Bionic electronic skin capable of capturing three-dimensional multiple signals as well as preparation method and application of bionic electronic skin

Abstract

The invention discloses a three-dimensional multi-signal capture bionic electronic skin and a preparation method and application thereof. Polyvinyl alcohol (PVA) is used as a substrate, a conducting layer is piled on the interface of the substrate through a template layer-by-layer assembly technology assisted by in-situ oxidative polymerization, and the bionic electronic skin capable of capturing multiple signals is prepared. The material has excellent electrical conductivity, mechanical property and super-sensitive multiple signal capturing function, can quickly capture temperature, pressure change and gas signals, is simple to prepare and mild in reaction condition, can be integrated at the tail end of a manipulator of an intelligent robot, improves the dynamic adaptability of the manipulator, and is suitable for industrial production. The method has application prospects in the fields of industrial automation, medical auxiliary robots, dangerous environment detection and the like.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of bionic electronic skin, and relates to a bionic electronic skin for three-dimensional multiple signal capture, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of artificial intelligence, robotics, and wearable devices, bionic electronic skin, as a cutting-edge material that mimics the sensing functions of human skin, has become a hot topic in interdisciplinary research. Human skin not only has multiple sensing capabilities such as touch, temperature perception, and chemical signal detection, but also has characteristics such as flexibility, self-repair, and environmental adaptability. The goal of bionic electronic skin is to endow robots, prosthetics, or intelligent devices with skin-like sensing capabilities by integrating multiple sensors and flexible electronic components, so as to achieve breakthrough applications in fields such as medical health monitoring, intelligent robot interaction, and environmental detection.

[0003] In recent years, the progress of flexible electronics technology has promoted the rapid development of electronic skin. For example, sensors based on nanomaterials (such as carbon nanotubes, graphene, conductive polymers) have been widely studied for detecting single signals such as pressure, strain, temperature, and humidity. However, the multiple sensing characteristics of human skin require that electronic skin be able to capture multiple physical and chemical signals (such as pressure, temperature, gas composition) simultaneously or synergistically, which poses extremely high challenges to material design, manufacturing processes, and system integration. In addition, electronic skin also needs to have excellent mechanical properties (such as flexibility, stretchability) and biocompatibility to adapt to complex usage scenarios.

[0004] Despite significant progress in the field of electronic skin, there are still many bottlenecks in multi-signal sensing, material properties, and fabrication processes in the existing technologies. Traditional electronic skins mostly focus on single-signal detection, such as piezoresistive / capacitive sensors, thermoelectric / thermoresistive materials, gas sensors, etc. The integration of multiple signals usually requires stacking or splicing multiple independent sensors, resulting in complex device structures, signal crosstalk, and bulky volumes. The core of an electronic skin is the co-design of a flexible substrate and a conductive / sensitive layer. Although existing substrate materials (such as polydimethylsiloxane (PDMS), polyurethane (PU)) have good flexibility, their surface chemical inertness poses challenges to the uniform loading of the conductive layer. For example, graphene or silver nanowires need to be combined with the substrate through complex processes (such as chemical vapor deposition, vacuum sputtering), leading to high costs and difficulties in large-scale production. In addition, the hydrophobic properties of some substrate materials (such as PDMS) will hinder the in-situ polymerization of hydrophilic conductive polymers (such as polyaniline (PANI), polypyrrole), affecting the interfacial bonding strength. At the same time, the preparation of existing conductive layers often relies on high-temperature treatment, vacuum environment, or harmful solvents. For example, metal oxide gas sensors need to be annealed at high temperatures to improve crystallinity, but this will damage the mechanical properties of the flexible substrate. Similarly, the reduction process of graphene often involves strong acids or hydrazine-based reducing agents, posing environmental and safety risks. These harsh process conditions not only increase production costs but also limit the compatibility with biocompatible materials. Therefore, a method for preparing a bionic electronic skin with good compatibility between the substrate material and the conductive layer, a simple preparation process, and the ability to capture multiple signals is needed.

[0005] Patent CN202211184234.7 proposes a flexible pressure sensor composite based on polydimethylsiloxane (PDMS), which shows advantages such as fast response, high sensitivity, and process simplification in single-pressure detection scenarios. However, this material can only achieve single-modal capture of pressure signals, and due to the hydrophobic properties of PDMS, the interfacial bonding strength between its substrate and the conductive layer is insufficient, and delamination failure is likely to occur during long-term use. Summary of the Invention

[0006] Based on the above problems existing in the prior art, the purpose of the present invention is to provide a bionic electronic skin for three-dimensional multi-signal capture, its preparation method, and applications. The preparation method of the present invention has the advantages of simplicity, low cost, green and pollution-free, and is convenient for large-scale production; the bionic electronic skin prepared by the present invention has excellent mechanical properties and a super-sensitive multi-signal capture function, and can quickly capture signals of temperature, pressure change, and gas. It can be integrated at the end of the manipulator of an intelligent robot to improve the dynamic adaptability of the manipulator, and has application prospects in the fields of industrial automation, medical assistance robots, and hazardous environment detection.

[0007] In order to achieve the above technical effects, the following technical solutions are provided:

[0008] A preparation method of a bionic electronic skin for three-dimensional multiple signal capture, comprising the following steps:

[0009] (1) Construct a PVA substrate: Freeze and solidify an aqueous solution of polyvinyl alcohol (PVA) into a substrate;

[0010] (2) Preparation of a CNC mixture containing a conductive monomer: Uniformly disperse cellulose nanocrystals (CNC) in an aqueous solution to obtain a CNC dispersion; Then, under an ice bath, add a conductive monomer dispersion to the CNC dispersion to obtain a CNC mixture containing a conductive monomer;

[0011] (3) Preparation of an initiator solution: Mix a metal ion chloride with an aqueous solution of persulfate to obtain an initiator solution;

[0012] (4) Spray the CNC mixture containing a conductive monomer and the initiator solution onto the PVA substrate in batches and simultaneously. Immediately after each batch is sprayed, perform a freezing treatment to obtain a PVA substrate coated with a conductive layer. Finally, dry it to obtain a three-dimensional composite material, that is, a bionic electronic skin.

[0013] Preferably, the solid-liquid ratio of the PVA aqueous solution is 1 g:5 - 10 mL. The PVA solution is heated and stirred at 80 - 90 °C for 2 - 4 hours and then frozen and solidified.

[0014] Preferably, the solid-liquid ratio of the CNC dispersion is 1 g:40 - 50 mL.

[0015] Preferably, the conductive monomer is one of pyrrole and aniline; the solid-liquid ratio of the conductive monomer to water in the conductive monomer dispersion is 1 g:70 - 80 mL.

[0016] Preferably, the mass ratio of the CNC to the conductive monomer is 1:1.5 - 4.

[0017] Preferably, the metal ion chloride is one of potassium chloride, sodium chloride, zinc chloride, copper chloride, and ferric chloride, and the persulfate is ammonium persulfate; the ratio of the metal ion chloride, ammonium persulfate, and water is 1 g:7 g:60 mL.

[0018] Preferably, the CNC mixture containing a conductive monomer and the initiator solution are sprayed onto the PVA substrate according to a volume ratio of 1:1.

[0019] Preferably, in step (4), the CNC mixture containing a conductive monomer and the initiator solution are sprayed onto the PVA substrate 3 - 5 times. Finally, the volume ratio of the CNC mixture containing a conductive monomer, the initiator solution, and the PVA substrate is 3:3:5.

[0020] The present invention uses polyvinyl alcohol as the base material, and uses persulfate and metal chloride as initiators. The conductive monomer dispersion is added to the cellulose nanocrystal (CNC) dispersion, and then the initiator and the dispersion are sprayed onto the frozen PVA substrate simultaneously until a conductive layer is formed, and then dried to obtain a bionic electronic skin for three-dimensional multi-signal capture. During the polymerization process, pyrrole undergoes electron transfer through oxidative polymerization reaction to form a polymer chain structure. Persulfate and metal chloride can provide sufficient oxidation ability to enable the conductive monomer to carry out efficient polymerization reaction. At the same time, in the template layer-by-layer assembly technology, freezing can quickly solidify the solution state of each layer, prevent the interface mixing or collapse of the conductive layer due to the action of gravity, ensure the clear interface of the conductive layer, and improve the durability of the product.

[0021] The present invention also provides a bionic electronic skin for three-dimensional multi-signal capture obtained by the above preparation method.

[0022] The present invention also provides the application of the above bionic electronic skin in the fields of robots, environmental detection or sensors.

[0023] The beneficial effects of the present invention are as follows:

[0024] (1) The present invention uses CNC as the raw material, which has a wide source, and the preparation method of the present invention is simple and easy to mass-produce, meeting the advantages of large market demand, and having considerable social and economic benefits.

[0025] (2) The bionic electronic skin for three-dimensional multi-signal capture prepared by the present invention has excellent electrical conductivity, mechanical properties and ultra-sensitive multi-signal capture function, can be integrated at the end of the manipulator of an intelligent robot to realize the collaborative detection of multiple signals of pressure, temperature and gas, significantly improve the dynamic adaptability of the manipulator, and has important application value in the fields of industrial automation, medical assistance robots and dangerous environment detection. Description of the Drawings

[0026] Figure 1 It is a field emission scanning electron microscope image of the cross-section of the bionic electronic skin for three-dimensional multi-signal capture.

[0027] Figure 2 It is a field emission scanning electron microscope image of the surface of the bionic electronic skin for three-dimensional multi-signal capture.

[0028] Figure 3 It is a mechanical property diagram of the bionic electronic skin for three-dimensional multi-signal capture prepared in Example 1.

[0029] Figure 4 It is a tensile sensing performance test diagram of the bionic electronic skin for three-dimensional multi-signal capture prepared in Example 1.

[0030] Figure 5Test chart of the pressure sensing performance of the three-dimensional multi-signal capturing bionic e-skin prepared in Example 1.

[0031] Figure 6 Test chart of the temperature sensing performance of the three-dimensional multi-signal capturing bionic e-skin prepared in Example 1. Detailed implementation manners

[0032] The present invention will be further described below in conjunction with specific examples. These examples are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0033] For those conditions not clearly specified in the examples, they are carried out according to conventional conditions, and the instruments or reagents used are all purchased commercially.

[0034] The cellulose nanocrystals (CNC) used in the examples were obtained by self-preparation. The specific preparation method is as follows: After mixing 90% citric acid (270 mL, 3 mol / L) / 10% hydrochloric acid (30 mL, 6 mol / L), add it to microcrystalline cellulose, heat and stir at 80 °C for 4 h; after full reaction, cool to room temperature and dilute with deionized water; then perform centrifugation to remove the supernatant, and repeat the operation until it is close to neutral, and freeze-dry for 48 h to obtain cellulose nanocrystals.

[0035] Example 1

[0036] A preparation method of a three-dimensional multi-signal capturing bionic e-skin:

[0037] (1) Construct a PVA substrate: Mix polyvinyl alcohol (PVA) and water at a solid-liquid ratio of 1 g: 9 mL, place it in a water bath at 80 °C and stir (rotation speed is 30 r / min) for 4 h to prepare a PVA aqueous solution, and then freeze it to solidify into a substrate;

[0038] (2) Preparation of a CNC mixture containing a conductive monomer: Uniformly disperse cellulose nanocrystals (CNC) in an aqueous solution at a solid-liquid ratio of 1 g: 50 mL, and ultrasonically disperse for 30 min to obtain a CNC dispersion; then, under an ice bath at 0 °C, add a pyrrole dispersion (solid-liquid ratio of 1 g: 74 mL) to the CNC dispersion, where the mass ratio of CNC to the conductive monomer is 1:2, and ultrasonically disperse for 15 min to obtain a CNC mixture containing a conductive monomer;

[0039] (3) Preparation of an initiator solution: Mix ferric chloride, ammonium persulfate and water in a ratio of 1 g: 7 g: 60 ml, and ultrasonically disperse for 10 min to obtain a uniformly dispersed initiator solution;

[0040] (4) Pour 30 ml of the CNC mixture containing the conductive monomer and 30 ml of the initiator solution into spray bottles respectively. After shaking well, spray them simultaneously onto the substrate formed by freezing 50 ml of the PVA aqueous solution in 5 batches. Immediately after each batch is sprayed, perform a freezing treatment to obtain a PVA substrate coated with a conductive layer. Finally, dry it in an oven at 50 °C for 15 h to obtain a three-dimensional composite material, namely, the bionic electronic skin.

[0041] Example 2 (compared with Example 1, the conductive monomer is aniline)

[0042] A preparation method of a bionic electronic skin for three-dimensional multiple signal capture:

[0043] (1) Construct a PVA substrate: Mix polyvinyl alcohol (PVA) and water at a solid-liquid ratio of 1 g: 9 mL, place it in a water bath at 80 °C and stir (rotation speed is 30 r / min) for 4 h to prepare a PVA aqueous solution, and then freeze and solidify it into a substrate;

[0044] (2) Preparation of the CNC mixture containing the conductive monomer: Uniformly disperse cellulose nanocrystals (CNC) in an aqueous solution at a solid-liquid ratio of 1 g: 50 mL, and perform ultrasonic dispersion for 30 min to obtain a CNC dispersion; then, under an ice bath, add an aniline dispersion (solid-liquid ratio of 1 g: 74 mL) to the CNC dispersion, where the mass ratio of CNC to the conductive monomer is 1:2, and perform ultrasonic dispersion for 15 min to obtain a CNC mixture containing the conductive monomer;

[0045] (3) Preparation of the initiator solution: Mix ferric chloride, ammonium persulfate and water in a ratio of 1 g: 7 g: 60 ml, and perform ultrasonic treatment for 10 min to obtain a uniformly dispersed initiator solution;

[0046] (4) Pour 30 ml of the CNC mixture containing the conductive monomer and 30 ml of the initiator solution into spray bottles respectively. After shaking well, spray them simultaneously onto the substrate formed by freezing 50 ml of the PVA aqueous solution in 5 batches. Immediately after each batch is sprayed, perform a freezing treatment to obtain a PVA substrate coated with a conductive layer. Finally, dry it in an oven at 50 °C for 15 h to obtain a three-dimensional composite material, namely, the bionic electronic skin.

[0047] Example 3 (compared with Example 1, the concentration of CNC in the CNC dispersion is increased)

[0048] A preparation method of a bionic electronic skin for three-dimensional multiple signal capture:

[0049] (1) Construct a PVA substrate: Mix polyvinyl alcohol (PVA) and water at a solid-liquid ratio of 1 g: 9 mL, place it in a water bath at 80 °C and stir (rotation speed is 30 r / min) for 4 h to prepare a PVA aqueous solution, and then freeze and solidify it into a substrate;

[0050] (2) Preparation of CNC mixed solution containing conductive monomer: Uniformly disperse cellulose nanocrystals (CNC) in an aqueous solution with a solid-liquid ratio of 1 g: 40 mL, and ultrasonically disperse for 30 min to obtain a CNC dispersion; then, under an ice bath, add a pyrrole dispersion (solid-liquid ratio of 1 g: 74 mL) to the CNC dispersion, where the mass ratio of CNC to the conductive monomer is 1:2, and ultrasonically disperse for 15 min to obtain a CNC mixed solution containing the conductive monomer;

[0051] (3) Preparation of initiator solution: Mix ferric chloride, ammonium persulfate, and water in a ratio of 1 g: 7 g: 60 mL, and ultrasonically disperse for 10 min to obtain a uniformly dispersed initiator solution;

[0052] (4) After filling 30 mL of the CNC mixed solution containing the conductive monomer and 30 mL of the initiator solution into spray bottles and shaking them evenly, spray them simultaneously onto the substrate formed by freezing 50 mL of an aqueous PVA solution in 5 batches, and immediately perform freezing treatment after each batch is sprayed to obtain a PVA substrate coated with a conductive layer. Finally, dry it in an oven at 50 °C for 15 h to obtain a three-dimensional composite material, that is, a bionic electronic skin.

[0053] Example 4 (compared with Example 3, the conductive monomer is aniline)

[0054] A preparation method of a bionic electronic skin for three-dimensional multiple signal capture:

[0055] (1) Construction of PVA substrate: Mix polyvinyl alcohol (PVA) and water in a solid-liquid ratio of 1 g: 9 mL, place it in a water bath at 80 °C and heat and stir (rotation speed of 30 r / min) for 4 h to prepare an aqueous PVA solution, and then freeze and solidify it into a substrate;

[0056] (2) Preparation of CNC mixed solution containing conductive monomer: Uniformly disperse cellulose nanocrystals (CNC) in an aqueous solution with a solid-liquid ratio of 1 g: 40 mL, and ultrasonically disperse for 30 min to obtain a CNC dispersion; then, under an ice bath, add an aniline dispersion (solid-liquid ratio of 1 g: 74 mL) to the CNC dispersion, where the mass ratio of CNC to aniline is 1:2, and ultrasonically disperse for 15 min to obtain a CNC mixed solution containing the conductive monomer;

[0057] (3) Preparation of initiator solution: Mix ferric chloride, ammonium persulfate, and water in a ratio of 1 g: 7 g: 60 mL, and ultrasonically disperse for 10 min to obtain a uniformly dispersed initiator solution;

[0058] (4) After filling 30 ml of the CNC mixture containing conductive monomers and 30 ml of the initiator solution into spray bottles and shaking them evenly, they were sprayed onto the substrate formed by freezing 50 ml of the PVA aqueous solution in 5 batches simultaneously. Immediately after each batch was sprayed, a freezing treatment was carried out to obtain a PVA substrate coated with a conductive layer. Finally, it was dried in an oven at 50 °C for 15 h to obtain a three-dimensional composite material, namely a bionic electronic skin.

[0059] The performance test results of Examples 1-4 are as follows:

[0060] Figure 1 It is a field emission scanning electron microscope image of the cross-section of the bionic electronic skin for three-dimensional multiple signal capture. It can be seen that the material is a multi-layer structure, reflecting the characteristics of its three-dimensional structure.

[0061] Figure 2 It is a field emission scanning electron microscope image of the surface of the bionic electronic skin for three-dimensional multiple signal capture. It can be seen that the surface structure of the material is stable.

[0062] Figure 3 It is a mechanical property diagram of the bionic electronic skin for three-dimensional multiple signal capture prepared in Example 1. It can be seen that the mechanical properties of the material are outstanding.

[0063] Figure 4 It is a tensile sensing performance test diagram of the bionic electronic skin for three-dimensional multiple signal capture prepared in Example 1. The stretching of the material is divided into two segments, and the sensitivities of the two segments are 1.67 and 5.72 respectively.

[0064] Figure 5 It is a pressure sensing performance test diagram of the bionic electronic skin for three-dimensional multiple signal capture prepared in Example 1. The response times at both ends are 257 ms and 228 ms respectively.

[0065] Figure 6 It is a temperature sensing performance test diagram of the bionic electronic skin for three-dimensional multiple signal capture prepared in Example 1. Its temperature coefficient (TCR) is 1.13 °C -1 。

[0066] From the above results, it can be seen that: the bionic electronic skin for three-dimensional multiple signal capture prepared by the present invention has excellent electrical conductivity, mechanical properties and ultra-sensitive multiple signal capture functions. It can quickly capture signals of temperature, pressure change and gas, and can be integrated at the end of the manipulator of an intelligent robot to improve the dynamic adaptability of the manipulator, and has application prospects in the fields of industrial automation, medical assistance robots and dangerous environment detection.

[0067] The above-described embodiments are only a preferred solution of the present invention, and do not impose any form of limitation on the present invention. There are other variations and modifications without exceeding the technical solutions recorded in the claims.

Claims

1. A preparation method of a bionic electronic skin for three-dimensional multi-signal capture, characterized in that, It includes the following steps: (1) Construct a PVA substrate: Freeze and solidify an aqueous solution of polyvinyl alcohol (PVA) into a substrate; (2) Preparation of a CNC mixture containing a conductive monomer: Uniformly disperse cellulose nanocrystals (CNC) in an aqueous solution to obtain a CNC dispersion; then, under an ice bath, add a conductive monomer dispersion to the CNC dispersion to obtain a CNC mixture containing a conductive monomer; (3) Preparation of an initiator solution: Mix a metal ion chloride with an aqueous solution of ammonium persulfate to obtain an initiator solution; (4) Spray the CNC mixture containing a conductive monomer and the initiator solution onto the PVA substrate in batches simultaneously. Immediately after each batch is sprayed, perform a freezing treatment to obtain a PVA substrate coated with a conductive layer, and finally dry it to obtain a three-dimensional composite material, i.e., a bionic electronic skin.

2. The preparation method according to claim 1, characterized in that, The solid-liquid ratio of the PVA aqueous solution is 1 g:5 - 10 mL. The PVA solution is heated and stirred at 80 - 90 °C for 2 - 4 hours and then frozen and solidified.

3. The preparation method according to claim 1, characterized in that, The solid-liquid ratio of the CNC dispersion is 1 g:40 - 50 mL.

4. The preparation method according to claim 1, characterized in that, The conductive monomer is one of pyrrole and aniline; the solid-liquid ratio of the conductive monomer to water in the conductive monomer dispersion is 1 g:70 - 80 mL.

5. The preparation method according to claim 1, wherein The mass ratio of the CNC to the conductive monomer is 1:1.5 - 4.

6. The preparation method according to claim 1, wherein The metal ion chloride is one of potassium chloride, sodium chloride, zinc chloride, copper chloride, and ferric chloride. The persulfate is ammonium persulfate; the ratio of the metal ion chloride, ammonium persulfate, and water is 1 g:7 g:60 mL.

7. The preparation method according to claim 1, wherein The CNC mixture containing a conductive monomer and the initiator solution are sprayed onto the PVA substrate according to a volume ratio of 1:

1.

8. The preparation method according to claim 1, characterized in that, In step (4), the CNC mixture containing a conductive monomer and the initiator solution are sprayed onto the PVA substrate 3 - 5 times. Finally, the volume ratio of the CNC mixture containing a conductive monomer, the initiator solution, and the PVA substrate is 3:3:

5.

9. A three-dimensional multi-signal capturing bionic electronic skin obtained by the preparation method according to any one of claims 1 - 8.

10. Application of the three-dimensional multi-signal capturing bionic electronic skin according to any one of claims 1 - 9 in the fields of robots, environmental detection, or sensors.

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