A flexible heat pipe based on a bionic directional liquid delivery structure and its manufacturing process

Abstract

The present invention provides a flexible heat pipe based on a bionic directional liquid delivery structure and a manufacturing process, relating to the field of flexible heat pipes. To address the problem that the heat dissipation efficiency of current flexible heat pipes cannot meet demand, liquid absorption channels and raised columns are formed on the flexible substrate of the flexible heat pipe. The raised columns adopt a bionic structure to increase the capillary pressure of the flexible substrate serving as a liquid absorption core to pump the working fluid, effectively improve the gas-liquid circulation inside the flexible heat pipe, enhance the heat dissipation effect of the local area, thereby improving the heat dissipation capacity and environmental stability of the flexible heat pipe and increasing the service life of electronic equipment.

Description

Technical Field

[0001] The present invention relates to the field of flexible heat pipes, and in particular to a flexible heat pipe based on a bionic directional liquid transport structure and a manufacturing process thereof. Background Art

[0002] Flexible electronic technology involves multiple fields such as organic electronics, bioelectronics, and nanoelectronics. Continuous innovation in these fields has provided a strong impetus for the development of flexible electronic devices. At the same time, the application areas of flexible electronic devices have already covered a variety of scenarios such as sensors, flexible photovoltaics, flexible batteries, wearable devices, foldable phones, biosensors, implantable medical devices, and wearable medical monitoring systems. As the application areas of flexible electronic devices continue to expand, their heat dissipation needs are becoming increasingly prominent. To meet consumer demand for thinner and lighter products, the design of flexible electronic devices is becoming increasingly compact, which poses greater challenges to heat dissipation design. High-power consumption areas within flexible electronic devices become more densely concentrated, forming high-density energy areas. Most of the energy is ultimately converted into heat energy, resulting in a sharp increase in the effective heat load of the chip and a rapid increase in the temperature of some areas. In severe cases, it can cause "burning".

[0003] Flexible heat pipes are closed heat transfer elements that utilize the principle of liquid phase change to achieve high-performance heat transfer. They offer multiple advantages, including efficient heat dissipation, high reliability, strong flexibility and adaptability, environmental friendliness, insensitivity to vibration, low startup temperature, high thermal conductivity, good temperature uniformity, large deformation, large heat dissipation area, high bending fatigue life, and thinness. In particular, flexible heat pipes with polymer films or polymer-metal composite films as their shells also have electrical insulation properties, which can well meet the heat dissipation needs of flexible electronic devices such as multi-foldable screen mobile phones and wearable electronic devices. Flexible heat pipes typically include a flexible wick, an evaporation chamber, a condensation chamber, and a gas channel. The flexible wick is made of flexible material and can bend with the electronic device, thus meeting the heat dissipation needs of complex working conditions such as confined spaces and foldable electronic devices. However, current flexible heat pipes still have problems such as high internal gas-liquid circulation resistance, low pumping capacity of the wick material, and easy collapse of the gas-liquid space. This makes it difficult for flexible heat pipes to effectively control the gas-liquid flow, making the heat dissipation efficiency of flexible heat pipes difficult to meet the requirements. Summary of the Invention

[0004] The purpose of the present invention is to address the defects of the existing technology and provide a flexible heat pipe and manufacturing process based on a bionic directional liquid delivery structure. Liquid absorption channels and raised columns are formed on the flexible substrate of the flexible heat pipe. The raised columns adopt a bionic structure to increase the capillary pressure of the flexible substrate pumping the working fluid as the liquid absorption core, effectively improve the gas-liquid circulation inside the flexible heat pipe, enhance the heat dissipation effect of the local area, thereby improving the heat dissipation capacity and environmental stability of the flexible heat pipe and increasing the service life of electronic equipment.

[0005] The first object of the present invention is to provide a flexible heat pipe based on a biomimetic directional liquid transport structure, which adopts the following scheme:

[0006] It includes a flexible substrate, and multiple liquid absorption channels are formed inside the flexible substrate. Along the length direction of the liquid absorption channel, multiple V-shaped raised columns are arranged in sequence on the bottom surface of the liquid absorption channel. The tips of the raised columns corresponding to the V shape face the same end of the liquid absorption channel, and the raised columns corresponding to the V-shaped open ends are spaced apart from the side surfaces of the liquid absorption channel, so that the liquid in the liquid absorption channel is transported in a direction.

[0007] The second object of the present invention is to provide a flexible heat pipe based on a biomimetic directional liquid transport structure, which adopts the following scheme:

[0008] It includes a flexible substrate, and multiple liquid absorption channels are formed inside the flexible substrate. Along the length direction of the liquid absorption channel, multiple U-shaped raised columns are arranged at intervals on the bottom surface of the liquid absorption channel. The raised columns correspond to one end of the U-shaped arc facing the same end of the liquid absorption channel, and the raised columns correspond to both sides of the U-shaped open end and are spaced apart from the side surfaces of the liquid absorption channel, so that the liquid in the liquid absorption channel is transported in a direction.

[0009] Furthermore, an extension portion is provided at one end of the protruding column away from the inner bottom surface of the connected liquid suction channel, and the extension portion extends toward the inner side of the opening of the U-shaped protruding column to form a hanging structure.

[0010] Furthermore, along the width direction of the liquid suction channel, the width of the U-shaped opening end of the protrusion column is greater than the width of the U-shaped arc end of the protrusion.

[0011] The third object of the present invention is to provide a flexible heat pipe based on a biomimetic directional liquid transport structure, which adopts the following scheme:

[0012] The utility model comprises a flexible substrate, wherein a plurality of liquid absorption channels are formed inside the flexible substrate. Along the length direction of the liquid absorption channel, a plurality of raised columns are sequentially arranged on the side walls of the liquid absorption channel at intervals, and the raised columns form ratchet teeth. The ratchet teeth are obliquely distributed relative to the side walls of the liquid absorption channel. The ratchet teeth on the side walls of one side of the same liquid absorption channel are spaced apart from the ratchet teeth on the side walls of the other side. The ratchet teeth in the same liquid absorption channel are inclined toward the same end of the liquid absorption channel from one end of the side walls of the liquid absorption channel.

[0013] Furthermore, a perpendicular bisector of a line connecting the side walls of the liquid suction channel is used as a reference plane, and the ratchet teeth on the side walls of the liquid suction channel are symmetrically distributed relative to the reference plane.

[0014] Furthermore, the ratchet teeth on the same side wall of the liquid suction channel are distributed in parallel.

[0015] A fourth object of the present invention is to provide a manufacturing process for a flexible heat pipe based on a biomimetic directional liquid transport structure as described above, comprising:

[0016] A mixed liquid is prepared, the mixed liquid is filled into a mold, and after demolding, a flexible substrate with a liquid suction channel and raised columns is obtained, wherein the raised columns on the flexible substrate are arranged in the liquid suction channel;

[0017] A flexible substrate is used as a liquid wick and laid on the insulation section, a substrate cover is installed on the flexible substrate, and a gas-liquid cavity communicating with the liquid absorbing channel is formed between the flexible substrate and the substrate cover;

[0018] The condensing section and the evaporating section outside the two ends of the heat-insulating section are respectively connected with heat-conducting sheets to form a flexible heat pipe.

[0019] Furthermore, the mold is provided with characteristic structures of forming a liquid suction channel and a protruding column. When preparing the mixed liquid, the mixed liquid is defoamed and then filled into the mold.

[0020] Furthermore, the base bottom assembly and the base cover plate are made of the same material.

[0021] Compared with the prior art, the present invention has the following advantages and positive effects:

[0022] (1) In order to solve the problem that the heat dissipation efficiency of the current flexible heat pipe cannot meet the demand, a liquid absorption channel and a raised column are formed on the flexible substrate of the flexible heat pipe. The raised column adopts a bionic structure to increase the capillary pressure of the flexible substrate as the liquid absorption core to pump the working fluid, effectively improve the gas-liquid circulation inside the flexible heat pipe, enhance the heat dissipation effect in the local area, thereby improving the heat dissipation capacity and environmental stability of the flexible heat pipe and extending the service life of electronic equipment.

[0023] (2) The V-shaped raised column structure changes the shape and size of the liquid suction channel that forms the capillary channel, allowing the liquid to generate greater capillary pressure during the process of returning to the evaporation section of the flexible heat pipe, thereby enhancing the pumping capacity of the working fluid. The V-shaped raised column forms an asymmetric liquid suction channel, which helps reduce resistance during the liquid return process and increase the permeation return speed. By optimizing the structure of the liquid suction channel, the gas-liquid circulation is smoother, thereby improving the heat dissipation capacity of the heat pipe.

[0024] (3) The U-shaped raised column forms an asymmetric structure in the liquid absorption channel. The asymmetric structure can significantly enhance the capillary effect of the liquid, making it easier for the liquid to be adsorbed on the surface of the liquid absorption core. The liquid can reduce resistance during the penetration process, improve permeability, and reduce resistance during the liquid reflux process. The overhanging structure can effectively prevent the liquid from spreading in the opposite direction. The capillary channel formed by the asymmetric structure and the parallel microchannel can also quickly and directionally pump the liquid. The asymmetric micro-nanostructure with the overhanging structure can achieve directional liquid transmission with a lower contact angle, a longer transmission distance, and a faster transmission speed. It is conducive to the timely and rapid transportation of the condensed working medium inside the flexible heat pipe, and helps to solve the problem of insufficient capillary power of the traditional liquid absorption core.

[0025] (4) Multiple raised columns are arranged at intervals on the side walls of the liquid suction channel. The raised columns form ratchet teeth. Inclined ratchet structures are set on both sides of the parallel liquid suction channels to form bionic gear grooves. They can guide liquids of different properties to produce a certain transport direction on the surface of the structure, realizing unidirectional high-speed self-propulsion of the liquid. The design of the ratchet structure helps to reduce fluctuations and instability factors in the gas-liquid circulation process, thereby improving the circulation stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0027] Figure 1 Schematic diagram of a flexible substrate with V-shaped protruding columns in Examples 1 and 4 of the present invention.

[0028] Figure 2 Schematic diagram of a flexible substrate with U-shaped protruding columns in Examples 2 and 4 of the present invention.

[0029] Figure 3 Schematic diagram of the flexible substrate of the protruding columns forming the ratchet teeth in Examples 3 and 4 of the present invention.

[0030] Figure 4 Schematic diagram of the internal structure of the flexible heat pipe based on the bionic directional liquid transport structure in Examples 1-4 of the present invention.

[0031] Figure 5 Schematic diagram of the stretching of the flexible heat pipe in Examples 1-4 of the present invention.

[0032] Figure 6 Schematic diagram of the bending of the flexible heat pipe in Examples 1-4 of the present invention.

[0033] Figure 7 Schematic diagram of the twisting of the flexible heat pipe in Examples 1-4 of the present invention.

[0034] Among them, 1. flexible substrate; 2. liquid absorption channel; 3. raised column; 4. insulation section; 5. gas-liquid cavity; 6. condensation section; 7. evaporation section. DETAILED DESCRIPTION

[0035] Example 1

[0036] In a typical embodiment of the present invention, Figure 1 、 Figure 4-Figure 7 As shown, a flexible heat pipe based on a bionic directional liquid transport structure is provided.

[0037] Current flexible heat pipes suffer from issues such as high internal gas-liquid circulation resistance, low fluid pumping capacity of the wick material, and easy collapse of the gas-liquid space. These issues make it difficult for flexible heat pipes to meet heat dissipation requirements. Based on this, this embodiment proposes a flexible heat pipe based on a biomimetic directional liquid transport structure. By forming a liquid absorption channel 2 and a biomimetic raised column 3 on the flexible base 1 of the flexible heat pipe, the heat dissipation capacity and environmental stability of the flexible heat pipe are improved.

[0038] The main structure of the flexible heat pipe based on the bionic directional liquid transport structure is a flexible substrate 1, which is made of flexible materials and can bend with electronic devices to meet the heat dissipation requirements under complex working conditions. Figure 4 As shown, the flexible substrate 1 is arranged in the flexible heat pipe as a liquid absorption core, and a gas-liquid cavity 5 is formed in the flexible heat pipe. Gas and liquid coexist in the gas-liquid cavity 5. The flexible substrate 1 can transport the liquid in the flexible heat pipe and move the liquid from the condensation section 6 to the evaporation section 7.

[0039] like Figure 1 As shown, a liquid aspiration channel 2 is formed within the flexible substrate 1 and is used for liquid transport and circulation during evaporation and condensation. The aspiration channel 2 utilizes a grooved capillary structure to transport liquid within the aspiration channel 2. Raised columns 3 are arranged sequentially along the length of the aspiration channel 2, with multiple V-shaped raised columns 3 spaced sequentially along the bottom surface of the channel 2. These columns 3 utilize a biomimetic structure, mimicking biological structures found in nature, to enhance the unidirectional transport of liquids.

[0040] In this embodiment, the V-shaped raised column 3 is inspired by the surface structure of a lizard and a pitcher plant, and is combined with the liquid suction channel 2 to form a bionic directional liquid transport structure. The surface structure of the lizard and the pitcher plant can achieve rapid and directional spreading of the liquid, and the ultra-thin water film formed can enhance the evaporation efficiency of the liquid working medium.

[0041] The V-shaped tips of the raised columns 3 face the same end of the liquid pipetting channel 2, and the two sides of the V-shaped opening are spaced apart from the sides of the liquid pipetting channel 2, so that the liquid forms a unidirectional flow in the liquid pipetting channel 2, thereby improving the liquid transmission efficiency.

[0042] By designing a bionic directional liquid delivery structure, the flow resistance of the liquid in the liquid suction channel 2 is reduced, and the gas-liquid circulation efficiency is improved. The raised columns 3 of the bionic structure increase the capillary pressure of the liquid suction core and improve the ability to pump the working medium. The structural stability of the flexible heat pipe is enhanced, and the collapse of the gas-liquid space is avoided. When applied to electronic devices, the flexible heat pipe has good deformation ability and can be applied to a variety of electronic devices, such as Figure 5-Figure 7 As shown, effective heat dissipation can reduce the temperature of electronic equipment, reduce equipment damage caused by overheating, and thus extend the service life of electronic equipment.

[0043] Example 2

[0044] In a typical embodiment of the present invention, Figure 2 、 Figure 4-Figure 7 As shown, a flexible heat pipe based on a bionic directional liquid transport structure is provided.

[0045] In this embodiment, the U-shaped raised column 3 is inspired by the surface structure of a bionic lizard and a pitcher plant, and is combined with the liquid suction channel 2 to form a bionic directional liquid transport structure. Different from Example 1, the flexible heat pipe based on the bionic directional liquid transport structure provided in this embodiment is characterized in that the U-shaped raised column 3 is arranged on the internal liquid suction channel 2. The liquid suction channel 2 and the U-shaped raised column 3 work together to achieve unidirectional transport of the liquid, thereby improving the heat dissipation efficiency of the flexible heat pipe.

[0046] like Figure 2 As shown, the flexible heat pipe based on the bionic directional liquid transport structure includes a flexible substrate 1. The flexible substrate 1 serves as the main support structure of the flexible heat pipe and can bend with the electronic device, such as Figure 5-Figure 7 As shown, it can meet the heat dissipation requirements under complex working conditions. A plurality of liquid absorption channels 2 are formed inside the flexible substrate 1 for liquid transmission and liquid circulation during evaporation and condensation.

[0047] The liquid absorption channel 2, located within the flexible substrate 1, provides a flow path for the liquid, ensuring efficient circulation between the evaporation chamber and the condensation chamber. Multiple U-shaped protrusions 3 are arranged at intervals along its length on the inner bottom surface of the liquid absorption channel 2. The flexible substrate 1 serves as a liquid absorption wick within the flexible heat pipe, forming a gas-liquid cavity 5 within which gas and liquid coexist. The flexible substrate 1 transports the liquid within the flexible heat pipe, moving it from the condensation section 6 to the evaporation section 7.

[0048] like Figure 2 As shown, the raised columns 3 are U-shaped, with one curved end facing the same end of the aspiration channel 2 and the open ends spaced from the sides of the aspiration channel 2. Their unique shape and arrangement guide unidirectional liquid transport within the aspiration channel 2, improving heat dissipation efficiency. The aspiration channel 2 is formed within the flexible substrate 1 and is used for liquid transport and circulation during evaporation and condensation. The aspiration channel 2 utilizes a grooved capillary structure to transport liquid within the aspiration channel 2.

[0049] An extension portion is provided at one end of the protruding column 3 away from the inner bottom surface of the connected liquid suction channel 2, extending toward the inner side of the opening of the U-shaped protruding column 3 to form a hanging structure, which is used to further increase the capillary action of the liquid and promote the unidirectional flow of the liquid.

[0050] Along the width of the liquid suction channel 2, the width of the open end of the U-shaped protrusion 3 is greater than the width of the curved end, which helps to generate a certain pressure difference during the liquid flow, thereby enhancing the unidirectional liquid transport effect. The design of the U-shaped protrusion 3 and its extension achieves unidirectional liquid transport and improves heat dissipation efficiency. The design of the open end of the U-shaped protrusion 3 being wider than the curved end helps to reduce the resistance of the liquid during the flow process, allowing the liquid to flow more smoothly.

[0051] The U-shaped raised column 3 makes the liquid absorption channel 2 form an asymmetric structure. The asymmetric structure can significantly enhance the capillary effect of the liquid, making it easier for the liquid to be adsorbed onto the surface of the liquid absorption core. The liquid can reduce resistance during the penetration process, improve permeability, and reduce resistance during the liquid reflux process. The asymmetric micro-nanostructure with a pendant structure can achieve directional liquid transmission with a lower contact angle, a longer transmission distance, and a faster transmission speed, which is conducive to the timely and rapid delivery of the condensed working medium inside the flexible heat pipe, and helps to solve the problem of insufficient capillary power of the traditional liquid absorption core.

[0052] Example 3

[0053] In a typical embodiment of the present invention, Figure 3 、 Figure 4-Figure 7 As shown, a flexible heat pipe based on a bionic directional liquid transport structure is given.

[0054] In this embodiment, the ratchet structure raised column 3 is biomimetic on the surface structure of green plants and pitcher plants, and is combined with the liquid suction channel 2 to form a biomimetic directional liquid transport structure. The diffusion mode of the selective directional liquid transport of green plants causes the liquid to be periodically transported in its preferred direction, and the pinning site can also promote spontaneous and continuous liquid transport. Different from Example 1, the flexible heat pipe based on the biomimetic directional liquid transport structure provided in this embodiment is that the raised column 3 is arranged on the side wall of the liquid suction channel 2 inside it, thereby forming a ratchet structure that imitates nature, optimizing the liquid flow path inside the flexible heat pipe, and achieving more efficient and directional liquid transport. Not only is the heat dissipation efficiency of the flexible heat pipe improved, but also its structural stability and adaptability are enhanced.

[0055] like Figure 3 As shown, the flexible heat pipe based on a biomimetic directional liquid transport structure includes a flexible substrate 1, which serves as the main body of the flexible heat pipe. It provides the necessary flexibility and strength, allowing it to bend with electronic devices to meet the heat dissipation requirements of various complex working conditions. Multiple liquid absorption channels 2 are formed on the flexible substrate 1, serving as the main paths for liquid flow within the flexible heat pipe.

[0056] The aspiration channel 2 provides a flow path for the liquid, ensuring efficient circulation between the evaporation and condensation zones, thereby achieving heat transfer and dissipation. The aspiration channel 2 employs a grooved capillary structure, transporting liquid within the channel. Multiple raised columns 3 are spaced along the length of the channel 2 on its sidewalls, forming a ratchet structure.

[0057] The raised columns 3 form ratchet teeth, which are tilted relative to the sidewalls of the liquid absorption channel 2 at a specific angle. This tilted arrangement of the ratchet teeth guides the liquid flow in a directional manner within the liquid absorption channel 2, improving heat dissipation efficiency. The flexible substrate 1 serves as a liquid absorption wick within the flexible heat pipe, forming a gas-liquid cavity 5 within the flexible heat pipe. Gas and liquid coexist within the cavity 5. The flexible substrate 1 transports the liquid within the flexible heat pipe, moving it from the condensation section 6 to the evaporation section 7.

[0058] like Figure 3 As shown, the ratchet teeth on one side of the same aspiration channel 2 are spaced apart from those on the other side, preventing excessive obstruction to liquid flow. Using the perpendicular bisector of the line connecting the two side walls of the aspiration channel 2 as a reference plane, the ratchet teeth on each side of the aspiration channel 2 are symmetrically arranged relative to the reference plane, ensuring more uniform liquid flow within the aspiration channel 2. The parallel orientation of the ratchet teeth on the same side wall of the aspiration channel 2 further enhances the directionality and stability of liquid flow.

[0059] Traditional flexible heat pipes often lack directional flow, resulting in low heat dissipation efficiency. The present invention, by introducing a ratchet structure, achieves directional flow of liquid and improves heat dissipation efficiency. Flexible heat pipes are susceptible to structural instability under complex operating conditions, which can affect heat dissipation. The present invention enhances the structural stability of the flexible heat pipe by optimizing the distribution and shape of the ratchet structure.

[0060] Multiple raised columns 3 are arranged at intervals on the sidewalls of the aspiration channel 2. These columns 3 form ratchet teeth. Inclined ratchet structures are placed on either side of the parallel aspiration channel 2, forming a biomimetic ratchet groove. This structure guides liquids of varying properties in a defined direction along the surface of the structure, achieving unidirectional, high-speed self-propulsion of the liquid. The ratchet structure helps reduce fluctuations and instabilities in the gas-liquid circulation process, thereby improving cycle stability.

[0061] Example 4

[0062] In another typical embodiment of the present invention, Figure 1-Figure 7 As shown, a manufacturing process of a flexible heat pipe based on a bionic directional liquid transport structure is provided, using the flexible heat pipe based on a bionic directional liquid transport structure as in Example 1.

[0063] A manufacturing process of a flexible heat pipe based on a biomimetic directional liquid transport structure, comprising:

[0064] A mixed liquid is prepared, and the mixed liquid is filled into a mold. After demolding, a flexible substrate 1 with a liquid suction channel 2 and a protruding column 3 is obtained, wherein the protruding column 3 on the flexible substrate 1 is arranged in the liquid suction channel 2;

[0065] The flexible substrate 1 is used as a liquid wick and laid on the insulation section 4. A substrate cover is installed on the flexible substrate 1, and a gas-liquid cavity 5 connected to the liquid absorbing channel 2 is formed between the flexible substrate 1 and the substrate cover.

[0066] The condensing section 6 and the evaporating section 7 outside the two ends of the heat-insulating section 4 are respectively connected to heat-conducting sheets to form a flexible heat pipe.

[0067] In this embodiment, polydimethylsiloxane (PDMS) is used as the material for preparing the flexible substrate 1. The biomimetic PDMS sample manufactured using polymer PDMS has good flexibility. Figure 5 、 Figure 6 and Figure 7 , the stretching, bending and twisting of biomimetic PDMS samples can be achieved.

[0068] Polydimethylsiloxane (PDMS) has many excellent properties such as flexibility, biocompatibility, thermal stability, chemical inertness, corrosion resistance, low cost, ease of use, proliferation characteristics and breathability. This patent mainly utilizes the properties of PDMS, such as its certain elasticity, easy adhesion to heterogeneous materials, and ability to well reproduce biomimetic microstructure surfaces. During the demolding process, the cured PDMS sample can be easily peeled off from the mold without damaging the microstructure of the mold, which is conducive to the recycling of the mold, the reuse of the mold and the mass production of biomimetic structure surfaces. PDMS is the main material for processing biomimetic surfaces and is composed of a matrix and a curing agent.

[0069] Mold Preparation Process: A mold with a special biomimetic surface structure was fabricated using standard photolithography techniques. A layer of SU-8 photoresist was applied to a silicon wafer using a spin coater at 3000 rpm. The soft-baked silicon wafer was then exposed to high-intensity UV light through the pattern on the mask. After development with propylene glycol methyl ether (PGME) and hard baking, a mold with the characteristic structures of the liquid aspiration channel 2 and the raised pillars 3 was obtained.

[0070] The preparation process of the flexible substrate 1 includes the following steps:

[0071] Prepare the glue: Pour the PDMS matrix into the container along the wall of the cup, and use a disposable dropper to absorb a certain amount of liquid curing agent. The mass ratio of matrix to curing agent is 10:1.

[0072] Stirring: Use a glass rod to stir continuously and evenly to ensure that the matrix and curing agent are fully mixed;

[0073] Vacuum defoaming: put the mixed liquid into a vacuum drying oven and perform vacuum operation to ensure that the bubbles in the mixed liquid disappear completely;

[0074] After secondary defoaming and curing, the mold filled with PDMS mixture is placed in a vacuum drying oven again for vacuuming;

[0075] After defoaming, the vacuum drying oven is heated to completely solidify the bionic structure.

[0076] Demolding and cutting: different structures are cut and sorted on a clean platform, the integrity of the structure is observed through an optical microscope, and the appropriate flexible substrate 1 is selected for subsequent experiments.

[0077] A flexible substrate 1 made of PDMS serves as the liquid wick structure within the insulating section 4, laid on the lower surface of the insulating section 4. A large groove cavity made of PDMS serves as the cover of the insulating section 4. Uncured PDMS liquid seals the two, and after curing, forms a closed gas-liquid cavity 5. This flexible assembly serves as the flexible insulating section 4.

[0078] A condensation section 6 and an evaporation section 7 are formed outside the two ends of the insulation section 4. The condensation section 6 and the evaporation section 7 are respectively connected to the heat conducting plates. The heat conducting plates connected to the evaporation section 7 and the condensation section 6 are both copper plates with high thermal conductivity, which are sensitive to changes in ambient temperature and can achieve effective heat dissipation.

[0079] The evaporation section 7 and the condensation section 6 of the heat pipe are connected by casting. When the PDMS is completely solidified, the shell of the entire heat pipe is an integral molding with extremely high airtightness.

[0080] The copper sheet and insulation section 4 are connected with glue. Apply a moderate amount of glue evenly to the clean, oil-free connection surface, ensuring that the glue covers the entire contact surface. Mechanical devices such as hose clamps can be used to mechanically reinforce the connection to ensure stability and airtightness. Compared to welding, adhesive bonding is not limited by material type or thickness, offers lower cost, lighter weight, and improved strength. Laser surface pretreatment can improve the surface roughness and chemical activity of the material, thereby enhancing the bond between the glue and the material and improving the strength and durability of the adhesive joint.

[0081] It is important to avoid bubbles or cracks during the pouring process; the pouring layer should be as thin as possible to reduce thermal resistance. When gluing, ensure that the connection surface is clean, free of oil and impurities to improve bonding strength. The glue should be applied evenly to avoid gaps and maintain good airtightness to prevent refrigerant leakage inside the heat pipe.

[0082] After each step of operation, a quality inspection should be carried out to promptly identify and resolve problems. The above method can produce a flexible heat pipe with excellent performance and stable structure, which is suitable for various occasions requiring efficient heat dissipation.

[0083] After the flexible heat pipe is prepared, reliability tests should be carried out, such as air tightness test (use pressure testing equipment to test the heat pipe for air tightness to ensure that there is no internal leakage), thermal performance test (heat the evaporation section 7 and monitor the temperature change of the condensation section 6 to evaluate the heat transfer efficiency of the heat pipe), durability test (simulate vibration, temperature changes and other conditions in actual applications to test the long-term stability and durability of the heat pipe), etc.

[0084] The main factors affecting the heat flow of flexible heat pipes are insufficient pumping capacity of the wick material, capillary pressure and liquid flow pressure drop of the wick, and liquid penetration and reflux rate. In this embodiment, a flexible substrate 1 with a bionic directional liquid transport structure is used as the wick, replacing the traditional capillary wick as the capillary structure of the new flexible heat pipe, which can significantly improve the performance of the flexible heat pipe.

[0085] Flexible heat pipes based on biomimetic directional liquid transport structures can increase the capillary pressure of the pumped fluid within the flexible heat pipe wick material, effectively improving gas-liquid circulation within the flexible heat pipe and enhancing localized heat dissipation, thereby enhancing the heat dissipation capacity and environmental stability of the flexible heat pipe and increasing the service life of electronic devices. Flexible heat pipes based on biomimetic directional liquid transport structures can achieve a rectification coefficient that is different from that of traditional flexible heat pipes. The rectification coefficient k of a biomimetic directional liquid transport surface is defined as the ratio of the liquid transport distance in the spreading direction (positive direction) to the pinning direction (negative direction). Liquid directional transport experiments were conducted on the biomimetic surface, and the liquid rectification coefficient of the biomimetic surface was measured and calculated. In comparison, traditional wick materials have no rectification effect, i.e., k = 1. By manipulating the parameters of the biomimetic directional liquid transport structure of the wick, its rectification coefficient can reach k > 1.5. Therefore, from the perspective of the rectification coefficient, the biomimetic directional liquid transport structure can more accurately transport the condensed fluid from the condensing end to the evaporating end, improving the heat dissipation performance of the flexible heat pipe.

[0086] Flexible heat pipes based on bionic directional liquid transport structures can achieve a total thermal coefficient that is different from traditional flexible heat pipes. When the direction from the condensation end to the evaporation end in the bionic heat pipe is consistent with the liquid spreading direction on the bionic surface, the heat transfer coefficient (equivalent heat transfer coefficient) of the heat pipe at this time is called the positive heat transfer coefficient, and vice versa, it is called the negative heat transfer coefficient. The ratio of the positive heat transfer coefficient to the negative heat transfer coefficient is defined as the total thermal coefficient n of the heat pipe. The total thermal coefficient of the flexible heat pipe based on the traditional liquid wick is equal to 1, while the flexible heat pipe based on the bionic directional liquid transport structure can adjust the total thermal coefficient to be greater than 1 or less than 1, and can be applied to different heat transfer and heat dissipation scenarios.

[0087] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A flexible heat pipe based on a biomimetic directional liquid transport structure, characterized in that: The invention comprises a flexible substrate, wherein a plurality of liquid absorption channels are formed inside the flexible substrate. A plurality of U-shaped raised columns are sequentially arranged on the bottom surface of the liquid absorption channel along the length direction of the liquid absorption channel. The raised columns correspond to one end of the U-shaped arc toward the same end of the liquid absorption channel, and the raised columns correspond to both sides of the U-shaped open end and are spaced apart from the side surfaces of the liquid absorption channel, so that the liquid in the liquid absorption channel is transported in a directional manner. An extension portion is provided at one end of the protruding column away from the inner bottom surface of the connected liquid suction channel, and the extension portion extends toward the inner side of the opening of the U-shaped protruding column to form a hanging structure; Along the width direction of the liquid suction channel, the width of the U-shaped opening end of the protrusion column is greater than the width of the U-shaped arc end of the protrusion.

2. A manufacturing process for a flexible heat pipe based on a biomimetic directional liquid delivery structure, comprising manufacturing the flexible heat pipe based on a biomimetic directional liquid delivery structure as claimed in claim 1, characterized in that: include: A mixed liquid is prepared, the mixed liquid is filled into a mold, and after demolding, a flexible substrate with a liquid suction channel and raised columns is obtained, wherein the raised columns on the flexible substrate are arranged in the liquid suction channel; A flexible substrate is used as a liquid wick and laid on the insulation section, a substrate cover is installed on the flexible substrate, and a gas-liquid cavity communicating with the liquid absorbing channel is formed between the flexible substrate and the substrate cover; The condensing section and the evaporating section outside the two ends of the heat-insulating section are respectively connected with heat-conducting sheets to form a flexible heat pipe.

3. The manufacturing process of the flexible heat pipe based on the bionic directional liquid transport structure according to claim 2, characterized in that: The mold is provided with characteristic structures of a formed liquid suction channel and a protruding column. When preparing the mixed liquid, the mixed liquid is defoamed and then filled into the mold.

4. The manufacturing process of the flexible heat pipe based on the biomimetic directional liquid transport structure according to claim 2, characterized in that: The flexible substrate and the substrate cover are made of the same material.

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