A high thermal conductivity substrate, flexible thermoelectric device, and wearable device

Abstract

The application develops a high-thermal-conductivity substrate, a flexible thermoelectric device and a wearable device. Relates to the field of thermoelectric devices, the high-thermal-conductivity substrate comprises three parts from top to bottom, which are layer one, layer two and layer three. The first layer is a heat-conducting silica gel pad, which can tightly adhere to an external heat source; the second layer is a flexible substrate, which enables the device to better adhere to a curved surface; and the third layer is a metal electrode deposited on the flexible substrate, which is used for welding thermoelectric particles. The application obtains the high-thermal-conductivity substrate through ultrasonic welding, constructs an efficient heat transfer channel, and thus improves the adhesion to the surface of the external heat source and the comprehensive performance of the f-TED.

Description

Technical Field

[0001] This application relates to the field of thermoelectric devices, specifically to a high thermal conductivity substrate, a flexible thermoelectric device, and a wearable device. Background Technology

[0002] Thermoelectric devices have attracted great research interest due to their ability to directly convert heat energy into electrical energy and their adjustable active cooling capabilities. Among them, flexible thermoelectric devices (f-TED) are continuously expanding their application fields due to their lightweight, flexible structural design, high efficiency, and low power consumption.

[0003] There are three main approaches to achieving flexibility in wearable f-TEDs. The first is to fabricate f-TEDs using flexible thermoelectric materials. While these materials exhibit excellent inherent flexibility, their relatively low ZT (thermoelectric figure of merit) often limits the overall performance of f-TEDs. The second approach involves designing thin-film f-TEDs. This design offers excellent compatibility with wearable applications, but its performance is limited by a small effective temperature difference, thus affecting its effectiveness in practical applications. The third approach uses a flexible substrate to connect rigid thermoelectric materials with excellent bonding properties. This method not only retains the high performance of thermoelectric materials but also endows f-TEDs with good flexibility, achieving a dual optimization of performance and flexibility.

[0004] However, many candidate flexible substrate materials have poor thermal conductivity and wearing comfort. Due to the complex curved shape and heat source distribution of the external heat source surface, traditional flexible substrate-based f-TEDs are difficult to perfectly fit with the external heat source surface, resulting in air gaps and significant contact thermal resistance. A large amount of heat loss occurs during the heat transfer from the external heat source to the device, affecting the overall device performance. Thermally conductive silicone pads have good thermal conductivity and flexibility, easily adapting to surfaces of different shapes and sizes and achieving a tight fit. However, their mechanical properties are poor, and their soft texture makes them unsuitable for direct use as substrate materials. They can, however, be used as thermal interface materials to optimize thermal conductivity.

[0005] Therefore, a laminated substrate can be fabricated by connecting a thermally conductive silicone pad to a flexible substrate, combining the high thermal conductivity and skin-adhesive properties of the silicone pad with the excellent mechanical strength and stability of the flexible substrate. This complementary performance not only endows the laminated substrate with excellent thermal conductivity but also ensures its adhesion to external heat sources, strength, and long-term stability in complex application environments, meeting the needs of various complex application scenarios.

[0006] Traditional connection methods, such as adhesive bonding, are simple, but they are prone to aging and detachment after long-term use, affecting the stability and reliability of the connection. Summary of the Invention

[0007] This application aims to address the problems of low thermal conductivity and poor adhesion to curved surfaces in traditional flexible substrates. To solve these problems, a high thermal conductivity substrate, a flexible thermoelectric device, and a wearable device are proposed. This application obtains the high thermal conductivity substrate through ultrasonic welding, constructing an efficient heat transfer channel, thereby improving the adhesion to the external heat source surface and enhancing the overall performance of f-TED.

[0008] To achieve the above objectives, this application adopts the following technical solution:

[0009] In a first aspect, this application provides a high thermal conductivity substrate, comprising:

[0010] The first layer is a thermal pad; the thermal pad is made of high thermal conductivity silicone material.

[0011] The second layer is a flexible substrate; the flexible substrate is ultrasonically welded to the thermal pad; the flexible substrate is a high-temperature resistant flexible material.

[0012] The third layer is a metal electrode layer; the metal electrode layer is formed by depositing metal electrodes on the flexible substrate and is used to weld thermoelectric particles; wherein, the thermal pad, the flexible substrate and the metal electrode layer are stacked sequentially from bottom to top.

[0013] As a further improvement of the present invention, the thermal pad is selected from silicone, fluororubber, EPDM rubber or fluorosilicone rubber.

[0014] As a further improvement of the present invention, the flexible substrate is selected from polyimide or polydimethylsiloxane.

[0015] As a further improvement of the present invention, the metal electrode is Cu, Ni or Au.

[0016] In a second aspect, the present invention provides a method for preparing a high thermal conductivity substrate, comprising:

[0017] First, a metal electrode layer is deposited on the surface of the flexible substrate;

[0018] Then, the thermal pad is ultrasonically welded to the flexible substrate.

[0019] As a further improvement of the present invention, the flexible substrate and the thermal pad are ultrasonically welded together, wherein the ultrasonic welding parameters are:

[0020] Ultrasonic frequency 20-40kHz, ultrasonic amplitude 20-80%, welding time 3-12s.

[0021] Thirdly, this application provides a flexible thermoelectric device, comprising:

[0022] The lower substrate is a high thermal conductivity substrate as described above;

[0023] Thermoelectric particles; the thermoelectric particles are welded to the metal electrode layer of the lower substrate;

[0024] The upper substrate is used to connect the heat sink.

[0025] As a further improvement of the present invention, the thermoelectric particle material is one or more of Bi2Te3-based compounds, Ag2Q-based compounds, SnSe-based compounds, Mg2Si-based compounds, MgAgSb-based compounds, MgSiSn-based compounds, and Mg3Sb2-based compounds.

[0026] As a further improvement of the present invention, the thermoelectric particles are selected from P-type Bi. 0.5 Sb 1.5 Te3 and N-type Bi2Se 0.3 Te 2.7 Materials, p-type α-MgAg 0.97 Sb 0.99 and n-type Ag2Se, p-type SnSe and n-type Bi2Te 2.7 Se 0.3 .

[0027] As a further improvement of the present invention, the heat sink is made of foamed copper with a porosity of 40-60 per inch, and is connected to the substrate by high-temperature soldering using solder paste.

[0028] As a further improvement of the present invention, the thermoelectric particles are arranged in a π-type structure.

[0029] As a further improvement of the present invention, the heat sink and the upper substrate are cut into multiple unconnected strip structures according to the connection method of the thermoelectric particles.

[0030] Fourthly, this application provides a wearable device, including the aforementioned flexible thermoelectric device.

[0031] The embodiments of this application may include the following beneficial effects:

[0032] This invention achieves a tight connection between a thermally conductive pad and a flexible substrate using ultrasonic welding technology. This significantly reduces the contact thermal resistance between the external heat source surface and the f-TED (thermal conductive pad-tetrafluoroethylene ether) substrate, creating a highly efficient heat transfer channel. This, in turn, improves the adhesion to the external heat source surface and enhances the overall performance of the f-TED. A thermally conductive silicone pad is used as the heat-collecting material, and ultrasonic welding technology is employed to achieve a tight connection between the thermally conductive silicone pad and the flexible substrate. The resulting thermally conductive silicone pad laminate substrate significantly reduces the contact thermal resistance between the external heat source surface and the f-TED, creating a highly efficient heat transfer channel and improving the overall performance of the f-TED.

[0033] This application provides a flexible thermoelectric device using the aforementioned high thermal conductivity substrate, enabling the device to have dual functions of power generation and cooling, as well as wearability.

[0034] This application provides a wearable device including the aforementioned flexible thermoelectric device. Thermal management strategies can be adjusted as needed to provide users with personalized health management and a comfortable experience. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the fabrication of a high thermal conductivity substrate in one embodiment of this application;

[0036] Figure 2 This application describes the change in the thermal conductivity of the substrate during the exploration of a welding process according to one embodiment of the present application.

[0037] Figure 3 This is a microscopic morphology diagram of the welding interface according to an embodiment of this application;

[0038] Figure 4 This is a schematic diagram of a thermoelectric device structure according to an embodiment of this application;

[0039] Figure 5 This is a flexible thermoelectric device prepared according to one embodiment of this application;

[0040] Figure 6 This is a comparative performance test diagram of one embodiment of this application;

[0041] Figure 7 This is a physical image of a flexible human body thermoelectric device according to an embodiment of this application;

[0042] Figure 8 This is a diagram illustrating the cooling and heating performance of a flexible human body thermoelectric device according to an embodiment of this application. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0044] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0046] To better understand this application, the following embodiments further illustrate the content of this application, but the content of this application is not limited to the following embodiments.

[0047] Ultrasonic welding is a fast and efficient solid-state welding technology. Its principle involves transmitting mechanical vibrations at ultrasonic frequencies to the surface of the objects being welded, generating high-frequency friction between the material surfaces, thereby forming solid-phase bonds. Ultrasonic welding not only offers high processing speed but also exhibits high compatibility with a wide range of materials, requires no additional consumables, and significantly reduces production costs and environmental impact.

[0048] Firstly, such as Figure 1 As shown, this application provides a high thermal conductivity substrate, comprising:

[0049] The first layer is a thermal pad;

[0050] The second layer is a flexible substrate; the flexible substrate is ultrasonically welded to the thermal pad.

[0051] The third layer is a metal electrode layer; the metal electrode layer is formed by depositing metal electrodes on the flexible substrate and is used for welding thermoelectric particles.

[0052] The high thermal conductivity substrate provided in this application achieves efficient heat conduction through a three-layer structure design. First, the first layer, a thermally conductive silicone pad, possesses excellent thermal conductivity, enabling it to closely adhere to external heat sources and rapidly transfer heat to the substrate's interior. Second, the second layer, a flexible substrate, provides good flexibility and surface conformability, allowing the substrate to adapt to various complex surface shapes. Finally, the third layer, a metal electrode layer, is deposited on the flexible substrate via metal electrodes, providing not only a reliable substrate for the welding of thermoelectric particles but also further optimizing the heat conduction path.

[0053] Ultrasonic welding technology is key to achieving a tight bond between these three layers. This technology utilizes the mechanical vibrations of ultrasonic waves to generate high-frequency friction on the surfaces of the objects being welded, thereby achieving solid-phase bonding. This welding method is not only fast but also highly compatible with a variety of materials, requiring no additional consumables, significantly reducing production costs and environmental impact.

[0054] By combining a thermally conductive silicone pad and a metal electrode layer, a highly efficient heat transfer channel is constructed, significantly reducing contact thermal resistance. The flexible substrate allows the base plate to adapt to various curved shapes, improving the fit to the external heat source surface. Ultrasonic welding technology eliminates the need for additional consumables, reducing production costs and environmental impact. Ultrasonic welding technology achieves a tight connection between the thermally conductive silicone pad and the flexible base plate, significantly reducing contact thermal resistance, constructing a highly efficient heat transfer channel, and thus improving the fit to the external heat source surface.

[0055] As a specific example, this application develops a method for combining a high thermal conductivity heat collector and a flexible thermoelectric device via ultrasonic welding. The high thermal conductivity substrate comprises three parts, from top to bottom, namely, layers one, two, and three. The first layer is a thermally conductive silicone pad that can tightly adhere to an external heat source; the second layer is a flexible substrate, such as polyimide (PI), which allows the device to better fit curved surfaces; the third layer is a metal electrode deposited on the flexible substrate for welding thermoelectric particles.

[0056] As an example, the thermal pad is made of a high thermal conductivity silicone material, such as silicone, fluororubber, EPDM rubber, fluorosilicone rubber, etc. High thermal conductivity silicone is primarily composed of organosilicon compounds such as siloxanes and silanes, refined with the addition of high-quality thermally conductive materials, fillers, and other polymeric materials. This application uses existing high thermal conductivity silicone materials. High thermal conductivity silicone has excellent thermal conductivity, with a cured thermal conductivity typically between 1.1 and 1.3 W / (m·K), or even higher. This characteristic enables it to effectively transfer and disperse the heat generated by electronic devices, reducing the temperature of electronic components and ensuring the normal operation of the equipment.

[0057] As an example, the flexible substrate is a high-temperature resistant flexible material; a flexible substrate is a special material that can maintain its flexibility and mechanical strength in high-temperature environments. It is suitable for applications that require flexibility, high-temperature resistance, and specific electrical or thermal properties simultaneously. For example, the flexible substrate may be polyimide, polydimethylsiloxane, etc.

[0058] As an example, the metal electrode is made of materials such as Cu, Ni, or Au. It serves to conduct electricity.

[0059] In this application, the substrate fabrication process specifically includes the following steps:

[0060] First, the deposition of Cu electrodes on the surface of the flexible substrate is crucial. This process requires high-precision deposition techniques to ensure that the Cu electrodes adhere uniformly and stably to the surface of the flexible ceramic substrate. This deposition method has undergone repeated experiments and optimizations, resulting in Cu electrodes that not only possess excellent conductivity but also form a stable bond with the flexible ceramic substrate, laying a solid electrical foundation for subsequent thermoelectric device manufacturing processes.

[0061] Secondly, the core of this application lies in the innovative operation of ultrasonic welding between a thermally conductive silicone pad and a flexible substrate. In traditional thermoelectric device manufacturing, the connection methods often present various problems, such as loose connections and gaps, leading to low heat transfer efficiency. Advanced ultrasonic welding technology cleverly solves these problems. Ultrasonic welding technology is highly sophisticated, achieving an unprecedentedly tight connection between the thermally conductive silicone pad and the flexible substrate by precisely controlling parameters such as ultrasonic frequency, power, and welding time. This tight connection significantly reduces the contact thermal resistance between the external heat source and the flexible thermoelectric device. Compared to traditional connection methods, the contact thermal resistance can be reduced by more than 50%, thus creating a highly efficient heat transfer channel. In this channel, heat can be rapidly transferred from the external heat source to the flexible thermoelectric device with minimal loss, effectively improving the overall heat transfer efficiency and performance of the thermoelectric device, providing strong technical support for its application in a wider range of fields.

[0062] Furthermore, as a medium for transferring heat, the thermal conductivity of the thermal pad is crucial. High thermal conductivity silicone material should have a high thermal conductivity coefficient to ensure that heat can be quickly and effectively transferred from the heat source to the heat dissipation system. The thermal pad needs to be able to accommodate gaps between heat sources and heat dissipation systems of different shapes and sizes; therefore, high thermal conductivity silicone material should possess good flexibility to ensure a tight fit to the contact surface during installation and use.

[0063] Furthermore, ultrasonic welding is a method that uses high-frequency vibration to generate heat energy, thereby achieving material bonding. An ultrasonic generator converts mains power into high-frequency, high-voltage signals, which are then converted into high-frequency mechanical vibrations by a transducer. These high-frequency mechanical vibrations are transmitted through a welding head to the high thermal conductivity silicone material and the flexible substrate to be welded. In this process, the shape and size of the welding head are designed according to specific application requirements. Under the action of the welding head, high-speed friction occurs between the high thermal conductivity silicone material and the flexible substrate, causing the temperature to rise. When the temperature reaches the melting point of the material, the contact surface begins to melt. During the melting process, the welding head applies a certain pressure to tightly bond the molten material together. Subsequently, the welding head stops vibrating, but the pressure continues for a period of time to ensure that the molten material can fully cool and solidify. When the molten material has completely solidified, the welding process is complete. At this point, a strong bond has formed between the high thermal conductivity silicone material and the flexible substrate.

[0064] The flexible substrate and the thermal pad are ultrasonically welded together, with the ultrasonic welding parameters being: ultrasonic frequency 20-40kHz, ultrasonic amplitude 20-80%, and welding time 3-12s; preferably, ultrasonic frequency 30-40kHz, ultrasonic amplitude 40-80%, and welding time 5-12s. More preferably, ultrasonic frequency 20-30kHz, ultrasonic amplitude 20-60%, and welding time 3-10s; ultrasonic frequency 20kHz, ultrasonic amplitude 50%, and welding time 6s; ultrasonic frequency 30kHz, ultrasonic amplitude 40%, and welding time 8s; ultrasonic frequency 40kHz, ultrasonic amplitude 80%, and welding time 3s; ultrasonic frequency 35kHz, ultrasonic amplitude 40%, and welding time 12s; ultrasonic frequency 20kHz, ultrasonic amplitude 70%, and welding time 3s; ultrasonic frequency 25kHz, ultrasonic amplitude 60%, and welding time 10s, etc.

[0065] Based on the above scheme, a tight connection between the thermally conductive silicone pad and the flexible substrate was achieved by precisely controlling the ultrasonic welding parameters (such as ultrasonic frequency 20-40kHz, ultrasonic amplitude 20-80%, and welding time 3-12s). This tight connection reduces gaps at the joint, thus avoiding the problem of reduced heat transfer efficiency caused by loose connections. The tight connection also leads to a significant reduction in contact thermal resistance. Compared with traditional connection methods, contact thermal resistance can be reduced by more than 50%. This means that heat loss during the transfer process is greatly reduced, thereby improving the overall heat transfer efficiency of the thermoelectric device.

[0066] Furthermore, due to the reduced contact thermal resistance and tight connection, heat can be rapidly transferred from the external heat source to the flexible thermoelectric device with minimal loss. This not only improves heat transfer efficiency but also enhances the performance of the thermoelectric device, enabling it to play a role in a wider range of applications. The ultrasonic welding technology used in this application is innovative in the field of thermoelectric device manufacturing. By precisely controlling the welding parameters, an unprecedented tight connection effect is achieved, which is difficult to achieve in traditional thermoelectric device manufacturing. This technological innovation provides new ideas and solutions for the production and application of thermoelectric devices. The core advantages of connecting flexible substrates and thermally conductive silicone pads through ultrasonic welding are mainly reflected in tight connection, reduced contact thermal resistance, improved heat transfer efficiency and performance, technological innovation and uniqueness, and broad application prospects.

[0067] Another objective of this application is to provide a flexible thermoelectric device, primarily for use in wearable devices, employing the aforementioned thermally conductive silicone pad laminate substrate to improve the device's power generation and cooling performance. This application provides a flexible thermoelectric device comprising:

[0068] The lower substrate is a high thermal conductivity substrate as described above;

[0069] Thermoelectric particles; the thermoelectric particles are welded to the metal electrode layer of the lower substrate;

[0070] The upper substrate is used to connect the heat sink.

[0071] The flexible thermoelectric device uses the aforementioned high thermal conductivity substrate as the lower substrate, with thermoelectric particles welded onto the metal electrode layer to form a thermoelectric conversion unit. The upper substrate is used to connect a heat sink to dissipate the heat generated during the thermoelectric conversion process. When there is a temperature difference between the human body and the environment, the thermoelectric particles can convert the body's heat into electrical energy or use it for cooling, thereby achieving thermal management.

[0072] This device features dual power generation and cooling functions: thermoelectric particles can simultaneously achieve electrical energy conversion and cooling effects, meeting diverse human thermal management needs. It also boasts high flexibility and adaptability: the flexible design based on a high thermal conductivity substrate allows the device to adapt to various curved shapes of the human body, improving wearing comfort and thermal management effectiveness. Furthermore, it is wearable: the device is small and lightweight, easily integrated into wearable devices, providing users with a convenient thermal management experience.

[0073] The thermoelectric particle material is one or more of the following: Bi2Te3-based compounds, Ag2Q-based compounds, SnSe-based compounds, Mg2Si-based compounds, MgAgSb-based compounds, MgSiSn-based compounds, and Mg3Sb2-based compounds.

[0074] Bi2Te3-based compounds are currently the best-performing thermoelectric conversion materials near room temperature and are widely used in refrigeration applications. These materials are small, noiseless, long-lasting, and do not release harmful substances, making them environmentally friendly. They are also highly responsive, precise, and can be installed and operated at any angle without moving parts.

[0075] Ag₂Q (Q=S,Se,Te)-based compounds possess complex crystal structures, exhibiting high carrier mobility and low lattice thermal conductivity. This makes these materials potentially valuable for thermoelectric applications. Their thermoelectric properties can be further optimized through compositional adjustments and phase structure control.

[0076] SnSe-based compounds: SnSe-based crystalline materials possess high thermoelectric properties, are low in cost, and are abundant. They exhibit excellent performance in thermoelectric power generation and electronic refrigeration, showing great application potential. Compared to traditional thermoelectric materials, SnSe has better processability, facilitating device fabrication.

[0077] Mg₂Si-based compounds possess excellent thermoelectric properties: Mg₂Si is a high-performance thermoelectric material applicable in the temperature range of 500K~800K. Raw materials are abundant and inexpensive: its constituent elements are characterized by abundant and inexpensive raw materials.

[0078] MgAgSb-based compounds: High ZT values. MgAgSb-based materials exhibit high ZT values ​​near room temperature, filling the temperature gap between Bi2Te3 materials and materials in the mid-temperature range. With the cold end at room temperature and a temperature difference of 225 degrees Celsius, the conversion efficiency of a single-arm device reaches 8.5%.

[0079] MgSiSn-based compounds and others (such as Mg3Sb2-based compounds) have potential thermoelectric properties: These materials also have certain application potential in the thermoelectric field. Through further research and development, it is hoped that more excellent thermoelectric properties can be discovered.

[0080] Thirdly, this application provides a wearable device, including the aforementioned flexible thermoelectric device.

[0081] Wearable devices integrate the aforementioned flexible thermoelectric components, converting body heat into electrical energy or for cooling through thermoelectric conversion. These devices can monitor physiological indicators such as body temperature and heart rate in real time and adjust thermal management strategies as needed, providing users with personalized health management and a comfortable experience.

[0082] The wearable device prepared by the method described in this application integrates sensors and algorithms, enabling real-time monitoring and analysis of human physiological data to provide users with intelligent health management suggestions. The high flexibility and adaptability of the flexible thermoelectric device make the wearable device more comfortable, lightweight, and easy to wear and carry. Utilizing human body heat for thermoelectric conversion achieves sustainable energy use while reducing dependence on traditional energy sources and environmental pollution. It achieves multiple advantages such as efficient heat conduction, good fit, low cost and environmental friendliness, and intelligent health management, providing new solutions and technical support for the field of human thermal management.

[0083] The following specific embodiments illustrate the specific solutions of this application, but are not limited to these embodiments:

[0084] Example 1

[0085] The following is combined Figures 1 to 4 This application describes an embodiment of a high thermal conductivity substrate welded by ultrasonic welding.

[0086] This embodiment describes a high thermal conductivity substrate welded by ultrasonic welding, comprising a thermally conductive silicone pad 1, which effectively adheres to the surface of an external heat source and reduces contact thermal resistance; a polyimide substrate 2, used for depositing electrodes and providing a certain mechanical strength to the structure; and a copper electrode layer 3, prepared by deposition technology, used for welding thermoelectric particles to form a circuit.

[0087] The actual application process employs ultrasonic welding technology, with the following technical parameters: ultrasonic frequency 30kHz, ultrasonic amplitude 50%, and welding time 6s. The final product is a thermally conductive silicone pad-PI multilayer substrate.

[0088] A heating platform was used as the heat source, and thermocouples were used to monitor the surface temperature of the platform in real time to maintain it constant. Commercially available high-temperature tape was used to tightly fix the laminated substrate and the ceramic plate to minimize contact thermal resistance. During the test, the heating platform was preheated to 70°C, and then the ceramic plate with the laminated substrate was placed on the hot platform. An infrared thermal imager was used to record the change in the surface temperature of the laminated substrate over time. The resulting temperature-time curve is shown below. Figure 2 As shown, the surface temperatures of the PI thin film substrate and the un-ultrasonically welded multilayer substrate rise slowly with increasing heating time, reaching only 55.3℃ and 59.2℃ respectively after 300 s of heating. However, the heating rate of the multilayer substrate after ultrasonic welding is significantly improved. With the extension of welding time, the heat transfer rate of the multilayer substrate first increases and then decreases, reaching its maximum at a welding time of 6 s, where it can reach the highest temperature (63.3℃).

[0089] Figure 3The interface morphology between the thermally conductive silicone pad and the PI substrate, connected by two methods—traditional thermally conductive adhesive bonding and ultrasonic welding—was observed using SEM. The images show that the interface of the thermally conductive adhesive bonding method has many pores, which increase the interfacial thermal resistance and thus affect device performance. In contrast, the ultrasonically welded substrate exhibits a well-bonded cross-section with no obvious pores, demonstrating the advantages of this method.

[0090] Example 2

[0091] The following is combined Figures 4 to 8 This application describes a flexible thermoelectric device with a high thermal conductivity substrate according to an embodiment of the present application.

[0092] This application employs a "rigid material (thermoelectric material) - flexible connection" method to fabricate devices such as... Figure 5 As shown. For example, thermoelectric particles employ high-performance P-type Bi... 0.5 Sb 1.5 Te3 and N-type Bi2Se 0.3 Te 2.7 The material, P / N type thermoelectric particles, has a cross-sectional area of ​​1 × 1 mm. 2 The height is 5 mm. The lower substrate of the thermoelectric device is the thermally conductive silicone pad-PI laminate substrate prepared in Example 1, and the upper substrate is a PI film with electroplated copper foil, which facilitates the connection of the heat sink. The heat sink is made of foamed copper with a height of 5 mm and a porosity per inch (ppi) of 40. SnBi solder paste is used to connect the foamed copper to TED by high-temperature soldering. Then, the heat sink and the upper substrate are cut as a whole along the top electrode to ensure that the device has good flexibility.

[0093] To further verify the specific impact of the thermally conductive silicone pad-PI multilayer substrate prepared by ultrasonic welding technology on device performance, two devices were fabricated: a TED device using an ultrasonically welded thermally conductive silicone pad-PI multilayer substrate as the lower substrate, and a TED device using a PI film as the lower substrate. The output performance of the two devices was compared under constant temperature difference conditions. Figure 3 As shown.

[0094] Figure 3 The results show the relationship between output voltage (Voc) and output power (P) and current (I) for two different TEDs within a temperature difference (ΔT) range of 10 K to 25 K when the cold junction temperature is fixed at 25°C.

[0095] Figure 3In the figures, "Silicon pad" refers to a silicon pad; "PI film" refers to a PI film; "Gap" refers to a gap; "Pore" refers to a pore; "Bonding" refers to adhesion; and "Few pores" refers to a low-pore state. These terms describe the different states and characteristics between the silicon pad and the PI film shown in the figures. Figure i shows the gap between the silicon pad and the PI film, Figure ii shows the formation of pores, Figure iii shows the state with fewer pores, and Figure iv shows the adhesion between the silicon pad and the PI film. These images may be used to illustrate the microstructural changes of a material or structure at different processing stages.

[0096] Comparing the output performance of devices with two different substrates, it can be seen that the trends of output performance are consistent. However, the output voltage and output power of the device using the ultrasonically welded thermally conductive silicone pad-PI stacked substrate as the lower substrate are significantly better than those using the PI film as the lower substrate. Furthermore, the maximum output power P increases with the increase of temperature difference ΔT.

[0097] Figure 4 The image shows a cross-section of a flexible thermoelectric device, with different colors representing different materials and structural features.

[0098] Skin, PI film (polyimide film), a high-performance insulating material with good heat resistance and mechanical strength, used as a flexible substrate. Copper foam, a porous copper material that provides good electrical conductivity and heat dissipation while reducing weight. Copper, a common conductive material used to make circuits and wires. TE legs, the pins of a thermoelectric module used for thermoelectric conversion or heat dissipation. Tin paste, a tin-based alloy paste used for soldering in surface mount technology (SMT) for electronic components.

[0099] These materials and structural features together constitute a complex electronic component, in which copper foam and copper layers are used for heat dissipation and conductivity, polyimide film provides insulation, surface layer is used to improve electromagnetic compatibility, and solder paste is used for soldering and connection.

[0100] See Figure 4 The thermoelectric particles are arranged in a π-type structure. The heat sink is cut into multiple unconnected strip structures according to the connection method of the thermoelectric particles.

[0101] π-type thermoelectric particles exhibit highly efficient heat flow propagation. The π-type module features heat flow perpendicular to the substrate plane and propagating along the height of the thermoelectric material. This structure best utilizes the performance of thermoelectric materials and is particularly suitable for the operating conditions of various flat-plate heat sources. Within the π-type module, the heat flow distribution is uniform, making it the optimal thermoelectric unit structure for achieving unidirectional heat flow propagation. This maximizes the material properties and thus maximizes thermoelectric energy conversion efficiency.

[0102] Furthermore, the π-type structure connects the p-type thermoelectric leg and the n-type thermoelectric leg in series via metal electrodes, forming a stable thermoelectric conversion unit. This structure maintains good stability during thermoelectric conversion, which is beneficial for improving the reliability and lifespan of thermoelectric devices.

[0103] The strip structure of a heatsink improves heat dissipation efficiency. The heatsink is cut into multiple unconnected strips based on the π-type connection of thermoelectric particles. This design increases the heat dissipation area and improves efficiency. Multiple strips can form heat dissipation channels, facilitating rapid heat dissipation, thereby reducing the operating temperature of the thermoelectric particles and improving thermoelectric conversion efficiency. Because π-type thermoelectric devices have different temperatures at their hot and cold ends during operation, the different degrees of thermal expansion at both ends of the thermoelectric material can easily lead to significant stress within the device. However, by adopting a strip structure in the heatsink, the coefficient of thermal expansion can be optimized by adjusting the size and layout of the strips, thereby reducing the impact of thermal stress on the device and improving its reliability.

[0104] Furthermore, the strip-shaped structure of the heat sink simplifies the manufacturing process. For example, advanced technologies such as laser cutting can be used to precisely process the heat sink, improving processing efficiency and accuracy. This structure also facilitates subsequent assembly and testing. Based on a flexible substrate and a strip-shaped heat sink, flexible thermoelectric devices possess certain flexibility characteristics, enabling their use in wearable devices, especially in uneven environments.

[0105] Furthermore, by optimizing the π-type structure of the thermoelectric particles and the strip-type structure of the heat sink, the thermoelectric conversion efficiency can be further improved. This not only improves energy utilization efficiency but also reduces energy consumption and environmental pollution. By reducing thermal stress and optimizing heat dissipation performance, the reliability of thermoelectric devices can be enhanced. This is beneficial for improving the service life and stability of thermoelectric devices and reducing maintenance costs. These advantages make this solution a promising candidate for application in the field of thermoelectric conversion.

[0106] Furthermore, this application designs a wearable system with self-powered and temperature-adaptive functions. This system consists of the device fabricated in Example 1, a control circuit board, and a mobile terminal. It has three modes: cooling, heating, and energy harvesting. After selecting the desired mode, the input current value and direction can be automatically adjusted on the mobile app (application) according to needs, achieving personalized temperature control and ensuring the user is in a comfortable state when feeling hot or cold. Figure 6 As shown.

[0107] This application tests the system's dynamic thermal management capabilities under fixed environmental conditions. First, at an ambient temperature of 28.8°C, the system was switched to cooling mode. Using an app, the current was gradually increased from 0.1 A to 0.3 A, resulting in a decrease in skin temperature (Tskin) from an initial 34.3°C to 27.1°C, achieving a temperature drop of 7.2°C. Then, at a relatively lower ambient temperature (22°C), the system was switched to heating mode, and a current ranging from 0.1 A to 0.3 A was applied. Tskin temperature increased from 31.1°C to 40.5°C. This demonstrates that the system can be set with different target temperatures to meet the personalized comfort temperature needs of different individuals. Figure 4 The device also demonstrated its long-term cooling capability. After a 0.3 A current was applied, the temperature immediately dropped by about 5.1 °C and remained stable for up to 6 hours until it was turned off. During this period, the temperature only rose slightly by about 1.2 °C, indicating that the wearable system of this application has good stability and durability, which is sufficient to support long-term use.

[0108] Example 3

[0109] A high thermal conductivity substrate, a flexible thermoelectric device, and a wearable device are described below:

[0110] 1) Thermoelectric cooling devices are fabricated using MgAgSb-based thermoelectric materials and Bi2Te3-based thermoelectric materials, wherein the thermoelectric particles are p-type α-MgAg 0.97 Sb 0.99 The material is n-type Ag2Se, the electrode is Ag, the solder is SnSb solder, the substrate material is PDMS, and the flexible substrate is a thermally conductive silicone pad.

[0111] 2) Wear the device on the injured area. The thermoelectric cooling device uses electrical energy to generate a temperature difference. The cold end comes into contact with the skin, causing it to undergo forced heat exchange, thereby achieving the purpose of cooling and cold compress.

[0112] 3) By changing the current, the temperature range can be controlled. At the same time, the COP of the TEC can be further improved by optimizing the structural design for a specified power.

[0113] Example 4

[0114] A high thermal conductivity substrate, a flexible thermoelectric device, and a wearable device are described below:

[0115] 1) Thermoelectric cooling devices are fabricated using MgAgSb-based thermoelectric materials and Bi2Te3-based thermoelectric materials, wherein the thermoelectric particles are p-type SnSe and n-type Bi2Te. 2.7 Se 0.3 The electrode is Cu, the solder is SAC305 solder, the substrate material is polyimide, and the flexible substrate is a thermally conductive rubber pad.

[0116] 2) The device is worn on joints and acupoints in traditional Chinese medicine. The thermoelectric cooling device uses electrical energy to generate a temperature difference. The hot end comes into contact with the skin to force heat exchange, so as to achieve the purpose of hot compress and blood circulation.

[0117] 3) By changing the current, the temperature range can be controlled. At the same time, the COP of the TEC can be further improved by optimizing the structural design for a specified power.

[0118] Many embodiments and applications beyond the examples provided will be apparent to those skilled in the art upon reading the foregoing description. Therefore, the scope of this teaching should not be determined by reference to the foregoing description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

[0119] The above content provides a further detailed description of this application and should not be construed as limiting the specific implementation of this application to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of this application, and all such deductions or substitutions should be considered as falling within the scope of protection defined by the submitted claims.

Claims

1. A high thermal conductivity substrate for use in flexible thermoelectric devices, characterized in that, include: Thermal pad, wherein the thermal pad is made of high thermal conductivity silicone material; A flexible substrate, which is ultrasonically welded to the thermal pad; the flexible substrate is a high-temperature resistant flexible material. A metal electrode layer, formed by metal electrode deposition on the flexible substrate, is used for welding thermoelectric particles; The thermal pad, flexible substrate and metal electrode layer are stacked sequentially from bottom to top. The flexible substrate is selected from polyimide or polydimethylsiloxane; The flexible substrate and the thermal pad are ultrasonically welded together to form a solid-phase bonding interface without obvious pores, wherein the ultrasonic welding parameters are: Ultrasonic frequency 20-40kHz, ultrasonic amplitude 20-80%, welding time 3-12s.

2. The high thermal conductivity substrate according to claim 1, characterized in that, The metal electrode is Cu, Ni, or Au.

3. A method for preparing a high thermal conductivity substrate according to claim 1, characterized in that, include: First, a metal electrode layer is deposited on the surface of the flexible substrate; Then, the thermal pad is ultrasonically welded to the flexible substrate.

4. A flexible thermoelectric device, characterized in that, include: The lower substrate is a high thermal conductivity substrate as described in claim 1; Thermoelectric particles; The thermoelectric particles are welded onto the metal electrode layer of the lower substrate; The upper substrate, mounted on the thermoelectric particles, is used to connect the heat sink.

5. A flexible thermoelectric device according to claim 4, characterized in that, The thermoelectric particle material is one or more of the following: Bi2Te3-based compounds, Ag2Q-based compounds, SnSe-based compounds, Mg2Si-based compounds, MgAgSb-based compounds, MgSiSn-based compounds, and Mg3Sb2-based compounds.

6. A flexible thermoelectric device according to claim 4, characterized in that, The thermoelectric particles are selected from P-type Bi. 0.5 Sb 1.5 Te3 and N-type Bi2Se 0.3 Te 2.7 Materials, p-type α-MgAg 0.97 Sb 0.99 and n-type Ag2Se, p-type SnSe and n-type Bi2Te 2.7 Se 0.3 .

7. A flexible thermoelectric device according to claim 4, characterized in that, The heat sink is made of foamed copper with 40-60 pores per inch, and is connected to the substrate by high-temperature soldering using solder paste.

8. A flexible thermoelectric device according to claim 4, characterized in that, The thermoelectric particles are arranged in a π-type structure.

9. A flexible thermoelectric device according to claim 4, characterized in that, The heat sink and the upper substrate are cut into multiple unconnected strip structures according to the connection method of the thermoelectric particles.

10. A wearable device, characterized in that, Includes a flexible thermoelectric device as described in any one of claims 4 to 9.

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