of an organic substance and an inorganic substance can also be used. Generally, when the breaking strain of the thermoelectric conversion material is 10% or more, it is easy to follow the deformation of the substrate.

<Example of thermoelectric conversion material made of conductive polymer>
As the p-type conductive polymer (conductive polymer having p-type semiconductor characteristics), a polymer compound having a conjugated molecular structure (conjugated polymer) can be used.
Conjugated polymers include polythiophene compounds (breaking strain 10 to 20%), polypyrrole compounds (breaking strain 20%), polyaniline compounds (breaking strain ~ 35%), and polyacetylene compounds (breaking strain ~ 800%). , Poly (p-phenylene) -based compound, Poly (p-phenylene vinylene) -based compound (PPV-based compound, breaking strain 5% after heat-stretching treatment at 150 ° C.), Poly (p-phenylene ethynylene) -based compound (breaking strain) 2.5%), poly (p-fluorenylene vinylene) -based compounds (breaking strain 2.5%), polyacene-based compounds (breaking strain 1%), polyphenanthrene-based compounds (breaking strain 1%).
Further, a conjugated polymer having a repeating unit composed of a derivative in which a substituent is introduced into the monomer of the polymer compound can also be mentioned.
Examples of the n-type conductive polymer (conductive polymer having n-type semiconductor characteristics) include polymer compounds having a conjugated molecular structure, but many of them are unstable substances.

<About the first and second layers>
At least one of the first layer and the second layer is made of thermoelectric conversion material, and the first layer and the second layer are made of the same material or different materials. When the first layer and the second layer are made of different materials, wiring (upper wiring) connecting the first layer and the second layer in the thermoelectric conversion unit is formed at the top of the convex portion.
That is, when the first layer and the second layer are made of different materials, the combination of materials is p-type thermoelectric material and n-type thermoelectric material, p-type thermoelectric material and conductive material (without thermoelectric conversion function), n-type thermoelectric material. And conductive materials (without thermoelectric conversion function). However, as described above, many n-type thermoelectric materials (n-type conductive polymers) made of conductive polymers are unstable substances.

<Board>
The type of the substrate is not particularly limited, but it is preferable to use a substrate (breaking strain of 50% or more) that is not easily affected by the formation of electrodes and the thermoelectric conversion layer and is not easily cracked during deformation. From the viewpoint of cost and flexibility, plastic film is preferable, and polyester terephthalate, polyethylene isophthalate, polyethylene naphthalate, polybutylene terephthalate, poly (1,4-cyclohexylene methylene terephthalate), polyester-2,6-phthalendicarboxylate. Examples thereof include polyester films such as polyester films obtained by polymerization of rate, bisphenol A and iso and terephthalic acid, polycycloolefin films, polyimide films, polycarbonate films, polyether ether ketone films, polyphenyl sulfide films and the like.
Of these, commercially available polyethylene terephthalate (PET), polyethylene naphthalate (PEN), various polyimides and polycarbonate films are preferable from the viewpoints of availability, heat resistance of 100 ° C. or higher, processability, economy and effect. Considering the printing process, for example, a sheet that has been easily bonded on one side is preferable.

[Preferable embodiment]
The thermoelectric conversion element of the first aspect of the present invention may have the following configuration (5) or (5') in addition to the above configurations (1) to (4).
(5) The unit forming portion has a plurality of cut surfaces independently separated for each thermoelectric conversion unit within the range of the convex portion.
In this case, for each thermoelectric conversion unit, the atmosphere can be brought into contact with the surroundings of the thermoelectric conversion unit.

(5') The unit forming portion is separated from the non-forming portion within the range of the convex portion. In this case, the substrate surface exists in one surface (the surface including the first low surface portion and the second low surface portion) including the non-forming portion between the thermoelectric conversion units adjacent to each other in parallel. Therefore, having the above-mentioned configuration (5') has a higher effect of being able to be stably installed on a flat heating device than the case without the above-mentioned configuration (5').
Further, while having the above configuration (5'), a plurality of thermoelectric conversion units are arranged in a matrix of X columns and Y rows (X ≧ 1, Y ≧ 2), and between adjacent thermoelectric conversion units between the rows of the substrate. However, if they are separated within the range of all the convex parts, the space below all the convex parts is connected on the top side of the convex parts for each row of thermoelectric conversion units, and becomes a flow path for the atmosphere.

Therefore, when the thermoelectric conversion element of the first aspect has the configuration (5) or (5'), when it is placed on a flat heating device and heated, the atmosphere is circulated in the flow path formed by the space below the convex portion. By cooling the top, a larger temperature difference can be created between the low and high parts of the thermoelectric conversion unit.
In the thermoelectric element of Patent Document 1, since it is not possible to bring the atmosphere into contact with the periphery of the thermoelectric conversion unit for each thermoelectric conversion unit, there is also a problem in that the top of the convex portion is effectively cooled. This problem can be solved by having the thermoelectric conversion element of the first aspect having the configuration (5) or (5').

The thermoelectric conversion element of the first aspect of the present invention can have the following configuration (6) in addition to the above configurations (1) to (4).
(6) The plurality of thermoelectric conversion units and the wiring are formed on both the upper surface and the lower surface of the substrate. The upper surface and the connection terminals on the lower surface are connected to each other at at least one end of the series connection.
The thermoelectric conversion element of the first aspect of the present invention can have the following configuration (7) in addition to the above configurations (1) to (4).
(7) The first layer and the second layer are made of different materials, and a wiring connecting the first layer and the second layer in the thermoelectric conversion unit is formed on the top.

The thermoelectric conversion element of the first aspect of the present invention can have the following configuration (8) in addition to the above configurations (1) to (4).
(8) The plurality of thermoelectric conversion units and the wiring are covered with a weather resistant material.
The thermoelectric conversion element of the first aspect can have the following configuration (9) in addition to the above configurations (1) to (4).
(9) A plurality of the thermoelectric conversion units are provided via an insulating layer in the thickness direction of the substrate.

The thermoelectric conversion element according to the first aspect of the present invention preferably further has at least one of the following configurations (a) to (e).
(a) At least one of the first layer and the second layer is made of a conductive polymer.
(b) At least one of the first layer and the second layer is a polythiophene compound, a polypyrrole compound, a polyaniline compound, a polyacetylene compound, a poly (p-phenylene) compound, or a poly (p-phenylene vinylene). From system compounds, poly (p-phenylene ethynylene) -based compounds, poly (p-fluorenylene vinylene) -based compounds, polyacene-based compounds, polyphenanthrene-based compounds, and derivatives in which substituents are introduced into the monomers of these compounds. It has at least one selected from conjugated polymers having a repeating unit of.

(c) The thermoelectric conversion material is a p-type conductive polymer.
(d) The substrate is a polyethylene terephthalate film, a polyethylene isophthalate film, a polyethylene naphthalate film, a polybutylene terephthalate film, a poly (1,4-cyclohexylene methylene terephthalate) film, a polyethylene-2,6-phthalendicarboxylate. It consists of at least one selected from a film, a polyimide film, a polycarbonate film, a polyether ether ketone film, and a polyphenyl sulfide film.
(e) The printing pattern of the thermoelectric conversion element is covered with a protective layer (for example, a layer coated with a coating agent made of synthetic resin and cured, a layer made of a weather resistant material).

The thermoelectric conversion element having the above configurations (1) to (5) can be manufactured, for example, by a method having the above configurations (11) to (13) and the following configurations (14).
(14) A step of providing a through hole in a portion of the substrate between the rows adjacent to each other within the range in which the convex portion is formed before the convex portion forming step.
As a third aspect of the present invention, there is a power source for a wireless sensor provided with the thermoelectric conversion element of the first aspect.
As a fourth aspect of the present invention, an independent power supply composed of the thermoelectric conversion element of the first aspect, a signal processing / transmission circuit, a voltage amplification unit / battery, and a circuit board on which an antenna circuit and a sensor terminal are formed are provided. Examples include wireless sensors having.

As a fifth aspect of the present invention, an attachment attached to a part of the body surface such as a limb, neck, or body of a homeothermic animal, and a thermoelectric conversion element of the first aspect fixed to the surface of the attachment. A power supply for a wearable device having the above can be mentioned.
Since the power source for the wearable device of the fifth aspect uses the body temperature of a homeothermic animal including a human as an energy source, the electric power is not significantly attenuated as long as the life activity of the homeothermic animal being worn is maintained. Further, since the thermoelectric conversion element of the first aspect has the above-mentioned configuration (8), it can be expected that the electric power will continue to be supplied for a long period of time even when used outdoors.
On the other hand, in energy harvesting technology using electromagnetic waves and mechanical energy, electric power is significantly attenuated depending on conditions such as location and time. That is, the wearable wireless sensor transmitter using the power supply of the fifth aspect is excellent as a self-supporting wireless sensor transmitter that can always operate.

[About thermoelectric conversion materials]
As the material of the first layer 31, "Clevios PH1000 (aqueous dispersion)" of Heraeus Co., Ltd., which is a coating agent containing a polythiophene compound, was used. The polythiophene-based compound is a p-type conductive polymer, and the main component of this coating agent is "poly (3,4-ethylenedioxythiophene): polystyrene sulfide".
Cellulose nanofibers (manufactured by Chuetsu Pulp & Paper Co., Ltd., maximum width 500 nm or less, average width 50 nm or less, average fiber length 0.5 μm, degree of polymerization 350) were added in an amount of 10% by mass based on the active ingredient of PH1000, and ethylene glycol was added to PH1000. After adding so as to be 5% by volume, the mixture was heated with stirring to evaporate the water content to obtain a gel-like p-type thermoelectric conversion material.
Silver paste was used as the material for the second layer 32, the lower wiring 41, the connection terminal 43, and the upper wiring 42. The lower wiring 41, the connection terminal 43, and the upper wiring 42 were formed by screen printing. As the silver paste, for example, "Dotite FA-333" manufactured by Fujikura Kasei Co., Ltd. can be used. Further, in order to suppress the oxidation of silver, the carbon paste may be overlaid on the silver paste for printing.

[Manufacturing of thermoelectric conversion element]
<Sample No.1>
A thermoelectric conversion element having 312 thermoelectric conversion units in a matrix of 13 columns and 24 rows was manufactured by the following method. In the first embodiment, the thermoelectric conversion element 1 having 7 rows in 2 columns and 14 thermoelectric conversion units 10 has been described, but each step is each step described in the first embodiment except that the number of thermoelectric conversion units 10 is different. It was done in the same way as.
First, a metal mask having a thickness of 0.1 mm was prepared in which the opening patterns of the first layer 31 in 16 columns and 24 rows were alternately formed in each column and each row as in FIG. Using this metal mask, the above-mentioned gel-like p-type thermoelectric conversion material was printed on the upper surface of the substrate 2 made of a PET film having a thickness of 100 μm. As a result, the print pattern of the first layer 31 made of the p-type thermoelectric conversion material was formed in each thermoelectric conversion unit 10 in the same arrangement as in FIG.

Next, the substrate 2 in this state was heated at 120 ° C. for 2 hours to dry the p-type thermoelectric conversion material. The thickness of the first layer 31 after drying was 10 μm.
Next, a second layer 32 made of silver paste was printed next to the first layer 31 of all the thermoelectric conversion units 10, and the silver paste was dried by heating at 120 ° C. for 2 hours. This printing was done by screen printing. The silver paste was printed so that the second layer 32 after drying was 10 μm. As a result, 312 thermoelectric conversion patterns including the first layer 31 and the second layer 32 similar to those in FIG. 3 were formed.
Next, a conductive layer pattern composed of the lower wiring 41, the connection terminal 43, and the upper wiring 42 was formed on all the thermoelectric conversion patterns, as in FIG. The conductive layer pattern was formed by screen-printing the silver paste and then heating it at 120 ° C. for 2 hours to dry it.

Next, a through hole 25 was formed in the same arrangement as in FIG. 5 by a cutting method by laser processing. In this state, the thermoelectric conversion unit 10 is formed in a flat plate shape on the flat plate-shaped substrate 2 as shown in FIG.
Next, using a mold having a male portion and a female portion corresponding to all 312 convex portions 211, the convex portion forming step by heat and pressure molding described in the first embodiment is performed at 120 ° C. for 120 minutes. I went under the conditions of. As a result, all 312 thermoelectric conversion units 10 were brought into the state shown in FIG. The protruding height T of the convex portion 211 was set to 1.7 mm. Further, the first layer 31 and the second layer 32 were also stretched and deformed together with the substrate 2.
As shown in FIG. 1, the thermoelectric conversion element 1 thus obtained has an atmospheric flow path in which the lower space K of the convex portion 211 is connected for each thermoelectric conversion unit 10 in each row.

<Sample No.2>
A thermoelectric conversion element having 312 thermoelectric conversion units in a matrix of 13 columns and 24 rows (642 in total on both sides) on the upper surface and the lower surface of the substrate 2 was manufactured by the following method. In the second embodiment, the thermoelectric conversion element 101 having 2 columns and 7 rows and 14 thermoelectric conversion units 10 and 10A on the upper surface and the lower surface of the substrate 2 has been described, except that the number of thermoelectric conversion units 10 and 10A is different. , Each step was carried out in the same manner as each step described in the second embodiment.
First, a conductive layer pattern composed of a lower wiring 41, a connection terminal 43, and an upper wiring 42 was formed on both the upper surface and the lower surface of the substrate 2 in the same manner as in sample No.1. The pattern of each layer was the same arrangement on the upper surface and the lower surface of the substrate 2 (arrangement of overlapping the substrates 2).

Next, a through hole forming step and a convex portion forming step were performed in the same manner as in Sample No.1. That is, the protruding height T of the convex portion 211 is 1.7 mm, which is the same as that of sample No.1.
Next, the connection terminals 43a on the upper surface and the lower surface that overlap each other across the substrate 2 were electrically connected. As a result, a thermoelectric conversion element 101 in which 642 thermoelectric conversion units were connected in series was obtained.
As shown in FIG. 7, the thermoelectric conversion element 101 thus obtained has an atmospheric flow path in which the lower space K of the convex portion 211 is connected for each of the thermoelectric conversion units 10 and 10A in each row.

[Break strain test]
The fracture strain of the thermoelectric conversion layer constituting the thermoelectric conversion elements of Samples No. 1 and No. 2 was tested by the following method.
In both samples, the thermoelectric conversion material constituting the first layer 31 is "poly (3,4-ethylenedioxythiophene): polystyrene sulfide", so that "poly (3,4-ethylenedioxythiophene): poly (3,4-ethylenedioxythiophene)" is placed on the PET film. ): A test piece on which "polystyrene sulfide" was formed was prepared and a tensile break test was conducted. As a result, the breaking strain of the thermoelectric conversion layer was 10%. That is, in the thermoelectric conversion elements of Samples No. 1 and No. 2, the first layer 31 easily follows the deformation of the substrate 2.

[Evaluation of thermoelectric conversion element]
The thermoelectric conversion elements of Samples No. 1 and No. 2 were placed on a hot plate at 80 ° C. while holding the non-formed portion 22 of the substrate 2 horizontally in an environment of room temperature of 25 ° C., and via the substrate 2. The lower portion 31a of the first layer 31 and the lower portion 32a of the second layer 32 were heated. In this state, the voltage generated between both terminals 43 was measured with a tester.
The measured voltage values were 80 mV for sample No. 1 and 150 mV for sample No. 2, and any thermoelectric conversion element obtained an electromotive force that could be used as a power source for a wireless sensor.
The above results are summarized in Table 1 below.

1 Thermoelectric conversion element 10 Thermoelectric conversion unit on the upper surface of the substrate 10A Thermoelectric conversion unit on the lower surface of the substrate 10B Thermoelectric conversion unit on the second layer 2 Substrate 21 Unit forming part 211 Convex part 211a Top of convex part 212 First low surface part 213 Second low surface part 214 Cut surface 22 Non-formed part 25 Through hole 31 First layer 31a First layer low part 31b First layer high part 32 Second layer 32b Second layer high part 32a Second layer low part 41 Lower wiring 42 Upper wiring 43 Connection terminal 44 Insulation layer 45 Coating layer made of weather-resistant material 5 Wireless sensor transmitter 51 Circuit board 52 Antenna circuit 53 Sensor terminal 54 Signal processing / transmission circuit 55 Voltage amplification unit / battery 6 Cow collar 61 Collar body (Installation)
7 Cow (warm-blooded animal)
71 neck

Claims (6)

With the board
A plurality of thermoelectric conversion units formed on the upper surface or the lower surface of the substrate, and
Have,
The cross-sectional shape of the unit forming portion on which the thermoelectric conversion unit is formed of the substrate is composed of a convex portion and a first low surface portion and a second low surface portion lower than the convex portions on both sides thereof.
The non-formed portion of the substrate on which the thermoelectric conversion unit is not formed is located at a position lower than the top of the convex portion.
The thermoelectric conversion unit has a first layer extending from the first low surface portion of the unit forming portion to the top portion of the convex portion, and a second layer extending from the top portion to the second low surface portion.
At least one of the first layer and the second layer is made of a thermoelectric conversion material.
The plurality of thermoelectric conversion units are connected in series by wirings formed on the first low surface portion and the second low surface portion to connect the first layer and the second layer of the adjacent thermoelectric conversion units.
A thermoelectric conversion element having connection terminals at both ends of the series connection. The thermoelectric conversion element according to claim 1, wherein the unit forming portion has a cut surface independently separated for each thermoelectric conversion unit within the range of the convex portion. The plurality of thermoelectric conversion units and the wiring are formed on both the upper surface and the lower surface of the substrate.
The thermoelectric conversion element according to claim 1 or 2, wherein the upper surface and the connection terminals on the lower surface are connected to each other at at least one end of the series connection. The thermoelectric conversion element according to any one of claims 1 to 3, wherein the plurality of thermoelectric conversion units and the wiring are covered with a weather resistant material. The method for manufacturing the thermoelectric conversion element according to claim 1.
A first printing step of forming a thermoelectric conversion pattern composed of the first layer and the second layer constituting the plurality of thermoelectric conversion units on a substrate.
A second printing step of forming a conductive layer pattern composed of the wiring and the connection terminals on the thermoelectric conversion pattern.
A convex portion forming step of forming the convex portion by stretching and deforming the first layer and the second layer and the portion of the substrate on which the first layer and the second layer are formed.
A method for manufacturing a thermoelectric conversion element having. 5. The step of further comprising a step of providing a through hole in a portion of the substrate between the rows adjacent to each other within the range in which the convex portion is formed before the convex portion forming step. The method for manufacturing a thermoelectric conversion element according to the description.

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