Flexible liquid metal electrode based on gallium-indium-tin alloy and preparation method and application thereof

Abstract

The invention belongs to the technical field of electrode materials, and particularly relates to a flexible liquid metal electrode based on gallium-indium-tin alloy and a preparation method and application thereof.Liquid metal ink is prepared through an ultrasonic method, a screen printing technology is adopted, the liquid metal ink is coated on a flexible substrate, meanwhile, mechanical activation and nanoparticle strategies are introduced, and the flexible liquid metal electrode based on gallium-indium-tin alloy is prepared. The preparation method of the high-performance flexible liquid gold electrode with excellent conductivity and mechanical stability is developed. In the flexible liquid metal electrode based on the gallium-indium-tin alloy, due to the good conductivity and biocompatibility of gallium-based liquid metal, the flexible stretchable conductive electrode based on the gallium-indium-tin liquid metal becomes an ideal wearable flexible device circuit material, and the patterning ability of the gallium-indium-tin liquid metal is further improved. Patterning preparation of the circuit is carried out in a mode of silk-screen printing of the gallium-based liquid metal particles, and the patterned liquid metal circuit with excellent conductivity and flexibility is obtained through mechanical activation.

Description

Technical Field

[0001] The present invention relates to the technical field of electrode materials, and in particular to a flexible liquid metal electrode based on a gallium-indium-tin alloy and a preparation method and application thereof. Background Art

[0002] With the rapid development of modern electronic devices, especially the rapid rise of wearable devices, flexible displays, and smart medical devices, the demand for flexible electronic devices is growing. The application of traditional rigid electrode materials in these flexible electronic devices is often limited because they cannot meet the three requirements of high conductivity, excellent flexibility, and reliable mechanical stability. Therefore, the development of flexible electrode materials with good conductivity, repeatable bending and stretching has become a research hotspot in this field.

[0003] At present, most flexible electrode materials in the field of flexible electronic devices are conductive polymers, metal nanowires or carbon-based materials (such as graphene and carbon nanotubes). Although these flexible electrode materials have certain flexibility and conductivity, they still have many technical defects in practical applications, as follows:

[0004] 1. Existing conductive polymers and metal nanowire flexible electrode materials have certain advantages in flexibility, but their conductivity is relatively poor, especially in application scenarios that require large current conduction, and they often cannot meet the requirements. Although highly conductive materials such as copper and silver have excellent conductivity, due to the solid nature of conductive materials, they are prone to breakage during repeated bending and stretching, and cannot be used stably for a long time.

[0005] 2. Flexible electronic devices need to withstand repeated deformations, such as bending and stretching, but existing flexible electrode materials have poor stability in deformation environments. For example, metal nanowires or graphene films are prone to break or fall off after multiple bending, and the conductive path is discontinuous, resulting in a decrease in the performance of flexible electronic devices. This defect greatly limits the actual service life of flexible electrode materials.

[0006] 3. In the prior art, the adhesion between the flexible electrode material and the flexible substrate is poor, especially under deformation conditions, which easily leads to delamination or peeling, resulting in failure of the flexible electrode material. In addition, when preparing on a large area, the uniformity and consistency of the flexible electrode material are difficult to ensure, especially for applications on complex surfaces or multiple substrates, which poses a technical bottleneck.

[0007] 4. Some high-performance flexible electrode materials (such as carbon nanotubes or graphene) require complex preparation processes and are costly, making them difficult to mass-produce. At the same time, some flexible electrode materials require special treatment or expensive equipment during the production process, which further increases the difficulty of large-scale application.

[0008] In this context, liquid metal materials, especially gallium indium tin alloys, have attracted widespread attention due to their unique physical properties. Gallium indium tin alloys are liquid at room temperature, have good electrical conductivity, and can maintain a continuous conductive path under strain conditions, showing their potential application value in flexible electronic devices. However, research on how to effectively apply this liquid metal to flexible electrode materials is still in its early stages, especially in large-scale preparation and practical applications, facing many challenges, such as material adhesion, stability, and compatibility with the substrate. These technical bottlenecks limit its widespread application. Summary of the invention

[0009] In view of the deficiencies in the above-mentioned prior art, the purpose of the present invention is to provide a flexible liquid metal electrode based on gallium indium tin alloy and a preparation method and application thereof. The present invention uses gallium indium tin liquid metal as a raw material, prepares liquid metal ink by ultrasonic method, then performs pattern design on a flexible substrate, and then adopts mechanical activation to obtain a flexible liquid metal electrode based on gallium indium tin alloy. The present invention simultaneously introduces the ratio of a new liquid metal ink and a strategy for mechanical activation of the subsequent patterned circuit, and develops a high-performance flexible liquid metal electrode with excellent conductivity and mechanical stability, which overcomes the technical defects of the prior art gallium indium tin alloy used in flexible electrode materials, such as poor adhesion, stability and compatibility with the substrate.

[0010] To achieve the above object, the present invention adopts the following technical solution:

[0011] A method for preparing a flexible liquid metal electrode based on gallium-indium-tin alloy comprises the following steps:

[0012] Mixing a viscosity modifier, polyvinyl pyrrolidone, and a n-decanol solvent in anhydrous ethanol to obtain a PVP-n-decanol-ethanol solution;

[0013] Wherein, polyvinyl pyrrolidone is 5wt%, n-decyl alcohol is 5wt%-10wt%, anhydrous ethanol is 85wt%-90wt%, and the sum of the mass percentages of the three is 100%;

[0014] Under stirring conditions, gallium indium tin liquid metal is added to the PVP-n-decyl alcohol-ethanol solution. N-decyl alcohol can improve the wettability of the PVP-n-decyl alcohol-ethanol solution by reducing the surface tension. It can significantly reduce the surface tension of gallium indium tin liquid metal in the PVP solution, helping the gallium indium tin liquid metal particles to disperse more evenly, and then ultrasonication is performed in an ice water bath. The ice water bath ensures that the temperature is kept low during the subsequent ultrasonic treatment process to prevent the gallium indium tin liquid metal and PVP-n-decyl alcohol-ethanol solution from being overheated and the PVP-n-decyl alcohol-ethanol solution from being over-volatile. Compared with a simple anhydrous ethanol liquid metal dispersion, the addition of n-decyl alcohol and polyvinyl pyrrolidone improves the fluidity of the liquid metal ink on the flexible substrate, avoiding the aggregation of gallium indium tin liquid metal particles during stirring and ultrasonic treatment. This improvement improves the dispersion stability of the liquid metal ink and the uniformity of the printed pattern, laying the foundation for subsequent conductivity and patterning capabilities;

[0015] The liquid metal ink is patterned and coated on a flexible substrate, and then the particles of the gallium indium tin liquid metal are broken by mechanical activation to promote the formation of a conductive network, thereby obtaining a flexible liquid metal electrode based on a gallium indium tin alloy. The mass ratio of polyvinyl pyrrolidone to n-decanol is 1:1 to 2. Within this range, the ratio of polyvinyl pyrrolidone to n-decanol optimizes the viscosity, stability and dispersibility of the liquid metal ink. If the polyvinyl pyrrolidone ratio is too high, the viscosity of the liquid metal ink increases, which will result in an inability to evenly coat or print, affecting the conductivity of the flexible liquid metal electrode based on the gallium indium tin alloy. If the n-decanol ratio is too high, the dispersibility of the liquid metal ink will decrease, causing the particles of the gallium indium tin liquid metal to settle or aggregate, forming an uneven ink, which affects the stability and pattern accuracy of the flexible liquid metal electrode.

[0016] The volume ratio of the mass of gallium indium tin liquid metal to the PVP-n-decyl alcohol-ethanol solution is 0.5g~2g:1mL. If the proportion of gallium indium tin liquid metal is too high, it will cause uneven dispersion of the gallium indium tin liquid metal, affecting the printing performance; if the proportion of gallium indium tin liquid metal is too low, it will lead to poor dispersion of gallium indium tin liquid metal particles, affecting the conductivity and stability of the electrode.

[0017] Preferably, the flexible substrate includes an electrospun fiber substrate, a polyimide substrate, a polyethylene terephthalate substrate, a thermoplastic polyurethane elastomer rubber substrate or a polyvinyl alcohol film substrate. The selected flexible substrate material has excellent mechanical flexibility and can support the deformation application of the flexible liquid metal electrode.

[0018] Preferably, conductive polymers or conductive nanoparticles can also be mixed into the liquid metal ink. By adding MXene, carbon nanotubes, graphene, metal nanoparticles (such as silver, copper, gold), conductive polymers (such as PEDOT:PSS) or metal oxides (such as CuO, ZnO), the conductivity, stability and mechanical properties of the liquid metal ink can be improved. The composite ink doped with conductive polymers or conductive nanoparticles can meet the needs of different application scenarios.

[0019] Preferably, after the liquid metal ink is patterned and coated on the flexible substrate, a local heating operation is also performed. In the patterning step, the liquid metal ink is directionally heated by using local heating technology, and the temperature of the flexible substrate is controlled within a low temperature range of 40-50°C by using a precise local heating device in the printing area to ensure that the liquid metal ink can be uniformly cured. In addition, local heating can improve the resolution of the pattern through precise heating area control, avoid overflow or uneven deposition, and reduce the thermal stress of the flexible substrate through low-temperature drying. This local heating technology is combined with n-decanol modification to further optimize the deposition effect of the liquid metal ink during the patterning process, ensure the clarity and uniformity of the pattern, and compared with traditional oven drying and room temperature static drying methods, local heating is more accurate and effectively improves the long-term stability of the flexible liquid metal electrode based on gallium indium tin alloy.

[0020] Preferably, the mechanical activation method is repeated deformation or stress, which acts on the gallium indium tin liquid metal nanoparticles inside the flexible liquid metal electrode based on the gallium indium tin alloy, and causes the nanoparticles to break to form a connected conductive path.

[0021] Preferably, the liquid metal ink is patterned on the flexible substrate by screen printing or 3D printing.

[0022] The present invention also protects the flexible liquid metal electrode based on gallium indium tin alloy prepared by the above preparation method.

[0023] The present invention also protects the application of flexible liquid metal electrodes based on gallium-indium-tin alloy in the preparation of flexible electronic devices.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention uses gallium indium tin liquid metal as raw material, disperses gallium indium tin liquid metal in PVP-n-decyl alcohol-ethanol solution to form liquid metal ink, and then pattern-coats the liquid metal ink on a flexible substrate, and then performs mechanical activation to obtain a flexible liquid metal electrode based on gallium indium tin alloy. The present invention simultaneously introduces the strategies of mechanical activation and nanoparticle enhancement to overcome the problems of poor adhesion, stability and compatibility with the substrate of the flexible electrode materials in the prior art.

[0026] Nanoparticle enhancement is to disperse gallium indium tin liquid metal into nanoparticles, which significantly improves the patterning ability of liquid metal ink on flexible substrates. Specifically, the small size of nanoparticles allows the liquid metal ink to be more evenly distributed and accurately applied to the flexible substrate, improving its patterning effect. This nanoscale dispersed liquid metal ink can form more delicate and precise electrode patterns during the patterning process, adapting to complex microstructure design requirements. In addition, the introduction of nanoparticles can not only improve the fluidity and dispersibility of liquid metal ink during the patterning process, but also enhance its stability under high-resolution patterning. Therefore, the nanoparticle enhancement strategy enables liquid metal ink to be patterned on a finer scale, providing more possibilities for the preparation of flexible electrodes, while also improving the mechanical stability and conductivity of flexible electrodes.

[0027] Due to the good conductivity and biocompatibility of gallium-based liquid metal, flexible liquid metal electrodes based on gallium indium tin alloy can be used as circuit materials for wearable flexible devices. In order to further improve the patterning of gallium indium tin liquid metal, patterning is performed by screen printing or 3D printing of liquid metal ink, and patterned liquid metal circuits with excellent conductivity and flexibility are obtained by mechanical activation.

[0028] n-Decanol and PVP work synergistically. n-Decanol improves the wettability of PVP-n-Decanol-Ethanol solution to gallium indium tin liquid metal by reducing surface tension. PVP acts as a thickener to further stabilize the dispersion state of gallium indium tin liquid metal particles in PVP-n-Decanol-Ethanol solution, avoiding the aggregation of gallium indium tin liquid metal particles during the deposition process. PVP also helps to improve the adhesion of liquid metal ink during the patterning process, ensuring the adhesion of gallium indium tin liquid metal on the flexible substrate. Through the combination of these two materials, the dispersibility and stability of liquid metal ink are doubled. Compared with the use of n-Decanol or anhydrous ethanol alone, the liquid metal ink based on PVP-n-Decanol-Ethanol solution has excellent dispersibility and stability. On the basis of achieving longer-term stability of gallium indium tin liquid metal, the liquid metal ink based on PVP-n-Decanol-Ethanol solution has excellent patterning ability, which significantly improves the applicability of flexible liquid metal electrodes based on gallium indium tin alloys in large-scale production.

[0029] 2. The flexible liquid metal electrode based on gallium indium tin alloy of the present invention has excellent conductive properties: by evenly distributing gallium indium tin liquid metal nanoparticles on a flexible substrate and using mechanical activation technology, the connection between the particles is significantly enhanced to form an efficient conductive network, greatly improving the conductivity of the electrode.

[0030] 3. The flexible liquid metal electrode based on gallium indium tin alloy of the present invention has excellent mechanical flexibility: the flexible liquid metal electrode based on gallium indium tin alloy of the present invention can withstand multiple bending and stretching deformations without damaging its conductive properties, and is suitable for the field of flexible electronic devices and wearable devices.

[0031] 4. The flexible liquid metal electrode based on gallium indium tin alloy of the present invention has excellent mechanical stability: existing flexible electrode materials are often difficult to have sufficient flexibility while maintaining conductivity, and traditional electrode materials are prone to failure or reduced conductivity when bent or deformed multiple times. The flexible liquid metal electrode based on gallium indium tin alloy of the present invention exhibits high mechanical stability, can maintain its structural integrity and conductivity under repeated deformation and stress, and is suitable for a variety of flexible electronic devices.

[0032] 5. The flexible liquid metal electrode based on gallium indium tin alloy of the present invention has good cycle durability: the flexible liquid metal electrode based on gallium indium tin alloy shows excellent stability in multiple cycle bending or stretching experiments, and its resistance change rate is extremely small, ensuring the reliability of the flexible liquid metal electrode based on gallium indium tin alloy in long-term use.

[0033] 6. The flexible liquid metal electrode based on gallium indium tin alloy of the present invention is compatible with a variety of sensor applications: The flexible liquid metal electrode based on gallium indium tin alloy of the present invention can be combined with a variety of sensors to provide accurate sensing response, expanding the application of the flexible liquid metal electrode based on gallium indium tin alloy in the fields of smart devices, flexible sensors and electronic skin.

[0034] 7. Simplify the manufacturing process and reduce costs: The current preparation process of flexible electrodes is relatively complicated and difficult to apply in large-scale production. The preparation method of the present invention is simple and efficient. Through patterning and mechanical activation processes, it is easy to achieve large-scale production, significantly reducing the manufacturing cost and having good industrialization prospects.

[0035] 8. The present invention uses n-decanol as a raw material. N-decanol effectively reduces the surface tension between gallium indium tin liquid metal and the solvent, helps the gallium indium tin liquid metal particles to be more evenly dispersed in the solution, and prevents the particles from aggregating during stirring and ultrasonic treatment. The long carbon chain of n-decanol provides a more stable interface layer structure, which enhances the dispersibility and fluidity of the liquid metal ink. By adding n-decanol, the surface of the gallium indium tin liquid metal particles is more stably coated, thereby improving the uniform distribution of the gallium indium tin liquid metal particles in the ink and reducing the sedimentation of the ink. During the patterning process, the liquid metal ink can flow more smoothly and form a clearer pattern on the substrate. This method has better dispersion stability, especially in the application of flexible electronics, and can enhance the processability and conductivity of flexible liquid metal electrodes based on gallium indium tin alloys.

[0036] In summary, the present invention not only has significant technical advantages in conductivity and flexibility, but also shows good effects in mechanical stability, cycle durability and application scalability, and is widely applicable to flexible electronics and smart devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of preparing liquid metal ink by ultrasonic method according to Examples 1 to 3 of the present invention.

[0038] Figure 2 This is a SEM image of nanoparticles of gallium, indium, and tin liquid metal according to Example 1 of the present invention.

[0039] Figure 3 This is a SEM image of the unactivated gallium-indium-tin alloy-based flexible liquid metal electrode of comparative example 1 of the present invention.

[0040] Figure 4 This is a SEM image of the flexible liquid metal electrode based on gallium indium tin alloy in Example 1 of the present invention.

[0041] Figure 5 This is a graph showing the cyclic stability experiment of the flexible liquid metal electrode based on gallium-indium-tin alloy in Example 1 of the present invention. DETAILED DESCRIPTION

[0042] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention. The experimental methods described in the embodiments of the present invention are conventional methods unless otherwise specified.

[0043] The present invention develops a new type of flexible liquid metal electrode based on gallium indium tin alloy by optimizing the preparation process of gallium indium tin alloy. This flexible liquid metal electrode not only has excellent conductive properties, but also can remain stable under complex bending and deformation environments. It is particularly suitable for the fields of flexible sensors, electronic skin and wearable devices.

[0044] Compared with the prior art, the present invention has creativity, novelty and practicality, as shown below:

[0045] The practicality of the present invention is mainly reflected in its wide adaptability to the field of flexible electronics. The flexible liquid metal electrode based on gallium indium tin alloy can be applied to a variety of fields such as smart medical sensors and wearable devices, meeting the requirements of these devices for the flexibility, reliability and conductivity of electrode materials. In addition, the flexible liquid metal electrode based on gallium indium tin alloy can be prepared on a large scale through a simple process, making it have potential commercial prospects.

[0046] From the perspective of novelty, the present invention proposes a flexible liquid metal electrode based on gallium indium tin alloy and a preparation method thereof, which breaks through the bottleneck problem of existing solid electrodes and some liquid electrodes in terms of flexibility and conductivity. The application of gallium indium tin alloy is a completely new direction. It utilizes the liquid properties of metal and can continuously maintain a conductive path when the electrode is deformed. This novel technology breaks through the problem that traditional electrode materials are prone to breakage or failure under flexibility and deformation, and provides new possibilities for the design of flexible electronic devices.

[0047] The creativity of the present invention is mainly reflected in the following aspects:

[0048] 1. Use gallium indium tin liquid metal as electrode material: The unique properties of gallium indium tin liquid metal provide an innovative solution for flexible electrodes, which has better flexibility and deformability than existing solid electrodes.

[0049] 2. Innovation in preparation process: The present invention can achieve stable adhesion of gallium indium tin liquid metal and combination with a flexible substrate through a simple and effective screen printing preparation process, breaking through the technical bottleneck of liquid metal application in the field of flexible electronics and providing the possibility for large-scale production.

[0050] 3. Performance improvement: Compared with traditional flexible electrode materials, the flexible liquid metal electrode based on gallium indium tin alloy of the present invention can remain stable under multiple deformations while maintaining excellent conductive properties, which greatly improves the reliability and durability of the flexible liquid metal electrode based on gallium indium tin alloy.

[0051] 4. The preparation method of the present invention only requires two steps, namely ultrasonic treatment and patterning. The process flow is simple, efficient production can be achieved, and it is suitable for large-scale industrial applications. In addition, through the combination of ultrasonic treatment and patterning, it is ensured that the nanoparticles of gallium indium tin liquid metal can be evenly dispersed and accurately printed on the flexible substrate, effectively improving the conductivity and stability of the flexible liquid metal electrode based on gallium indium tin alloy.

[0052] In summary, the present invention not only fills the gap in the field of flexible electrodes in terms of technology, but also has broad prospects in practical applications.

[0053] The present invention is based on a flexible liquid metal electrode of a gallium indium tin alloy. Nanoparticles of gallium indium tin liquid metal are prepared by an ultrasonic method, and the nanoparticles of gallium indium tin liquid metal are coated on a flexible substrate by screen printing technology. At the same time, mechanical activation and nanoparticle enhancement strategies are introduced to develop a preparation method for a high-performance flexible liquid metal electrode with excellent conductivity and mechanical stability. Through the innovative combination of each step, the present invention effectively solves the technical difficulties of the flexible liquid metal electrode based on gallium indium tin alloy in terms of conductivity, flexibility and mechanical stability, and has broad application potential.

[0054] The technical solution of the present invention is further described in detail below in conjunction with the embodiments, comparative examples and accompanying drawings, as shown below:

[0055] Example 1

[0056] A method for preparing a flexible liquid metal electrode based on gallium-indium-tin alloy comprises the following steps:

[0057] S1. Add 0.5 g polyvinyl pyrrolidone (PVP) powder and 0.5 g n-decanol to 9.0 g ethanol and stir at room temperature for 48 h to ensure that PVP is completely dissolved in ethanol to form a uniform and transparent PVP-n-decanol-ethanol solution.

[0058] S2. Under stirring conditions, 1 g of gallium indium tin liquid metal is added to 1 mL of PVP-n-decyl alcohol-ethanol solution. The purpose of stirring is to prevent the gallium indium tin liquid metal from agglomerating in the PVP-n-decyl alcohol-ethanol solution and ensure initial uniform dispersion to obtain a mixed solution. The mixed solution is placed in an ice water bath, and then a probe ultrasonic instrument (model: 1000Y, produced by Shanghai Hanno Instrument Co., Ltd.) is used, the amplitude is set to 100%, and intermittent ultrasonic treatment is used, that is, the ultrasonic treatment mode of 3 seconds on and 3 seconds off is used, and the ultrasonic treatment is performed for 600 seconds. This operation helps to refine the gallium indium tin liquid metal into nanoparticles and evenly disperse them in the PVP-n-decyl alcohol-ethanol solution, thereby forming a stable liquid metal ink.

[0059] S3. Use a screen with a size of 44mm×315mm and select a screen with a mesh size of 400. The pore size of the 400-mesh screen is small, which helps to ensure the fine pattern printing of the liquid metal ink on the screen and improve the uniform distribution effect of the liquid metal ink. Use a flexible electrospinning membrane as a flexible substrate, and the flexible electrospinning membrane as a flexible substrate is a TPU electrospinning nanofiber membrane flexible substrate. The flexible electrospinning membrane is prepared according to the following steps: dissolve thermoplastic polyurethane elastomer rubber (TPU) in DMF, stir at a speed of 500rpm for 10h at room temperature to prepare a 5wt% TPU spinning solution, then load the TPU spinning solution into a 10mL syringe, and electrospin through an 18-gauge needle at a constant flow rate of 1mL / h. The working distance is set to 15cm. Under the conditions of a drum speed of 120r / min and an applied voltage of 12kV, a TPU electrospinning nanofiber membrane flexible substrate is successfully prepared. Place the screen on top of the flexible electrospinning membrane, prepare a polyurethane scraper, hold the polyurethane scraper at a 45° angle to the screen base, and evenly brush the liquid metal ink on the prepared screen. The angle and strength of the scraper are crucial to ensure that the liquid metal ink can be evenly applied to the screen and form a continuous pattern on the flexible electrospinning membrane.

[0060] S4. In the screen printing step, the liquid metal ink on the flexible electrospinning membrane is heated in a direction by using local heating technology until the solvent is completely evaporated, and then the gallium indium tin liquid metal nanoparticles are crushed by rolling to obtain a flexible liquid metal electrode based on gallium indium tin alloy.

[0061] Example 2

[0062] A method for preparing a flexible liquid metal electrode based on gallium-indium-tin alloy comprises the following steps:

[0063] S1. Add 0.5 g polyvinyl pyrrolidone (PVP) powder and 0.5 g n-decanol to 9.0 g ethanol and stir at room temperature for 48 h to ensure that PVP is completely dissolved in ethanol to form a uniform and transparent PVP-n-decanol-ethanol solution.

[0064] S2. Under stirring conditions, 2 g of gallium indium tin liquid metal is added to 1 mL of PVP-n-decyl alcohol-ethanol solution. The purpose of stirring is to prevent the gallium indium tin liquid metal from agglomerating in the PVP-n-decyl alcohol-ethanol solution and ensure initial uniform dispersion to obtain a mixed solution. The mixed solution is placed in an ice water bath, and then a probe ultrasonic instrument (model: 1000Y, produced by Shanghai Hanno Instrument Co., Ltd.) is used, the amplitude is set to 100%, and intermittent ultrasonic treatment is used, that is, the ultrasonic treatment mode of 3 seconds on and 3 seconds off is used, and the ultrasonic treatment is performed for 180 seconds. This operation helps to refine the gallium indium tin liquid metal into nanoparticles and evenly disperse them in the PVP-n-decyl alcohol-ethanol solution, thereby forming a stable liquid metal ink.

[0065] S3. Use a screen with a size of 44mm×315mm and a mesh of 400. The pore size of the 400-mesh screen is small, which helps to ensure the fine pattern printing of the liquid metal ink on the screen and improve the uniform distribution of the liquid metal ink. Use the polyimide substrate as the flexible substrate, place the screen on top of the polyimide substrate, prepare a polyurethane scraper, hold the polyurethane scraper at a 45° angle to the screen substrate, and evenly brush the liquid metal ink on the prepared screen. The angle and strength of the scraper are crucial to ensure that the liquid metal ink can be evenly coated on the screen and form a continuous pattern on the polyimide substrate.

[0066] S4. In the screen printing step, the liquid metal ink on the polyimide substrate is heated in a direction by using local heating technology until the solvent is completely evaporated, and then the gallium indium tin liquid metal nanoparticles are crushed by rolling to obtain a flexible liquid metal electrode based on gallium indium tin alloy.

[0067] Example 3

[0068] A method for preparing a flexible liquid metal electrode based on gallium-indium-tin alloy comprises the following steps:

[0069] S1. Add 0.5 g polyvinyl pyrrolidone (PVP) powder and 1 g n-decanol to 9.0 g ethanol and stir at room temperature for 48 h to ensure that PVP is completely dissolved in ethanol to form a uniform and transparent PVP-n-decanol-ethanol solution.

[0070] S2. Under stirring conditions, 0.5 g of gallium indium tin liquid metal is added to 1 mL of PVP-n-decyl alcohol-ethanol solution. The purpose of stirring is to prevent the gallium indium tin liquid metal from agglomerating in the PVP-n-decyl alcohol-ethanol solution and ensure initial uniform dispersion to obtain a mixed solution. The mixed solution is placed in an ice water bath, and then a probe ultrasonic instrument (model: 1000Y, produced by Shanghai Hanno Instrument Co., Ltd.) is used, the amplitude is set to 100%, and intermittent ultrasonic treatment is used, that is, the ultrasonic treatment mode of 3 seconds on and 3 seconds off is used, and the ultrasonic treatment is performed for 180 seconds. This operation helps to refine the gallium indium tin liquid metal into nanoparticles and evenly disperse them in the PVP-n-decyl alcohol-ethanol solution, thereby forming a stable liquid metal ink.

[0071] S3. Use a screen with a size of 44mm×315mm and a mesh of 400. The pore size of the 400-mesh screen is small, which helps to ensure the fine pattern printing of the liquid metal ink on the screen and improve the uniform distribution of the liquid metal ink. Use the thermoplastic polyurethane elastomer rubber substrate as the flexible substrate, place the screen on top of the thermoplastic polyurethane elastomer rubber substrate, prepare a polyurethane scraper, hold the polyurethane scraper at a 45° angle to the screen substrate, and evenly brush the liquid metal ink on the prepared screen. The angle and strength of the scraper are crucial to ensure that the liquid metal ink can be evenly coated on the screen and form a continuous pattern on the thermoplastic polyurethane elastomer rubber substrate.

[0072] S4. In the screen printing step, the liquid metal ink on the thermoplastic polyurethane elastomer rubber substrate is directionally heated by using local heating technology until the solvent is completely evaporated, and then the gallium indium tin liquid metal nanoparticles are crushed by rolling to obtain a flexible liquid metal electrode based on gallium indium tin alloy.

[0073] Comparative Example 1

[0074] The preparation method of the flexible liquid metal electrode based on gallium indium tin alloy is the same as the preparation steps of Example 1, except that no mechanical activation operation is performed, and includes the following steps:

[0075] A method for preparing an unactivated flexible liquid metal electrode based on gallium-indium-tin alloy comprises the following steps:

[0076] S1. Add 0.5 g polyvinyl pyrrolidone (PVP) powder and 0.5 g n-decanol to 9.0 g ethanol and stir at room temperature for 48 h to ensure that PVP is completely dissolved in ethanol to form a uniform and transparent PVP-n-decanol-ethanol solution.

[0077] S2. Under stirring conditions, 1 g of gallium indium tin liquid metal is added to 1 mL of PVP-n-decyl alcohol-ethanol solution. The purpose of stirring is to prevent the gallium indium tin liquid metal from agglomerating in the PVP-n-decyl alcohol-ethanol solution and ensure initial uniform dispersion to obtain a mixed solution. The mixed solution is placed in an ice water bath, and then a probe ultrasonic instrument (model: 1000Y, produced by Shanghai Hanno Instrument Co., Ltd.) is used, the amplitude is set to 100%, and intermittent ultrasonic treatment is used, that is, the ultrasonic treatment mode of 3 seconds on and 3 seconds off is used, and the ultrasonic treatment is performed for 180 seconds. This operation helps to refine the gallium indium tin liquid metal into nanoparticles and evenly disperse them in the PVP-n-decyl alcohol-ethanol solution, thereby forming a stable liquid metal ink.

[0078] S3. Use a screen with a size of 44mm×315mm and a mesh of 400. The pore size of the 400-mesh screen is small, which helps to ensure the fine pattern printing of the liquid metal ink on the screen and improve the uniform distribution of the liquid metal ink. Use the flexible electrospinning membrane as the flexible substrate, place the screen on top of the flexible electrospinning membrane, prepare a polyurethane scraper, and hold the polyurethane scraper at a 45° angle to the screen substrate. Brush the liquid metal ink evenly on the prepared screen. The angle and strength of the scraper are crucial to ensure that the liquid metal ink can be evenly coated on the screen and form a continuous pattern on the flexible electrospinning membrane.

[0079] S4. In the screen printing step, the liquid metal ink on the flexible electrospinning membrane is directionally heated by using local heating technology until the solvent is completely evaporated to obtain an unactivated flexible liquid metal electrode based on gallium indium tin alloy.

[0080] The present invention relates to a method for preparing a flexible liquid metal electrode based on a gallium indium tin alloy, which specifically includes preparing liquid metal ink by an ultrasonic method, coating and mechanically activating a circuit using the liquid metal ink, thereby improving the conductivity and mechanical stability of the flexible liquid metal electrode based on a gallium indium tin alloy. Embodiments 1 to 3 of the present invention obtain a flexible liquid metal electrode based on a gallium indium tin alloy with high conductivity, flexibility, mechanical stability and ease of preparation. The following is a study of the flexible liquid metal electrode based on a gallium indium tin alloy in Embodiment 1, and the specific research method and results are as follows:

[0081] Figure 1The process of preparing liquid metal ink by ultrasonic method is demonstrated. The specific steps are as follows: Liquid metal mixing: Use ultrasonic device to disperse gallium indium tin liquid metal in PVP-n-decyl alcohol-ethanol solution. The high-frequency vibration of ultrasonic wave can effectively break up gallium indium tin liquid metal agglomerates and disperse them into nano-scale particles to obtain uniform liquid metal ink; liquid metal ink has good fluidity and is suitable for making flexible liquid metal electrodes on flexible substrates by screen printing technology. This process is simple and efficient, suitable for large-scale production, and can ensure the uniform distribution of liquid metal ink on flexible substrates.

[0082] Figure 2 This is a SEM image of liquid metal ink. It can be seen from the image that the size of the gallium indium tin liquid metal after ultrasound is uniform, with an average diameter of nanometers. The advantage of nano-scale particles is that they can be evenly distributed on the surface of the flexible substrate, improving the conductivity and uniformity of the flexible liquid metal electrode based on gallium indium tin alloy. In addition, the smaller volume of nanoparticles enables liquid metal ink to achieve more detailed circuit design during coating and printing.

[0083] Figure 3 The SEM image of the flexible liquid metal electrode circuit based on gallium indium tin alloy before mechanical activation is shown. When the flexible liquid metal electrode based on gallium indium tin alloy is not mechanically activated, the gallium indium tin liquid metal presents a relatively flat film structure on the surface of the flexible substrate, but the internal conductive path of the flexible liquid metal electrode based on gallium indium tin alloy is not fully formed. At this time, the circuit resistance is high and the conductive performance is not optimal. In this case, although the gallium indium tin liquid metal has been attached to the flexible substrate, mechanical activation can further improve its internal structure and conductive performance.

[0084] Figure 4 The SEM image of the flexible liquid metal electrode circuit based on gallium indium tin alloy after mechanical activation is shown. After the flexible liquid metal electrode based on gallium indium tin alloy is mechanically activated, the connection between the particles of gallium indium tin liquid metal is strengthened, and the internal conductive network is further formed. The activation process includes mechanical stress through bending or stretching, which increases the contact area between the particles of gallium indium tin liquid metal, thereby reducing the resistance and significantly improving the conductivity of the circuit. From the SEM image, it can be seen that after mechanical activation, the particle structure on the surface of the flexible liquid metal electrode based on gallium indium tin alloy becomes more compact, the conductive path of the circuit becomes more continuous, and the conductive performance is significantly improved.

[0085] Figure 5The conductivity change curve of the flexible liquid metal electrode based on gallium indium tin alloy in the cycle stability experiment is shown. Through multiple bending or stretching experiments, it can be seen that the resistance of the flexible liquid metal electrode based on gallium indium tin alloy remains basically stable, showing excellent cycle stability. After a 10,000-second cycle experiment, the resistance change rate is still within an acceptable range, indicating that the flexible liquid metal electrode based on gallium indium tin alloy of the present invention has high durability and reliability. This result verifies its stability in long-term use, especially its ability to maintain conductivity after multiple deformations in flexible electronic devices, which greatly improves its practical application prospects.

[0086] In summary, through the preparation process of the present invention, the flexible liquid metal electrode based on gallium indium tin alloy has excellent conductivity and flexibility. Nanoparticles of gallium indium tin liquid metal are prepared by ultrasonic method, and screen printing and mechanical activation process are used to improve not only the conductivity of the flexible liquid metal electrode based on gallium indium tin alloy, but also significantly enhance its mechanical stability and durability. The present invention has broad application prospects in the fields of flexible electronics, wearable devices and smart sensors.

[0087] The following application is made by taking the gallium-indium-tin alloy-based flexible liquid metal electrode obtained in Example 1 as an example, as shown below:

[0088] 1. Preparation and application of flexible liquid metal temperature sensor:

[0089] Preparation of graphene oxide / PEDOT:PSS mixed solution: GO dispersion and PEDOT:PSS were mixed in a ratio of 1:1, and then stirred at 1000 rpm for 12 hours. 200 μL of GO / PEDOT:PSS ink was drop-cast onto the pattern of a flexible liquid metal electrode based on gallium indium tin alloy to form a temperature sensing layer. The mixed solution had good temperature response characteristics and was evenly distributed on the flexible liquid metal electrode based on gallium indium tin alloy by a simple spin coating method. After the sensing layer was encapsulated, a flexible liquid metal temperature sensor was formed.

[0090] This flexible liquid metal temperature sensor demonstrates high-sensitivity temperature detection capabilities and can accurately respond within the temperature range of 0°C to 100°C. Due to the high conductivity and flexibility of the flexible liquid metal electrode, the flexible liquid metal temperature sensor can still maintain stable operation under multiple deformation conditions and is suitable for application in wearable medical devices for real-time body temperature monitoring.

[0091] 2. Preparation and application of flexible liquid metal humidity sensor:

[0092] Multi-walled carbon nanotubes were dispersed in water (2 mg / mL) to prepare a multi-walled carbon nanotube solution, the multi-walled carbon nanotube solution was mixed with a graphene oxide dispersion so that the mass ratio of graphene oxide to multi-walled carbon nanotubes was 2.5:1 to obtain a mixed solution, and the mixed solution was ultrasonically treated for 6 h to obtain a graphene oxide / multi-walled carbon nanotube mixed solution.

[0093] A layer of graphene oxide / multi-walled carbon nanotube mixed liquid was coated on the pattern of the flexible liquid metal electrode based on gallium indium tin alloy in Example 1, and then vacuum dried at 45°C for 12 hours to prepare a flexible humidity sensor. The graphene oxide / multi-walled carbon nanotube composite material has high humidity response characteristics, and is applied to the surface of the flexible liquid metal electrode of gallium indium tin alloy by a spin coating process, and then low-temperature packaging is performed to obtain a flexible liquid metal humidity sensor.

[0094] This flexible liquid metal humidity sensor is very sensitive to changes in relative humidity and can accurately measure within the humidity range of 20% to 90%. This flexible liquid metal humidity sensor can be used in environmental monitoring systems, especially in the fields of smart homes and air quality detection, showing broad application prospects.

[0095] 3. Application of flexible liquid metal electrodes in electronic skin:

[0096] The flexible liquid metal electrode based on gallium indium tin alloy in Example 1 is further combined with a TPU flexible substrate and multiple sensors (such as temperature sensors and pressure sensors) to prepare flexible electronic skin. The precise printing of the circuit is achieved through the screen printing process to ensure that the signal output end of each sensor is connected to the flexible liquid metal electrode based on gallium indium tin alloy.

[0097] This electronic skin can monitor external environmental parameters such as temperature, pressure and humidity in real time, and has extremely high sensitivity and flexibility. When the wearer performs complex movements (such as bending and stretching), the flexible liquid metal electrodes and sensors based on gallium indium tin alloy can work normally, demonstrating the application potential of flexible liquid metal electrodes based on gallium indium tin alloy in future human-computer interaction and medical devices.

[0098] Through the verification of the above examples, the present invention demonstrates its wide application potential in the fields of flexible electronics, sensors and smart devices. At the same time, it has excellent conductivity, flexibility and mechanical stability, and has good industrialization prospects.

[0099] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and variations. The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and their protection scope is not limited thereto. Equivalent substitutions or changes made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention, and the protection scope of the present invention shall be subject to the claims.

Claims

1. A method for preparing a flexible liquid metal electrode based on gallium-indium-tin alloy, characterized in that: The steps include: Mixing a viscosity modifier, polyvinyl pyrrolidone, and a n-decanol solvent in anhydrous ethanol to obtain a PVP-n-decanol-ethanol solution; Adding gallium indium tin liquid metal to PVP-n-decyl alcohol-ethanol solution under stirring conditions, and then ultrasonicating in an ice water bath to obtain liquid metal ink; The liquid metal ink is patterned on a flexible substrate, and then the particles of the gallium indium tin liquid metal are broken by mechanical activation to promote the formation of a conductive network, thereby obtaining a flexible liquid metal electrode based on a gallium indium tin alloy.

2. The method for preparing a flexible liquid metal electrode based on gallium indium tin alloy according to claim 1, characterized in that: The mass ratio of polyvinyl pyrrolidone to n-decanol is 1:1-2.

3. The method for preparing a flexible liquid metal electrode based on gallium-indium-tin alloy according to claim 1, characterized in that: The mass ratio of the gallium indium tin liquid metal to the volume ratio of the PVP-n-decyl alcohol-ethanol solution is 0.5 g to 2 g: 1 mL.

4. The method for preparing a flexible liquid metal electrode based on gallium indium tin alloy according to claim 1, characterized in that: The flexible substrate includes an electrospun fiber substrate, a polyimide substrate, a polyethylene terephthalate substrate, a thermoplastic polyurethane elastomer rubber substrate or a polyvinyl alcohol film substrate.

5. The method for preparing a flexible liquid metal electrode based on gallium indium tin alloy according to claim 1, characterized in that: Conductive polymers or conductive nanoparticles can also be mixed into the liquid metal ink.

6. The method for preparing a flexible liquid metal electrode based on gallium indium tin alloy according to claim 1, characterized in that: After the liquid metal ink is patterned and coated on the flexible substrate, local heating is also performed.

7. The method for preparing a flexible liquid metal electrode based on gallium-indium-tin alloy according to claim 1, characterized in that: Mechanical activation occurs through repeated deformation or stress.

8. The method for preparing a flexible liquid metal electrode based on gallium indium tin alloy according to claim 1, characterized in that: The patterning of liquid metal ink is performed on a flexible substrate by screen printing or 3D printing.

9. A flexible liquid metal electrode based on gallium indium tin alloy prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the gallium-indium-tin alloy-based flexible liquid metal electrode according to claim 9 in the preparation of flexible electronic devices.

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