Composite nanofiber electronic skin as well as preparation method and application thereof

Abstract

The invention relates to the technical field of electronic skin and flexible sensing, in particular to composite nanofiber electronic skin and a preparation method and application thereof. The composite nanofiber electronic skin comprises a first composite nanofiber layer, a dielectric layer and a second composite nanofiber layer which are stacked, the composite nanofiber layer comprises a substrate layer and a conductive layer; the substrate layer is prepared from spinning slurry through electrostatic spinning; the spinning slurry comprises polydimethylsiloxane, polymer particles and a surfactant; the mass ratio of the polydimethylsiloxane to the polymer particles is (0.3-8): 1; the surface, facing the dielectric layer, of the composite nanofiber layer is provided with periodically arranged bulge structures; the protruding structure comprises N prismatic tables which are sequentially stacked from bottom to top in a stepped mode. The electronic skin disclosed by the invention has the characteristics of high sensitivity, wide detection range and short response time, also has tensile strength and durability, and shows a wide application prospect in the fields of intelligent wearable equipment and the like in the future.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electronic skin and flexible sensing technology, in particular to a composite nanofiber electronic skin and a preparation method and application thereof. BACKGROUND

[0002] Electronic skin is a new type of flexible electronic sensing system that simulates the characteristics and functions of human skin, integrates various sensing units, conductive networks and signal processing modules, and can realize real-time sensing and information interaction of external physical, chemical and physiological stimuli. In recent years, with the rapid development of intelligent technology, humanoid robots have higher requirements for multi-modal sensing and environmental adaptability, and the application demand of human wearable devices in the field of health monitoring, human-computer interaction and other fields also increases year by year, which promotes the continuous evolution of electronic skin technology towards high performance and multifunctionalization.

[0003] Modern electronic skin not only has high requirements for sensing characteristics such as high sensitivity, low detection limit and fast response, but also needs to have properties such as stretchability, air permeability, self-healing and biocompatibility, aiming to realize integrated sensing of pressure, temperature, humidity and even biochemical signals. Such technology is becoming a core component of intelligent robot sensing systems and the next generation of wearable medical devices, and has important scientific research value and wide application prospects.

[0004] However, electronic skin still faces key challenges such as limited functional integration, difficulty in synergistically improving multiple properties, and high preparation cost, which seriously restricts its large-scale application. At present, the sensing sensitivity of electronic skin and the mechanical stretchability and air permeability of the device are mutually restricted. High-sensitivity materials usually have high rigidity and are difficult to achieve high mechanical stretchability. Porous or network substrates usually have good air permeability, but their conductivity and sensing sensitivity are relatively poor. In addition, traditional conductive materials are prone to structural damage under repeated deformation, and have relatively poor stability. Therefore, how to synergistically construct composite nanofiber-based electronic skin with high sensitivity, excellent mechanical adaptability and stable conductive network through material design and structural innovation has become a core scientific problem that needs to be broken through in this field.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The purpose of the present application is to provide a composite nanofiber electronic skin and a preparation method and application thereof. The composite nanofiber electronic skin of the present application has the characteristics of high sensitivity, wide detection range and fast response time, and also has tensile strength and durability.

[0007] To achieve the above object of the present application, the first aspect of the present application provides a composite nanofiber electronic skin, comprising a first composite nanofiber layer, a dielectric layer and a second composite nanofiber layer arranged in a stack; The first composite nanofiber layer and the second composite nanofiber layer comprise a substrate layer and a conductive layer; the conductive layer is arranged in close contact with the dielectric layer; The substrate layer is prepared by electrospinning of a spinning dope; the spinning dope comprises polydimethylsiloxane, polymer particles and a surfactant; the mass ratio of the polydimethylsiloxane to the polymer particles is (0.3-8):1; The first composite nanofiber layer and the second composite nanofiber layer have periodically arranged protruding structures on the surface facing the dielectric layer; the protruding structures comprise N prisms stacked in a step-by-step manner from bottom to top, N being an integer between 3 and 10.

[0008] In the detailed embodiment of the present application, the polymer particles comprise at least one of polyvinyl alcohol, nylon, polyglycolide and polycaprolactone.

[0009] In the detailed embodiment of the present application, the particle size of the polymer particles is 0.05-20 μm.

[0010] In the detailed embodiment of the present application, the amount of the surfactant is 2wt%-8wt% of the total amount of the polydimethylsiloxane and the polymer particles.

[0011] In the detailed embodiment of the present application, the thickness of the substrate layer is 50-300 μm.

[0012] In the detailed embodiment of the present application, the diameter of the minimum circumscribed circle of the bottom surface of the protruding structure is 10-60 μm, and the height of the protruding structure is 20-100 μm.

[0013] In the detailed embodiment of the present application, the height of the prism is 2-10 μm. Further, the included angle between the side surface and the bottom surface of the prism is 60°-90°.

[0014] In the detailed embodiment of the present application, the prism is a regular prism.

[0015] In the detailed embodiment of the present application, the conductive layer comprises at least one of MXenes, carbon nanotubes, silver nanowires and graphene.

[0016] In the detailed embodiment of the present application, the dielectric layer comprises at least one of polyethylene, polyurethane, polystyrene and polydimethylsiloxane.

[0017] The second aspect of the present application provides a preparation method of the composite nanofiber provided by the first aspect of the present application, comprising the following steps: (a) electrospinning a spinning dope to obtain a base layer; (b) spraying a conductive slurry on the surface of the base layer, and performing a compression molding treatment on the side of the base layer on which the conductive slurry is sprayed through a mold to obtain a composite nanofiber layer; (c) oppositely arranging two composite nanofiber layers, and attaching a dielectric layer material between the two composite nanofiber layers to laminate to form a composite nanofiber electronic skin.

[0018] In the specific embodiment of the present application, the spraying thickness of the conductive slurry is 50-150 μm.

[0019] The third aspect of the present application provides an application of the composite nanofiber electronic skin in a wearable electronic device.

[0020] Compared with the prior art, the present application has the following beneficial effects: (1) The electronic skin of the present application comprises a base layer and a conductive layer, and has a periodic arrangement of protruding structures on the surface, the arrangement of the protruding structures increases the contact area and sensitive sites of the conductive layer, effectively improves the electrical performance, and has the characteristics of high sensitivity, wide detection range and fast response time; through material regulation, the tensile strength and durability of the base layer are significantly improved; (2) The electronic skin of the present application has the characteristics of high sensitivity, wide detection range and fast response time, and also has tensile strength and durability, and has broad application prospects and important material potential in the field of future intelligent wearable devices. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0022] Figure 1 The structure schematic diagram of the composite nanofiber electronic skin provided by the embodiment of the present application is shown in the figure; Figure 2 The structure schematic diagram of the composite nanofiber layer provided by the embodiment of the present application is shown in the figure; Figure 3 The top view structure schematic diagram of the composite nanofiber layer provided by the embodiment of the present application is shown in the figure; Figure 4 The structure schematic diagram of the mold for forming the protruding structure provided by the embodiment of the present application is shown in the figure; Figure 5 TEM image of the substrate layer provided for the embodiment 1 of the present application; Figure 6 Structural schematic diagram of the composite nanofiber layer provided for the comparative example 6 of the present application.

[0023] Reference signs: 1-first composite nanofiber layer; 2-dielectric layer; 3-second composite nanofiber layer; 4-mold body; 11-substrate layer; 12-conductive layer; 121-protruding structure; 41-groove structure. DETAILED DESCRIPTION

[0024] The technical solutions of the present application will be described clearly and completely in combination with the drawings and specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of the present application. The specific conditions are not specified in the embodiments, which are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, which are conventional products that can be purchased on the market.

[0025] Figure 1 Structural schematic diagram of the composite nanofiber electronic skin provided for the embodiment of the present application, Figure 2 Structural schematic diagram of the composite nanofiber layer provided for the embodiment of the present application, Figure 3 Top view structural schematic diagram of the composite nanofiber layer provided for the embodiment of the present application; the composite nanofiber electronic skin of the present application comprises a first composite nanofiber layer 1, a dielectric layer 2 and a second composite nanofiber layer 3 which are stacked; The first composite nanofiber layer 1 and the second composite nanofiber layer 3 comprise a substrate layer 11 and a conductive layer 12; the conductive layer 12 is arranged in close contact with the dielectric layer 2; The substrate layer 11 is prepared by electrospinning of a spinning dope; the spinning dope comprises polydimethylsiloxane, polymer particles and a surfactant; the mass ratio of polydimethylsiloxane to polymer particles is (0.3-8) : 1; The surface of the first composite nanofiber layer 1 and the second composite nanofiber layer 3 towards the dielectric layer 2 has periodically arranged protruding structures 121; the protruding structures 121 comprise N prisms stacked in a step type from bottom to top, and N is an integer between 3 and 10.

[0026] The electronic skin of the present application comprises a substrate layer and a conductive layer, and has periodic arrangement of convex structures on the surface, the arrangement of the convex structures increases the contact area and sensitive sites of the conductive layer, effectively improves the electrical performance, and has the characteristics of high sensitivity, wide detection range and fast response time; through material regulation, the tensile strength and durability of the substrate layer are significantly improved. Moreover, the electronic skin of the present application retains excellent air permeability and superhydrophobicity of the material.

[0027] In some embodiments, the convex structure 121 comprises N prisms stacked in a step-by-step manner from bottom to top, and N is an integer between 3 and 10, for example, N can be 3, 4, 5, 6, 7, 8, 9 or 10.

[0028] In some embodiments, in the convex structure 121, the i+1th prism is located above the ith prism, and the bottom surface diameter of the i+1th prism is smaller than the top surface diameter of the ith prism, and i takes a value in the range of 1≤i<N-1.

[0029] In some embodiments, the diameter of the minimum circumscribed circle of the bottom surface of the convex structure 121 is 10-60 μm, for example, it can be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm or a range formed by any two of them; the height of the convex structure 121 is 20-100 μm, for example, it can be 20 μm, 30 μm, 50 μm, 60 μm, 80 μm, 100 μm or a range formed by any two of them.

[0030] In some embodiments, the height of the prism is 2-10 μm, for example, it can be 2 μm, 3 μm, 5 μm, 7 μm, 8 μm, 10 μm or a range formed by any two of them. Further, the angle between the side surface and the bottom surface of the prism is 60°-90°, which can be 60°, 65°, 70°, 75°, 80°, 85°, 90° or a range formed by any two of them.

[0031] In some embodiments, the prism is a regular prism. Further, the prism is a triangular prism.

[0032] In some embodiments, the convex structure 121 is arranged in a periodic matrix. Further, along the transverse direction of the matrix arrangement, the bottom corners of the first prisms of adjacent convex structures 121 are sequentially connected; along the longitudinal direction of the matrix arrangement, the center of the bottom edge of the first prism of adjacent convex structures 121 and the top corner of the first prism are sequentially connected.

[0033] In some embodiments, the convex structure 121 penetrates the conductive layer 12 and extends to the substrate layer 11. Further, the height of the convex structure extending to the substrate layer 11 is 0-20 μm.

[0034] In some embodiments, the mass ratio of the polydimethylsiloxane to the polymer particles is (0.3-8) : 1, such as 0.3:1, 0.5:1, 1:1, 2:1, 3:1, 5:1, 8:1, or a range defined by any two of them, thereby improving the strength and flexibility of the base layer.

[0035] In some embodiments, the polydimethylsiloxane is prepared from a polydimethylsiloxane prepolymer and a silicone curing agent. Further, the mass ratio of the polydimethylsiloxane prepolymer to the silicone curing agent is (8-15) : 1, such as 8:1, 10:1, 12:1, 14:1, 15:1, or a range defined by any two of them; and the silicone curing agent includes Dow Sylgard 184.

[0036] In some embodiments, the polymer particles include at least one of polyvinyl alcohol (PVA), nylon (PA), polyglycolide (PLGA), and polycaprolactone (PCL).

[0037] In some embodiments, the polymer particles have a particle size of 0.05-20 μm, such as 0.05 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 20 μm, or a range defined by any two of them, preferably 0.2-2 μm, thereby further improving the mechanical properties of the base layer 11.

[0038] In some embodiments, the spinning dope includes a surfactant; the surfactant is present in an amount of 2wt%-8wt% of the total amount of the polydimethylsiloxane and the polymer particles, such as 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 8wt%, or a range defined by any two of them. Further, the surfactant includes cetyltrimethylammonium bromide or Pluronic F-127. The introduction of the appropriate amount of the surfactant adjusts the surface tension of the spinning dope, thereby improving the uniformity of the base layer 11.

[0039] In some embodiments, the spinning dope further includes a solvent; the spinning dope has a solid content of 20%-30%, such as 20%, 22%, 25%, 28%, 30%, or a range defined by any two of them. Further, the solvent includes at least one of N,N-dimethylformamide, tetrahydrofuran, dimethyl sulfoxide, and isopropyl alcohol.

[0040] In some embodiments, the base layer 11 has a thickness of 50-300 μm, such as 50 μm, 80 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, or a range defined by any two of them.

[0041] In some embodiments, the conductive layer 12 comprises at least one of MXenes, carbon nanotubes, silver nanowires and graphene.

[0042] In some embodiments, the dielectric layer 2 is filled in the groove formed by the convex structure 121 of the two-sided composite nanofiber layer.

[0043] In some embodiments, the dielectric layer 2 comprises at least one of polyethylene, polyurethane, polystyrene and polydimethylsiloxane. Further, the average thickness of the dielectric layer 2 is 50 μm-300 μm, which can be specifically 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm or a range between any two of them.

[0044] The second aspect of the present application provides a preparation method of the composite nanofiber provided by the first aspect of the present application, which comprises the following steps: (a) electrospinning the spinning dope to obtain a base layer; (b) spraying the conductive slurry on the surface of the base layer, and performing embossing treatment on the side of the base layer with the conductive slurry by a mold to obtain a composite nanofiber layer; (c) oppositely arranging two composite nanofiber layers, and attaching a dielectric layer material between the two composite nanofiber layers to laminate and form a composite nanofiber electronic skin.

[0045] In some embodiments, the preparation of the spinning dope comprises: mixing the components in proportion and stirring until completely homogeneous. Further, the preparation of the spinning dope comprises: stirring the polydimethylsiloxane prepolymer and silica gel curing agent at 20-150°C to obtain polydimethylsiloxane; then adding polymer particles, surfactants and solvents, and stirring to obtain the spinning dope.

[0046] In some embodiments, in the electrospinning, the spinning voltage is 8-25 kV, the receiving distance is 5-20 cm, and the liquid supply speed is 0.1-10 ml / h.

[0047] In some embodiments, the preparation of the conductive slurry comprises: mixing MXenes, carbon nanotubes, silver nanowires and / or graphene with water and ethanol, and ultrasonic dispersion to form the conductive slurry. Further, the volume ratio of water and ethanol is 7:3-3:7.

[0048] In some embodiments, the solid content of the conductive slurry is 4%-20%, which can be specifically 4%, 6%, 8%, 10%, 15%, 20% or a range between any two of them.

[0049] In some embodiments, the spraying thickness of the conductive paste is 50-150 μm, for example, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm or a range defined by any two of them.

[0050] In some embodiments, the spraying method comprises ultrasonic spraying. Further, in the ultrasonic spraying, the spraying flow rate is 0.5-5 ml / min, the nozzle moving speed is 5-50 mm / s, and the spraying height is 5-80 mm.

[0051] In some embodiments, during the spraying process, the substrate layer is placed on a heating platform, and the heating temperature is controlled to be 40-90℃, for example, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃ or a range defined by any two of them. The heating platform can be a vacuum adsorption heating platform.

[0052] Figure 4 The structural schematic diagram of the mold for forming the protruding structure provided in the embodiments of the present application, in some embodiments, the mold has a mold body 4 and a groove structure 41 periodically arranged on the surface of the mold body 4. In the imprinting process, the side provided with the groove structure 41 is covered on the side sprayed with the conductive paste to perform the imprinting process to form the protruding structure 121.

[0053] In some embodiments, the groove structure 41 and the protruding structure 121 are complementary to each other.

[0054] In some embodiments, the mold is a PDMS mold, and the specific preparation method refers to the existing PDMS mold preparation method, which is not described here.

[0055] In some embodiments, in the imprinting process, the mold is covered on the side sprayed with the conductive paste and hot-pressed. Further, in the hot-pressing, the heating temperature is 180-450℃, and the pressing time is 30-180 s.

[0056] In actual operation, the pressing process can be repeated 2-3 times until the protruding structure is obtained.

[0057] In some embodiments, in the imprinting process, the substrate layer 11 is softened by heating and deformed under the action of pressure, so that the sprayed conductive paste layer is deformed, thereby forming the periodically arranged protruding structure 121. In this process, the protruding structure 121 can penetrate the conductive layer 12 and extend to the substrate layer 11.

[0058] In some embodiments, in step (c), the thickness of the attached dielectric layer material is 50-300 μm. Further, the laminating comprises: sequentially laying up the composite nanofiber layer, the dielectric layer and the composite nanofiber layer, clamping and fixing, the laminating pressure is 0.3-1.5 MPa, specifically, it can be 0.3 MPa, 0.5 MPa, 0.8 MPa, 1 MPa, 1.2 MPa, 1.5 MPa or a range formed by any two of them; the laminating time is 60-180 s, specifically, it can be 60 s, 90 s, 120 s, 150 s, 180 s or a range formed by any two of them; the laminating temperature is 90-135℃, specifically, it can be 90℃, 100℃, 110℃, 120℃, 130℃, 135℃ or a range formed by any two of them.

[0059] The third aspect of the present application provides the use of the composite nanofiber electronic skin in a wearable electronic device.

[0060] Example 1 The present embodiment provides a preparation method of the composite nanofiber electronic skin, comprising the following steps: (1) Take PDMS prepolymer and Dow Sylgard 184 curing agent with a mass ratio of 10:1, stir at 80℃ for 2h to obtain a PDMS mixture; then mix the PDMS mixture with PVA particles (average particle size of 2μm) at a mass ratio of 1:1, add 5wt% of Pluronic F-127 surfactant based on the total mass of the PDMS mixture and PVA particles, then add a certain amount of solvent, stir at room temperature for 10h to obtain a spinning dope with a solid content of 25%; wherein the solvent is N,N-dimethylformamide, tetrahydrofuran and dimethyl sulfoxide with a volume ratio of 1:3:1.

[0061] Transfer the spinning dope to a 10ml disposable syringe equipped with a steel needle for electrospinning; in the electrospinning, the spinning voltage is 15kV, the liquid supply speed is 5ml / h, and the receiving distance is 12cm; after spinning, take off the white PDMS / PVA base layer with a thickness of 210μm from the aluminum foil. Figure 5 The TEM image of the base layer shows that the base layer has nanofiber-like properties.

[0062] (2) Take MXenes and silver nanowires with a mass ratio of 1:1, add deionized water and anhydrous ethanol with a volume ratio of 1:2, ultrasonic treatment for 2h to achieve uniform dispersion, forming a conductive slurry with a solid content of 7.5%.

[0063] The PDMS / PVA base layer is placed on a vacuum adsorption heating platform, and the heating temperature is controlled to be 70 DEG C; the conductive paste is placed in the slurry tank of the ultrasonic spraying machine, the ultrasonic spraying flow is set to 1.5 ml / min, the nozzle moving speed is 30 mm / s, the spraying height is 30 mm, the conductive paste is ultrasonic sprayed on the surface of the PDMS / PVA base layer, and the spraying thickness of the conductive paste is 95 mu m.

[0064] The mold is covered on the side sprayed with the conductive paste, and the groove structure of the mold faces the conductive paste, and the hot pressing is performed three times to form a convex structure, and a composite nanofiber layer is obtained; the hot pressing comprises: using a hot air gun to heat the material from above, controlling the outlet temperature of the hot air gun to be 380 DEG C, and the distance between the outlet of the hot air gun and the conductive paste is about 5 cm, and after the surface of the base layer covered with the conductive paste is heated and softened, a uniform vertical pressure is applied on the mold to press for 60 s. The convex structure formed is arranged in a periodic matrix, the bottom angle of the first prism of the adjacent convex structures is sequentially connected along the transverse direction of the matrix arrangement; the center of the bottom side of the first prism of the adjacent convex structures is sequentially connected with the top angle of the first prism along the longitudinal direction of the matrix arrangement; the convex structure comprises five prisms stacked in a step type from bottom to top, the prisms are all three prisms, the diameter of the minimum circumscribed circle of the bottom surface of the convex structure is 40 mu m, the height of the convex structure is 80 mu m (of which, the height extending to the base layer is 10 mu m), and the height of each prism is 10 mu m; the angle between the side surface of each prism and the bottom surface is 80 DEG.

[0065] (3) The two composite nanofiber layers are oppositely arranged, the conductive layers face the inner side, and a polyurethane film with a thickness of 120 mu m is placed between the two composite nanofiber layers, and the lamination assembly is implemented at a pressure of 0.5 MPa at 110 DEG C for 100 s, and then copper wires are welded on the surfaces of the two composite nanofiber layers as leads, to construct an electronic skin sensor.

[0066] Example 2 In this embodiment, the preparation method of Example 1 is referred to, and the only difference is that in step (1), the types of polymer particles in the spinning slurry are different; in step (2), the outlet temperature of the hot air gun is different.

[0067] In this embodiment, equal mass of PLGA particles is used to replace the PVA particles in Example 1 in the spinning slurry; and the outlet temperature of the hot air gun is 350 DEG C.

[0068] Example 3 In this embodiment, the preparation method of Example 1 is referred to, and the only difference is that in step (1), the types of polymer particles in the spinning slurry are different, and the thickness of the base layer is different; in step (2), the outlet temperature of the hot air gun is different.

[0069] The spinning dope of the present example uses equal mass of mixed polymer particles to replace the PVA particles in Example 1; the mixed polymer particles include PLGA particles and PVA particles with a mass ratio of 1:1; the thickness of the base layer obtained in step (1) of the present example is 230 μm; the hot air gun outlet temperature is 400 °C.

[0070] Example 4 The present example refers to the preparation method of Example 2, the only difference being that in step (2), the hot air gun outlet temperature is different; and in step (3), the dielectric layer material is different.

[0071] The hot air gun outlet temperature of the present example is 380 °C; and the dielectric layer material of step (3) is a polyethylene film.

[0072] Example 5 The present example refers to the preparation method of Example 1, the only difference being that in step (1), the mass ratio of the PDMS mixture and PVA particles in the spinning dope is different.

[0073] The mass ratio of the PDMS mixture and PVA particles of the present example is 2:1.

[0074] Comparative Example 1 Comparative Example 1 refers to the preparation method of Example 1, the only difference being that in step (1), the spinning dope does not contain PVA particles.

[0075] Comparative Example 2 Comparative Example 2 refers to the preparation method of Example 1, the only difference being that in step (1), the spinning dope does not contain PVA particles; and in step (2), after spraying the conductive slurry, no subsequent hot pressing treatment is performed.

[0076] Comparative Example 3 Comparative Example 3 refers to the preparation method of Example 1, the only difference being that in step (2), after spraying the conductive slurry, no subsequent hot pressing treatment is performed.

[0077] Comparative Example 4 Comparative Example 4 refers to the preparation method of Example 1, the only difference being that in step (1), the types of polymer particles in the spinning dope are different.

[0078] The spinning dope of the present comparative example uses equal mass of TPU particles to replace the PVA particles in Example 1.

[0079] Comparative Example 5 Comparative Example 5 refers to the preparation method of Example 1, the only difference being that in step (1), the mass ratio of the PDMS mixture and PVA particles in the spinning dope is different.

[0080] The mass ratio of the PDMS mixture and PVA particles of the present comparative example is 10:1.

[0081] Comparative Example 6 Comparative Example 6 refers to the preparation method of Example 1, the only difference is that in step (2), the protruding structure formed by hot pressing is different.

[0082] The protruding structure formed in this comparative example is arranged in a periodic matrix, and the distance between adjacent protruding structures is 20 μm in the transverse and longitudinal directions of the matrix arrangement; the protruding structure is a cuboid, the base diameter is 40 μm, and the protruding structure height is 50 μm. The structure diagram of the composite nanofiber layer provided by this comparative example is shown in Figure 6 .

[0083] Experimental Example The electronic skin sensor devices prepared in different examples and comparative examples were tested for performance at room temperature, and the test method was as follows, and the test results are shown in Table 1.

[0084] Sensitivity: tested by a universal material testing machine combined with a precision digital resistor, set the loading rate to 5 mm / min, simultaneously collect the pressure and electrical signals, analyze the relationship between the resistance change rate and the pressure, fit the linear response interval, and calculate the sensitivity value.

[0085] Pressure detection range: during the loading process of the sensitivity test, determine the pressure interval in which the sensor electrical signal response is linearly changed, record the electrical signal response in real time by continuous loading, analyze the resistance change curve, and determine the pressure interval in which the sensor maintains linear response and the pressure value (maximum range) when the electrical signal reaches saturation or mutation.

[0086] Tensile strength: the sample was prepared into a standard sample, and tested by a universal material testing machine equipped with a tensile clamp, uniaxial stretching was carried out at a rate of 20 mm / min, and the stress-strain curve was recorded synchronously, so as to determine the mechanical breaking strength of the material.

[0087] Table 1 Performance test results of different examples and comparative examples

[0088] From the above test results, it can be seen that the electronic skin of the present application includes a substrate layer and a conductive layer, and has a periodic arrangement of protruding structures on the surface. The arrangement of the protruding structures increases the contact area and sensitive sites of the conductive layer, effectively improves the electrical performance, and has the characteristics of high sensitivity, wide detection range and fast response time; through material regulation, the tensile strength and durability of the substrate layer are significantly improved.

[0089] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A composite nanofiber electronic skin, characterized by, The composite nanofiber electronic skin comprises a first composite nanofiber layer, a dielectric layer and a second composite nanofiber layer arranged in a stack. The first composite nanofiber layer and the second composite nanofiber layer comprise a base layer and a conductive layer; the conductive layer is arranged in close contact with the dielectric layer. The base layer is prepared by electrospinning of a spinning dope; the spinning dope comprises polydimethylsiloxane, polymer particles and a surfactant; the mass ratio of the polydimethylsiloxane to the polymer particles is (0.3-8):

1. The first composite nanofiber layer and the second composite nanofiber layer have periodically arranged protruding structures on the surface facing the dielectric layer; the protruding structures comprise N prisms stacked in a step-by-step manner from bottom to top, and N is an integer between 3 and 10.

2. The composite nanofiber electronic skin according to claim 1, wherein, The polymer particles comprise at least one of polyvinyl alcohol, nylon, polyglycolide and polycaprolactone; the particle size of the polymer particles is 0.05-20 μm.

3. The composite nanofiber electronic skin according to claim 1, wherein, The amount of the surfactant is 2wt%-8wt% of the total amount of the polydimethylsiloxane and the polymer particles.

4. The composite nanofiber electronic skin according to claim 1, wherein, The thickness of the base layer is 50-300 μm.

5. The composite nanofiber electronic skin according to claim 1, wherein, The protruding structures have at least one of the following characteristics: (1) the diameter of the minimum circumscribed circle of the bottom surface of the protruding structures is 10-60 μm; (2) the height of the protruding structures is 20-100 μm; (3) the height of the prisms is 2-10 μm; (4) the angle between the side surface and the bottom surface of the prisms is 60°-90°; (5) the prisms are regular prisms.

6. The composite nanofiber electronic skin according to claim 1, wherein The conductive layer comprises at least one of MXenes, carbon nanotubes, silver nanowires and graphene.

7. The composite nanofiber electronic skin according to claim 1, wherein The dielectric layer comprises at least one of polyethylene, polyurethane, polystyrene and polydimethylsiloxane.

8. The method of claim 1 to 7, wherein the composite nanofiber electronic skin is prepared by the steps of: The method comprises the following steps: (a) electrospinning of a spinning dope to obtain a base layer; (b) spraying of a conductive paste on the surface of the base layer, and compression molding of the side of the base layer with the conductive paste by a mold to obtain a composite nanofiber layer; (c) arranging two composite nanofiber layers in opposition, and attaching a dielectric layer material between the two composite nanofiber layers to laminate and form a composite nanofiber electronic skin.

9. The production method according to claim 8, characterized by, The spraying thickness of the conductive paste is 50-150 μm.

10. Use of the composite nanofiber electronic skin of any one of claims 1-7 or the composite nanofiber electronic skin prepared by the method of any one of claims 8-9 in a wearable electronic device.

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