Flexible heat pipe based on bionic directional liquid conveying structure and manufacturing process

Abstract

The invention provides a flexible heat pipe based on a bionic directional liquid conveying structure and a manufacturing process, relates to the field of flexible heat pipes, and aims to solve the problem that the heat dissipation efficiency of a current flexible heat pipe is difficult to meet the requirement. A liquid suction channel and a protruding column are formed on a flexible base body of the flexible heat pipe, and the protruding column is of a bionic structure; the capillary pressure of the working medium pumped by the flexible substrate serving as the wick is improved, the gas-liquid circulation in the flexible heat pipe is effectively improved, and the heat dissipation effect of a local area is enhanced, so that the heat dissipation capability and the environmental stability of the flexible heat pipe are improved, and the service life of electronic equipment is prolonged.

Description

Technical Field

[0001] The 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 covered multiple scenarios such as sensors, flexible photovoltaics, flexible batteries, wearable devices, folding mobile 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. In order to meet consumers' demand for thin and light products, the design of flexible electronic devices is becoming more and more compact, which brings greater challenges to heat dissipation design. The high-power consumption areas inside flexible electronic devices become more densely concentrated, thus forming high-density energy areas. Most of the energy is eventually 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, which can cause "burning" in severe cases.

[0003] Flexible heat pipes are closed heat transfer elements that use the principle of liquid phase change to achieve high-performance heat transfer. They have multiple advantages, such as efficient heat dissipation, high reliability, strong flexibility and adaptability, environmental protection and pollution-free, insensitive to vibration, low starting 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 shells also have electrical insulation properties, which can well meet the heat dissipation needs of flexible electronic devices such as multi-folding screen mobile phones and wearable electronic devices. Flexible heat pipes usually include parts such as flexible wicks, evaporation chambers, condensation chambers, and gas channels. The flexible wick is made of flexible materials and can be bent with electronic devices, so that it can meet the heat dissipation needs of complex working conditions such as small spaces and foldable electronic devices. However, the current flexible heat pipes still have problems such as large internal gas-liquid circulation resistance, small pumping capacity of the wick material, and easy collapse of the gas-liquid space, which makes it difficult for flexible heat pipes to effectively regulate gas-liquid flow, making it difficult for the heat dissipation efficiency of flexible heat pipes to meet the needs. Summary of the invention

[0004] The purpose of the present invention is to address the defects of the prior art and provide a flexible heat pipe and a 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, and enhance the heat dissipation effect in 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 bionic directional liquid transport structure, using the following scheme:

[0006] The invention comprises a flexible substrate, wherein a plurality of liquid absorption channels are formed inside the flexible substrate. A plurality of V-shaped raised columns are sequentially arranged at intervals on the inner bottom surface of the liquid absorption channel along the length direction 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-shape open ends are spaced apart from the sides of the liquid absorption channel respectively, so that the liquid in the liquid absorption channel is transported in a directionally manner.

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

[0008] The invention 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 U-shaped raised columns are arranged at intervals on the inner bottom surface of the liquid absorption channel. One end of the raised column corresponding to the arc of the U shape faces the same end of the liquid absorption channel. Both sides of the raised column corresponding to the open end of the U shape 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 protruding column is greater than the width of the arc-shaped end of the protrusion corresponding to the U-shape.

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

[0012] The invention comprises a flexible substrate, wherein a plurality of liquid absorption channels are formed inside the flexible substrate, and a plurality of raised columns are sequentially arranged on the side walls of the liquid absorption channels at intervals along the length direction of the liquid absorption channels, wherein the raised columns form ratchet teeth, and the ratchet teeth are obliquely distributed relative to the side walls of the liquid absorption channels, and the ratchet teeth on the side walls on one side of the same liquid absorption channel are spaced apart from the ratchet teeth on the side walls on the other side, and the end of the ratchet teeth in the same liquid absorption channel away from the side walls of the liquid absorption channel is inclined toward the same end 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 of a flexible heat pipe based on a bionic directional liquid transport structure as described above, comprising:

[0016] A mixed liquid is prepared, and the mixed liquid is filled into a mold, and a flexible substrate with a liquid suction channel and protruding columns is obtained after demolding, wherein the protruding 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 connected to a 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 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.

[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 protruding column are formed on the flexible substrate of the flexible heat pipe. The protruding 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, and enhance the heat dissipation effect in the local area, thereby improving the heat dissipation capacity and environmental stability of the flexible heat pipe and prolonging 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, so that the liquid can generate greater capillary pressure during the reflux process 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 to reduce resistance during the reflux process and increase the penetration reflux rate. 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 makes the liquid absorption channel 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 overhanging structure can effectively prevent the liquid from spreading in reverse, and 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 transmission of liquid 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 fluid 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 wall of the liquid suction channel, and the raised columns form ratchet teeth. Inclined ratchet structures are arranged on both sides of the parallel liquid suction channels to form bionic gear grooves, which can guide liquids of different properties to produce a certain transport direction on the surface of the structure, thereby realizing unidirectional high-speed self-propulsion of the liquid. The design of the ratchet structure helps to reduce fluctuations and unstable factors in the gas-liquid circulation process, thereby improving the circulation stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings in the specification, 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] The current flexible heat pipe has problems such as large internal gas-liquid circulation resistance, low working fluid pumping capacity of the liquid wick material, and easy collapse of the gas-liquid space, which makes it difficult for the heat dissipation efficiency of the flexible heat pipe to meet the demand. Based on this, this embodiment proposes a flexible heat pipe based on a bionic directional liquid delivery structure. By forming a liquid absorption channel 2 and a raised column 3 with a bionic structure on the flexible substrate 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 delivery 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, the liquid absorption channel 2 is formed inside the flexible substrate 1, which is used for liquid transmission and liquid circulation during evaporation and condensation. The liquid absorption channel 2 adopts a groove-type capillary structure, and the liquid is transported in the liquid absorption channel 2. The raised columns 3 are arranged in sequence along the length direction of the liquid absorption channel 2, and a plurality of V-shaped raised columns 3 are arranged in sequence on the bottom surface of the liquid absorption channel 2. The raised columns 3 adopt a bionic structure, imitating the biological structure in nature, to improve the unidirectional transport capability of the liquid.

[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 directional spreading of the liquid, and the formed ultra-thin water film 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 pipetting channel 2, and the two sides of the V-shaped opening are spaced apart from the sides of the pipetting channel 2, so that the liquid forms a unidirectional flow in the 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 absorption channel 2 is reduced, and the gas-liquid circulation efficiency is improved. The raised column 3 of the bionic structure increases the capillary pressure of the liquid absorption core and improves the ability to pump the working medium. The structural stability of the flexible heat pipe is enhanced, and the collapse problem of the gas-liquid space is avoided. When applied to electronic devices, the flexible heat pipe can be applied to a variety of electronic devices due to its good deformation ability, such as Figure 5-Figure 7 As shown, effective heat dissipation can reduce the temperature of electronic equipment and reduce equipment damage caused by overheating, thereby extending 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 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 that the U-shaped raised column 3 is arranged on the liquid suction channel 2 inside it. 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, which serves as the main support structure of the flexible heat pipe and can be bent along with the electronic device. 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 is located inside the flexible substrate 1, providing a flow path for the liquid to ensure effective circulation of the liquid between the evaporation chamber and the condensation chamber. Along its length, a plurality of U-shaped protrusions 3 are arranged at intervals on the inner bottom surface of the liquid absorption channel 2. 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.

[0048] like Figure 2 As shown, the raised column 3 is U-shaped, with one arc end facing the same end of the liquid suction channel 2, and the two sides of the open end are spaced from the sides of the liquid suction channel 2. Through its special shape and arrangement, the liquid is guided to be transported unidirectionally in the liquid suction channel 2 to improve the heat dissipation efficiency. The liquid suction channel 2 is formed inside the flexible substrate 1 and is used for liquid transmission and liquid circulation during evaporation and condensation. The liquid suction channel 2 adopts a groove-type capillary structure, and the liquid is transported in the liquid suction channel 2.

[0049] An end of the protruding column 3 away from the inner bottom surface of the connected liquid suction channel 2 is provided with an extension portion, which extends 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 direction of the liquid suction channel 2, the width of the open end of the U-shaped protrusion column 3 is greater than the width of the arc-shaped end, which helps to generate a certain pressure difference during the flow of the liquid, thereby enhancing the unidirectional delivery effect of the liquid. By designing the U-shaped protrusion column 3 and its extension, the unidirectional delivery of the liquid is achieved and the heat dissipation efficiency is improved. The design that the width of the open end of the U-shaped protrusion column 3 is greater than the width of the arc-shaped end helps to reduce the resistance of the liquid during the flow process, so that the liquid can 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-nano structure with a pendant structure can achieve directional transmission of liquid 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 condensing working fluid 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 provided.

[0054] In this embodiment, the protruding column 3 of the ratchet structure is biomimetic to the surface structure of green plants and pitcher plants, and is combined with the liquid absorption channel 2 to form a biomimetic directional liquid transport structure. The diffusion mode of the selective directional liquid transport of green plants enables 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 protruding column 3 is arranged on the side wall of the liquid absorption channel 2 inside it, thereby forming a ratchet structure that imitates nature, optimizing the liquid flow path inside the flexible heat pipe, and realizing more efficient and directional liquid delivery. Not only the heat dissipation efficiency of the flexible heat pipe is improved, but also its structural stability and adaptability are enhanced.

[0055] like Figure 3 As shown, the flexible heat pipe based on the bionic directional liquid transport structure includes a flexible substrate 1, which is the main part of the flexible heat pipe and provides the necessary flexibility and strength, and can be bent with the electronic device to meet the heat dissipation requirements under various complex working conditions. A plurality of liquid absorption channels 2 are formed on the flexible substrate 1 as the main path for the liquid to flow inside the flexible heat pipe.

[0056] The liquid suction channel 2 provides a flow path for the liquid to ensure that the liquid circulates effectively between the evaporation zone and the condensation zone, thereby achieving heat transfer and heat dissipation. The liquid suction channel 2 adopts a groove-type capillary structure, and the liquid is transported in the liquid suction channel 2. Along the length direction of the liquid suction channel 2, a plurality of raised columns 3 are sequentially arranged at intervals on the side wall of the liquid suction channel 2, and the raised columns 3 form a ratchet structure.

[0057] The protruding column 3 forms ratchet teeth, which are inclined relative to the side wall of the liquid absorption channel 2 to form a certain angle. The inclined distribution of the ratchet teeth guides the liquid to flow in the liquid absorption channel 2 in a directional manner, thereby improving the heat dissipation efficiency. 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.

[0058] like Figure 3 As shown, the ratchet teeth on one side wall of the same liquid suction channel 2 are spaced apart from the ratchet teeth on the other side wall to prevent the liquid from being obstructed too much during the flow. The vertical bisector of the line connecting the two side walls of the liquid suction channel 2 is used as the reference plane, and the ratchet teeth on the two side walls of the liquid suction channel 2 are symmetrically distributed relative to the reference plane to ensure that the liquid flows more evenly in the liquid suction channel 2. The ratchet teeth on the same side wall of the liquid suction channel 2 are distributed in parallel, further enhancing the directionality and stability of the liquid flow.

[0059] The flow of liquid inside a conventional flexible heat pipe often lacks directionality, resulting in low heat dissipation efficiency. The present invention achieves directional flow of liquid and improves heat dissipation efficiency by introducing a ratchet structure. Flexible heat pipes are prone to affect heat dissipation effects due to structural instability under complex working conditions. The present invention enhances the structural stability of the flexible heat pipe by optimizing the distribution and shape of the ratchet structure.

[0060] A plurality of raised columns 3 are arranged at intervals on the side wall of the liquid suction channel 2, and the raised columns 3 form ratchets. Inclined ratchet structures are respectively arranged on both sides of the parallel liquid suction channel 2 to form a bionic ratchet groove, which can guide liquids of different properties to produce a certain transport direction on the surface of the structure, and realize unidirectional high-speed self-propulsion of the liquid. The ratchet structure helps to reduce fluctuations and unstable factors in the gas-liquid circulation process, thereby improving the circulation 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 bionic directional liquid transport structure, comprising:

[0064] Prepare a mixed liquid, fill the mixed liquid into a mold, and after demolding, obtain a flexible substrate 1 with a liquid suction channel 2 and a protruding column 3, 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 heat 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 condensation section 6 and the evaporation section 7 outside the two ends of the insulation 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 bionic PDMS sample manufactured using the polymer PDMS has good flexibility. Figure 5 , Figure 6 and Figure 7 , the stretching, bending and twisting of bionic 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 uses the properties of PDMS, such as its certain elasticity, easy bonding with heterogeneous materials, and its ability to reproduce bionic 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 bionic structure surfaces. PDMS is the main material for processing bionic surfaces, consisting of a matrix and a curing agent.

[0069] Mold preparation process: A mold with a special biomimetic structure surface was manufactured using standard photolithography technology. A layer of SU-8 photoresist was coated on a silicon wafer using a spin coater at a speed of 3000 rpm. The soft-baked silicon wafer was then exposed to high-intensity ultraviolet light through the pattern on the mask. After development with propylene glycol methyl ether of pyruvate and hard baking, a mold with a characteristic structure of a formed liquid suction channel 2 and a protruding column 3 was obtained.

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

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

[0072] Stirring: Use a glass rod to stir continuously and at a uniform speed 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 the PDMS mixture is placed in the 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 a suitable flexible substrate 1 is selected for subsequent experiments.

[0077] The flexible substrate 1 made of PDMS is used as the liquid wick structure in the insulation section 4 and is laid on the lower surface of the insulation section 4; the large groove cavity made of PDMS is used as the cover of the insulation section 4; the uncured PDMS liquid is used to seal the two, and after curing, a closed gas-liquid cavity 5 is formed. The flexible assembly is used as the flexible insulation 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 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 integrally formed body with extremely high airtightness.

[0080] The copper sheet and the insulation section 4 are connected with glue. A proper amount of glue is evenly applied on the clean and oil-free connection surface to ensure that the glue covers the entire contact surface. Mechanical devices such as hose clamps can be used to mechanically connect and reinforce the connection parts to ensure the stability and airtightness of the connection. Compared with welding technology, adhesive bonding technology is not limited by material variety and thickness, has lower cost, lighter weight, and improved strength. Through laser surface pretreatment technology, the roughness and chemical activity of the material surface can be improved, thereby enhancing the bonding force between the glue and the material and improving the strength and durability of the adhesive joint.

[0081] It should be pointed out that bubbles or cracks should be avoided during the pouring process; the pouring layer should be as thin as possible to reduce thermal resistance. When connecting with glue, the connection surface should be clean, free of oil and impurities to improve the 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 find and solve problems in time. Through the above method, a flexible heat pipe with excellent performance and stable structure can be prepared, 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 the flexible heat pipe are the insufficient pumping capacity of the wick material, the capillary pressure of the wick and the liquid flow pressure drop, the penetration and reflux rate of the liquid, etc. In this embodiment, the flexible substrate 1 with a bionic directional liquid transport structure is used as the wick, replacing the traditional structure 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 bionic directional liquid transport structures can improve the capillary pressure of the pumped fluid of the flexible heat pipe wick material, effectively improve the gas-liquid circulation inside the flexible heat pipe, and enhance the heat dissipation effect in the local area, thereby improving the heat dissipation capacity and environmental stability of the flexible heat pipe and improving the service life of electronic equipment. Flexible heat pipes based on bionic directional liquid transport structures can achieve a rectification coefficient that is different from that of traditional flexible heat pipes. The rectification coefficient k of the bionic directional liquid transport surface is defined as the ratio of the transmission distance of the liquid in the spreading direction (positive direction) and in the pinning direction (reverse direction). By conducting liquid directional transport experiments on the bionic surface, the liquid rectification coefficient of the bionic surface is measured and calculated. In comparison, the traditional wick material has no rectification effect, that is, k = 1. By adjusting the parameters of the bionic directional liquid transport structure of the wick, its rectification coefficient can reach k>1.5. Therefore, from the perspective of rectification coefficient, the bionic directional liquid transport structure can more accurately transport the condensed working fluid from the condensation end to the evaporation end, thereby 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 above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A flexible heat pipe based on a bionic 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 V-shaped raised columns are sequentially arranged at intervals on the inner bottom surface of the liquid absorption channel along the length direction 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-shape open ends are spaced apart from the sides of the liquid absorption channel respectively, so that the liquid in the liquid absorption channel is transported in a directionally manner.

2. A flexible heat pipe based on a bionic 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. Along the length direction of the liquid absorption channel, a plurality of U-shaped raised columns are arranged at intervals on the inner bottom surface of the liquid absorption channel. One end of the raised column corresponding to the arc of the U shape faces the same end of the liquid absorption channel. Both sides of the raised column corresponding to the open end of the U shape 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.

3. The flexible heat pipe based on the bionic directional liquid transport structure according to claim 2, characterized in that: 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.

4. The flexible heat pipe based on the bionic directional liquid transport structure according to claim 2 or 3, characterized in that: Along the width direction of the liquid suction channel, the width of the U-shaped opening end of the protruding column is greater than the width of the arc-shaped end of the protrusion corresponding to the U-shape.

5. A flexible heat pipe based on a bionic 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, and a plurality of raised columns are sequentially arranged on the side walls of the liquid absorption channels at intervals along the length direction of the liquid absorption channels, wherein the raised columns form ratchet teeth, and the ratchet teeth are obliquely distributed relative to the side walls of the liquid absorption channels, and the ratchet teeth on the side walls on one side of the same liquid absorption channel are spaced apart from the ratchet teeth on the side walls on the other side, and the end of the ratchet teeth in the same liquid absorption channel away from the side walls of the liquid absorption channel is inclined toward the same end of the liquid absorption channel.

6. The flexible heat pipe based on the bionic directional liquid transport structure according to claim 5, characterized in that: 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.

7. The flexible heat pipe based on the bionic directional liquid transport structure according to claim 5 or 6, characterized in that: The ratchet teeth on the same side wall of the liquid suction channel are distributed in parallel.

8. A manufacturing process for a flexible heat pipe based on a bionic directional liquid delivery structure, comprising manufacturing the flexible heat pipe based on a bionic directional liquid delivery structure as claimed in any one of claims 1 to 8, characterized in that: include: A mixed liquid is prepared, and the mixed liquid is filled into a mold, and a flexible substrate with a liquid suction channel and protruding columns is obtained after demolding, wherein the protruding 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 connected to a 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.

9. The manufacturing process of the flexible heat pipe based on the bionic directional liquid transport structure according to claim 8, 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.

10. The manufacturing process of the flexible heat pipe based on the bionic directional liquid transport structure according to claim 8, characterized in that: The base bottom component and the base cover plate are made of the same material.

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