Stretchable thermoelectric material and thermoelectric device including the same

A thermoelectric material includes a stretchable polymer, and a thermoelectric structure and an electrically conductive material that are mixed together with the stretchable polymer. The thermoelectric material may be applied to self-power generating wearable electronic apparatuses.

RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2014-0066523, filed on May 30, 2014, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

The present disclosure relates to a stretchable thermoelectric material and/or a thermoelectric device including the stretchable thermoelectric material.

2. Description of Related Art

Thermoelectric conversion is the conversion of thermal energy to electric energy and vice versa. The Peltier effect refers to an effect in which a temperature difference is generated between both ends of a thermoelectric material when a current flows through the thermoelectric material, and the Seebeck effect refers to an reverse effect in which electricity is generated when there is a temperature difference between both ends of a thermoelectric material.

Cooling systems operating by the Peltier effect may be effective to use in some applications where it may be difficult to use existing cooling systems such as passive cooling systems or refrigerant gas compression type cooling systems. Thermoelectric cooling is an eco-friendly cooling technique which does not use refrigerant gas, thereby limiting and/or preventing any environmental problems. If the efficiency of thermoelectric cooling is improved by the development of highly efficient thermoelectric cooling materials, the application field thereof may be expanded to general-purpose cooling apparatuses such as refrigerators and air conditioners.

In addition, the Seebeck effect may be used to produce electric energy from heat generated by computers, automobile engines, industrial plants, etc. Thermoelectric power generated by the Seebeck effect may become a new renewable energy source. Along with the increasing interest in new energy sources, the environment, the reuse of waste energy, etc., the interest in thermoelectric devices has increased.

There is an increasing interest in polymer thermoelectric materials or flexible thermoelectric materials for large-area thermoelectric devices or wearable thermoelectric apparatuses.

As compared with thermoelectric inorganic materials, polymer thermoelectric materials or flexible thermoelectric materials are non-toxic and inexpensive, and it is easy to manufacture large-area thermoelectric devices using polymer thermoelectric materials or flexible thermoelectric materials. In general, however, the thermoelectric conversion efficiency of polymer thermoelectric materials or flexible thermoelectric materials is low.

SUMMARY

Provided is a thermoelectric material having stretchability and high thermoelectric conversion efficiency.

Provided is a thermoelectric device including the thermoelectric material and applicable to wearable electronic apparatuses.

According to example embodiments, a thermoelectric material includes a stretchable polymer, and a thermoelectric structure and an electrically conductive material that are mixed together with the stretchable polymer.

In example embodiments, the thermoelectric structure may include at least one of an Sb—Te-containing material, a Bi—Te-containing material, a Bi—Sb—Te-containing material, a Co—Sb-containing material, a Pb—Te-containing material, a Ge—Tb-containing material, a Si—Ge-containing material, a Sm—Co-containing material, and a carbon-containing material.

In example embodiments, the carbon-containing material may include at least one of carbon nanotubes, graphene, and graphite.

In example embodiments, the electrically conductive material may include at least one of a carbon nanomaterial and a metallic material.

In example embodiments, the carbon nanomaterial may include at least one of carbon nanotubes, graphene, and graphene nanoparticles.

In example embodiments, the electrically conductive material may include the carbon nanotubes and the metallic material. The metallic material may be metal nanoparticles. The metal nanoparticles may be adsorbed on surfaces of the carbon nanotubes.

In example embodiments, the metallic material may include gold (Au), silver (Ag), platinum (Pt), copper (Cu), nickel (Ni), aluminum (Al), palladium (Pd), rhodium (Rh), and ruthenium (Ru).

In example embodiments, the thermoelectric structure and the electrically conductive material mixed together may be carbon nanotubes and metal nanoparticles. The metal nanoparticles may be adsorbed on surfaces of the carbon nanotubes.

In example embodiments, the thermoelectric structure and the electrically conductive material may include carbon nanotubes.

In example embodiments, the carbon nanotubes may be a multi-walled carbon nanotube (MWCNT) array. The carbon nanotubes may be arranged in a direction.

In example embodiments, the multi-walled carbon nanotube array may be embedded in the stretchable polymer.

In example embodiments, the stretchable polymer may have uniaxial stretchability. A length of the carbon nanotubes in the multi-walled carbon nanotube array may be parallel to a stretching direction of the stretchable polymer.

In example embodiments, the stretchable polymer may have uniaxial stretchability. A length of the carbon nanotubes in the multi-walled carbon nanotube array may be perpendicular to a stretching direction of the stretchable polymer. According to example embodiments, a thermoelectric device may include the thermoelectric material, and first and second electrodes electrically connected to respective ends of the thermoelectric material.

In example embodiments, the thermoelectric device may further include an electronic device electrically connected to the first and second electrodes.

In example embodiments, the electronic device may be one of a power consuming device, a power storage device, and a power supply device.

According to example embodiments, a wearable electronic apparatus may be configured to be put on an object for inspecting the object. The wearable electronic apparatus may include the thermoelectric material, first and second electrodes electrically connected to respective ends of the thermoelectric material, a power storage device connected to the first and second electrodes, and an operation unit. The power storage device may be configured to store electric energy generated in the thermoelectric material based on a temperature difference between both the ends of the thermoelectric material. The temperature difference may be caused by heat provided by the object. The operation unit may be configured to receive the electric energy from the power storage device and to perform an inspection operation on the object.

In example embodiments, the operation unit may be configured to measure a health or motion status of the object.

According to example embodiments, an electronic apparatus includes the thermoelectric material, first and second electrodes electrically connected to respective ends of the thermoelectric material, and a power supply device connected to the first and second electrodes. The power supply device is configured to apply a current to the thermoelectric material for forming a hot spot cooling region at one of the respective ends of the thermoelectric material.

According to example embodiments, a thermoelectric material includes a stretchable polymer, a thermoelectric structure mixed in the stretchable polymer, and an electrically conductive material mixed in the stretchable polymer. The thermoelectric material contains carbon.

In example embodiments, the electrically conductive material may include metal nanoparticles.

In example embodiments, the thermoelectric structure may include carbon nanotubes embedded in the stretchable polymer. The metal nanoparticles may be adsorbed on the carbon nanotubes.

In example embodiments, the carbon nanotubes may be arranged in an array and lengths of the carbon nanotubes may be parallel to each other.

DETAILED DESCRIPTION

FIG. 1is a schematic view illustrating a thermoelectric material100according to example embodiments.

In example embodiments, the thermoelectric material100may have high thermoelectric conversion efficiency and stretchability.

In general, the thermoelectric figure of merit (zT) of a thermoelectric material is defined by Equation 1 below:
zT=(α2σT)/κ  (1)
wherein α denotes a Seebeck coefficient, σ denotes electric conductivity, T denotes absolute temperature, and κ denotes thermal conductivity.

In Equation 1, α2σ is called a power factor.

Referring to Equation 1, the thermoelectric figure of merit (zT) of a thermoelectric material may be increased by increasing the Seebeck coefficient and the electric conductivity of the thermoelectric material and decreasing the thermal conductivity of the thermoelectric material.

As a result of effort to obtain a thermoelectric material having high thermoelectric conversion efficiency and stretchability based on the above-described relation, the thermoelectric material100according to example embodiments may be formed by mixing a thermoelectric structure140and an electrically conductive material160together with a stretchable polymer120.

Examples of the Sb—Te-containing thermoelectric inorganic material may include Sb2Te3, AgSbTe2, and CuSbTe2, and examples of the Bi—Te-containing thermoelectric inorganic material may include Bi2Te3, and a thermoelectric inorganic material containing (Bi,Sb)2(Te,Se)3. Examples of the Co—Sb-containing thermoelectric inorganic material may include CoSb3, and examples of the Pb—Te-containing thermoelectric inorganic material may include PbTe and (PbTe)mAgSbTe2. In addition, any other inorganic material used in the thermoelectric field may be used as the thermoelectric inorganic material140.

Examples of the carbon-containing material may include carbon nanotubes, graphene, and graphite. In detail, examples of the carbon-containing material may include single walled carbon nanotubes, double walled carbon nanotubes (CNTs), multi-walled carbon nanotubes (MWCNTs), rope carbon nanotubes, graphene oxides, graphene nanoribbons, carbon black, and carbon nanofibers. However, the carbon-containing material is not limited thereto.

The electrically conductive material160may be a metallic material or a carbon nanomaterial. Examples of the metallic material may include gold (Au), silver (Ag), platinum (Pt), copper (Cu), nickel (Ni), aluminum (Al), palladium (Pd), rhodium (Rh), and ruthenium (Ru), and examples of the carbon nanomaterial may include carbon nanotubes, graphene, and graphene nanoparticles.

The thermoelectric material100may be manufactured by various mixing methods.

For example, the thermoelectric structure140and the electrically conductive material160may be prepared in the form of powder or flakes and may be dispersed into a solution of the stretchable polymer120. Thereafter, a solvent may be evaporated from the solution to form the thermoelectric material100. The solvent may be water or any one selected from various organic solvents. The solvent may be evaporated naturally or by heat.

Alternatively, the thermoelectric material100may be manufactured by preparing powder of the stretchable polymer120, the thermoelectric structure140, and the electrically conductive material160, mixing the powder with a solvent, and evaporating the solvent.

Alternatively, a dry mixing method may be used. That is, particles of the stretchable polymer120, the thermoelectric structure140, and the electrically conductive material160may be mixed together by using a general mixer, and the mixture may be compressed to form the thermoelectric material100.

FIG. 2is an image illustrating a stretched state of a sample of the thermoelectric material100, andFIG. 3is a scanning electron microscope (SEM) image taken from a surface of the sample on an enlarged scale.

The sample was made by mixing silver (Ag) flakes, carbon nanotubes, and poly(styrene-isoprene-styrene) (SIS), and was stretched by about 70% in a tension test as shown inFIG. 2.

A brief description will now be given of how the sample was made. However, the method described below is a non-limiting example.

First, 2 g of poly(styrene-isoprene-styrene) (SIS) polymer was put into 50 ml of toluene solution and was agitated for about 1 hour while heating the solution at 60° C. to prepare a dispersion solution.

Next, 0.8 g of silver (Ag) flakes and 0.1 g of carbon nanotubes were added to the dispersion solution as an electrically conductive material and a thermoelectric structure, and were mixed for 10 minutes by using a tip sonicator at the power of 700 W.

Thereafter, a dispersion medium was naturally dried at room temperature. In this way, the sample was made in the form of a film.

FIGS. 4 to 6are graphs illustrating the electric conductivity, Seebeck coefficient, and power factor of the thermoelectric material100with respect to tensile strain of the thermoelectric material100according to example embodiments.

Referring toFIG. 4, the electric conductivity of the thermoelectric material100reduces as the tensile strain of the thermoelectric material100increases, and the electric conductivity starts to reduce steeply when the tensile strain is about 50% or greater.

Referring toFIG. 5, the Seebeck coefficient of the thermoelectric material100is almost constant with respect to the tensile strain of the thermoelectric material100.

Referring toFIG. 6, the power factor of the thermoelectric material100reduces as the tensile strain of the thermoelectric material100increases. However, the power factor reduces very little and remains almost constant when the tensile strain is about 20% or greater.

The power factor is α2σ in Equation 1 described above to introduce the thermoelectric figure of merit (zT).

The above-described experimental results may prove that the thermoelectric material100could be manufactured to have desired stretchability and thermoelectric efficiency by properly combining components of the thermoelectric material100.

Hereinafter, thermoelectric materials according to example embodiments will be described.

FIG. 7Ais a schematic view illustrating a thermoelectric material200according to example embodiments.FIG. 7Ais a schematic view illustrating a thermoelectric material200according to example embodiments.FIG. 8is a detailed view illustrating a nanostructure250included in the thermoelectric material200illustrated inFIG. 7A.

In example embodiments, as shown inFIG. 7A, the thermoelectric material200may be made by mixing a stretchable polymer120with nanostructures250having conductivity and thermoelectric characteristics.

Referring toFIG. 8, each of the nanostructures250includes a carbon nanotube CNT and metal nanoparticles MNP adsorbed on the surface of the carbon nanotube.

The carbon nanotubes CNT have thermoelectric characteristics and conductivity, and since the metal nanoparticles MNP are adsorbed on the surfaces of the carbon nanotubes CNT, the nanostructures250may have thermoelectric characteristics and high conductivity. Since the thermoelectric material200is made by dispersing the nanostructures250into the stretchable polymer120, the thermoelectric material200has stretchability.

The nanostructures250may be used as the thermoelectric structure140of the thermoelectric material100illustrated inFIG. 1. That is, the thermoelectric material100may be made by mixing the nanostructures250and the electrically conductive material160with the stretchable polymer120. In addition, as shown inFIG. 7B, a thermoelectric material200′ according to example embodiments may further include electrically conductive material260that is spaced apart from the nanostructures250. The electrically conductive material260may be particles. The electrically conductive material260may be may be a metallic material or a carbon nanomaterial. Examples of the metallic material may include gold (Au), silver (Ag), platinum (Pt), copper (Cu), nickel (Ni), aluminum (Al), palladium (Pd), rhodium (Rh), and ruthenium (Ru), and examples of the carbon nanomaterial may include carbon nanotubes, graphene, and graphene nanoparticles. The electrically conductive material260may be a different material than the metallic nanoparticle MNP included in the nanostructures250.

Hereinafter, explanations will be given of the electrical conductivity values, Seebeck coefficients, and power factors of thermoelectric material samples made while varying constitutional components of the samples and contents of the components.

Table 1 below shows thermoelectric properties of samples having different contents of thermoelectric structures and electrically conductive materials.

The samples were made by using SIS polymer as a stretchable polymer, CNTs and/or Sb2Te3as thermoelectric structures, and silver (Ag) and/or CNTs as electrically conductive materials. That is, CNTs were used as a material having electric conductivity and thermoelectric characteristics. While maintaining the content of the stretchable polymer at a constant value, the contents of the thermoelectric structures and the electrically conductive materials were varied. As a result, the electrical conductivity values of the samples were markedly varied according to the use or content of silver (Ag), and it was analyzed that the power factors of the samples were mainly affected by the use or content of silver (Ag).

Table 2 below shows thermoelectric properties of samples having different contents of thermoelectric structures and electrically conductive materials and the same contents of silver (Ag) flakes and SIS polymer.

The samples were made by using SIS polymer as a stretchable polymer, CNTs as a thermoelectric structure, and silver (Ag) and CNTs as electrically conductive materials. Ag/CNTs of Sample 7 refers to nanostructures in which silver (Ag) nanoparticles are absorbed on surfaces of CNTs, like the nanostructures250of thermoelectric material200according to example embodiments that is explained with reference toFIG. 7A. Referring to Table 2, if the content of CNTs is low, the Seebeck coefficient is low but the electric conductivity is high due to a relatively high content of silver (Ag). As a result, the power factor is high.

Referring toFIG. 9A, the thermoelectric material300aincludes carbon nanotubes having thermoelectric characteristics and electric conductivity. In detail, the thermoelectric material300aincludes a stretchable polymer120and a multi-walled carbon nanotube array350a.

In the multi-walled carbon nanotube array350a, carbon nanotubes may be arranged in one direction. That is, lengths of a plurality of nanotubes constituting the multi-walled carbon nanotube array350amay be parallel to each other. The multi-walled carbon nanotube array350amay be embedded in the stretchable polymer120. The stretchable polymer120may have uniaxial stretchability as indicated by an arrow A1. In other words, a stretching direction of the stretchable polymer120may be indicated by the arrow A1. A length direction A2of the carbon nanotubes of the multi-walled carbon nanotube array350aand a stretchable direction A1of the stretchable polymer120may be perpendicular to each other.

Referring toFIG. 9B, the thermoelectric material300bincludes carbon nanostructures having thermoelectric characteristics and electric conductivity. In detail, the thermoelectric material300bincludes a stretchable polymer120and a nanostructure array350b. The nanostructures in the nanostructure array350bmay include multi-walled carbon nanotubes with metal nanoparticles adsorbed on the surfaces of the carbon nanotubes (e.g., multi-walled carbon nanotubes), such as a plurality of the nanostructures250described previously with reference toFIG. 8.

In the nanostructure array350b, the carbon nanotubes of the nanostructures in the nanostructure array350bmay be arranged in one direction. That is, lengths of nanotubes in the nanostructures constituting the nanostructure array350bmay be parallel to each other. The nanostructure array350bmay be embedded in the stretchable polymer120. The stretchable polymer120may have uniaxial stretchability as indicated by an arrow A1. A length direction A2of the carbon nanotubes in the nanostructures of the nanostructure array350band a stretchable direction A1of the stretchable polymer120may be perpendicular to each other.

Referring toFIG. 9C, the thermoelectric material300cmay be the same as the thermoelectric material300bdescribed inFIG. 9B, except the nanostructure array350cfurther includes additional electrically conductive material dispersed in the stretchable polymer120and separate from the nanostructure array350c, similar to the electrically conductive material260described inFIG. 7B.

Although examples are described with reference toFIGS. 9A to 9Cwhere the carbon nanotube arrays350ato350cmay include multi-walled carbon nanotubes, example embodiments are not limited thereto. For example, single-walled carbon nanotubes or a different carbon-containing structure (e.g., rope carbon nanotubes) may be used instead of multi-walled carbon nanotubes.

Referring toFIG. 10A, the thermoelectric material400amay have a structure that is similar to the thermoelectric material300aofFIG. 9A, except for an arrangement of the carbon nanotubes in the multi-walled carbon nanotube array450acompared to the carbon nanotubes in the multi-walled carbon nanotube array350a. That is, in the thermoelectric material400a, a multi-walled carbon nanotube array450ain which carbon nanotubes are arranged in one direction is embedded in a stretchable polymer120having uniaxial stretchability (A1). In the thermoelectric material400a, a length direction A3of the multi-walled carbon nanotube array450amay be parallel to a stretchable direction A1. In other words, a length direction A3of the carbon nanotubes in the multi-walled carbon nanotube array450amay be parallel to a stretching direction of the stretchable polymer120.

Referring toFIG. 10B, the thermoelectric material400bmay have a structure that is similar to the thermoelectric material300bofFIG. 9B, except for an arrangement of the carbon nanotubes in the nanostructure array450bcompared the carbon nanotubes in the nanostructure array350b. That is, in the thermoelectric material400b, a nanostructure array450bin which carbon nanotubes are arranged in one direction is embedded in a stretchable polymer120having uniaxial stretchability (A1). In the thermoelectric material400b, a length direction A3of the carbon nanotubes in the nanostructure array450bmay be parallel to a stretchable direction A1. In other words, a length direction A3of the carbon nanotubes in the nanostructure array450bmay be parallel to a stretching direction of the stretchable polymer120.

Referring toFIG. 10C, the thermoelectric material400cmay have a structure that is the same as the thermoelectric material400binFIG. 10B, except that the nanostructure array450cfurther includes additional electrically conductive material dispersed in the stretchable polymer and separate from the nanostructure array450c, similar to the electrically conductive material260described inFIG. 7B.

The above-described thermoelectric materials100,200,200′,300a,300b,300c,400a,400b, and400cmay further include electrode structures to provide a current for inducing thermoelectric conversion therein or to use or collect electricity generated by thermoelectric conversion therein. Each of the electrode structures may include two electrodes disposed on and electrically connected to both ends of each of the thermoelectric materials100,200,200′,300a,300b,300c,400a,400b, and400c. The thermoelectric materials100,200,200′,300a,300b,300c,400a,400b, and400c, and electronic devices such as power consuming devices, power storage devices, or power supply devices connected to the electrodes may be used as thermoelectric devices having various functions.

FIG. 11is a schematic view illustrating a thermoelectric device1000according to example embodiments.

The thermoelectric device1000includes a thermoelectric material TM, first and second electrodes EL1and EL2formed at respective both ends of the thermoelectric material TM, and a power consuming device ED1disposed between the first and second electrodes EL1and EL2.

An end of the thermoelectric material TM (for example, where the first electrode EL1is formed) may be in contact with a relatively high temperature region H1, and the other end of the thermoelectric material TM (for example, where the second electrode EL2is formed) may be in contact with a relatively low temperature region L1. In this case, electricity may be generated in the thermoelectric material TM by the thermoelectric effect. For example, electrons e−(or holes) may move from the end of the thermoelectric material TM making contact with the high temperature region H1to the other end of the thermoelectric material making contact with the low temperature region L1. The electrons e−(or holes) may flow through the power consuming device ED1. In this way, electricity generated by the thermoelectric material TM may be consumed by the power consuming device ED1.

A bulb is shown as the power consuming device ED1. However, the bulb is a non-limited example. That is, various kinds of loads consuming electricity generated by the thermoelectric material TM may be used.

The thermoelectric material TM may be any one of the above-described thermoelectric materials100,200,200′,300a,300b,300c,400a,400b, and400cor may be a combination thereof. Since the thermoelectric material TM has stretchability and improved thermoelectric characteristics, the thermoelectric device1000may have high thermoelectric conversion efficiency.

FIG. 12is a schematic view illustrating a thermoelectric device2000according to example embodiments.

The thermoelectric device2000is different from the thermoelectric device1000ofFIG. 11, in that an electronic device connected to both ends of the thermoelectric device2000is a power storage device ED2. For example, the power storage device ED2may be a storage battery configured to store electricity generated by a thermoelectric material TM of the thermoelectric device2000.

FIG. 13is a schematic view illustrating a thermoelectric device3000according to example embodiments.

The thermoelectric device3000may be a thermoelectric cooling device.

Referring toFIG. 13, first and second electrodes EL1and EL2may be provided on both ends of a thermoelectric material TM, and a power supply device ED3may be connected between the first and second electrodes EL1and EL2. If a current is supplied from the power supply device ED3to the thermoelectric material TM, an end of the thermoelectric material TM may absorb heat from surrounding objects by the Peltier effect. That is, heat may be absorbed at an end of the thermoelectric material TM. Therefore, the surrounding area of the end of the thermoelectric material TM may be cooled. The structure of the power supply device ED3may be variously changed.

The thermoelectric device3000may be used for various electronic apparatuses requiring hot spot cooling. For example, the thermoelectric device3000may be applied to portable electronic apparatuses such as smartphones, tablet personal computers (PCs), or micro packages, or may be applied to wearable small electronic apparatuses.

Each of the thermoelectric materials TM of the thermoelectric devices1000,2000, and3000described with reference toFIGS. 11 to 13may be one selected from the above-described thermoelectric materials100,200,200′,300a,300b,300c,400a,400b, and400caccording to example embodiments, and combinations thereof.

InFIGS. 11 to 13, electrode structures of the thermoelectric devices1000,2000, and3000are plate-shaped. However, the electrode structures may have other shapes such as wire shapes. If the thermoelectric materials300and400ofFIGS. 9 and 10in which the multi-walled carbon nanotube arrays350and450are embedded in the stretchable polymers120are used as the thermoelectric materials TM of the thermoelectric devices1000,2000, and3000, wire structures may be further used to electrically expose the multi-walled carbon nanotube arrays350and450to the outsides of the stretchable polymers120and to thus electrically connect the first and second electrodes EL1and EL2to the multi-walled carbon nanotube arrays350and450. For example, the thermoelectric materials300and400may be manufactured by forming wires to be exposed to the outsides on the multi-walled carbon nanotube arrays350and450using a material such as metal flakes, and then embedding the multi-walled carbon nanotube arrays350and450in the stretchable polymers120.

Since the thermoelectric devices1000,2000, and3000according to example embodiments include the thermoelectric materials TM having stretchability, the thermoelectric devices1000,2000, and3000may easily be applied to wearable apparatuses such as self-power generating wearable apparatuses.

FIG. 14is a schematic block diagram of a wearable electronic apparatus7000according to example embodiments.

The wearable electronic apparatus7000may be put on an object OBJ for detecting states of the object OBJ. The wearable electronic apparatus7000includes a thermoelectric device7200and an operation unit7400.

The thermoelectric device7200includes one of the above-described thermoelectric materials according to example embodiments, and a power storage device such as the power storage device ED2shown inFIG. 12for storing electricity generated by the thermoelectric material.

The thermoelectric device7200may function as a self-power generating device capable of converting thermal energy TE of the object OBJ into electricity. That is, due to thermal energy provided by the object OBJ, a temperature difference is generated between adjacent and far regions of the thermoelectric device7200relative to the object OBJ, and thus electricity is generated in the thermoelectric device7200having a temperature gradient. Then, electric energy is stored in the thermoelectric device7200.

The operation unit7400may inspect the object OBJ by using electric energy received from the thermoelectric device7200. For example, the operation unit7400may send an input signal S1to the object OBJ and may receive an output signal S2generated from the input signal S1as a result of interaction with the object OBJ. For example, the input signal S1may be light or ultrasonic waves, and the output signal S2may be light or ultrasonic waves modified by interaction with the object OBJ and thus having properties different from those of the input signal S1.

The operation unit7400may be used to inspect the health or motion of the object OBJ. For example, the operation unit7400may include a light source or ultrasonic device for generating input signals S1. In addition, the operation unit7400may include one or more of various sensors for receiving output signals S2. For example, the operation unit7400may include an optical sensor, an ultrasonic sensor, a pressure sensor, or a strain sensor.

The operation unit7400may be controlled in a wired or wireless manner. For example, the operation unit7400may be an element of a remote medical examination system capable of measuring the health status of the object OBJ.

The above-described wearable electronic apparatus7000is a non-limiting example. That is, various modifications or changes may be made. For example, any kind of wearable apparatus including a thermoelectric device as a self-power generating device may be provided. For example, example embodiments may provide electronic goggles, watches, or clothes capable of generating electricity from a temperature difference between a human body and the surroundings and using the electricity as operation energy. In addition, example embodiments may provide military uniforms equipped with such wearable electronic apparatuses.

As described above, according to example embodiments, thermoelectric materials may have stretchability and high thermoelectric efficiency.

Therefore, the thermoelectric materials may be used in the manufacture of thermoelectric devices having high thermoelectric conversion efficiency, together with power consuming devices, power storage devices, or power supply devices.

The thermoelectric devices may be applied to self-power generating wearable electronic apparatuses or other various electronic apparatuses requiring hot spot cooling.

It should be understood that the example embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each thermoelectric material and/or device according to example embodiments should typically be considered as available for other similar features or aspects in other thermoelectric materials and/or devices according to example embodiments.