Rigid-supported flexible semiconductor refrigeration device and preparation method and application thereof

Abstract

The invention discloses a rigidly-supported flexible semiconductor refrigeration device and a preparation method and application thereof, and belongs to the technical field of wearable electronic products. The device comprises a flexible substrate and a plurality of flexible refrigeration units, and each unit is composed of an interconnection electrode, a thermoelectric pair and a selective packaging layer. According to the invention, after the low-thermal-conductivity rigid packaging material is embedded into the thermoelectric pair, the flexible packaging material is integrally embedded into the thermoelectric pair, so that a rigid support-flexible interconnection composite structure is formed, and collaborative optimization of high-efficiency heat dissipation at a high-temperature end and heat insulation and cold insulation at a low-temperature end is realized. The selective packaging layer is constructed by adopting a template solvent method or a foaming method, and then thermal compression welding assembly is combined. The structure has high flexibility, high reliability and efficient refrigeration performance.

Description

Technical Field

[0001] This invention belongs to the field of wearable electronic product technology, and particularly relates to a rigid-supported flexible semiconductor cooling device, its preparation method and application. Background Technology

[0002] Thermoelectric technology achieves solid-state energy conversion based on the Seebeck and Peltier effects. With its lack of moving parts, high operational reliability, and precise temperature control, it has achieved long-term large-scale application in fields such as specialized refrigeration and industrial waste heat recovery power generation. Its core mechanism is clear: when current flows through a circuit composed of different semiconductor materials, the circuit nodes will experience directional heat absorption or release (i.e., the Peltier effect), which is the core principle of thermoelectric refrigeration. Conversely, if there is a temperature difference between the two ends of the circuit, an electromotive force will be spontaneously generated (i.e., the Seebeck effect), providing the theoretical basis for thermoelectric power generation. The energy conversion efficiency of thermoelectric devices is determined by two key factors: first, the dimensionless figure of merit (ZT value) of the thermoelectric material itself; the higher the ZT value, the stronger the thermoelectric conversion capability of the material; second, the effective temperature difference maintained across the thermoelectric unit during device operation; the greater the temperature difference, the more outstanding the actual energy conversion efficiency.

[0003] The human body, as a constant heat source at 37°C, naturally exhibits a temperature gradient (typically 1-3°C) between its skin surface and the surrounding environment. This characteristic provides an ideal application scenario for building self-powered wearable electronic systems using the Seebeck effect. However, traditional thermoelectric modules are mostly designed with rigid structures, making it difficult to adapt to the curved shapes and deformation requirements of the human body during dynamic activities. When directly applied to wearable scenarios, they not only suffer from poor fit and low wearing comfort, but are also prone to device damage due to mechanical stress, becoming the primary technical obstacle restricting their wearable application.

[0004] Currently, the development of wearable thermoelectric devices (WTEDs) still faces a core contradiction between thermal management, mechanical properties, and biocompatibility. Specific technical bottlenecks are mainly reflected in the following aspects: First, low temperature difference utilization efficiency. The natural temperature difference between human skin and the environment is already small, and the power generation or cooling efficiency of the device highly depends on the effective temperature difference transfer between the two ends of the thermoelectric leg. In actual wear, the hot end (the side in contact with the skin) is prone to unavoidable contact thermal resistance due to the skin's stratum corneum, sweat, and clothing, leading to heat transfer loss. The cold end (the side in contact with the environment) is limited by the compact structure of the wearable device, resulting in a limited heat dissipation surface area, and the low convective heat transfer coefficient of still air further weakens the heat dissipation efficiency. The superposition of these two thermal resistances causes the already limited internal and external temperature difference to be significantly lost when transferred to the thermoelectric functional unit, ultimately resulting in the device's output power or cooling temperature difference being far lower than the theoretical design value, failing to meet practical application requirements. Second, flexibility and thermal management performance are difficult to balance. To achieve conformal fit with the human body, researchers have developed flexible (FTEDs) and stretchable (s-FTEDs) thermoelectric devices. However, flexible design often comes at the cost of sacrificing thermal management performance. For example, existing flexible devices commonly use flexible encapsulation materials such as PDMS (polydimethylsiloxane) and silicone. These materials have extremely low thermal conductivity (typically below 0.2 W / m·K), which severely hinders the lateral diffusion and longitudinal conduction of heat, exacerbating thermal crosstalk between thermoelectric units. At the same time, in order to maintain the overall flexibility of the device, it is impossible to integrate traditional rigid metal heat sinks and other efficient heat dissipation structures, making cold-end heat dissipation problems more prominent in flexible devices, further limiting device performance.

[0005] To overcome the aforementioned bottlenecks, the research field has attempted to develop novel thermoelectric material systems that surpass traditional bismuth telluride bulk materials. These systems are mainly divided into two categories: conductive polymer materials and inorganic plastic crystal materials. Conductive polymer materials, represented by PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate), possess excellent flexibility and solution processability, allowing them to be fabricated into flexible devices through low-cost processes such as spin coating and printing. However, their thermoelectric figure of merit (ZT) is generally low (typically less than 0.75), and their energy conversion efficiency is far from meeting the power supply or cooling requirements of most wearable electronic devices. Another type of inorganic plastic crystal material (such as Ag2S-based compounds) attempts to combine the high thermoelectric properties of inorganic materials (ZT value close to that of traditional bismuth telluride materials) with the deformability of metals through crystal structure design. However, this type of material is still in the basic research stage in the laboratory. There are still many unsolved problems in long-term environmental stability (susceptible to the effects of humidity and oxygen, leading to performance degradation), reliability of ohmic contact with electrodes (interfacial resistance easily increases with deformation), and large-scale preparation process (difficult to achieve uniform film formation and precise doping). There is still a large gap between these materials and industrial wearable applications.

[0006] In summary, the lack of lightweight, efficient, and flexible heat dissipation solutions compatible with flexible systems has become a core bottleneck restricting the large-scale commercialization of wearable thermoelectric technology, especially in refrigeration applications that are more sensitive to temperature differences. This is true for both rigid / flexible thermoelectric devices based on traditional inorganic materials and flexible devices based on novel materials. Existing flexible heat dissipation solutions, such as water evaporation-based heat dissipation structures or phase change material heat dissipation layers, all have significant drawbacks: water evaporation requires frequent replenishment of the working fluid, making long-term stable operation impossible; phase change materials suffer from large volumetric properties and require external heat sources to reset after the latent heat of phase change is released, making it difficult to provide sustained and efficient heat dissipation support for devices while ensuring wearable comfort.

[0007] Therefore, the field of wearable thermoelectrics urgently needs to innovate its design at the device structure level and develop a new thermoelectric device solution that can significantly improve the heat dissipation capacity of the hot end without sacrificing flexibility and reliability, so as to fully unleash the application potential of wearable thermoelectric technology. Summary of the Invention

[0008] To address this urgent need, this invention proposes a rigidly supported flexible semiconductor refrigeration device, its fabrication method, and its application. The aim is to overcome the aforementioned technical contradictions through structural innovation and promote the practical development of wearable thermoelectric refrigeration devices.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] One objective of this invention is to provide a rigidly supported flexible semiconductor cooling device, the structure of which includes: a flexible substrate and a plurality of flexible cooling units; each of the plurality of flexible cooling units includes an interconnect electrode, a thermocouple and a selective encapsulation layer, and the flexible cooling units are interconnected with each other through the interconnect electrode and disposed on the flexible substrate;

[0011] The thermocouple consists of an N-type semiconductor thermoelectric arm and a P-type semiconductor thermoelectric arm, which are connected by the interconnecting electrode and arranged at intervals.

[0012] The selective encapsulation layer includes rigid encapsulation materials and flexible encapsulation materials;

[0013] The thermocouple is embedded in the rigid encapsulation material, and then the entire assembly is embedded in the flexible encapsulation material;

[0014] The height of the selective encapsulation layer is 1 / 5 to 1 times the height of the thermocouple.

[0015] The core of the selective encapsulation principle of this invention lies in precisely controlling the height of the encapsulation layer to actively match the axial temperature gradient of the thermoelectric arm during operation with the external ambient temperature, thereby achieving global optimization of heat flow management. Specifically, when the ambient temperature is low (<30°C), a section of the thermoelectric arm has a temperature significantly higher than the environment. This invention employs a semi-encapsulated structure to actively expose this high-temperature section, utilizing its positive temperature difference with the environment to drive efficient heat dissipation, effectively increasing the distributed heat dissipation surface and thus enhancing heat dissipation and improving cooling performance. When the ambient temperature is high (>30°C), most areas of the thermoelectric arm have temperatures lower than or close to the environment. In this case, a fully encapsulated structure is adopted, utilizing the continuous low thermal conductivity of the encapsulation material to construct a complete thermal insulation barrier. This aims to maximally prevent the reverse intrusion of heat from the high-temperature environment to the low-temperature thermoelectric arm, preventing an increase in the cold-end heat load and a decrease in cooling efficiency. Through the synergistic design of "high-efficiency heat dissipation at high temperature end + thermal insulation and cold preservation at low temperature end", the device's heat dissipation performance and thermal utilization efficiency are optimized in two ways. This breaks through the technical contradiction of "insufficient heat dissipation" and "excessive heat loss" in traditional fully packaged or unpackaged designs from the structural level, and significantly improves the actual efficiency of thermoelectric cooling.

[0016] Furthermore, the flexible substrate is polydimethylsiloxane (PDMS), biodegradable plastic (Ecoflex), or thermally conductive silicone.

[0017] Furthermore, the interconnecting electrode is made of conductive metal with a thickness of 0.02-0.2 mm.

[0018] Furthermore, the thermoelectric pair material is selected from chalcogenide thermoelectric materials based on (Bi,Sb)2(Te,Se)3, MgAgSb, Mg3(Bi,Sb)2, Ag2Se, or SnSe.

[0019] Furthermore, the rigid encapsulation material is a rigid encapsulation material with a thermal conductivity of less than 0.16 W / mK, such as any one of polyurethane, polydimethylsiloxane, polyvinyl chloride, and epoxy resin doped with silica microspheres, wherein the silica microspheres account for 10-70 vol% of the rigid encapsulation material; and the particle size of the silica microspheres is 20-500 μm.

[0020] Furthermore, the flexible encapsulation material is selected from Ecoflex prepolymer or polyurethane.

[0021] A second objective of this invention is to provide a method for fabricating a rigidly supported flexible semiconductor cooling device, comprising the following steps:

[0022] (1) Pour the uncured rigid encapsulation material into a mold, heat and cure it, and cut it into a preset shape to obtain a mold containing rigid encapsulation material; use a template solvent method or a foaming method to embed the mold containing rigid encapsulation material into a flexible encapsulation material to obtain a selective encapsulation layer; fill the through holes of the selective encapsulation layer with thermocouples and form an electrical series structure through interconnecting electrodes to obtain a flexible cooling unit;

[0023] (2) Multiple flexible cooling units are connected in series by interconnecting electrodes and attached to a flexible substrate by a colloidal binder (Sil-Poxy™) and cured to obtain a rigidly supported flexible semiconductor cooling device.

[0024] Furthermore, the material of the mold is acrylonitrile-styrene-acrylate terpolymer (ASA).

[0025] Furthermore, the encapsulation width of the rigid encapsulation material is greater than 0-2 mm of the thermopair edge.

[0026] The third objective of this invention is to provide an application of a rigidly supported flexible semiconductor cooling device in flexible wearable devices.

[0027] Compared with the prior art, the present invention has the following advantages and technical effects:

[0028] To address the current technical bottleneck of packaging materials failing to simultaneously achieve high structural reliability, excellent flexibility, and efficient thermoelectric performance, this invention proposes a "rigid support-flexible interconnection" composite packaging configuration. This configuration achieves synergistic fulfillment of multiple performance requirements through a differentiated filling strategy. Specifically, a low thermal conductivity rigid support material is filled in the gaps between the thermoelectric arms. The structural stability of the rigid material provides precise support for the brittle thermoelectric arms, preventing breakage due to stress concentration during device deformation. Simultaneously, the low thermal conductivity reduces lateral thermal crosstalk between the thermoelectric arms. Meanwhile, the overall gaps in the thermoelectric pair array are filled with a porous flexible packaging material prepared using a template method. The high elasticity and stretchability of the flexible material ensure excellent bending and deformation capabilities, adapting to the dynamic fit requirements of wearable devices. Through the design logic of "local rigid support for stability + overall flexible interconnection for adaptability," the final fabricated wearable thermoelectric cooling device possesses excellent structural reliability and flexibility, while also suppressing heat loss through low thermal conductivity materials to ensure efficient cooling performance, achieving a three-in-one performance breakthrough of "high flexibility, high reliability, and high performance." Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0030] Figure 1 This is a schematic diagram of the cross-sectional structure of the flexible semiconductor cooling device prepared in Example 1 of the present invention;

[0031] Figure 2 This is a schematic diagram of the fabrication process of the flexible semiconductor cooling device in Embodiment 1 of the present invention;

[0032] Figure 3 This is a 3D schematic diagram of the flexible semiconductor cooling device prepared in Example 1 of the present invention;

[0033] Figure 4 These are physical images of the flexible semiconductor cooling devices prepared in Examples 1 and 4 of this invention;

[0034] Figure 5 This is a comparison chart of the cooling and power generation efficiency data of the flexible semiconductor refrigeration devices prepared in Examples 1 and 4 of the present invention under different temperature environments;

[0035] Figure 6 These are cooling data graphs of flexible semiconductor cooling devices with different packaging structures prepared in Examples 1 and 4 of the present invention under different temperature environments.

[0036] Among them, 1-interconnect electrode, 2-flexible packaging material, 3-thermoelectric pair, 41, 42-rigid packaging material, 5-flexible substrate, 6-flexible cooling unit. Detailed Implementation

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0039] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0040] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0041] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0042] Figure 1 This is a cross-sectional schematic diagram of a rigidly supported flexible semiconductor cooling device provided in Embodiment 1 of the present invention. Its structure includes: a flexible substrate 5 and multiple flexible cooling units 6; each flexible cooling unit 6 includes an interconnecting electrode 1, a thermocouple 3, and a selective encapsulation layer. The flexible cooling units 6 are interconnected via the interconnecting electrode 1 and disposed on the flexible substrate 5. The thermocouple 3 is composed of N-type semiconductor thermoelectric arms and P-type semiconductor thermoelectric arms, which are connected via the interconnecting electrode 1 and arranged at intervals. The selective encapsulation layer includes rigid encapsulation materials 41 and 42 and a flexible encapsulation material 2, wherein the width of the encapsulation material 41 is greater than the edge of the thermocouple to be filled by 0-2 mm. The N-type semiconductor thermoelectric arms and P-type semiconductor thermoelectric arms are embedded in the rigid encapsulation material 4, and then embedded entirely in the flexible encapsulation material 2 to obtain the rigidly supported flexible cooling unit.

[0043] In the following optional embodiments of the present invention, the interconnecting electrodes are made of conductive metal with a thickness controlled within the range of 0.02-0.2 mm, typically including 0.03 mm, 0.05 mm, 0.06 mm, and 0.08 mm. This thickness design optimizes device performance in two core dimensions: mechanical adaptability and thermoelectric efficiency. From a mechanical perspective, thinner metal electrodes significantly reduce the overall bending stiffness of the device, giving the electrodes excellent flexible deformation capabilities. When the device bends or stretches due to human movement, the thin electrodes effectively reduce strain on themselves and at the connection points with the thermoelectric arm, avoiding fatigue fracture caused by stress accumulation during long-term use, and significantly improving the structural reliability and lifespan of the device in wearable scenarios. From the perspective of thermoelectric conversion efficiency, the design of thin metal electrodes is equally crucial: on the one hand, they can minimize "parasitic thermal conduction." Excessively thick metal forms a shortcut for heat conduction, weakening the temperature difference between the hot and cold ends of the thermoelectric circuit (i.e., "thermal short circuit"). Thin electrodes effectively block this ineffective heat conduction path, ensuring the effective temperature difference required for thermoelectric conversion. On the other hand, thin electrodes can significantly reduce the overall weight of the device, meeting the core requirement of "lightweight" in wearable devices. Simultaneously, their lower heat capacity accelerates the device's response to temperature changes, making cooling or power generation functions more easily and quickly adapt to the dynamic temperature requirements of the environment and the human body. In the following preferred embodiments of the present invention, the interconnecting electrodes are selected from copper sheets with dimensions of 50mm × 50mm and a thickness of 0.05mm.

[0044] In the following optional embodiments of the present invention, the thermoelectric pair (N-type semiconductor thermoelectric arm and P-type semiconductor thermoelectric arm) materials are selected from chalcogenide thermoelectric materials based on (Bi,Sb)2(Te,Se)3, MgAgSb, Mg3(Bi,Sb)2, Ag2Se, or SnSe. The materials selected in this invention possess clear temperature adaptability advantages. Among them, Bi2Te3, Sb2Te3, and MgAgSb materials exhibit excellent thermoelectric performance in the near-room temperature range (highly matching the temperature environment of human wearable devices), while SnSe and Mg3Sb2 materials perform well in the medium-to-high temperature range, covering a wider range of application temperature requirements. The core indicator for measuring the performance of these thermoelectric materials is the dimensionless thermoelectric figure of merit (ZT value), whose value directly determines the material's energy conversion efficiency: a higher ZT value means a stronger ability to convert thermal energy into electrical energy, thus providing more efficient cooling or power generation for the device. It is a key material characteristic parameter ensuring the actual performance of flexible semiconductor cooling devices. In the following preferred embodiments of the present invention, the N-type semiconductor thermoelectric arm is Bi2Sb. 2.7 Te 0.3 Or Mg3(Bi,Sb)2; the P-type semiconductor thermoelectric arm is Bi. 0.5 Sb 1.5 Te3 or Mg3(Bi,Sb)2.

[0045] In the following optional embodiments of the present invention, the flexible encapsulation material is selected from porous silicone, porous polydimethylsiloxane, polyurethane, Ecoflex prepolymer, or foam. The performance advantages of the flexible encapsulation material selected in the present invention can be reflected in three core dimensions: mechanical protection, biocompatibility, and thermal management. In terms of mechanical protection and flexible compatibility, silicone has excellent flexibility and stretchability, not only with excellent elasticity but also with an elongation at break of over 100% and good deformation recovery ability. When used for encapsulation, it can completely encapsulate the brittle thermoelectric materials (such as Bi2Te3 bulk) and electrodes inside the device. When the device undergoes dynamic deformation such as bending, stretching, or twisting with human activity, the external stress will be preferentially borne by the soft silicone matrix and released through elastic deformation, effectively preventing internal thermoelectric functional units from cracking or breaking due to stress concentration, providing key protection for wearable devices to adapt to complex human activities. In terms of biocompatibility and environmental stability, silicone exhibits significant chemical inertness, remaining stable to most chemical substances and possessing strong weather resistance. It can effectively block the penetration of external contaminants such as dust and sweat, reducing the risk of device corrosion. More importantly, silicone is non-toxic and non-allergenic, possessing excellent biocompatibility. This ensures that the encapsulated device can directly contact human skin for extended periods, perfectly meeting the core safety and comfort requirements of wearable health monitoring devices. Regarding thermal management optimization, silicone itself has a low thermal conductivity (0.15-0.2 W / m·K), making it an excellent thermal insulation material. When filled between thermoelectric arms, it effectively suppresses "lateral heat leakage" between P-type and N-type thermoelectric arms, forcing heat to flow longitudinally through the thermoelectric arms along the designed path, providing crucial support for establishing and maintaining a stable temperature difference (ΔT) in the device. Furthermore, by processing silicone into a porous structure, its thermal conductivity can be further reduced to 0.09 W / m·K, significantly improving thermal insulation performance and more efficiently reducing ineffective heat conduction, maximizing thermoelectric conversion efficiency. In the following preferred embodiments of the present invention, the flexible encapsulation material is Ecoflex prepolymer or polyurethane.

[0046] In the following optional embodiments of the present invention, the rigid encapsulation material is a rigid encapsulation material with a thermal conductivity of less than 0.16 W / mK, and the encapsulation width is greater than the edge of the thermoelectric arm by 0-2 mm. For example, any one of polyurethane, polydimethylsiloxane, polyvinyl chloride, and epoxy resin is incorporated with silica microspheres, wherein the silica microspheres account for 10-70 vol% of each; and the particle size of the silica microspheres is 20-500 μm. The core objective of this formulation design is to achieve a performance balance of "low thermal conductivity - high rigidity - easy processing" while minimizing the thermal conductivity of the material and taking into account the good mechanical strength and processability of the PDMS composite material. From the perspective of encapsulation structure design, the encapsulation width of the rigid encapsulation material needs to exceed the edge of the thermoelectric arm by 0-2 mm. This size setting ensures that the thermoelectric arm is accurately wrapped and stably supported, preventing misalignment or damage to the thermoelectric arm due to lack of support when the device deforms. From a thermal management perspective, selecting encapsulation materials with a thermal conductivity below 0.16 W / m·K (including the aforementioned rigid encapsulation materials and similar flexible encapsulation systems) for flexible thermoelectric devices is a key design consideration to ensure cooling efficiency. The core requirement for encapsulation materials in flexible devices is "flexible adaptation + structural protection," while low thermal conductivity is a crucial prerequisite for efficient thermal management. It can maximally prevent "parasitic thermal short circuits" between the hot end (high-temperature region) and cold end (low-temperature region) of the device through the encapsulation material. If the thermal conductivity of the encapsulation material is too high, heat will bypass the thermoelectric functional unit and be directly conducted from the hot end to the cold end, severely offsetting the Peltier cooling effect, leading to a sharp decrease in the temperature difference between the two ends of the thermoelectric pair and a significant drop in cooling efficiency. Therefore, the application of such low thermal conductivity encapsulation materials essentially aims to establish an optimal balance among "flexibility and adaptability," "structural protection," and "critical thermal insulation": satisfying the flexible deformation requirements and internal structural protection requirements of devices in wearable scenarios, while also forcing heat dissipation along a predetermined path (from the hot end to the external environment), preventing leakage back to the cold end through the encapsulation layer, and ultimately ensuring stable cooling performance of the device in wearable applications. In the following preferred embodiments of the present invention, the rigid encapsulation material is polydimethylsiloxane doped with silica microspheres, with the silica microspheres accounting for 30 vol%; or the rigid encapsulation material is epoxy resin doped with silica microspheres, with the silica microspheres accounting for 50 vol%.

[0047] In the following optional embodiments of the present invention, the flexible substrate is polydimethylsiloxane, biodegradable plastic, or thermally conductive silicone. Among them, polydimethylsiloxane is the preferred solution for adapting thermoelectric flexible devices due to its excellent comprehensive performance. Its core advantages can be described from three dimensions: wearability, safety of use, and ease of device fabrication. In terms of wearability, polydimethylsiloxane has excellent flexibility and stretchability, which can synchronously conform to the movement of human joints and the deformation of limbs, avoiding discomfort caused by rigid friction. At the same time, its Young's modulus is close to that of human skin, which can significantly reduce the contact pressure between the device and the skin, further improving the comfort of long-term wear, perfectly meeting the core requirement of "shape-fitting" wearable devices. In terms of safety and stability, polydimethylsiloxane (PDMS) exhibits excellent biocompatibility, is non-toxic and non-allergenic, and can be in direct, long-term contact with human skin without safety hazards. Furthermore, its chemical stability allows it to withstand the effects of common wearable factors such as sweat and environmental humidity, and it is not prone to degradation or performance decline. It also possesses good electrical insulation properties, effectively isolating the internal circuitry from electrical contact with human skin and avoiding the risk of leakage. Regarding device fabrication and performance assurance, PMS has a simple processing technology, enabling large-scale molding through low-cost methods such as casting and molding, reducing the difficulty and cost of device fabrication. More importantly, its low thermal conductivity reduces ineffective heat conduction between the flexible substrate and the thermoelectric unit, helping to maintain an effective temperature difference between the two ends of the thermocouple, providing crucial support for the stable performance of the device in cooling or power generation. In the following preferred embodiments of the present invention, the flexible substrate is PMS.

[0048] In the following optional embodiments of the present invention, the height of the selective encapsulation layer is 1 / 5 to 1 times the height of the thermocouple. It can be flexibly adjusted within this range according to the heat dissipation requirements and flexible adaptation requirements of the actual application scenario. To accurately determine the optimal encapsulation height to maximize the device's cooling performance, the present invention fabricates physical devices with corresponding encapsulation heights and verifies their actual cooling performance through experimental testing. The comprehensive experimental results show that when the height of the selective encapsulation layer is 1 / 2 the height of the thermocouple, the device can simultaneously achieve the best balance between "efficient heat dissipation at the hot end" and "thermal insulation and cold preservation at the cold end." This ensures sufficient contact between the hot-end thermocouple arm and the air to enhance heat dissipation, while effectively blocking external heat from penetrating to the cold end through the encapsulation layer, ultimately exhibiting optimal cooling performance and providing precise parameter basis for device structure design. In environments below 30°C, the semi-encapsulated (selective encapsulation) mode offers advantages. Its principle lies in precisely controlling the ratio of exposed to covered areas of the thermoelectric arm. When the ambient temperature is lower than the temperature of a specific section of the thermoelectric arm, the high-temperature section is actively exposed by controlling the encapsulation layer height to 25% to 80% of the thermoelectric arm height, utilizing the positive temperature difference between it and the environment to drive efficient heat dissipation. Simultaneously, the remaining portion is covered to maintain basic structural protection. This height range ensures that the exposed section has sufficient length (>20% H_leg) for effective heat dissipation, while also guaranteeing that the encapsulated section has sufficient height (>25% H_leg) to provide reliable mechanical anchoring and electrical insulation. In environments above 30°C, the full encapsulation mode is more advantageous. The principle is to utilize the continuous encapsulation characteristics of the encapsulation material to build a complete high thermal barrier thermal layer around the thermoelectric arm. This structure can suppress all radial heat exchange between the device and the external environment to the greatest extent, regardless of the direction of heat flow. This creates a controlled thermal isolation environment for the core area of ​​thermoelectric conversion in harsh or high-temperature environments, ensuring the stability of the internal operating temperature field. The height of the encapsulation layer needs to completely cover and slightly exceed the thermoelectric arm, usually 80% to 100% of the height of the thermoelectric arm (H_leg), to ensure the integrity of mechanical protection and eliminate edge heat leakage.

[0049] In the following preferred embodiments of the invention, the height of the selective encapsulation layer is 25% or 60% of the thermocouple height.

[0050] This invention provides a method for fabricating a rigidly supported flexible semiconductor cooling device, specifically including the following steps:

[0051] (a) Preparations before the experiment:

[0052] (1) Material preparation: Rigid encapsulation material (any one of polyurethane, polydimethylsiloxane, polyvinyl chloride or epoxy resin, doped with 10-70 vol% silica microspheres with a particle size of 20-500 μm, ensuring thermal conductivity is below 0.16 W / mK), flexible encapsulation material (porous silicone, porous polydimethylsiloxane, Ecoflex prepolymer, polyurethane or foam), flexible substrate (polydimethylsiloxane (PDMS), biodegradable plastic (Ecoflex) or thermally conductive silicone), interconnect electrode material (conductive metal, cut to a thickness of 0. 0.02-0.2mm), thermoelectric pair materials ((Bi,Sb)2(Te,Se)3-based, MgAgSb-based, Mg3(Bi,Sb)2-based, Ag2Se-based or SnSe-based chalcogenide thermoelectric materials, processed into N-type semiconductor thermoelectric arms and P-type semiconductor thermoelectric arms), sodium chloride granules (superior grade), deionized water, colloidal binder (Sil-Poxy™), acrylonitrile-styrene-acrylate terpolymer (ASA) material mold (customized according to the preset device size to ensure that the rigid encapsulation material can be cut into the target shape after filling).

[0053] (2) Equipment preparation: heating and curing equipment (such as vacuum drying oven), cutting equipment (such as precision cutting machine), pressure control equipment (such as vacuum pressure tank), drying equipment (such as blower drying oven), stirring equipment (such as magnetic stirrer), scraper, tweezers, welding equipment (such as hot press welding machine).

[0054] (II) Specific experimental steps (taking the template solvent method as an example):

[0055] (1) Preparation of rigid packaging material mold

[0056] Slowly pour the uncured rigid encapsulation material into the acrylonitrile-styrene-acrylate terpolymer (ASA) mold, taking care to avoid creating air bubbles;

[0057] Place the mold containing the rigid encapsulation material into the heating and curing equipment, set the curing temperature (e.g., 40℃ for PDMS-based rigid encapsulation material) and curing time (e.g., 6 hours) according to the material properties, and remove it after the material has completely cured.

[0058] The cured rigid encapsulation material is cut into a preset shape (such as a cuboid array) using a precision cutting machine. This ensures that the encapsulation width of the rigid encapsulation material after cutting is 0-2mm greater than the edge of the thermocouple to be filled, thus obtaining a mold containing the rigid encapsulation material.

[0059] (2) Preparation of sodium chloride template

[0060] Weigh out sodium chloride granules and deionized water in a mass ratio of (3-5):1, pour them into a container, stir with a magnetic stirrer for 10-15 minutes, and mix evenly to obtain a salt slurry;

[0061] Slowly fill the above salt slurry into the mold containing the rigid encapsulation material obtained in step (1), ensuring that the solution fills all the gaps in the mold;

[0062] Place the mold filled with salt slurry into a forced-air drying oven, set the temperature to 60℃, and dry for 8 hours to completely evaporate the moisture, thus obtaining a sodium chloride template with a porous structure.

[0063] (3) Filling and curing of flexible packaging materials

[0064] Place the sodium chloride template obtained in step (2) into a vacuum pressure vessel, pour uncured flexible encapsulation material into the vessel, and ensure that the template is completely immersed in the flexible encapsulation material.

[0065] Start the vacuum pressure tank and adjust the pressure inside the tank to -0.8 to -1 MPa. Maintain this pressure for 30 minutes to allow the uncured flexible encapsulation material to fully immerse itself in the pores of the sodium chloride template.

[0066] Close the vacuum pressure tank, remove the soaked sodium chloride template, and gently scrape off the excess uncured flexible encapsulation material on the template surface with a scraper to ensure that the rigid encapsulation material is exposed.

[0067] The treated sodium chloride template is placed in a forced-air drying oven, set at a temperature of 50-60℃, and cured for 2 hours to obtain a sodium chloride template whose internal pores are filled with flexible encapsulation material.

[0068] (4) Preparation of selective encapsulation layer

[0069] Prepare a sufficient amount of deionized water, pour it into a container, and immerse the sodium chloride template with internal pores filled with flexible encapsulation material obtained in step (3) in the water.

[0070] To accelerate the dissolution of sodium chloride particles, the container can be placed in a water bath and heated to 70°C. During this process, the deionized water should be replaced every 2 hours until the sodium chloride template is completely disintegrated (no white sodium chloride residue remains on the template) can be visually confirmed.

[0071] The disassembled product was removed from the water and placed in a forced-air drying oven. The temperature was set to 60℃ and dried for 4 hours to remove residual moisture.

[0072] After the product cools to room temperature, it is demolded to obtain a selective encapsulation layer (the encapsulation layer includes a flexible encapsulation material and a rigid encapsulation material embedded therein, and through holes with a cross-sectional size matching the thermocouple are formed on the rigid encapsulation material).

[0073] (5) Thermocouple assembly and device molding

[0074] S1. Pre-processed interconnect electrodes: The conductive metal sheet is processed using transfer and re-etching technology to obtain interconnect electrodes that match the size of the thermocouple.

[0075] S2. Thermocouple filling and electrical series connection: N-type semiconductor thermocouples and P-type semiconductor thermocouples are alternately filled into the through-holes of the rigid encapsulation material in the selective encapsulation layer. The thermocouples are then connected to the interconnecting electrodes by a thermo-press welding machine to form an electrical series structure, thus obtaining a single flexible cooling unit.

[0076] S3. Flexible refrigeration unit series connection and substrate bonding: Connect multiple flexible refrigeration units through interconnecting electrodes to form a thermal series structure; uniformly apply a layer of colloidal binder (Sil-Poxy™) to the surface of a flexible substrate (such as PDMS), and gently bond the series-connected flexible refrigeration unit array to the flexible substrate to ensure a flat and non-offset bonding.

[0077] S4. Final Curing: Place the bonded device into a forced-air drying oven, set the curing temperature (e.g., 60℃) and curing time (e.g., 4 hours) according to the characteristics of the colloidal binder (Sil-Poxy™), and remove it after the colloidal binder (Sil-Poxy™) has completely cured to obtain a rigidly supported flexible semiconductor refrigeration device.

[0078] In the following optional embodiments of the present invention, acrylonitrile-styrene-acrylate terpolymer (ASA) mold material is selected because ASA material has good mechanical properties, the mold produced is strong and durable, and the surface of the mold printed by ASA is delicate, not easy to stick to the encapsulation material, and easy to demold.

[0079] The aforementioned flexible semiconductor cooling devices can be applied in flexible wearable devices. These devices can provide active, precise, rapid, and controllable cooling or heating to specific areas of the skin as needed. Through active temperature control technology, they eliminate the need for compressors and refrigerants, operate completely silently, and, thanks to their unique flexible structure, conform to the irregular contours of the human body. While ensuring wearing comfort, they directly intervene in the microenvironment through efficient local energy regulation, enabling applications ranging from improving athletic performance to ensuring safety during outdoor work.

[0080] The applications of flexible semiconductor cooling devices can be as follows:

[0081] 1. Personalized thermal comfort and thermoregulation clothing: Multiple small, thin flexible thermoelectric devices (WTEDs) are embedded or woven into specific areas of the clothing, such as the back, chest, neck, and wrists—areas with high blood circulation—like "patches." These units are connected by flexible circuitry and powered by a small wearable battery.

[0082] 2. Medical and Health Treatment Equipment: Utilizing precise local temperature control to achieve treatment and rehabilitation purposes.

[0083] 3. Thermal simulation in virtual reality.

[0084] 4. Performance and reliability assurance of wearable devices.

[0085] Unless otherwise specified, "room temperature" in this invention refers to 25±2℃.

[0086] All raw materials used in this invention were purchased from the market.

[0087] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. Unless otherwise specified, specific techniques or conditions in the embodiments are conventional methods and can be performed according to the techniques or conditions described in the literature in this field or according to the product manual.

[0088] Example 1

[0089] Fabrication of a rigidly supported flexible semiconductor cooling device, the fabrication process is shown in the schematic diagram below. Figure 2 As shown (template solvent method), the specific steps are as follows:

[0090] (1) Add diluent (n-hexane) to uncured PDMS in a beaker at a mass ratio of 10:2, then add 30 vol% SiO2 microspheres (i.e., the volume of SiO2 microspheres is 30% of the volume of PDMS, purchased from 3M Company, USA - A16 model), stir for 30 minutes to obtain a uniform mixture, pour the mixture into an ASA material mold, heat at 40°C in a vacuum drying oven for 6 hours to cure, and cut it into a 6×3 cuboid array along the outer edge of the thermocouple 1 mm to obtain a mold containing rigid encapsulation material;

[0091] (2) Mix sodium chloride granules of superior purity and deionized water in a mass ratio of 3:1, pour the mixture into a mold containing rigid packaging material, and dry it in a vacuum drying oven at 60°C for 8 hours to obtain a sodium chloride template with a porous structure.

[0092] (3) Immerse the sodium chloride template with a porous structure in Ecoflex prepolymer (purchased from Smooth-On, USA), stand for 30 minutes at -1 MPa atmospheric pressure, and then stand for 12 hours at -10°C to allow the Ecoflex prepolymer to be completely immersed in the pores of the sodium chloride template. Take out the sodium chloride template immersed in Ecoflex prepolymer and remove the excess Ecoflex prepolymer on its surface with a scraper to expose the rigid encapsulation material. Dry at 60°C for 2 hours to solidify the Ecoflex prepolymer in the pores and obtain a sodium chloride template with Ecoflex filling the internal pores.

[0093] (4) Soak the sodium chloride template filled with Ecoflex in deionized water and heat it in a water bath to 70°C to accelerate the disassembly of the sodium chloride template and dissolve the sodium chloride particles. Change the water every 2 hours until the sodium chloride template is completely disassembled. Dry the remaining part of the template at 60°C for 4 hours and then demold to obtain a selective encapsulation layer. The selective encapsulation layer includes porous Ecoflex and rigid encapsulation material. The rigid encapsulation material has through holes of the same size as the thermoelectric arm cross section and is embedded in the porous Ecoflex.

[0094] (5) Prepare two copper sheets with a length and width of 50mm×50mm as the material for interconnecting electrodes. The thickness of the copper sheets is 0.05mm. Use the transfer and etching technique to obtain electrodes that match the size of the thermoelectric arm.

[0095] (6) A 1.5mm×1.5mm×5mm P-type semiconductor thermoelectric arm (Bi 0.5 Sb 1.5 Te3) and N-type semiconductor thermoelectric arms (Bi2Sb) 2.7 Te 0.3 The selective encapsulation layer is alternately filled into the through-holes of the rigid encapsulation material (where the height of the selective encapsulation layer is 2.5 mm and the height of each thermoelectric arm pair is 5 mm), and an electrically connected series structure is formed by thermo-pressing interconnection electrodes to obtain a single flexible cooling unit. Six × three individual flexible cooling units are connected in a thermo-connected series structure through interconnection electrodes and attached to a PDMS substrate using a Sil-Poxy™ adhesive. After curing, a rigidly supported flexible semiconductor cooling device is obtained (see 3D schematic diagram). Figure 3 See actual product photos Figure 4 ).

[0096] Example 2

[0097] Same as Example 1, except that step (1) is as follows: add diluent (polypropylene glycol diglycidyl ether) to uncured epoxy resin in a beaker at a mass ratio of 10:2, then add 50 vol% SiO2 microspheres, stir with a stirrer for 30 minutes to obtain a uniform mixture, pour the mixture into an ASA material mold, heat it at 40°C in a vacuum drying oven for 6 hours to cure, and cut it into a 6×3 cuboid array to obtain a mold containing rigid encapsulation material.

[0098] Example 3

[0099] The fabrication steps of a rigidly supported flexible semiconductor cooling device (foam method) are as follows:

[0100] (1) Add diluent (n-hexane) to uncured PDMS in a beaker at a mass ratio of 10:2, then add 30 vol% SiO2 microspheres and stir for 30 minutes to obtain a uniform mixture. Pour the mixture into an ASA material mold, heat it at 40°C in a vacuum drying oven for 6 hours to cure it, and cut it into a 6×3 cuboid array along the outer edge of the thermocouple 1 mm to obtain a rigid encapsulation material.

[0101] (2) The rigid encapsulation material is immersed in a polyurethane mixture (purchased from Beijing Haibeis Technology Co., Ltd., the polyurethane mixture is made by mixing polyether polyol (component A) and isocyanate curing agent (component B) at a mass ratio of 1:0.4; wherein, the main components of the polyether polyol are a mixture of polyether polyol, catalyst, foam stabilizer and foaming agent, and its main function is to give the cured material flexibility and foam structure) and left to stand for 20 minutes. A cube weight is placed on the device to provide uniform pressure. After the polyurethane foaming is completed, a selective encapsulation layer is obtained. The rigid encapsulation material has through holes of the same size as the thermoelectric arm cross section and the rigid encapsulation material is embedded in the polyurethane.

[0102] (3) Prepare two copper sheets with a length and width of 50mm×50mm as the material for interconnecting electrodes. The thickness of the copper sheets is 0.05mm. Use the transfer and etching technique to obtain electrodes that match the size of the thermoelectric arm.

[0103] (4) A 1.5mm×1.5mm×5mm P-type semiconductor thermoelectric arm (Bi 0.5 Sb 1.5 Te3) and N-type semiconductor thermoelectric arms (Bi2Sb) 2.7 Te 0.3The selective encapsulation layer is alternately filled into the through-holes of the rigid encapsulation material (where the height of the selective encapsulation layer is 2.5 mm and the height of the thermoelectric arm pairs is 5 mm), and an electrical series structure is formed by thermo-pressing the interconnecting electrodes to obtain a single flexible cooling unit. Six × three single flexible cooling units are connected by interconnecting electrodes to form a thermal series structure, and then attached to the PDMS substrate with a colloidal binder (Sil-Poxy™) and cured to obtain a rigidly supported flexible semiconductor cooling device.

[0104] Example 4

[0105] Same as in Example 1, except that step (6) is: inserting a 2.5mm×2.5mm×5mm P-type semiconductor thermoelectric arm (Bi 0.5 Sb 1.5 Te3) and N-type semiconductor thermoelectric arms (Bi2Sb) 2.7 Te 0.3 The flexible cooling units are alternately filled into the through-holes of the rigid encapsulation material (where the height of the selective encapsulation layer is 5 mm and the height of the thermoelectric arms is 5 mm), and an electrical series structure is formed by thermo-press welding through interconnecting electrodes to obtain a single flexible cooling unit. Six × three single flexible cooling units are connected through interconnecting electrodes to form a thermal series structure, and then attached to the PDMS substrate with a colloidal binder (Sil-Poxy™) and cured to obtain a fully encapsulated flexible semiconductor cooling device.

[0106] Performance testing:

[0107] The performance of the flexible semiconductor cooling devices prepared in Example 1 (semi-packaged) and Example 4 (fully packaged) was tested using the following methods:

[0108] (1) Setting the temperature of the heat source

[0109] A 5cm×5cm×1.2cm PDMS has a heat transfer system similar to human skin. A PDMS of this size is placed on a heating platform, and the temperature of the PDMS is adjusted by regulating the temperature of the heating platform. The specific operating steps are as follows: turn on the heating platform, place the prepared block PDMS on the heating platform, then place the prepared thermoelectric device on top of the PDMS, and connect the device to a regulated DC power supply. At this time, a thermocouple is attached between the PDMS and the thermoelectric device to record the cold junction temperature, and a thermocouple is attached to the top of the thermoelectric device to record the hot junction temperature. A thermocouple is placed on the heating platform to record the real-time temperature of the heating platform.

[0110] (2) Temperature monitoring instrument parameter settings

[0111] Connect the temperature monitoring device to the test computer, open the software, and select the relevant test channel. Then, collect temperature data at time intervals and record the temperature changes.

[0112] (3) Preheating wearable thermoelectric devices

[0113] Preheat the wearable thermoelectric device for 30 minutes, and monitor the temperature of the thermocouple using a temperature monitoring device, while also paying attention to changes in the ambient temperature. If the temperature is unstable, adjust the heating platform temperature accordingly to maintain thermocouple temperature stability. Once the temperature has stabilized, begin testing directly.

[0114] (4) Cooling test of wearable thermoelectric devices

[0115] After the temperature stabilizes, gradually adjust the current using a regulated DC power supply to determine the optimal cooling current for the device. The test duration is 30 minutes, and the cold and hot junction temperatures of the device are recorded. After each test, turn off the regulated DC power supply and wait for the PDMS temperature to stabilize before conducting the next test.

[0116] Figure 5 The figure shows a comparison of the cooling and power generation efficiency data of the flexible semiconductor cooling devices prepared in Examples 1 and 4. It can be seen from the figure that at a low temperature of 25°C, the cooling and power generation capabilities of the semi-encapsulated structure are better than those of the fully encapsulated structure; at a high temperature of 35°C, the cooling and power generation capabilities of the semi-encapsulated structure are lower than those of the fully encapsulated structure.

[0117] Figure 6 The figures show the cooling data of the flexible semiconductor cooling devices with different packaging structures prepared in Examples 1 and 4 under different temperature environments. It can be seen from the figures that the semi-encapsulated (selective packaging) mode has advantages in environments below 30°C, while the fully encapsulated mode is more advantageous in environments above 30°C.

[0118] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A rigidly supported flexible semiconductor cooling device, characterized in that, The structure includes: A flexible substrate and multiple flexible cooling units; each flexible cooling unit includes interconnecting electrodes, thermocouples and selective encapsulation layers, and the flexible cooling units are interconnected through the interconnecting electrodes and disposed on the flexible substrate; The thermocouple consists of an N-type semiconductor thermoelectric arm and a P-type semiconductor thermoelectric arm, which are connected by the interconnecting electrode and arranged at intervals. The selective encapsulation layer includes rigid encapsulation materials and flexible encapsulation materials; The thermocouple is embedded in the rigid encapsulation material, and then the entire assembly is embedded in the flexible encapsulation material to form the flexible refrigeration unit; The height of the selective encapsulation layer is 1 / 5 to 1 times the height of the thermocouple.

2. The rigidly supported flexible semiconductor cooling device according to claim 1, characterized in that, The flexible substrate is polydimethylsiloxane, biodegradable plastic, or thermally conductive silicone.

3. The rigidly supported flexible semiconductor cooling device according to claim 1, characterized in that, The interconnecting electrodes are made of conductive metal with a thickness of 0.02-0.2 mm.

4. The rigidly supported flexible semiconductor cooling device according to claim 1, characterized in that, The thermoelectric couple is made of chalcogenide thermoelectric materials selected from (Bi,Sb)2(Te,Se)3-based, MgAgSb-based, Mg3(Bi,Sb)2-based, Ag2Se-based, or SnSe-based materials.

5. The rigidly supported flexible semiconductor cooling device according to claim 1, characterized in that, The rigid encapsulation material is prepared by incorporating silica microspheres into any one of polyurethane, polydimethylsiloxane, polyvinyl chloride, and epoxy resin.

6. The rigidly supported flexible semiconductor cooling device according to claim 5, characterized in that, The silica microspheres account for 10-70 vol% of the rigid encapsulation material.

7. The rigidly supported flexible semiconductor cooling device according to claim 1, characterized in that, The flexible encapsulation material is selected from porous silicone, porous polydimethylsiloxane, polyurethane, Ecoflex prepolymer, or foam.

8. A method for fabricating a rigidly supported flexible semiconductor cooling device as described in any one of claims 1-7, characterized in that, Includes the following steps: (1) Pour the uncured rigid encapsulation material into a mold, heat and cure it, and cut it into a preset shape to obtain a mold containing rigid encapsulation material; use a template solvent method or a foaming method to embed the mold containing rigid encapsulation material into a flexible encapsulation material to obtain a selective encapsulation layer; fill the through holes of the selective encapsulation layer with thermocouples and form an electrical series structure through interconnecting electrodes to obtain a flexible cooling unit; (2) Multiple flexible cooling units are connected in series by interconnecting electrodes and attached to a flexible substrate by a colloidal binder and cured to obtain a rigidly supported flexible semiconductor cooling device.

9. The preparation method according to claim 8, characterized in that, The mold is made of acrylonitrile-styrene-acrylate terpolymer.

10. The application of a rigidly supported flexible semiconductor cooling device as described in any one of claims 1-7 in a flexible wearable device.

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