Adsorption layer for promoting patterning and separation of liquid metal, preparation method of adsorption layer and recoverable flexible liquid metal sensing device

Abstract

The invention belongs to the technical field of flexible electronic materials, and particularly relates to an adsorption layer for promoting patterning and separation of liquid metal, a preparation method of the adsorption layer and a recoverable flexible liquid metal sensing device. The metal organic framework material-polymer is used as an adsorption layer for promoting patterning and separation of the liquid metal, and the characteristics that the liquid metal is adsorbed on the surface of the polymer and repelled on the surface of the metal organic framework material are achieved by adjusting surface functional groups and roughness. And meanwhile, high-precision patterning is carried out on the polymer through a 3D printing or photoetching technology, and a high-precision liquid metal pattern is obtained under selective adsorption of the liquid metal. Besides, according to the dissolution characteristics of the metal-organic framework material and the polymer, a two-step recovery method for dissolving the polymer, separating the liquid metal from the polymer and then dissolving and separating the metal-organic framework material is designed, and the scheme of the invention is beneficial to the integration and sustainable development of the liquid metal-based electronic device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of flexible electronic materials, and specifically relates to an adsorption layer for promoting the patterning and separation of liquid metal, a preparation method thereof, and a recyclable flexible liquid metal sensor device. BACKGROUND

[0002] Traditional electronic devices often lack flexibility and compliance, making them unsuitable for applications that require flexibility and stretchability, and this limitation is particularly evident in wearable devices, which must conform to the contours of the human body and adapt to the bending, stretching or twisting deformation of various substrates. Currently, the latest developments in flexible and stretchable electronics effectively address the compatibility issues of rigid electronic devices on curved or wrinkled interfaces, and these developments have driven the development of emerging fields such as antennas, capacitors, electronic skins, energy harvesting devices, soft robots, implantable devices and wearable electronics.

[0003] Among conductive materials, gallium-indium alloy (GaIn) stands out in room-temperature liquid metals (RTLM) due to its unique and advantageous properties. GaIn not only has excellent electrical conductivity, making it highly effective in electronic applications, but also has low toxicity, reducing health risks and simplifying handling procedures. These combined attributes make GaIn an ideal choice for conductive elements in flexible electronics. By utilizing liquid metals to form various high-precision patterns on flexible substrates, different electronic components with high stretchability and bendability can be obtained, such as sensors, electronic circuit boards, etc. The precision of the patterns directly affects the performance of these devices, such as the sensitivity of sensors, the complexity of circuit boards, the size and integration of devices, etc. In addition, efficient separation of liquid metal and substrate through environmentally friendly methods, such as using green solvents to break the bond between them, can achieve the separate recycling and reuse of high-value liquid metal and flexible substrate, reducing the cost of flexible electronic devices and improving the ability of sustainable development.

[0004] However, the high surface tension of liquid metal brings challenges to the realization of patterning and easy separation; direct writing usually leads to the formation of intermittent low surface energy spheres instead of continuous patterns, making the creation of high-resolution patterns and circuits complicated. In order to overcome the agglomeration caused by the high surface tension of RTLM, the patterning methods of RTLM functional layer mainly include limited shaping method, additive adjustment method and selective wetting method. The limited shaping method is to first inject liquid metal into a prefabricated microchannel, fill the liquid metal by vacuum driving method and promote its patterning, the pattern forming precision of limited shaping method is high, but the demand for microchannel increases the production difficulty; in addition, it is also difficult for the wrapped liquid metal to be separated. The additive adjustment method needs to mix RTLM with additives (such as various polymers), and then the mixture is patterned on a flexible substrate by 3D printing or template method; however, due to the participation of low-performance polymers, the overall performance of the device is poor, and the mixed conductive ink has the problem of difficult recovery of liquid metal or the recovered liquid metal is not pure. For example, Chen et al. created a directly writable and recyclable LM / silica (LMS) ink, the recovered LMS ink contains Ga, In, O and Si elements, resulting in the recovered liquid metal being not pure. The mechanism of selective wetting method is to realize the selective adsorption of liquid metal in a specific area by means of the difference in the affinity of different materials to liquid metal, which utilizes the easy adsorption of liquid metal on smooth surface or high polarity functional groups, and can realize the high-precision patterning of liquid metal by controlling the adsorption layer more simply; it realizes the preparation of recyclable, easy-to-dismount flexible liquid metal sensor by making soluble materials as adsorption layer.

[0005] One of the mainstream selective wetting pattern methods in the prior art is to use various metals as the adsorption layer (such as copper, chromium, silver, etc.), and form a pattern on a flexible polymer substrate; liquid metal can form an alloy with various metals to form a high-precision pattern under guidance; but this method makes it difficult for liquid metal to separate from the adsorption layer metal, which is not conducive to recycling. In "Metallophobic Coatings to Enable Shape Reconfigurable Liquid Metal Inside 3D Printed Plastics.", SiO2 is used to manufacture surfaces with inconsistent roughness, and liquid metal can selectively adsorb in smooth areas, avoiding the formation of too strong chemical bonds with metals and being unable to separate, but SiO2 is easy to fall off and precipitate during the separation process, mixed with liquid metal, affecting the recovery rate. In "Stencil Printing of Liquid Metal upon Electrospun Nanofibers Enables High-Performance Flexible Electronics", TPU substrate is manufactured by electrospinning, the surface of the substrate is smooth, which is conducive to the adsorption of liquid metal, by using a PVC template, liquid metal is successfully printed on the TPU substrate, and thanks to the easy solubility of TPU in organic solvents, both liquid metal and TPU can be recycled and reused; but because the entire surface of the substrate is easy to combine with liquid metal, under intense external stress, liquid metal will spread around, affecting the pattern accuracy, at the same time, this method still needs a template, which will cause a certain degree of process complexity and resource waste. In addition, the prior art also discloses using a dissolvable polymer as an adsorption layer, first forming a pattern on a flexible substrate, and then guiding the patterning of liquid metal; but the affinity of the polymer adsorption layer to liquid metal is similar to that of some flexible polymer substrates, and selective adsorption cannot be achieved to achieve high-precision patterning of liquid metal. SUMMARY

[0006] In view of the deficiencies of the prior art, the application provides an adsorption layer for promoting liquid metal patterning and separation, a preparation method thereof and a recyclable flexible liquid metal sensor device, the adsorption layer for promoting liquid metal patterning and separation is made of metal organic framework material-polymer, the characteristics of adsorption of liquid metal on the surface of the polymer and repulsion on the surface of the metal organic framework material are realized by adjusting the surface functional groups and roughness. Meanwhile, the polymer is high-precision patterned through 3D printing or photolithography technology, and high-precision liquid metal patterns are obtained under the selective adsorption of the liquid metal. In addition, according to the dissolving characteristics of the metal organic framework material and the polymer, a two-step recycling method of dissolving the polymer first, separating the liquid metal from the polymer and then dissolving and separating the metal organic framework material is designed, and the raw materials are recycled. The scheme of the application is helpful for the integration and sustainable development of liquid metal-based electronic devices.

[0007] Based on the above technical purposes, the application adopts the following technical scheme: The application protects a preparation method of an adsorption layer for promoting liquid metal patterning and separation, comprising the following steps: The metal organic framework material is attached on the flexible substrate to form a MOF layer, then the polymer is patterned on the MOF layer by a material patterning forming method, and dried to obtain the adsorption layer for promoting liquid metal patterning and separation, the liquid metal is adsorbed on the surface of the polymer and repelled on the surface of the metal organic framework material, and the patterning is realized.

[0008] The polymer contains high-polarity functional groups selected from O, N, S, P, F or Cl, and the polymer can be dissolved in a non-acidic solution containing free hydrogen ions.

[0009] Preferably, the metal organic framework material of the application is selected from materials that can be dissolved in a low-concentration acid solution, and is specifically selected from MOF-BTC, MOF-BDC, ZIF-L or ZIF-8.

[0010] Preferably, the material patterning forming method includes 3D printing, photolithography, screen printing, mask printing method, stamping method, inkjet printing method.

[0011] Preferably, the polymer is selected from polyvinyl alcohol, lignin sulfonate, polyacrylic acid, polymethacrylic acid, polyacrylamide or water-based polyurethane.

[0012] Preferably, the non-acidic solution containing free hydrogen ions is selected from water, ethanol, sodium bicarbonate solution or phosphate buffer.

[0013] Preferably, the flexible substrate comprises a polyethylene terephthalate (PET) substrate, a polypropylene (PP) substrate, a thermoplastic polyurethane (TPU) elastomer rubber substrate, a polydimethylsiloxane (PDMS) substrate, an Ecoflex substrate, a polyimide (PI) substrate, a polyvinyl chloride (PVC) substrate.

[0014] The application also protects an adsorption layer for promoting the patterning and separation of liquid metal, which is prepared by the above preparation method.

[0015] The application also protects a recyclable flexible liquid metal sensing device, which is prepared by using the above adsorption layer for promoting the patterning and separation of liquid metal.

[0016] Preferably, the recyclable flexible liquid metal sensing device is prepared according to the following steps: The heated and liquefied liquid metal is coated on the adsorption layer for promoting the patterning and separation of liquid metal by means of scraping coating, at this time, the liquid metal is adsorbed on the polymer region and is repelled by the metal organic framework material region.

[0017] Preferably, the recyclable flexible liquid metal sensing device is recycled according to the following steps: The recyclable flexible liquid metal sensing device is placed in a non-acidic solution containing free hydrogen ions, so that the polymer is dissolved and the liquid metal is precipitated, and the liquid metal and the polymer are recycled.

[0018] Then the metal organic framework material is dissolved by using a low-concentration acid solution, and the flexible substrate is recycled; wherein the concentration of the low-concentration acid solution is 0.01 mol / L, and the acid solution is selected from dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid or dilute acetic acid.

[0019] Compared with the prior art, the application has the beneficial effects that: 1. The application uses MOF materials with adjustable functional groups and roughness, and smooth polymers with adjustable functional groups, to form rough low-polarity repulsive liquid metal regions and smooth high-polarity adsorbing liquid metal regions, to realize the patterning of liquid metal. At the same time, the MOF and the polymer are both easy to dissolve, to realize the precipitation and recycling of liquid metal without polluting the liquid metal.

[0020] 2、The application designs a metal organic framework material (MOF)-polymer patterned adsorption layer, on the one hand, the MOF and the polymer surface functional groups can be adjusted, the bonding ability to the liquid metal can be controlled, at the same time, the MOF is in a granular form, the surface is rough, and the polymer can fill the gap between the particles to form a smooth surface, through the adjustment and combination of the MOF and the polymer, the selective adsorption of the liquid metal on the polymer is promoted, and the liquid metal is repelled on the MOF around the polymer, so that the liquid metal can maintain the form under different strains, then the high-precision patterned forming of the liquid metal is realized through the polymer patterning, and the high-precision construction of the adsorption layer is realized, on the other hand, through the step-by-step dissolution ability of the polymer and the MOF in the green solution, the recovery process does not pollute the liquid metal, the MOF raw material and the polymer can be recovered while the liquid metal is separated, and closed-loop recovery is realized.

[0021] 3、The application also designs a recyclable flexible liquid metal sensing device, a plurality of guide layer materials are coated on a flexible substrate, a patterned functional layer and a flexible substrate are combined, the selective deposition of the room temperature liquid metal (RTLM) on different guide layers is explored, the liquid metal is placed in a solution, and the functional layer and the substrate are quickly separated.

[0022] 4、The recyclable flexible liquid metal sensing device realizes two-step recovery, in the first step, a non-acid solution containing free hydrogen ions is used to dissolve the polymer, the liquid metal falls off from the flexible substrate, and through filtration and solution evaporation, the liquid metal and the polymer are recovered separately, in the second step, a low-concentration acid solution is used to dissolve the metal organic framework material, the flexible substrate is recovered, and the metal organic framework material can also be obtained through solution evaporation. The method separates different materials, and finally realizes the full recovery of all materials, and the dissolution of the polymer and the metal organic framework material does not need to use strong acid, strong base, toxic organic solvent and other reagents harmful to the environment. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a structure diagram of the adsorption layer for promoting the patterned forming and separation of the liquid metal of the application.

[0024] Figure 2 It is a liquid metal patterning schematic diagram of the adsorption layer for promoting the patterned forming and separation of the liquid metal of the application.

[0025] Figure 3 It is a liquid metal separation principle diagram of the adsorption layer for promoting the patterned forming and separation of the liquid metal of the application.

[0026] Figure 4Figure 1 is a photograph of a liquid metal coating state, wherein (a) is a photograph of a real object after coating on the adsorption layer for promoting liquid metal patterning and separation in Example 1; (b) is a photograph of a real object after coating on the PET substrate in Comparative Example 1; (c) is a photograph of a real object after coating on the ZIF-L / PET substrate in Comparative Example 2.

[0027] Figure 5 Figure 2 is a graph of the change in capacitance of a finger touching the recyclable flexible liquid metal sensor device of Example 1.

[0028] Figure 6 Figure 3 is a graph of the change in capacitance of a finger touching the recyclable flexible liquid metal sensor device of Comparative Example 1. DETAILED DESCRIPTION

[0029] The specific embodiments of the present application are described in detail below, but it should be understood that the scope of protection of the present application is not limited by the specific embodiments. Based on the examples in the present application, all other examples obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application. The experimental methods described in the embodiments of the present application are conventional methods unless otherwise specified.

[0030] Considering the high-precision forming problem of liquid metal in the prior art: the room temperature liquid metal (RTLM) has agglomeration caused by high surface tension, and direct writing usually causes the formation of intermittent low surface energy spheres instead of continuous patterns, making it difficult to create high-resolution patterns and circuits and difficult to form with high precision; the present application utilizes the adsorption difference of different regions of the adsorption layer for liquid metal, and realizes the fine forming of liquid metal by selective deposition.

[0031] Considering the separation and recovery problem of liquid metal in the prior art: liquid metal is a material with high cost and high recycling value, however, in order to realize the stability of the connection between liquid metal and the substrate, most flexible devices mix liquid metal with materials having dynamic bonds such as hydrogen bonds, making it difficult to recycle liquid metal; the present application uses a soluble adsorption layer material to separate the liquid metal from the sediment, realizing the recycling of the liquid metal.

[0032] The technical solutions of the present application are further studied by using examples and comparative examples, and the specific research methods and results are as follows: Example 1 A preparation method of an adsorption layer for promoting liquid metal patterning and separation, comprising the following steps: Step 1: 1 g of polyvinyl alcohol is added to 9 g of deionized water, heated in a water bath at 70°C and stirred for 4 h to fully dissolve the polyvinyl alcohol, obtaining a 10 wt% polyvinyl alcohol solution.

[0033] Step 2, 0.65 g of cobalt nitrate hexahydrate and 1.46 g of 2-methylimidazole were respectively added to 45 mL of deionized water to disperse, then the two were mixed and stirred for 10 s to obtain a ZIF-L solution, and the pretreated PET substrate (ultrasonic cleaning with acetone and isopropanol, and then plasma activation) was quickly inserted into the ZIF-L solution at an angle, and stood for 3 h to obtain a ZIF-L / PET substrate.

[0034] Step 3, the polyvinyl alcohol solution was transferred to a syringe, and the printing parameters were set through a 3D flexible electronic printer, the needle tube specification of the dispensing printing was 23G, the printing speed was 2 mm s -1 , the extrusion pressure was 80 kPa, and the drawn interdigital pattern was printed on the ZIF-L / PET substrate, and after standing and drying for 10 min, a PVA@ZIF-L / PET substrate was obtained. The PVA@ZIF-L / PET substrate is composed of a PET substrate and an adsorption layer for promoting the patterning and separation of liquid metal.

[0035] Preparation of a recyclable flexible liquid metal sensor device: A liquid metal gallium-indium alloy was coated on the PVA@ZIF-L / PET substrate by blade coating, and after silica gel packaging, it was dried at room temperature for 45 min to obtain a recyclable flexible liquid metal sensor device, which was denoted as GaIn LM@PVA@ZIF-L / PET device.

[0036] Example 2 A method for preparing an adsorption layer for promoting the patterning and separation of liquid metal, comprising the following steps: Step 1, 3 g of lignin sulfonate was added to 7 g of deionized water, heated in a water bath at 70°C and stirred for 4 h to fully dissolve the lignin sulfonate, and a 30 wt% lignin sulfonate slurry was obtained.

[0037] Step 2, 0.67 g of cobalt nitrate hexahydrate and 1.46 g of 2-methylimidazole were respectively added to 45 mL of ethanol to disperse, then the two were mixed and stirred for 10 s to obtain a ZIF-8 solution, and the pretreated PP substrate (ultrasonic cleaning with acetone and isopropanol, and then plasma activation) was quickly inserted into the ZIF-8 solution at an angle, and stood for 3 h to obtain a ZIF-8 / PP substrate.

[0038] Step 3, select 300 mesh nylon screen plate, prepare the interdigital electrode pattern template by laser engraving, and tightly fix it on the aluminum alloy screen frame; place the ZIF-8 / PP substrate on the vacuum adsorption platform, and uniformly coat the lignosulfonate slurry with a scraper at an angle of 45°, control the scraper pressure at 0.3 MPa and the speed at 10 mm / s, so that the lignosulfonate slurry penetrates the mesh holes of the nylon screen plate to form a wet film; immediately transfer to an 80°C hot air circulation oven for stepwise temperature curing, the stepwise temperature is: 80°C / 30min→120°C / 20min→150°C / 10min, realize the crosslinking of lignosulfonate, and obtain lignosulfonate@ZIF-8 / PP substrate, which is composed of PP substrate and adsorption layer for promoting patternization and separation of liquid metal.

[0039] Preparation of a recyclable flexible liquid metal sensing device: The liquid metal gallium-indium alloy is coated on the lignosulfonate@ZIF-8 / PP substrate by using the blade coating method, and the silica gel is packaged after room temperature drying for 45 min, to obtain a recyclable flexible liquid metal sensing device, which is recorded as GaIn LM@lignosulfonate@ZIF-8 / PP device.

[0040] Example 3 A preparation method of an adsorption layer for promoting patternization and separation of liquid metal, comprising the following steps: Step 1, 7.5 g of polyacrylic acid (PAA, Mw≈450k) is added to 42.5 g of deionized water, and stirred at room temperature for 4 h to make PAA fully dissolved, to obtain a 15wt% polyacrylic acid slurry.

[0041] Step 2, the pretreated TPU substrate (ultrasonic cleaning with acetone and isopropanol, and then plasma activation) is fixed in an electrochemical synthesis device, with a copper plate as an anode and the TPU substrate as an interface support, immersed in an ethanol / water mixed solvent (volume ratio of 1:1) containing trimesic acid (H3BTC, concentration 0.1 mol / L), and a constant current density (1 mA / cm²) is applied at room temperature to perform anodic dissolution, continuously providing Cu²⁺ ions, while the ligand molecules diffuse and enrich on the TPU substrate surface to form a local supersaturated reaction interface, realizing in-situ nucleation and growth of Cu-BTC, and obtaining a Cu-BTC / TPU substrate.

[0042] Step 3, the photoresist solution was prepared, the polyacrylic acid slurry was mixed with 5wt% ammonium dichromate photosensitizer, filtered through a 0.22 μm filter membrane, and then spin-coated on the surface of the Cu-BTC / TPU substrate at a speed of 3000 rpm to form a 3 μm thick film. The film was first soft-baked at 90°C for 5 min to remove residual moisture, and then exposed to 365 nm ultraviolet light for 20 s (light intensity 15 mW / cm²) through a chromium mask with a finger-shaped electrode pattern using a contact photolithography machine. The exposed area of the polyacrylic acid was cross-linked and formed an insoluble network; the substrate was immersed in 4°C deionized water for 60 s to develop the unexposed area of the polyacrylic acid, which was dissolved and fell off, exposing the bottom layer of the Cu-BTC / TPU patterned area, and obtaining a PAA@Cu-BTC / TPU substrate. The PAA@Cu-BTC / TPU substrate was composed of a TPU substrate and an adsorption layer that promoted the patterning and separation of liquid metal.

[0043] Preparation of a recyclable flexible liquid metal sensing device: A liquid metal gallium-indium alloy was coated on the PAA@Cu-BTC / TPU substrate using a doctor blade method, and the device was packaged with silica gel and dried at room temperature for 45 min to obtain a recyclable flexible liquid metal sensing device, denoted as GaIn LM@PAA@Cu-BTC / TPU device.

[0044] Comparative Example 1 The preparation steps were the same as those of Example 1, except that the liquid metal in Step 4 was directly coated on the PET substrate using a doctor blade method, including the following steps: A liquid metal gallium-indium alloy was coated on the PET substrate using a doctor blade method, and the device was packaged with silica gel and dried at room temperature for 45 min to obtain a GaIn LM@PET device.

[0045] Comparative Example 2 The preparation steps were the same as those of Example 1, except that Step 3 was not performed, and the liquid metal was directly coated on the ZIF-L / PET substrate using a doctor blade method, including the following steps: Step 1, 1 g of polyvinyl alcohol was added to 9 g of deionized water, heated in a water bath at 70°C and stirred for 4 h to fully dissolve the polyvinyl alcohol, obtaining a 10wt% polyvinyl alcohol solution.

[0046] Step 2, 0.65 g of cobalt nitrate hexahydrate and 1.46 g of 2-methylimidazole were separately dispersed in 45 mL of deionized water, then mixed and stirred for 10 s to obtain a ZIF-L solution. The PET substrate was inserted obliquely into the ZIF-L solution and left to stand for 3 h to obtain a ZIF-L / PET substrate.

[0047] Step 3, liquid metal gallium-indium alloy was coated on the ZIF-L / PET substrate by doctor blade method, and the silica gel was encapsulated, and then dried at room temperature for 45 min to obtain GaIn LM@ZIF-L / PET device.

[0048] In the present application, the structure diagram of the adsorption layer for promoting the patterning and separation of liquid metal is shown in Figure 1 The liquid metal patterning diagram of the adsorption layer for promoting the patterning and separation of liquid metal is shown in Figure 2

[0049] In the present application, as shown in Figure 3 The recovery method is as follows: the GaIn LM@PVA@ZIF-L / PET device of Example 1 is placed in a beaker containing hot water, the PVA is dissolved, the dissolution time is 2 min, at the same time, the liquid metal falls off and deposits at the bottom of the beaker, a glass rod is used for stirring, it is found that the liquid metal balls at the bottom of the beaker are aggregated into larger spherical shape, through filtration and solvent evaporation, the liquid metal gallium-indium alloy and the polymer polyvinyl alcohol are recovered separately; then 0.01 mol / L HCl solution is added to the beaker, at this time, the MOF layer is dissolved, the PET substrate is recovered, and the metal organic framework material is also obtained by solvent evaporation. The drying temperature of the recovered liquid metal is 60℃, the time is 10 min, the liquid metal recovery rate can reach 99%, and the total amount of Ga and In can reach 95wt%; under the same treatment method, the liquid metal recovery rate of the GaIn LM@PET device of Comparative Example 1 is 85wt%, and the liquid metal recovery rate of the GaIn LM@ZIF-L / PET device of Comparative Example 2 is 90wt%.

[0050] Figure 4 It is a coating state diagram of liquid metal, and it can be known from Figure 4 that the liquid metal in Example 1 can be patterned; the liquid metal in Comparative Example 1 diffuses, the line width is thick, and the pattern precision is low; the liquid metal in Comparative Example 2 is aggregated in the rough MOF layer and cannot be patterned. According to the above comparative study, the adsorption layer design of MOF-polymer can form a rough low-polarity repulsive liquid metal region and a smooth high-polarity adsorbed liquid metal region, so as to realize the patterning of liquid metal.

[0051] By touching (pressing) the GaIn LM@PVA@ZIF-L / PET device of Example 1 with fingers, Figure 5 the response in several touch release cycles is shown, and the results show that the capacitance changes after touching, and the capacitance returns to the original value after the finger is retracted, which indicates that there is a large amplitude (which can reach 15%) between the non-touching and touching states.

[0052] By touching (pressing) the GaIn LM@PET device of Comparative Example 1 with fingers,​Figure 6 The response over several touch release cycles is shown, and the results indicate that due to the liquid metal spreading in Comparative Example 1, the line width is thick, the pattern precision is low, and the capacitance sensing signal has an unstable amplitude between the non-touch and touch states.

[0053] Obviously, various modifications and changes are possible in the present application without departing from the spirit and scope of the application. It is understood that the application encompasses all such modifications and changes that fall within the scope of the claims and their equivalents.

Claims

1. A method for preparing an adsorbed layer to facilitate the patterning and separation of liquid metals, comprising: providing a substrate; providing a liquid metal; providing a surfactant; and providing a substrate surface to which the liquid metal and surfactant are applied. Includes the following steps: Metal-organic framework materials are attached to a flexible substrate to form a MOF layer. The MOF layer is used to repel liquid metal. Then, a material patterning method is used to pattern a polymer on the MOF layer. The polymer is used to adsorb liquid metal. After drying, an adsorption layer that promotes the patterning and separation of liquid metal is obtained. The polymer contains highly polar functional groups, which are selected from O, N, S, P, F or Cl; and the polymer can dissolve in non-acidic solutions containing free hydrogen ions.

2. The method for preparing the adsorption layer for promoting the patterning and separation of liquid metal according to claim 1, characterized in that, Metal-organic framework materials are selected from MOF-BTC, MOF-BDC, ZIF-L, or ZIF-8.

3. The method for preparing the adsorption layer for promoting the patterning and separation of liquid metal according to claim 1, characterized in that, Material patterning methods include 3D printing, photolithography, screen printing, mask printing, stamping, and inkjet printing.

4. The method for preparing the adsorption layer for promoting the patterning and separation of liquid metal according to claim 1, characterized in that, The polymer is selected from polyvinyl alcohol, lignin sulfonate, polyacrylic acid, polymethacrylic acid, polyacrylamide, or waterborne polyurethane.

5. The method for preparing the adsorption layer for promoting the patterning and separation of liquid metal according to claim 1, characterized in that, Non-acidic solutions containing free hydrogen ions are selected from water, ethanol, sodium bicarbonate solution, or phosphate buffer.

6. The method for preparing the adsorption layer for promoting the patterning and separation of liquid metal according to claim 1, characterized in that, Flexible substrates include polyethylene terephthalate substrates, polypropylene substrates, thermoplastic polyurethane elastomer rubber substrates, polydimethylsiloxane substrates, Ecoflex substrates, polyimide substrates, and polyvinyl chloride substrates.

7. An adsorption layer for promoting the patterning and separation of liquid metal, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 6.

8. A recyclable flexible liquid metal sensor, characterized in that, It is prepared using the adsorption layer described in claim 7 that promotes the patterning and separation of liquid metal.

9. The recyclable flexible liquid metal sensor device according to claim 8, characterized in that, The recyclable flexible liquid metal sensor is prepared according to the following steps: The heated and liquefied liquid metal is coated onto an adsorption layer that promotes the patterning and separation of the liquid metal using a scraping method. At this time, the liquid metal is adsorbed in the polymer region and repelled by the metal-organic framework material region.

10. The recyclable flexible liquid metal sensor device according to claim 8, characterized in that, Recyclable flexible liquid metal sensor components are recovered according to the following steps: The recyclable flexible liquid metal sensor is placed in a non-acidic solution containing free hydrogen ions, causing the polymer to dissolve and the liquid metal to precipitate, thus recovering both the liquid metal and the polymer. Then, a low-concentration acid solution is used to dissolve the metal-organic framework material, and the flexible substrate is recovered. The concentration of the low-concentration acid solution is 0.01 mol / L, and the acid solution is selected from dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, or dilute acetic acid.

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