High-heat-conductivity substrate, flexible thermoelectric device and wearable equipment

Abstract

The invention discloses a high-heat-conductivity substrate, a flexible thermoelectric device and wearable equipment. Relates to the field of thermoelectric devices, in particular to a high-heat-conduction substrate which comprises a first layer, a second layer and a third layer from top to bottom. The first layer is a heat-conducting silica gel pad and can be tightly attached to an external heat source; the second layer is a flexible substrate, so that the device can be better attached to a curved surface; and the third layer is a metal electrode deposited on the flexible substrate and is used for welding thermoelectric particles. The high-heat-conductivity substrate is obtained through ultrasonic welding, and an efficient heat transfer channel is constructed, so that the fitting degree with the surface of an external heat source is improved, and the comprehensive performance of f-TED is improved.

Description

Technical Field

[0001] The present application relates to the field of thermoelectric devices, and in particular to a high thermal conductivity substrate, a flexible thermoelectric device and a wearable device. Background Art

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

[0003] There are three main ways to achieve the flexibility of wearable f-TED. The first is to use flexible thermoelectric materials to manufacture f-TED. Although these materials show excellent intrinsic flexibility, their relatively low ZT value (thermoelectric figure of merit) often limits the overall performance of f-TED. The second is to design a thin-film f-TED, which has excellent compatibility with wearable applications, but its performance is limited by the small effective temperature difference, which affects its effectiveness in practical applications. The third is to use rigid thermoelectric materials with excellent connection performance on flexible substrates. This method not only retains the high performance of thermoelectric materials, but also gives f-TED good flexibility, achieving dual optimization of performance and flexibility.

[0004] However, the thermal conductivity and wearing comfort of many candidate flexible substrate materials are poor. Due to the complex curved surface morphology and heat source distribution of the external heat source surface, it is difficult for f-TED made of traditional flexible substrates to achieve perfect fit with the external heat source surface, resulting in the generation of air gaps, which in turn causes significant contact thermal resistance. There is a large amount of heat loss in the process of heat transfer from the external heat source to the device, which affects the overall performance of the device. Thermal conductive silicone pads have good thermal conductivity and flexibility, can easily adapt to surfaces of different shapes and sizes, and achieve tight fit, but their mechanical properties are poor and their texture is soft. They cannot be used directly as substrate materials, but can be used as thermal interface materials to optimize thermal conductivity.

[0005] Therefore, the thermally conductive silicone pad can be connected to the flexible substrate to produce a laminated substrate, which combines the high thermal conductivity and skin-fitting properties of the thermally conductive silicone pad with the good mechanical strength and stability of the flexible substrate. This complementary performance not only gives the laminated substrate excellent thermal conductivity, but also ensures that it has external heat source surface fit, strength and long-term stability in complex application environments, and can meet the needs of various complex application scenarios.

[0006] Traditional connection methods, such as gluing, are simple, but are prone to aging and falling off after long-term use, affecting the stability and reliability of the connection. Summary of the invention

[0007] This application aims to solve the problems of low thermal conductivity and poor surface adhesion of traditional flexible substrates. In view of the above existing problems, a high thermal conductivity substrate, a flexible thermoelectric device and a wearable device are proposed. This application obtains a high thermal conductivity substrate through ultrasonic welding, constructs an efficient heat transfer channel, thereby improving the adhesion with the surface of the external heat source and improving the comprehensive performance of f-TED.

[0008] To achieve the above objectives, this application adopts the following technical solutions: In a first aspect, the present application provides a high thermal conductivity substrate, comprising: The first layer is a thermal pad; the thermal pad is made of high thermal conductivity silicone material; The second layer is a flexible substrate; the flexible substrate is connected to the thermal pad by ultrasonic welding; the flexible substrate is a high temperature resistant flexible material; The third layer is a metal electrode layer; the metal electrode layer is formed by depositing a metal electrode on the flexible substrate and is used for welding thermoelectric particles; wherein the thermal pad, the flexible substrate and the metal electrode layer are stacked in sequence from bottom to top.

[0009] As a further improvement of the present invention, the thermally conductive pad is selected from silicone rubber, fluororubber, EPDM rubber or fluorosilicone rubber.

[0010] As a further improvement of the present invention, the flexible substrate is selected from polyimide or polydimethylsiloxane.

[0011] As a further improvement of the present invention, the metal electrode is Cu, Ni or Au.

[0012] In a second aspect, the present invention provides a method for preparing a high thermal conductivity substrate, comprising: First, a metal electrode layer is deposited on the surface of the flexible substrate; The thermal conductive pad is then ultrasonically welded to the flexible substrate.

[0013] As a further improvement of the present invention, the flexible substrate is connected to the thermal pad by ultrasonic welding, wherein the ultrasonic welding parameters are: Ultrasonic frequency is 20-40kHz, ultrasonic amplitude is 20-80%, and welding time is 3-12s.

[0014] In a third aspect, the present application provides a flexible thermoelectric device, comprising: The lower substrate adopts the high thermal conductivity substrate mentioned above; Thermoelectric particles; the thermoelectric particles are welded on the metal electrode layer of the lower substrate; Upper base plate, used to connect the heat sink.

[0015] 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.

[0016] 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 Material, 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 .

[0017] As a further improvement of the present invention, the heat sink is a foam copper with 40-60 pores per inch, and is connected to the substrate by high-temperature soldering using solder paste.

[0018] As a further improvement of the present invention, the thermoelectric particles are arranged in a π-type structure.

[0019] As a further improvement of the present invention, the heat sink and the upper substrate are cut into a plurality of unconnected strip structures according to the connection method of the thermoelectric particles.

[0020] In a fourth aspect, the present application provides a wearable device, comprising the flexible thermoelectric device described above.

[0021] The embodiments of the present application may have the following beneficial effects: The present invention realizes a close connection between the thermal pad and the flexible substrate through ultrasonic welding technology, significantly reduces the contact thermal resistance between the surface of the external heat source and the f-TED, constructs an efficient heat transfer channel, thereby improving the fit with the surface of the external heat source, and improving the comprehensive performance of the f-TED. The thermally conductive silicone pad is used as a heat collecting material, and with the help of ultrasonic welding technology, a close connection between the thermally conductive silicone pad and the flexible substrate is achieved. The thermally conductive silicone pad laminate substrate prepared in this way significantly reduces the contact thermal resistance between the surface of the external heat source and the f-TED, constructs an efficient heat transfer channel, and improves the comprehensive performance of the f-TED.

[0022] The present application provides a flexible thermoelectric device, which adopts the high thermal conductivity substrate; so that the device has the dual functions of power generation and refrigeration and is wearable.

[0023] The present application provides a wearable device, including the flexible thermoelectric device, which can adjust the thermal management strategy as needed to provide users with personalized health management and comfortable experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of the preparation of a high thermal conductivity substrate in an embodiment of the present application; Figure 2 is a change in thermal conductivity of a substrate during a welding process exploration process of an embodiment of the present application; Figure 3 This is a microscopic morphology diagram of a welding interface in an embodiment of the present application; Figure 4 This is a schematic diagram of the structure of a thermoelectric device according to an embodiment of the present application; Figure 5 It is a flexible thermoelectric device prepared in one embodiment of the present application; Figure 6 This is a comparative performance test diagram of an embodiment of the present application; Figure 7 This is a physical picture of a flexible human body thermoelectric device according to an embodiment of the present application; Figure 8 This is a cooling and heating performance diagram of a flexible human body thermoelectric device according to an embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0026] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0028] In order to better understand the present application, the content of the present application is further explained below in conjunction with the embodiments, but the content of the present application is not limited to the following embodiments.

[0029] Ultrasonic welding is a fast and effective solid-state welding technology. Its principle is to transmit mechanical vibrations of ultrasonic frequency to the surface of the object to be welded, generate high-frequency friction between the material surfaces, and thus form a solid phase bond. The ultrasonic welding method not only has a fast processing speed, but also shows a high degree of compatibility with a variety of materials, does not require additional consumables, and significantly reduces production costs and environmental burdens.

[0030] First, as Figure 1 As shown, the present application provides a high thermal conductivity substrate, comprising: The first layer is the thermal pad; The second layer is a flexible substrate; the flexible substrate is connected to the thermal pad by ultrasonic welding; The third layer is a metal electrode layer; the metal electrode layer is formed by depositing a metal electrode on the flexible substrate and is used for welding thermoelectric particles.

[0031] The high thermal conductivity substrate provided by the present application realizes efficient heat conduction through a three-layer structural design. First, the first layer of thermal conductive silicone pad has excellent thermal conductivity, can fit tightly to the external heat source, and quickly transfer heat to the inside of the substrate. Secondly, the second layer of flexible substrate provides good flexibility and curved surface fitting ability, so that the substrate can adapt to various complex surface shapes. Finally, the third layer of metal electrode layer is deposited on the flexible substrate through metal electrodes, which not only provides a reliable base for the welding of thermoelectric particles, but also further optimizes the heat conduction path.

[0032] Ultrasonic welding technology is the key to achieve the tight connection of these three layers. This technology uses mechanical vibrations at ultrasonic frequencies to generate high-frequency friction on the surface of the objects to be welded, thereby achieving solid-phase bonding. This welding method is not only fast in processing speed, but also highly compatible with a variety of materials, without the need for additional consumables, significantly reducing production costs and environmental burdens.

[0033] Through the cooperation of the thermally conductive silicone pad and the metal electrode layer, an efficient heat transfer channel is constructed, which significantly reduces the contact thermal resistance. The flexible substrate enables the substrate to adapt to various curved shapes and improves the fit of the external heat source surface. Ultrasonic welding technology does not require additional consumables, reducing production costs and environmental burden. With the help of ultrasonic welding technology, the thermally conductive silicone pad and the flexible substrate are tightly connected, which can significantly reduce the contact thermal resistance, construct an efficient heat transfer channel, and thus improve the fit of the external heat source surface.

[0034] As a specific example, this application has developed a method for combining a high thermal conductivity collector and a flexible thermoelectric device by ultrasonic welding. The high thermal conductivity substrate consists of three parts, namely, the first, second, and third layers from top to bottom. The first layer is a thermally conductive silicone pad that can fit tightly to the external heat source; the second layer is a flexible substrate that allows the device to better fit the curved surface, such as polyimide (PI); the third layer is a metal electrode deposited on the flexible substrate, which is used to weld thermoelectric particles.

[0035] As an example, the thermal pad is a high thermal conductivity silicone material, such as silicone, fluororubber, EPDM rubber, fluorosilicone rubber and other thermal conductive rubber pads. High thermal conductivity silicone is mainly made of organic silicon compounds such as siloxane and silane, and is refined with high-quality thermal conductive materials, fillers and other polymer materials. This application adopts existing high thermal conductivity silicone materials. High thermal conductivity silicone has excellent thermal conductivity. The thermal conductivity coefficient after curing is usually between 1.1~1.3W / (m·k), or even higher. This feature enables it to effectively transfer and disperse the heat generated by electronic equipment, reduce the temperature of electronic components, and ensure the normal operation of the equipment.

[0036] As an example, the flexible substrate is a high temperature resistant flexible material; the flexible substrate is a special material that can maintain its flexibility and mechanical strength in a high temperature environment. In applications where flexibility, high temperature resistance, and specific electrical or thermal properties need to be satisfied at the same time, for example, the flexible substrate is polyimide, polydimethylsiloxane, etc.

[0037] As an example, the metal electrode is Cu, Ni or Au, etc., which plays a role of conducting electricity.

[0038] In this application, the preparation process of the substrate specifically includes the following steps: First, the step of depositing Cu electrodes on the surface of the flexible substrate is crucial. This process requires the use of high-precision deposition technology to ensure that the Cu electrodes can be evenly and stably attached to the surface of the flexible substrate ceramic. This deposition method has been repeatedly experimented and optimized. The deposited Cu electrodes not only have good conductivity, but also form a stable bond with the flexible substrate ceramic, laying a solid electrical foundation for the subsequent thermoelectric device production process.

[0039] Secondly, the core of this application lies in the innovative operation of ultrasonic welding the thermally conductive silicone pad to the flexible substrate. In the production of traditional thermoelectric devices, there are often various problems in the connection between the two, such as loose connection and easy gaps, which leads to low heat transfer efficiency. With the help of advanced ultrasonic welding technology, these problems are cleverly solved. Ultrasonic welding technology has extremely high technical content in application. By precisely controlling parameters such as ultrasonic frequency, power and welding time, an unprecedented tight connection between the thermally conductive silicone pad and the flexible substrate is achieved. The effect of this tight connection is significant, which greatly reduces the contact thermal resistance between the external heat source and the flexible thermoelectric device. Compared with the traditional connection method, the contact thermal resistance can be reduced by more than 50%, thereby constructing an efficient heat transfer channel. In this heat transfer channel, heat can be quickly transferred from the external heat source to the flexible thermoelectric device with minimal loss, effectively improving the heat transfer efficiency and working performance of the entire thermoelectric device, and providing strong technical support for the application of thermoelectric devices in a wider range of fields.

[0040] Furthermore, as a medium for transferring heat, the thermal conductivity of the thermal pad is crucial. High thermal conductivity silicone materials 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 adapt to the gap between the heat source and the heat dissipation system of different shapes and sizes, so the high thermal conductivity silicone material should have good flexibility so that it can fit the contact surface tightly during installation and use.

[0041] Furthermore, ultrasonic welding is a method of connecting materials by using high-frequency vibration to generate heat energy. The ultrasonic generator converts the mains electricity into high-frequency and high-voltage signals, which are converted into high-frequency mechanical vibrations through the transducer. The high-frequency mechanical vibrations are transmitted to the high thermal conductivity silicone material and the flexible substrate to be welded through the welding head. In this process, the shape and size of the welding head are designed according to the specific application requirements. Under the action of the welding head, high-speed friction is generated 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 amount of pressure to make the molten materials fit tightly together. Subsequently, the welding head stops vibrating, but the pressure continues to be maintained for a period of time to ensure that the molten material can be fully cooled and solidified. When the molten material is completely solidified, the welding process is completed. At this time, a solid connection is formed between the high thermal conductivity silicone material and the flexible substrate.

[0042] The flexible substrate is ultrasonically welded to the thermal pad, wherein the ultrasonic welding parameters are: ultrasonic frequency 20-40kHz, ultrasonic amplitude 20-80%, welding time 3-12s; preferably, ultrasonic frequency 30-40kHz, ultrasonic amplitude 40-80%, welding time 5-12s. Preferably, ultrasonic frequency 20-30kHz, ultrasonic amplitude 20-60%, welding time 3-10s; ultrasonic frequency 20kHz, ultrasonic amplitude 50%, welding time 6s; ultrasonic frequency 30kHz, ultrasonic amplitude 40%, welding time 8s; ultrasonic frequency 40kHz, ultrasonic amplitude 80%, welding time 3s; ultrasonic frequency 35kHz, ultrasonic amplitude 40%, welding time 12s; ultrasonic frequency 20kHz, ultrasonic amplitude 70%, welding time 3s; ultrasonic frequency 25kHz, ultrasonic amplitude 60%, welding time 10s, etc.

[0043] Based on the above scheme, by precisely controlling the parameters of ultrasonic welding (such as ultrasonic frequency 20-40kHz, ultrasonic amplitude 20-80%, welding time 3-12s), a tight connection between the thermally conductive silicone pad and the flexible substrate is achieved. This tight connection reduces the gap at the connection, thereby avoiding the problem of reduced heat transfer efficiency due to loose connection. The tight connection brings about a significant reduction in contact thermal resistance. Compared with traditional connection methods, the contact thermal resistance can be reduced by more than 50%. This means that the loss of heat during the transfer process is greatly reduced, thereby improving the heat transfer efficiency of the entire thermoelectric device.

[0044] Furthermore, due to the reduction of contact thermal resistance and tight connectivity, heat can be quickly transferred from an external heat source to the flexible thermoelectric device with minimal loss. This not only improves the heat transfer efficiency, but also improves the working 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 production. By precisely controlling the welding parameters, an unprecedented tight connection effect is achieved, which is difficult to achieve in the production of traditional thermoelectric devices. This technological innovation provides new ideas and solutions for the production and application of thermoelectric devices. The core advantages of connecting the flexible substrate and the thermally conductive silicone pad by ultrasonic welding are mainly reflected in tight connectivity, reduced contact thermal resistance, improved heat transfer efficiency and working performance, technological innovation and uniqueness, and broad application prospects.

[0045] Another object of the present application is to propose a flexible thermoelectric device, which is mainly used in wearable devices for human body, and adopts the above-mentioned thermal conductive silicone pad laminate substrate to improve the power generation and cooling performance of the device. The present application provides a flexible thermoelectric device, including: The lower substrate adopts the high thermal conductivity substrate mentioned above; Thermoelectric particles; the thermoelectric particles are welded on the metal electrode layer of the lower substrate; Upper base plate, used to connect the heat sink.

[0046] The flexible thermoelectric device uses the above-mentioned high thermal conductivity substrate as the lower substrate, and the thermoelectric particles are welded on the metal electrode layer to form a thermoelectric conversion unit. The upper substrate is used to connect the heat sink to dissipate the heat generated during the thermoelectric conversion process in a timely manner. 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 realizing the thermal management function.

[0047] The device has the dual functions of power generation and cooling: thermoelectric particles can achieve power conversion and cooling effects at the same time, meeting the diverse needs of human thermal management. It is also highly flexible and adaptable: the flexible design based on the high thermal conductivity substrate enables the device to adapt to various curved shapes of the human body, improving wearing comfort and thermal management effects. And wearability: the device is small and light, easy to integrate into wearable devices, providing users with a convenient thermal management experience.

[0048] The thermoelectric particle material is one or more of Bi2Te3-based compounds, Ag2O-based compounds, SnSe-based compounds, Mg2Si-based compounds, MgAgSb-based compounds, MgSiSn-based compounds and Mg3Sb2-based compounds.

[0049] Among them, Bi2Te3-based compounds are currently the best thermoelectric conversion materials with the best performance near room temperature and are widely used in the field of refrigeration. This material is small in size, noiseless, long in life, does not release harmful substances, and is environmentally friendly. It is sensitive, highly accurate, can be installed and operated at any angle, and has no moving parts.

[0050] Ag2Q (Q=S,Se,Te) based compounds: complex crystal structure, high carrier mobility and low lattice thermal conductivity. This makes this material have potential application value in the field of thermoelectrics. Its thermoelectric performance can be further optimized by adjusting the composition and controlling the phase structure.

[0051] SnSe-based compounds: SnSe-based crystalline materials have high thermoelectric properties, low cost and abundant reserves. They perform well in thermoelectric power generation and electronic refrigeration and have great application potential. Compared with traditional thermoelectric materials, SnSe has better processability and is easy to manufacture devices.

[0052] Mg2Si-based compounds have excellent thermoelectric properties: Mg2Si is a thermoelectric material with excellent performance in the temperature range of 500K~800K. Abundant raw materials and low prices: Its constituent elements are characterized by abundant raw materials and low prices.

[0053] MgAgSb-based compounds: high ZT value, MgAgSb-based materials have a high ZT value near room temperature, filling the temperature gap between Bi2Te3 materials and medium temperature zone materials. When the cold end is room temperature and the temperature difference is 225 degrees Celsius, the conversion efficiency of a single-arm device reaches 8.5%.

[0054] MgSiSn-based compounds and others (such as Mg3Sb2-based compounds), potential thermoelectric properties: These materials also have certain application potential in the thermoelectric field. Through further research and development, more excellent thermoelectric properties are expected to be discovered.

[0055] In a third aspect, the present application provides a wearable device, comprising the flexible thermoelectric device described above.

[0056] Wearable devices integrate the above-mentioned flexible thermoelectric devices, which convert human body heat into electrical energy or use it for cooling through the principle of thermoelectric conversion. These devices can monitor physiological indicators such as human body temperature and heart rate in real time, and adjust thermal management strategies as needed to provide users with personalized health management and comfort experience.

[0057] The wearable device prepared by the method of the present application integrates sensors and algorithms, and the wearable device can monitor and analyze human physiological data in real time, providing users with intelligent health management suggestions. The high flexibility and adaptability of flexible thermoelectric devices make wearable devices more comfortable and lightweight, easy to wear and carry. The use of human body heat for thermoelectric conversion not only achieves sustainable energy utilization, but also reduces dependence on traditional energy and environmental pollution. It achieves multiple advantages such as efficient heat conduction, good fit, low-cost environmental protection, and intelligent health management, providing new solutions and technical support for the field of human thermal management.

[0058] The specific solutions of the present application are given below in combination with specific embodiments, which are certainly not limited to the following embodiments: Example 1 Combine the following Figures 1 to 4 , describing a high thermal conductivity substrate welded by ultrasonic welding in an embodiment of the present application.

[0059] The present embodiment is a high thermal conductivity substrate that is ultrasonically welded, comprising a thermally conductive silicone pad 1, which is effectively bonded to the surface of an external heat source to reduce contact thermal resistance; a polyimide substrate 2, which is used to deposit electrodes and provide a certain mechanical strength for the structure; and a copper electrode layer 3, which is prepared by deposition technology and is used to weld thermoelectric particles to form a loop.

[0060] The actual use process uses ultrasonic welding technology, and the technical parameters are as follows: ultrasonic frequency 30kHz, ultrasonic amplitude 50%, welding time 6s. Finally, a thermal conductive silicone pad-PI laminate substrate is obtained.

[0061] The heating platform is used as the heat source, and the surface temperature of the heating platform is monitored in real time by a thermocouple to keep it constant. The laminated substrate and the ceramic plate are tightly fixed with commercial high-temperature tape to minimize the contact thermal resistance. During the test, the heating platform is first preheated to 70°C, and then the ceramic sheet with the laminated substrate is placed on the hot platform. The surface temperature of the laminated substrate changes with time using an infrared thermal imager. The resulting temperature-time curve is shown in the figure below. Figure 2 As shown in the figure. The surface temperature of the PI film substrate and the laminated substrate without ultrasonic welding increases slowly with the extension of heating time, and the temperature only reaches 55.3℃ and 59.2℃ respectively after heating for 300 s. However, the heating rate of the laminated substrate after ultrasonic welding is significantly improved. With the extension of welding time, the heat transfer rate of the laminated substrate increases first and then decreases, and is the largest when the welding time is 6 s, and can reach the highest temperature (63.3℃).

[0062] Figure 3 The interface morphology between the thermal conductive silicone pad and the PI substrate connected by traditional thermal conductive adhesive and ultrasonic welding was observed by SEM. As can be seen from the figure, the interface bonded by thermal conductive adhesive has many holes, and the presence of these holes will increase the interface thermal resistance and thus affect the performance of the device. However, the cross section of the ultrasonically welded substrate is well bonded without obvious holes, which shows the advantages of this method.

[0063] Example 2 Combine the following Figures 4 to 8 , describing a flexible thermoelectric device with a high thermal conductivity substrate according to an embodiment of the present application.

[0064] This application adopts the method of "rigid material (thermoelectric material)-flexible connection" to prepare devices such as Figure 5 For example, the thermoelectric particles use high-performance P-type Bi 0.5 Sb 1.5 Te3 and N-type Bi2Se 0.3 Te 2.7 Material, cross-sectional area of ​​P / N type thermoelectric particles is 1×1 mm 2 , with a height of 5 mm. The lower substrate of the thermoelectric device is the thermal conductive silicone pad-PI laminate substrate prepared in Example 1, and the upper substrate is a PI film electroplated with copper foil, which is convenient for connecting to the radiator. The radiator uses a foam copper with a height of 5 mm and a pore number per inch (ppi) of 40. SnBi solder paste is used to connect the foam copper and TED by high-temperature welding, and then the radiator and the upper substrate are cut as a whole along the top electrode to ensure that the device has good flexibility.

[0065] In order to further verify the specific effect of the thermal conductive silicone pad-PI laminated substrate prepared by ultrasonic welding technology on the device performance, two devices were made respectively: TED using ultrasonic welded thermal conductive silicone pad-PI laminated substrate as the lower substrate, and TED using PI film as the lower substrate. The output performance of the two devices was compared under constant temperature difference conditions. Figure 3 shown.

[0066] Figure 3 The figure shows the relationship between the output voltage (Voc) and output power (P) of the two TEDs and the current (I) in the temperature difference (ΔT) range from 10 K to 25 K when the cold end temperature is fixed at 25°C.

[0067] Figure 3 In the figure, Silicon pad is silicon pad; PI film is PI film, Gap is gap; Pore is hole; Bonding is bonding; Few pore is few pores; these terms describe the different states and characteristics between the silicon pad and PI film shown in the figure. Figure i shows the gap between the silicon pad and the PI film, Figure ii shows the formation of holes, Figure iii shows the state with few holes, and Figure iv shows the bonding between the silicon pad and the PI film. These images may be used to show the microstructural changes of a certain material or structure at different processing stages.

[0068] Comparing the output performance of devices with two different substrates, it can be seen that the change trends of the output performance of the two are consistent, but the output voltage and output power of the TED using the ultrasonic welded thermal conductive silicone pad-PI laminate substrate as the lower substrate are significantly better than those of the TED using the PI film as the lower substrate, and the maximum output power P increases with the increase of the temperature difference ΔT.

[0069] Figure 4 A cross-section of a flexible thermoelectric device is shown, with different colors representing different materials and structural features.

[0070] Skin, PI 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, refers to the pins of a thermoelectric module, used for thermoelectric conversion or heat dissipation. Tin paste, a tin-based alloy paste used for soldering, used in surface mount technology (SMT) of electronic components.

[0071] These materials and structural features together form a complex electronic component, in which copper foam and copper layer 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.

[0072] See also Figure 4 The thermoelectric particles are arranged in a π-shaped structure. The heat sink is cut into a plurality of unconnected strip structures according to the connection mode of the thermoelectric particles.

[0073] The π-type structure thermoelectric particles have efficient heat flow transmission. The π-type module has the characteristics that the heat flow direction is perpendicular to the substrate plane and propagates along the height direction of the thermoelectric material. This structure can best exert the performance of thermoelectric materials and is particularly suitable for the working conditions of various flat-plate heat sources. In the π-type module, the heat flow is evenly distributed, which is the best thermoelectric unit structure to achieve unidirectional heat flow transmission, which can maximize the material properties and thus maximize the thermoelectric energy conversion efficiency.

[0074] In addition, the π-type structure connects the p-type thermoelectric single leg and the n-type thermoelectric single leg in series through a metal electrode to form a stable thermoelectric conversion unit. This structure can maintain good stability during the thermoelectric conversion process, which is beneficial to improving the reliability and service life of thermoelectric devices.

[0075] The strip structure of the heat sink can improve the heat dissipation efficiency. The heat sink is cut into multiple unconnected strip structures according to the π-type connection method of the thermoelectric particles. This design can increase the heat dissipation area and improve the heat dissipation efficiency. A heat dissipation channel can be formed between the multiple strip structures, which is conducive to the rapid dissipation of heat, thereby reducing the working temperature of the thermoelectric particles and improving the thermoelectric conversion efficiency. Since the temperatures of the hot and cold ends of the π-type thermoelectric device are different during operation, the degree of thermal expansion at both ends of the thermoelectric material is different, which can easily form a large stress in the device. After the heat sink adopts a strip structure, the thermal expansion coefficient can be optimized by adjusting the size and layout of the strip structure, thereby reducing the impact of thermal stress on the device and improving the reliability of the device.

[0076] In addition, the strip-shaped structure of the heat sink can simplify the preparation process. For example, advanced technologies such as laser cutting can be used to accurately process the heat sink to improve processing efficiency and accuracy. At the same time, this structure is also conducive to subsequent assembly and testing. Based on a flexible substrate and a strip-shaped heat sink, the flexible thermoelectric device has certain flexibility and can also be used on wearable devices, especially for applications in uneven environments.

[0077] Furthermore, by optimizing the π-shaped structure of the thermoelectric particles and the strip-shaped structure of the heat sink, the thermoelectric conversion efficiency can be further improved. This can not only improve energy utilization efficiency, but also reduce energy consumption and environmental pollution. By reducing thermal stress and optimizing heat dissipation performance, the reliability of thermoelectric devices can be enhanced. This is conducive to improving the service life and stability of thermoelectric devices and reducing maintenance costs. These advantages make this solution have broad application prospects in the field of thermoelectric conversion.

[0078] Furthermore, the present application designs a wearable system with self-powered and temperature adaptive functions, which is composed of the device prepared in Example 1, a control circuit board and a mobile phone terminal, and has three modes: cooling, heating and energy collection. After selecting the required mode, the value and direction of the input current can be automatically adjusted according to the needs on the mobile phone APP (application), so as to realize personalized temperature control, so that the user is in a comfortable state when feeling hot or cold, such as Figure 6 shown.

[0079] This application tests the dynamic thermal management capabilities of the system in a fixed environment. First, at an ambient temperature of 28.8°C, the system was adjusted to cooling mode for cooling, and the app was used to adjust the current from 0.1 A to 0.3 A. The skin temperature (Tskin) dropped from the initial 34.3°C to 27.1°C, achieving a temperature drop of 7.2°C; At a relatively low ambient temperature (22°C), the system was adjusted to heating mode, and a current of 0.1 A to 0.3 A was passed, and Tskin increased from 31.1°C to 40.5°C, indicating that the system of this application can set different target temperatures to meet the personalized needs of different individuals for comfortable temperatures. 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 there for up to 6 hours until it was turned off. During this period, it only rose slightly by about 1.2°C. This shows that the wearable system of the present application has good stability and durability, sufficient to support long-term use.

[0080] Example 3 A high thermal conductivity substrate, a flexible thermoelectric device and a wearable device, specifically as follows: 1) Thermoelectric cooling devices are made using MgAgSb-based thermoelectric materials and Bi2Te3-based thermoelectric materials, in which the thermoelectric particles are p-type α-MgAg 0.97 Sb 0.99 and 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; 2) Wear the device on the injured part. The thermoelectric cooling device uses electrical energy to generate a temperature difference. The cold end contacts the skin, forcing it to exchange heat and achieve the purpose of cooling and cold compress. 3) By changing the current, the temperature variation range can be controlled. At the same time, the COP of the TEC can be further improved by optimizing the structural design of the TEC for a specified power to enhance the cooling effect.

[0081] Example 4 A high thermal conductivity substrate, a flexible thermoelectric device and a wearable device, specifically as follows: 1) Thermoelectric cooling devices are made using MgAgSb-based thermoelectric materials and Bi2Te3-based thermoelectric materials, where 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; 2) Wear the device on joints and TCM acupuncture points. The thermoelectric cooling device uses electrical energy to generate temperature difference. The hot end contacts the skin, forcing heat exchange to achieve the purpose of hot compress and blood circulation. 3) By changing the current, the temperature variation 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 to enhance the heating effect.

[0082] Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the preceding claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a disclaimer of such subject matter, nor should it be considered that the applicants did not consider such subject matter to be part of the disclosed inventive subject matter.

[0083] The above content is a further detailed description of the present application. It cannot be determined that the specific implementation methods of the present application are limited to these. For ordinary technicians in the technical field to which the present application belongs, they can make several simple deductions or substitutions without departing from the concept of the present application, which should be deemed to belong to the scope of protection determined by the submitted claims of the present application.

Claims

1. A high thermal conductivity substrate for a flexible thermoelectric device, characterized in that: include: Thermally conductive pad, the thermally conductive pad is made of high thermal conductivity silicone material; A flexible substrate, wherein the flexible substrate is connected to the thermal pad by ultrasonic welding; the flexible substrate is a high temperature resistant flexible material; A metal electrode layer, which is formed by depositing a metal electrode on the flexible substrate and is used for welding thermoelectric particles; The thermal pad, the flexible substrate and the metal electrode layer are stacked in sequence from bottom to top.

2. A high thermal conductivity substrate according to claim 1, characterized in that: The thermal pad is selected from silica gel, fluororubber, EPDM rubber or fluorosilicone rubber.

3. The high thermal conductivity substrate according to claim 1, characterized in that: The flexible substrate is selected from polyimide or polydimethylsiloxane.

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

5. 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; The thermal conductive pad is then ultrasonically welded to the flexible substrate.

6. The method for preparing a high thermal conductivity substrate according to claim 5, characterized in that: The flexible substrate is connected to the thermal pad by ultrasonic welding, wherein the ultrasonic welding parameters are: Ultrasonic frequency is 20-40kHz, ultrasonic amplitude is 20-80%, and welding time is 3-12s.

7. A flexible thermoelectric device, characterized in that: include: The lower substrate is a high thermal conductivity substrate as claimed in claim 1; Thermoelectric particles; The thermoelectric particles are welded on the metal electrode layer of the lower substrate; The upper substrate is arranged on the thermoelectric particles and is used for connecting to the heat sink.

8. The flexible thermoelectric device according to claim 7, characterized in that: The thermoelectric particle material is one or more of Bi2Te3-based compounds, Ag2O-based compounds, SnSe-based compounds, Mg2Si-based compounds, MgAgSb-based compounds, MgSiSn-based compounds and Mg3Sb2-based compounds.

9. The flexible thermoelectric device according to claim 7, 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 Material, 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 .

10. The flexible thermoelectric device according to claim 7, characterized in that: The heat sink is a foam copper with 40-60 pores per inch, and is connected to the substrate by high-temperature soldering using solder paste.

11. The flexible thermoelectric device according to claim 7, characterized in that: The thermoelectric particles are arranged in a π-type structure.

12. The flexible thermoelectric device according to claim 7, characterized in that: The heat sink and the upper substrate are cut into a plurality of unconnected strip structures according to the connection mode of the thermoelectric particles.

13. A wearable device, characterized in that: A flexible thermoelectric device comprising any one of claims 7 to 10.

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