CN115219571A

CN115219571A - Self-powered flexible sensor and preparation method thereof

Info

Publication number: CN115219571A
Application number: CN202210820996.5A
Authority: CN
Inventors: 姜晟; 郝南京; 张进华
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2022-07-13
Filing date: 2022-07-13
Publication date: 2022-10-21

Abstract

The invention discloses a self-powered flexible sensor and a preparation method thereof, belonging to the technical field of electrochemical sensors and comprising a first flexible film layer, a first flexible electrode layer, a zinc oxide nanosheet layer, a second flexible film layer, a second flexible electrode layer and a third flexible film layer which are sequentially arranged; the sensor has the advantages that the wires are respectively led out of the first flexible electrode layer and the second flexible electrode layer, the sensor changes the microscopic morphology of a zinc oxide material by introducing metal ions as a doping agent so as to enhance the piezoelectric property of the material, the sensor has excellent flexibility and tensile property, the force-electricity sensitive correspondence of the sensor is improved, and the problems that in the prior art, the conductivity of the electrode of the sensor is weakened or even lost due to poor flexibility of the sensor and poor tensile property of the electrode material, and the requirements of a soft robot on the mechanical property and the monitoring property of the sensor cannot be met are solved.

Description

Self-powered flexible sensor and preparation method thereof

Technical Field

The invention belongs to the technical field of electrochemical sensors, and relates to a self-powered flexible sensor and a preparation method thereof.

Background

In the field of soft body robots, the deployment of sensors is often limited by aspects such as limited lifetime, high maintenance costs and heavy battery weight. In recent years, the self-powered piezoelectric sensor implanted externally or internally can provide long-time body and environment monitoring behaviors and enlarge sensory output, thereby greatly meeting the requirements of the soft robot and enlarging the application range of the soft robot. However, among various commonly used piezoelectric materials, inorganic piezoelectric materials such as BaTiO ₃ Lead zirconate titanate (PZT), lead niobate-lead titanate (PMN-PT), and the like, although having a high piezoelectric coefficient, have inherent stiffness characteristics that limit their application in flexible sensors.

Most flexible sensors such as sensors using polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES), kapton film or paper as a substrate still cannot meet the requirements of the soft robot on the flexibility in the practical application process, and have the obvious defect of unmatched performance with the requirements of the soft robot on the mechanical performance. Meanwhile, since the electrodes of the flexible sensor are usually platinum (Pt), copper (Cu) or Indium Tin Oxide (ITO) and are disposed on the polymer film by sputtering, these metal-based electrodes are very easy to break when stretched, so that the conductivity of the electrodes is reduced or even completely lost.

Therefore, a flexible sensor with excellent flexibility, tensile recovery, stable chemical components and excellent sensing and detecting performance is urgently needed to meet the requirement of the soft robot on the mechanical performance of the flexible sensor and promote the development of the soft robot.

Disclosure of Invention

The invention aims to solve the problems that the sensor electrode conductivity is weakened or even lost and the requirements of a soft robot on the mechanical property and the monitoring property of the sensor cannot be met due to poor flexibility and poor tensile property of an electrode material in the prior art, and provides a self-powered flexible sensor and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:

the invention provides a self-powered flexible sensor which comprises a first flexible thin film layer, wherein a first flexible electrode layer, a zinc oxide nanosheet layer, a second flexible thin film layer, a second flexible electrode layer and a third flexible thin film layer are sequentially arranged on the first flexible thin film layer; wires are respectively led out of the first flexible electrode layer and the second flexible electrode layer and used for collecting and leading out electric signals of the sensor; the first flexible electrode layer and the second flexible electrode layer are carbon nanotube electrode layers, graphene electrode layers or carbon powder electrode layers.

Preferably, the first flexible film layer, the second flexible film layer and the third flexible film layer are polydimethylsiloxane prepolymer films.

A preparation method of the self-powered flexible sensor comprises the following steps:

s1: preparing a first flexible film layer as a flexible substrate;

s2: preparing a first flexible electrode layer on the surface of a flexible substrate;

s3: growing a zinc oxide nanosheet layer on the surface of the first flexible electrode layer;

s4: coating a second flexible film layer on the surface of the zinc oxide nanosheet layer;

s5: pressing a second flexible electrode layer on the surface of the second flexible thin film layer;

s6: coating a third flexible thin film layer on the surface of the second flexible electrode layer;

s7: and connecting a lead into the first flexible electrode layer and the second flexible electrode layer to finish the preparation of the self-powered flexible sensor.

Preferably, the preparation method of the first flexible film layer, the second flexible film layer and the third flexible film layer is as follows:

weighing a polydimethylsiloxane prepolymer and a polydimethylsiloxane prepolymer curing agent, mixing, and uniformly stirring to form a polydimethylsiloxane prepolymer mixed solution;

discharging bubbles in the polydimethylsiloxane prepolymer mixed solution, coating the bubble-free polydimethylsiloxane prepolymer mixed solution on a carrier, heating and curing for 10-30 min at 65-85 ℃, washing, and drying to form the flexible film layer.

Preferably, the mass ratio of the polydimethylsiloxane prepolymer to the polydimethylsiloxane prepolymer curing agent is 10.

Preferably, the preparation method of the first flexible electrode layer and the second flexible electrode layer comprises the following steps:

dissolving a surfactant in water to form a surfactant aqueous solution;

dispersing a carbon material in an aqueous surfactant solution to form a carbon material dispersion;

and depositing the carbon material dispersion liquid on a filter membrane through vacuum filtration, standing at room temperature until the solvent is completely evaporated, transferring the carbon material on the filter membrane, adhering the carbon material to the surface of a required carrier, and drying to form the flexible electrode layer.

Preferably, the surfactant is alkylbenzene sulfonate, alkyl sulfonate salt, alkyl sulfonate, alkyl sulfate, fluorine-containing fatty acid salt, polysiloxane, fatty alcohol sulfate, fatty alcohol polyoxyethylene ether sulfate, α -alkenyl sulfonate, fatty alcohol polyoxyethylene ether phosphate, alkylolamide, alkylsulfoacetamide, alkyl succinate sulfonate, alkylolamines alkylbenzene sulfonate, naphthenate, alkylphenol sulfonate or polyoxyethylene monolaurate.

Preferably, the amount mass ratio of the carbon material to the surfactant is as follows: (1; the concentration of the surfactant aqueous solution is 2.5 mg/mL-20 mg/mL.

Preferably, the specific operation of growing the zinc oxide nanosheet layer on the surface of the first flexible electrode layer is as follows:

dissolving zinc acetate and alkali in an ethanol solution to form a first mixed solution;

dissolving zinc salt, aluminum salt and hexamethylene tetramine in an ethanol solution to form a second mixed solution;

spin-coating the first mixed solution on the surface of the first flexible electrode layer, drying, placing in the second mixed solution, and heating at a constant temperature of 75-95 ℃ for 5-6 h;

and repeatedly replacing new second mixed liquid for many times, and repeatedly heating the second mixed liquid for 5-6 h at the constant temperature of 75-95 ℃ every time of replacement until a densely arranged zinc oxide nano structure grows on the surface of the first flexible electrode layer, namely finishing the growth of the zinc oxide nano sheet layer.

Preferably, the concentration of zinc acetate in the first mixed solution is 5 mmol/L-15 mmol/L; the alkali concentration is 20 mmol/L-50 mmol/L; in the second mixed solution, the zinc salt is zinc nitrate or zinc chloride, and the concentration of the zinc salt is 20 mmol/L-50 mmol/L; the aluminum salt is aluminum nitrate or aluminum chloride, and the concentration of the aluminum salt is 6 mmol/L-8 mmol/L; the concentration of the hexamethylene tetramine is 20 mmol/L-50 mmol/L.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides a self-powered flexible sensor, which takes nano zinc oxide as a piezoelectric material, the raw materials are cheap and easy to obtain, the hexagonal wurtzite structure is the most stable structure under natural conditions, a piezoelectric potential can be generated under external tensile/compressive strain, the piezoelectric tensor is larger, the electromechanical coupling coefficient is large, the piezoelectric performance is good, the sensor can be directly synthesized on a flexible substrate, and the flexible sensor can be matched with the arrangement of a flexible film layer and a flexible electrode layer, so that the flexibility of the sensor can be improved, the energy consumption is reduced, and the influence of long-time torsion, tensile, bending and other complex deformations of the sensor on the electrode and the overall monitoring performance of the sensor is reduced; secondly, the sensor adopts carbon materials including carbon nano tubes, graphene or carbon powder as the flexible electrode layer, so that the sensor not only has very good conductivity, but also improves the tensile resistance of the flexible electrode, so that the flexible electrode still can keep very good mechanical property and conductivity in a stretching state, and the electrode breakage and even loss of conductivity of the sensor caused by stretching are avoided.

The invention also provides a preparation method of the self-powered flexible sensor, which can realize seamless connection and effective integration of the rigid piezoelectric ceramic nano zinc oxide, the flexible thin film layer of the non-piezoelectric soft material and the flexible electrode layer, is beneficial to optimizing the structural design of the piezoelectric device, analyzes the feasibility of the application of the piezoelectric nano material as the flexible sensor, and provides a theoretical basis for the application of the piezoelectric material in the aspects of the flexible sensing device, the piezoelectric nano generator and the like. The method has simple process and easy realization, and can obtain the self-powered flexible sensor with good flexibility and excellent monitoring performance without high-temperature treatment;

secondly, the invention effectively controls the reaction and changes the microscopic morphology of the nano zinc oxide crystal through the doping agent to enhance the piezoelectric output performance, and the zinc oxide nano array is directly grown on the surface of the first flexible electrode layer to form an elastic piezoelectric film, so that the sensor still keeps stability during complex deformation motions such as long-time torsion, stretching, bending and the like;

compared with the traditional metal electrode, the flexible electrode layer prepared by the vacuum filtration method can better keep better mechanical property and conductivity in a stretching state.

Drawings

In order to more clearly explain the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Figure 1 is a block diagram of a self-powered flexible sensor of the present invention.

FIG. 2 is a flow chart of a method for manufacturing a self-powered flexible sensor according to the present invention.

Figure 3 is a scanning electron microscope image of a self-powered flexible sensor zinc oxide nanosheet layer in an embodiment of the present invention.

Figure 4 is a torsion, tensile test chart of a self-powered flexible sensor in an embodiment of the present invention.

Figure 5 is a graph illustrating a self-powered flexible sensor tensile strength test in an embodiment of the present invention.

Fig. 6 is a scanning electron microscope image of the self-powered flexible sensor based on the zinc oxide nano-sheet piezoelectric structure prepared in the embodiment of the present invention and the conventional self-powered flexible sensor based on the zinc oxide nano-wire piezoelectric structure, and a voltage output curve comparison image of the corresponding excitation test under the same conditions.

Fig. 7 is a voltage output bar graph comparing the self-powered flexible sensor based on the zinc oxide nano-sheet piezoelectric structure prepared in the embodiment of the present invention with a conventional self-powered flexible sensor based on the zinc oxide nano-wire piezoelectric structure in an excitation test.

The flexible film comprises a first flexible film layer, b-a first flexible electrode layer, c-a zinc oxide nanosheet layer, d-a second flexible film layer, e-a second flexible electrode layer and f-a third flexible film layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. are used for indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship which is usually arranged when the product of the present invention is used, the description is merely for convenience and simplicity, and the indication or suggestion that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, cannot be understood as limiting the present invention. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.

Furthermore, the term "horizontal", if present, does not mean that the component is required to be absolutely horizontal, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the embodiments of the present invention, it should be further noted that unless otherwise explicitly stated or limited, the terms "disposed," "mounted," "connected," and "connected" should be broadly construed and interpreted as including, for example, fixed connections, detachable connections, or integral connections; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.

The invention is described in further detail below with reference to the accompanying drawings:

referring to fig. 1, the invention provides a self-powered flexible sensor, which includes a first flexible thin film layer a and a third flexible thin film layer f, wherein a first flexible electrode layer b, a zinc oxide nanosheet layer c, a second flexible thin film layer d and a second flexible electrode layer e are sequentially disposed between the first flexible thin film layer a and the third flexible thin film layer f; wires are led out of the first flexible electrode layer b and the second flexible electrode layer e respectively and used for collecting and leading out electric signals of the sensor; the first flexible electrode layer b and the second flexible electrode layer e are carbon nanotube electrode layers, graphene electrode layers or carbon powder electrode layers; the first flexible film layer a, the second flexible film layer d and the third flexible film layer f are polydimethylsiloxane prepolymer films.

Referring to fig. 2, the present invention further provides a method for preparing the self-powered flexible sensor, which includes the following steps:

s1: preparing a first flexible film layer a as a flexible substrate:

the specific operation is as follows: weighing polydimethylsiloxane prepolymer and polydimethylsiloxane prepolymer curing agent respectively according to the mass ratio of 10;

S2: preparing a first flexible electrode layer b:

the specific operation is as follows: taking alkylbenzene sulfonate, alkyl sulfonate salt, alkyl sulfonate, alkyl sulfate, fluorine-containing fatty acid salt, polysiloxane, fatty alcohol sulfate, fatty alcohol-polyoxyethylene ether sulfate, alpha-alkenyl sulfonate, fatty alcohol-polyoxyethylene ether phosphate, alkyl alcohol amide, alkyl sulfonic acetamide, alkyl succinate sulfonate, alcohol amine alkylbenzene sulfonate, naphthenate, alkyl phenol sulfonate or polyoxyethylene monolaurate as a surfactant to dissolve in water to form surfactant aqueous solution; wherein the concentration of the surfactant aqueous solution is 2.5 mg/mL-20 mg/mL;

dispersing a carbon material in an aqueous surfactant solution to form a carbon material dispersion; the mass ratio of the carbon material to the surfactant is as follows: (1;

and depositing the carbon material dispersion liquid on a filter membrane through vacuum filtration, standing at room temperature until the solvent is completely evaporated, transferring the carbon material on the filter membrane, adhering the carbon material to the surface of a required carrier, namely the surface of the first flexible thin film layer a in the S1, and drying to form a first flexible electrode layer b.

S3: growing a zinc oxide nanosheet layer c on the surface of the first flexible electrode layer b;

the specific operation is as follows: dissolving zinc acetate and alkali in an ethanol solution to form a first mixed solution; in the first mixed solution, the concentration of zinc acetate is 5 mmol/L-15 mmol/L; the alkali concentration is 20 mmol/L-50 mmol/L;

dissolving zinc salt, aluminum salt and hexamethylene tetramine in an ethanol solution to form a second mixed solution; in the second mixed solution, the zinc salt is zinc nitrate or zinc chloride, and the concentration of the zinc salt is 20 mmol/L-50 mmol/L; the aluminum salt is aluminum nitrate or aluminum chloride, and the concentration of the aluminum salt is 6 mmol/L-8 mmol/L; the concentration of the hexamethylene tetramine is 20 mmol/L-50 mmol/L;

spin-coating the first mixed solution on the surface of the first flexible electrode layer b, drying, placing in the second mixed solution, and heating at a constant temperature of 75-95 ℃ for 5-6 h;

and repeatedly replacing new second mixed liquid for many times, and repeatedly heating the second mixed liquid for 5-6 h at the constant temperature of 75-95 ℃ every time of replacement until a densely arranged zinc oxide nanosheet structure grows on the surface of the first flexible electrode layer b, namely finishing the growth of the zinc oxide nanosheet layer c.

S4: coating a second flexible thin film layer d on the surface of the zinc oxide nanosheet layer c;

the specific operation is as follows: spin-coating the polydimethylsiloxane prepolymer mixed solution prepared in the step S1 on the surface of the zinc oxide nanosheet layer c, heating and curing for 10-30 min at the temperature of 65-85 ℃, washing, and drying to form a second flexible thin film layer d;

s5: pressing a second flexible electrode layer e on the surface of the second flexible thin film layer d;

the specific operation is as follows: depositing the carbon material dispersion liquid prepared in the step S2 on a filter membrane through vacuum filtration, standing at room temperature until the solvent is completely evaporated, transferring the carbon material on the filter membrane, adhering the carbon material on the surface of a required carrier, namely the surface of a second flexible thin film layer d, and drying to form a second flexible electrode layer e;

s6: coating a third flexible thin film layer f on the surface of the second flexible electrode layer e;

the specific operation is as follows: spin-coating the polydimethylsiloxane prepolymer mixed solution prepared in the step S1 on the surface of the second flexible electrode layer e, heating and curing for 10-30 min at the temperature of 65-85 ℃, washing, and drying to form a third flexible film layer f;

s7: and connecting a lead into the first flexible electrode layer b and the second flexible electrode layer e to complete the preparation of the self-powered flexible sensor.

Example 1

Preparing a glass sheet with the specification of 50mm multiplied by 2mm required by the test for standby; weighing 10g of polydimethylsiloxane prepolymer and 1g of polydimethylsiloxane prepolymer curing agent, wherein the polydimethylsiloxane prepolymer curing agent is a polydimethylsiloxane prepolymer matching product and has the product name of: SYLGARD ^TM 184 Silicone Elastomer Base; mixing, stirring at constant speed along the same direction to uniformly mix the polydimethylsiloxane prepolymer and the polydimethylsiloxane prepolymer curing agent to form polydimethylsiloxane prepolymer mixed solution;

placing the dimethyl silicone polymer prepolymer mixed solution into a vacuum drying oven for standing, and vacuumizing until all bubbles in the dimethyl silicone polymer mixed solution are discharged; sucking bubble-free polydimethylsiloxane prepolymer mixed liquor, uniformly dripping the bubble-free polydimethylsiloxane prepolymer mixed liquor on a prepared glass sheet, using a spin coater, rotating at 1000rpm/min, wherein the spin coating time is 1min, spin coating the polydimethylsiloxane prepolymer mixed liquor on the glass sheet, putting the glass sheet into a constant-temperature heating box, heating and curing for 30min at 65 ℃, respectively washing the glass sheet with deionized water, acetone and absolute ethyl alcohol in an ultrasonic cleaning machine for 5min to 15min, and drying at 65 ℃ for later use to form a first flexible thin film layer a.

Weighing 1g of sodium dodecyl sulfate powder and 5mg of multi-walled carbon nanotube powder, placing the powder in 100mL of deionized water, and performing ultrasonic treatment for 20min to uniformly disperse the powder to form a multi-walled carbon nanotube dispersion liquid;

and (2) padding a layer of PTFE filter membrane with the aperture of 50nm on a sand core of the vacuum filtration funnel, pouring the multi-wall carbon nano tube dispersion into the vacuum filtration funnel, depositing a layer of carbon nano tube electrode plate on the PTFE filter membrane after vacuum filtration, standing at room temperature until the solvent is completely evaporated, transferring the multi-wall carbon nano tube material on the filter membrane, adhering the multi-wall carbon nano tube material on the surface of the first flexible thin film layer a, and drying to form a first flexible electrode layer b.

Respectively weighing 92mg of zinc acetate and 80mg of sodium hydroxide, placing the zinc acetate and the sodium hydroxide into 100mL of absolute ethyl alcohol solution, and performing ultrasonic dispersion for 20min until the zinc acetate and the sodium hydroxide are uniformly mixed to form a first mixed solution;

respectively weighing 470mg of zinc nitrate, 350mg of hexamethylenetetramine and 140mg of aluminum nitrate, placing the weighed materials in 100mL of absolute ethyl alcohol, and ultrasonically dispersing the materials in an ultrasonic cleaning machine for 20min until the materials are uniformly mixed to form a second mixed solution;

spin-coating the first mixed solution on the surface of the first flexible electrode layer b at the rotation speed of 1000rpm/min, placing the first mixed solution in a constant-temperature heating box at 70 ℃ to dry completely, placing the first flexible electrode layer b in the second mixed solution with the surface facing downwards, and heating at the constant temperature of 85 ℃ for 5 hours;

and (3) repeatedly replacing the new second mixed solution for three times, and repeatedly heating at constant temperature of 85 ℃ for 5 hours every time the second mixed solution is replaced, until a densely arranged zinc oxide nanosheet structure grows on the surface of the first flexible electrode layer b, namely the growth of the zinc oxide nanosheet layer c is completed.

Spinning a layer of polydimethylsiloxane prepolymer mixed solution on the surface of the zinc oxide nanosheet layer c at the rotating speed of 3000rpm/min for 2min, heating and curing for 20min at the temperature of 65 ℃, sequentially cleaning for 5 min-15min in an ultrasonic cleaning machine through deionized water, acetone and absolute ethyl alcohol respectively, drying at the temperature of 65 ℃, and forming a second flexible thin film layer d on the surface of the zinc oxide nanosheet layer c;

depositing the multi-walled carbon nanotube dispersion liquid on a filter membrane through vacuum filtration, standing at room temperature until a solvent is completely evaporated, transferring a multi-walled carbon nanotube material on the filter membrane, adhering the multi-walled carbon nanotube material to the surface of a second flexible thin film layer d, and drying to form a second flexible electrode layer e;

spin-coating the polydimethylsiloxane prepolymer mixed solution for 2min at 3000rpm/min, spin-coating the polydimethylsiloxane prepolymer mixed solution on the surface of the second flexible electrode layer e, heating and curing for 10min at 65 ℃, washing, and drying to form a third flexible film layer f;

and adhering copper strips on the first flexible electrode layer b and the second flexible electrode layer e, and connecting the copper strips with a lead to finish the preparation of the self-powered flexible sensor.

Example 2

Preparing a glass sheet with the specification of 50mm multiplied by 2mm required by the test for standby; weighing 10g of polydimethylsiloxane prepolymer and 1g of polydimethylsiloxane prepolymer curing agent, mixing, and uniformly stirring along the same direction to uniformly mix the polydimethylsiloxane prepolymer and the polydimethylsiloxane prepolymer curing agent to form polydimethylsiloxane prepolymer mixed solution;

putting the polydimethylsiloxane prepolymer mixed solution into a vacuum drying oven for standing and vacuumizing until all bubbles in the polydimethylsiloxane prepolymer mixed solution are discharged; sucking bubble-free polydimethylsiloxane prepolymer mixed liquor, uniformly dripping the bubble-free polydimethylsiloxane prepolymer mixed liquor on a prepared glass sheet, using a spin coater, rotating at 1000rpm/min, wherein the spin coating time is 1min, spin coating the polydimethylsiloxane prepolymer mixed liquor on the glass sheet, putting the glass sheet into a constant-temperature heating box, heating and curing for 20min at 70 ℃, respectively washing the glass sheet with deionized water, acetone and absolute ethyl alcohol in an ultrasonic cleaning machine for 5min to 15min, and drying at 65 ℃ for later use to form a first flexible thin film layer a.

Weighing 0.25g of sodium dodecyl benzene sulfonate powder and 2.5mg of multi-walled carbon nanotube powder, placing in 100mL of deionized water, and performing ultrasonic treatment for 20min to uniformly disperse the powder to form a multi-walled carbon nanotube dispersion liquid;

183.5mg of zinc acetate and 120mg of sodium hydroxide are respectively weighed, placed in 100mL of absolute ethanol solution, and ultrasonically dispersed for 30min until being uniformly mixed to form a first mixed solution;

respectively weighing 272.6mg of zinc chloride, 280.4mg of hexamethylene tetramine and 80mg of aluminum chloride, placing the zinc chloride, 280.4mg of hexamethylene tetramine and 80mg of aluminum chloride into 100mL of absolute ethyl alcohol, and performing ultrasonic dispersion in an ultrasonic cleaning machine for 20min until the zinc chloride, the hexamethylene tetramine and the aluminum chloride are uniformly mixed to form a second mixed solution;

spin-coating the first mixed solution on the surface of the first flexible electrode layer b at the rotation speed of 1000rpm/min, placing the first mixed solution in a constant-temperature heating box at 75 ℃ to dry completely, placing the first flexible electrode layer b in the second mixed solution with the surface facing downwards, and heating at the constant temperature of 75 ℃ for 6 hours;

and (4) repeatedly replacing new second mixed liquid for three times, and repeatedly heating at the constant temperature of 75 ℃ for 6 hours every time the second mixed liquid is replaced, until a densely arranged zinc oxide nanosheet structure grows on the surface of the first flexible electrode layer b, namely the growth of the zinc oxide nanosheet layer c is completed.

Spin-coating a layer of polydimethylsiloxane prepolymer mixed solution on the surface of the zinc oxide nanosheet layer c at the rotating speed of 3000rpm/min for 2min, heating and curing for 20min at the temperature of 65 ℃, sequentially cleaning the mixed solution in an ultrasonic cleaning machine for 5min to 15min through deionized water, acetone and absolute ethyl alcohol respectively, and drying the mixed solution at the temperature of 65 ℃ to form a second flexible thin film layer d on the surface of the zinc oxide nanosheet layer c;

Example 3

Preparing a glass sheet with the specification of 50mm multiplied by 2mm required by the test for standby; weighing 20g of polydimethylsiloxane prepolymer and 2g of polydimethylsiloxane prepolymer curing agent, mixing, and uniformly stirring along the same direction to uniformly mix the polydimethylsiloxane prepolymer and the polydimethylsiloxane prepolymer curing agent to form polydimethylsiloxane prepolymer mixed solution;

putting the polydimethylsiloxane prepolymer mixed solution into a vacuum drying oven for standing and vacuumizing until all bubbles in the polydimethylsiloxane prepolymer mixed solution are discharged; sucking bubble-free polydimethylsiloxane prepolymer mixed liquor, uniformly dripping the bubble-free polydimethylsiloxane prepolymer mixed liquor on a prepared glass sheet, using a spin coater, rotating at 1000rpm/min, wherein the spin coating time is 1min, spin coating the polydimethylsiloxane prepolymer mixed liquor on the glass sheet, putting the glass sheet into a constant-temperature heating box, heating and curing for 30min at 75 ℃, respectively washing the glass sheet with deionized water, acetone and absolute ethyl alcohol in an ultrasonic cleaning machine for 5min to 15min, and drying at 70 ℃ for later use to form a first flexible thin film layer a.

Weighing 0.5g of polysiloxane and 3.3mg of carbon powder, placing in 100mL of deionized water, and performing ultrasonic treatment for 30min to uniformly disperse the polysiloxane and the carbon powder to form a carbon powder dispersion liquid;

and (3) filling a PTFE filter membrane with a pore diameter of 50nm on a sand core of the vacuum filtration funnel, pouring the carbon powder dispersion into the vacuum filtration funnel, depositing a layer of carbon powder electrode plate on the PTFE filter membrane after vacuum filtration, standing at room temperature until the solvent is completely evaporated, transferring the carbon powder material on the filter membrane, adhering the carbon powder material on the surface of the first flexible thin film layer a, and drying to form a first flexible electrode layer b.

Respectively weighing 128.45mg of zinc acetate and 160mg of sodium hydroxide, placing the zinc acetate and the sodium hydroxide into 100mL of absolute ethyl alcohol solution, and performing ultrasonic dispersion for 25min until the zinc acetate and the sodium hydroxide are uniformly mixed to form a first mixed solution;

respectively weighing 639mg of zinc nitrate, 420mg of hexamethylenetetramine and 149mg of aluminum nitrate, placing the zinc nitrate, the hexamethylenetetramine and the 149mg of aluminum nitrate into 100mL of absolute ethyl alcohol, and ultrasonically dispersing the zinc nitrate, the hexamethylenetetramine and the 149mg of aluminum nitrate in an ultrasonic cleaning machine for 30min until the zinc nitrate, the hexamethylenetetramine and the 149mg of aluminum nitrate are uniformly mixed to form a second mixed solution;

spin-coating the first mixed solution on the surface of the first flexible electrode layer b for 1min at the rotation speed of 1000rpm/min, placing the first mixed solution in a constant-temperature heating box at 65 ℃ to dry completely, placing the first flexible electrode layer b in the second mixed solution with the surface facing downwards, and heating at the constant temperature of 90 ℃ for 5.5h;

and repeatedly replacing the new second mixed solution for three times, and repeatedly heating at the constant temperature of 90 ℃ for 5.5 hours every time the second mixed solution is replaced, until a densely arranged zinc oxide nanosheet structure grows on the surface of the first flexible electrode layer b, namely the growth of the zinc oxide nanosheet layer c is completed.

Spin-coating a layer of polydimethylsiloxane prepolymer mixed solution on the surface of the zinc oxide nanosheet layer c at the rotating speed of 3000rpm/min for 2min, heating and curing for 15min at the temperature of 70 ℃, sequentially cleaning for 5 min-15min in an ultrasonic cleaning machine through deionized water, acetone and absolute ethyl alcohol respectively, and drying at the temperature of 65 ℃ to form a second flexible thin film layer d on the surface of the zinc oxide nanosheet layer c;

depositing the carbon powder dispersion liquid on a filter membrane through vacuum filtration, standing at room temperature until the solvent is completely evaporated, transferring the carbon powder material on the filter membrane, adhering the carbon powder material on the surface of the second flexible thin film layer d, and drying to form a second flexible electrode layer e;

and adhering copper strips on the first flexible electrode layer b and the second flexible electrode layer e, and connecting the copper strips with a lead to complete the preparation of the self-powered flexible sensor.

Example 4

putting the polydimethylsiloxane prepolymer mixed solution into a vacuum drying oven for standing and vacuumizing until all bubbles in the polydimethylsiloxane prepolymer mixed solution are discharged; sucking bubble-free polydimethylsiloxane prepolymer mixed liquor, uniformly dripping the bubble-free polydimethylsiloxane prepolymer mixed liquor on a prepared glass sheet, using a glue homogenizing machine, rotating at 1000rpm/min, and spin-coating for 1min, spin-coating the polydimethylsiloxane prepolymer mixed liquor on the glass sheet, putting the glass sheet into a constant-temperature heating box, heating and curing for 10min at the temperature of 80 ℃, respectively washing the glass sheet for 5 min-15min by deionized water, acetone and absolute ethyl alcohol in an ultrasonic cleaner in sequence, and drying the glass sheet for later use at the temperature of 65 ℃ to form a first flexible film layer a.

Weighing 2g of alkyl sulfonic acetamide and 10mg of multi-walled carbon nanotube powder, placing the powder in 100mL of deionized water, and performing ultrasonic treatment for 30min to uniformly disperse the powder to form a multi-walled carbon nanotube dispersion liquid;

and (2) padding a layer of PTFE filter membrane with the aperture of 50nm on a sand core of the vacuum filtration funnel, pouring the multi-wall carbon nano tube dispersion liquid into the vacuum filtration funnel, depositing a layer of carbon nano tube electrode plate on the PTFE filter membrane after vacuum filtration, standing at room temperature until the solvent is completely evaporated, transferring the carbon material on the filter membrane, adhering the carbon material on the surface of the first flexible thin film layer a, and drying to form a first flexible electrode layer b.

Respectively weighing 220.2mg of zinc acetate and 280mg of potassium hydroxide, placing the zinc acetate and the potassium hydroxide into 100mL of absolute ethanol solution, and performing ultrasonic dispersion for 25min until the zinc acetate and the potassium hydroxide are uniformly mixed to form a first mixed solution;

respectively weighing 757.6mg of zinc nitrate, 490.6mg of hexamethylenetetramine and 170.4mg of aluminum nitrate, placing the weighed materials in 100mL of absolute ethyl alcohol, and ultrasonically dispersing the materials in an ultrasonic cleaning machine for 30min until the materials are uniformly mixed to form a second mixed solution;

spin-coating the first mixed solution on the surface of the first flexible electrode layer b for 1min at the rotation speed of 1000rpm/min, placing the first mixed solution in a constant-temperature heating box at 68 ℃ to dry completely, placing the surface of the first flexible electrode layer b in a second mixed solution in a downward manner, and heating the second mixed solution at the constant temperature of 95 ℃ for 5h;

and (4) repeatedly replacing new second mixed liquid for three times, and repeatedly heating at the constant temperature of 95 ℃ for 5 hours every time the second mixed liquid is replaced, until a densely arranged zinc oxide nanosheet structure grows on the surface of the first flexible electrode layer b, namely the growth of the zinc oxide nanosheet layer c is completed.

Spin-coating a layer of polydimethylsiloxane prepolymer mixed solution on the surface of the zinc oxide nanosheet layer c at the rotating speed of 3000rpm/min for 2min, heating and curing for 10min at the temperature of 75 ℃, sequentially cleaning for 5 min-15min in an ultrasonic cleaning machine through deionized water, acetone and absolute ethyl alcohol respectively, drying at the temperature of 70 ℃, and forming a second flexible thin film layer d on the surface of the zinc oxide nanosheet layer c;

depositing the multi-walled carbon nanotube dispersion liquid on a filter membrane through vacuum filtration, standing at room temperature until a solvent is completely evaporated, transferring the multi-walled carbon nanotube material on the filter membrane, adhering the multi-walled carbon nanotube material on the surface of a second flexible thin film layer d, and drying to form a second flexible electrode layer e;

spin-coating the polydimethylsiloxane prepolymer mixed solution for 2min at 3000rpm/min, spin-coating the polydimethylsiloxane prepolymer mixed solution on the surface of the second flexible electrode layer e, heating and curing for 10min at 75 ℃, washing, and drying to form a third flexible film layer f;

Example 5

putting the polydimethylsiloxane prepolymer mixed solution into a vacuum drying oven for standing and vacuumizing until all bubbles in the polydimethylsiloxane prepolymer mixed solution are discharged; sucking bubble-free polydimethylsiloxane prepolymer mixed liquor, uniformly dripping the bubble-free polydimethylsiloxane prepolymer mixed liquor on a prepared glass sheet, using a spin coater, rotating at 1000rpm/min, wherein the spin coating time is 1min, spin coating the polydimethylsiloxane prepolymer mixed liquor on the glass sheet, putting the glass sheet into a constant-temperature heating box, heating and curing for 25min at 70 ℃, respectively washing the glass sheet with deionized water, acetone and absolute ethyl alcohol in an ultrasonic cleaning machine for 5min to 15min, and drying at 65 ℃ for later use to form a first flexible thin film layer a.

Weighing 1.5g of sodium dodecyl sulfate powder and 12.5mg of graphene, placing the powder in 100mL of deionized water, and carrying out ultrasonic treatment for 25min to uniformly disperse the powder to form graphene dispersion liquid;

and (2) padding a layer of PTFE filter membrane with the aperture of 50nm on a sand core of the vacuum filtration funnel, pouring the graphene dispersion liquid into the vacuum filtration funnel, depositing a graphene electrode plate on the PTFE filter membrane after vacuum filtration, standing at room temperature until the solvent is completely evaporated, transferring the graphene material on the filter membrane, adhering the graphene material on the surface of the first flexible thin film layer a, and drying to form a first flexible electrode layer b.

Respectively weighing 275.25mg of zinc acetate and 140mg of sodium hydroxide, placing the zinc acetate and the sodium hydroxide into 100mL of absolute ethyl alcohol solution, and performing ultrasonic dispersion for 25min until the zinc acetate and the sodium hydroxide are uniformly mixed to form a first mixed solution;

respectively weighing 477mg of zinc chloride, 560.76mg of hexamethylenetetramine and 102.7mg of aluminum chloride, placing the materials in 100mL of absolute ethyl alcohol, and performing ultrasonic dispersion in an ultrasonic cleaning machine for 20min until the materials are uniformly mixed to form a second mixed solution;

the first mixed solution is spin-coated on the surface of the first flexible electrode layer b at the rotation speed of 1000rpm/min for 1min, the first mixed solution is placed in a constant-temperature heating box at 63 ℃ to be dried completely, the surface of the first flexible electrode layer b is placed in a second mixed solution in a downward mode, and the second mixed solution is heated at the constant temperature of 80 ℃ for 6 hours;

and (4) repeatedly replacing new second mixed liquid for three times, and repeatedly heating at the constant temperature of 80 ℃ for 6 hours every time the second mixed liquid is replaced, until a densely arranged zinc oxide nanosheet structure grows on the surface of the first flexible electrode layer b, namely the growth of the zinc oxide nanosheet layer c is completed.

Spin-coating a layer of polydimethylsiloxane prepolymer mixed solution on the surface of the zinc oxide nanosheet layer c at the rotating speed of 3000rpm/min for 2min, heating and curing for 15min at the temperature of 75 ℃, sequentially cleaning for 5 min-15min in an ultrasonic cleaning machine through deionized water, acetone and absolute ethyl alcohol respectively, and drying at the temperature of 65 ℃ to form a second flexible thin film layer d on the surface of the zinc oxide nanosheet layer c;

depositing the graphene dispersion liquid on a filter membrane through vacuum filtration, standing at room temperature until the solvent is completely evaporated, transferring the graphene material on the filter membrane, adhering the graphene material to the surface of the second flexible thin film layer d, and drying to form a second flexible electrode layer e;

spin-coating the polydimethylsiloxane prepolymer mixed solution for 2min at 3000rpm/min, spin-coating the polydimethylsiloxane prepolymer mixed solution on the surface of the second flexible electrode layer e, heating and curing for 20min at 75 ℃, washing, and drying to form a third flexible film layer f;

Example 6

placing the dimethyl silicone polymer prepolymer mixed solution into a vacuum drying oven for standing, and vacuumizing until all bubbles in the dimethyl silicone polymer mixed solution are discharged; sucking bubble-free polydimethylsiloxane prepolymer mixed liquor, uniformly dripping the bubble-free polydimethylsiloxane prepolymer mixed liquor on a prepared glass sheet, using a spin coater, rotating at 1000rpm/min, wherein the spin coating time is 1min, spin coating the polydimethylsiloxane prepolymer mixed liquor on the glass sheet, placing the glass sheet into a constant-temperature heating box, heating and curing for 10min at the temperature of 85 ℃, respectively washing the glass sheet with deionized water, acetone and absolute ethyl alcohol in an ultrasonic washing machine for 5min to 15min in sequence, and drying the glass sheet for later use at the temperature of 60 ℃ to form a first flexible thin film layer a.

Weighing 0.8g of fatty alcohol-polyoxyethylene ether phosphate and 10mg of multi-walled carbon nanotube powder, placing in 100mL of deionized water, and performing ultrasonic treatment for 20min to uniformly disperse the powder to form a multi-walled carbon nanotube dispersion solution;

cushioning a layer of PTFE filter membrane with the aperture of 50nm on a sand core of a vacuum filtration funnel, pouring the multi-walled carbon nanotube dispersion into the vacuum filtration funnel, depositing a layer of carbon nanotube electrode plate on the PTFE filter membrane after vacuum filtration, standing at room temperature until a solvent is completely evaporated, transferring the multi-walled carbon nanotube material on the filter membrane, adhering the multi-walled carbon nanotube material on the surface of the first flexible thin film layer a, and drying to form a first flexible electrode layer b.

Respectively weighing 92mg of zinc acetate and 200mg of sodium hydroxide, placing the zinc acetate and the sodium hydroxide into 100mL of absolute ethyl alcohol solution, and performing ultrasonic dispersion for 20min until the zinc acetate and the sodium hydroxide are uniformly mixed to form a first mixed solution;

respectively weighing 1.065g of zinc nitrate, 700.1mg of hexamethylenetetramine and 149mg of aluminum nitrate, placing the zinc nitrate, the hexamethylenetetramine and the aluminum nitrate into 100mL of absolute ethyl alcohol, and ultrasonically dispersing the zinc nitrate, the hexamethylenetetramine and the aluminum nitrate in an ultrasonic cleaning machine for 30min until the zinc nitrate, the hexamethylenetetramine and the aluminum nitrate are uniformly mixed to form a second mixed solution;

the first mixed solution is spin-coated on the surface of the first flexible electrode layer b at the rotation speed of 1000rpm/min for 1min, the first mixed solution is placed in a constant-temperature heating box at 65 ℃ to be dried completely, the surface of the first flexible electrode layer b is placed in a second mixed solution in a downward mode, and the second mixed solution is heated at the constant temperature of 75 ℃ for 6h;

and (3) repeatedly replacing the new second mixed solution for three times, and repeatedly heating at the constant temperature of 75 ℃ for 6h every time the second mixed solution is replaced, until a densely arranged zinc oxide nanosheet structure grows on the surface of the first flexible electrode layer b, namely the growth of the zinc oxide nanosheet layer c is completed.

Example 7

putting the polydimethylsiloxane prepolymer mixed solution into a vacuum drying oven for standing and vacuumizing until all bubbles in the polydimethylsiloxane prepolymer mixed solution are discharged; sucking bubble-free polydimethylsiloxane prepolymer mixed liquor, uniformly dripping the bubble-free polydimethylsiloxane prepolymer mixed liquor on a prepared glass sheet, using a spin coater, rotating at 1000rpm/min, wherein the spin coating time is 1min, spin coating the polydimethylsiloxane prepolymer mixed liquor on the glass sheet, placing the glass sheet into a constant-temperature heating box, heating and curing for 20min at the temperature of 85 ℃, respectively washing the glass sheet with deionized water, acetone and absolute ethyl alcohol in an ultrasonic cleaning machine for 5min to 15min in sequence, and drying the glass sheet for later use at the temperature of 65 ℃ to form a first flexible thin film layer a.

Weighing 1.25g of polyoxyethylene monolaurate and 12.5mg of multi-walled carbon nanotube powder, placing in 100mL of deionized water, and carrying out ultrasonic treatment for 30min to uniformly disperse the powder to form a multi-walled carbon nanotube dispersion liquid;

Weighing 146.8mg of zinc acetate and 100mg of sodium hydroxide respectively, placing the zinc acetate and the sodium hydroxide into 100mL of absolute ethyl alcohol solution, and performing ultrasonic dispersion for 20min until the zinc acetate and the sodium hydroxide are uniformly mixed to form a first mixed solution;

respectively weighing 408.9mg of zinc chloride, 634.05mg of hexamethylenetetramine and 149mg of aluminum nitrate, placing the zinc chloride, the 634.05mg of hexamethylenetetramine and the 149mg of aluminum nitrate into 100mL of absolute ethyl alcohol, and ultrasonically dispersing in an ultrasonic cleaning machine for 20min until the mixture is uniformly mixed to form a second mixed solution;

the first mixed solution is spin-coated on the surface of the first flexible electrode layer b for 1min at the rotation speed of 1000rpm/min, the first mixed solution is placed in a constant-temperature heating box at 70 ℃ to be dried completely, the surface of the first flexible electrode layer b is placed in a second mixed solution in a downward mode, and the second mixed solution is heated at the constant temperature of 75 ℃ for 6h;

Example 8

putting the polydimethylsiloxane prepolymer mixed solution into a vacuum drying oven for standing and vacuumizing until all bubbles in the polydimethylsiloxane prepolymer mixed solution are discharged; sucking bubble-free polydimethylsiloxane prepolymer mixed liquor, uniformly dripping the bubble-free polydimethylsiloxane prepolymer mixed liquor on a prepared glass sheet, using a spin coater, rotating at 1000rpm/min, wherein the spin coating time is 1min, spin coating the polydimethylsiloxane prepolymer mixed liquor on the glass sheet, putting the glass sheet into a constant-temperature heating box, heating and curing for 30min at 70 ℃, respectively washing the glass sheet with deionized water, acetone and absolute ethyl alcohol in an ultrasonic cleaning machine for 5min to 15min, and drying at 65 ℃ for later use to form a first flexible thin film layer a.

Weighing 1.2g of sodium naphthenate and 12mg of multi-walled carbon nanotube powder, placing the powder in 100mL of deionized water, and performing ultrasonic treatment for 20min to uniformly disperse the powder to form a multi-walled carbon nanotube dispersion liquid;

Example 9

placing the polydimethylsiloxane prepolymer mixed solution into a vacuum drying oven for standing, and vacuumizing until all bubbles in the polydimethylsiloxane prepolymer mixed solution are discharged; sucking bubble-free polydimethylsiloxane prepolymer mixed liquor, uniformly dripping the bubble-free polydimethylsiloxane prepolymer mixed liquor on a prepared glass sheet, using a glue homogenizing machine, rotating at 1000rpm/min, and spin-coating for 1min, spin-coating the polydimethylsiloxane prepolymer mixed liquor on the glass sheet, putting the glass sheet into a constant-temperature heating box, heating and curing for 30min at the temperature of 75 ℃, respectively washing the glass sheet for 5min to 15min in an ultrasonic washing machine by deionized water, acetone and absolute ethyl alcohol in sequence, and drying the glass sheet for later use at the temperature of 70 ℃ to form a first flexible film layer a.

Weighing 1g of sodium alkyl succinate sulfonate and 5mg of carbon powder, placing the mixture in 100mL of deionized water, and performing ultrasonic treatment for 30min to uniformly disperse the mixture to form a carbon powder dispersion liquid;

and (3) padding a layer of PTFE filter membrane with the aperture of 50nm on a sand core of the vacuum filtration funnel, pouring the carbon powder dispersion liquid into the vacuum filtration funnel, depositing a layer of carbon powder electrode plate on the PTFE filter membrane after vacuum filtration, standing at room temperature until the solvent is completely evaporated, transferring the carbon powder material on the filter membrane, adhering the carbon powder material on the surface of the first flexible thin film layer a, and drying to form a first flexible electrode layer b.

spin-coating the first mixed solution on the surface of the first flexible electrode layer b for 1min at the rotation speed of 1000rpm/min, placing the first mixed solution in a constant-temperature heating box at 68 ℃ to dry completely, placing the first flexible electrode layer b in the second mixed solution with the surface facing downwards, and heating at the constant temperature of 90 ℃ for 5.2h;

and (3) repeatedly replacing the new second mixed solution for three times, and repeatedly heating at the constant temperature of 90 ℃ for 5.2h every time the second mixed solution is replaced, until a densely arranged zinc oxide nanosheet structure grows on the surface of the first flexible electrode layer b, namely the growth of the zinc oxide nanosheet layer c is completed.

spin-coating the polydimethylsiloxane prepolymer mixed solution for 2min at 3000rpm/min, spin-coating the polydimethylsiloxane prepolymer mixed solution on the surface of the second flexible electrode layer e, heating and curing for 20min at 70 ℃, washing, and drying to form a third flexible film layer f;

Referring to fig. 3, SEM characterization of the zinc oxide nanosheet layer c of the self-powered flexible sensor prepared in example 1 shows that the zinc oxide nanosheet layer c successfully grows a dense zinc oxide nanosheet structure.

Referring to fig. 4, the prepared self-powered flexible sensor is subjected to strength tests such as tensile test and torsional test, and it is found that the self-powered flexible sensor can maintain a good mechanical structure after macroscopic bending, tensile test and torsional test, and does not break.

Referring to fig. 5, the self-powered flexible sensor prepared in example 1 was subjected to a stress-strain test, and it was found that the self-powered flexible sensor has a sufficiently small elastic modulus and good tensile properties.

Referring to fig. 6 and 7, under the same condition, a conventional flexible sensor and a flexible sensor prepared by the present invention are subjected to an excitation test under the same condition, and a voltage output condition is tested, and as a result, it is found that as a microscopic morphology of a piezoelectric material is improved from a one-dimensional nanowire structure to a two-dimensional nanosheet structure, an output voltage of the sensor is increased from 1V to about 4V, which is improved by nearly four times.

In conclusion, the self-powered flexible sensor prepared by the invention has very good conductive performance and tensile resistance, so that the sensor can still keep very good mechanical property and conductive performance in a stretching state, and electrode breakage and even loss of conductivity of the sensor caused by stretching can be effectively avoided.

While the preferred embodiments of the present invention have been described and illustrated, it will be understood by those skilled in the art that various changes and modifications may be made therein. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A self-powered flexible sensor is characterized by comprising a first flexible film layer (a), wherein a first flexible electrode layer (b), a zinc oxide nanosheet layer (c), a second flexible film layer (d), a second flexible electrode layer (e) and a third flexible film layer (f) are sequentially arranged on the first flexible film layer (a); wires are led out of the first flexible electrode layer (b) and the second flexible electrode layer (e) respectively and used for collecting and leading out electric signals of the sensor; the first flexible electrode layer (b) and the second flexible electrode layer (e) are carbon nanotube electrode layers, graphene electrode layers or carbon powder electrode layers.

2. Self-powered flexible sensor according to claim 1, characterized in that the first (a), second (d) and third (f) flexible film layers are polydimethylsiloxane prepolymer films.

3. A method of manufacturing a self-powered flexible sensor as claimed in claim 1 or 2, comprising the steps of:

s1: preparing a first flexible film layer (a) as a flexible substrate;

s2: preparing a first flexible electrode layer (b) on a surface of a flexible substrate;

s3: growing a zinc oxide nanosheet layer (c) on the surface of the first flexible electrode layer (b);

s4: coating a second flexible film layer (d) on the surface of the zinc oxide nanosheet layer (c);

s5: pressing a second flexible electrode layer (e) on the surface of the second flexible thin film layer (d);

s6: coating a third flexible thin film layer (f) on the surface of the second flexible electrode layer (e);

s7: and connecting a lead into the first flexible electrode layer (b) and the second flexible electrode layer (e) to finish the preparation of the self-powered flexible sensor.

4. A method of manufacturing a self-powered flexible sensor according to claim 3, wherein the first (a), second (d) and third (f) flexible film layers are manufactured by:

weighing polydimethylsiloxane prepolymer and polydimethylsiloxane prepolymer curing agent, mixing, and uniformly stirring to form polydimethylsiloxane prepolymer mixed solution;

discharging bubbles in the polydimethylsiloxane prepolymer mixed solution, coating the bubble-free polydimethylsiloxane prepolymer mixed solution on a carrier, heating and curing for 10-30 min at the temperature of 65-85 ℃, washing, and drying to form a flexible film layer.

5. The method for preparing a self-powered flexible sensor according to claim 4, wherein the mass ratio of the polydimethylsiloxane prepolymer to the polydimethylsiloxane prepolymer curing agent is 10.

6. A method of manufacturing a self-powered flexible sensor according to claim 3, wherein the first flexible electrode layer (b) and the second flexible electrode layer (e) are manufactured by:

dissolving a surfactant in water to form a surfactant aqueous solution;

7. A method of making a self-powered flexible sensor as recited in claim 6, wherein the surfactant is an alkyl benzene sulfonate, alkyl sulfonate salt, alkyl sulfonate, alkyl sulfate, fluorinated fatty acid salt, polysiloxane, fatty alcohol sulfate, fatty alcohol polyoxyethylene ether sulfate, alpha-alkenyl sulfonate, fatty alcohol polyoxyethylene ether phosphate, alkyl alcohol amide, alkyl sulfonic acetamide, alkyl succinate sulfonate, alcohol amine alkyl benzene sulfonate, naphthenate, alkyl phenol sulfonate, or polyoxyethylene monolaurate.

8. A method for preparing a self-powered flexible sensor according to claim 6, wherein the amount mass ratio of the carbon material to the surfactant is as follows: (1; the concentration of the surfactant aqueous solution is 2.5 mg/mL-20 mg/mL.

9. A method for preparing a self-powered flexible sensor according to any of claims 3 to 8, wherein the specific operations of growing the zinc oxide nanosheet layer (c) on the surface of the first flexible electrode layer (b) are as follows:

spin-coating the first mixed solution on the surface of the first flexible electrode layer (b), drying, placing in the second mixed solution, and heating at a constant temperature of 75-95 ℃ for 5-6 h;

and (3) repeatedly replacing new second mixed liquor for many times, and repeatedly heating the second mixed liquor for 5-6 h at the constant temperature of 75-95 ℃ every time when the second mixed liquor is replaced, until a densely arranged zinc oxide nano structure grows on the surface of the first flexible electrode layer (b), namely the growth of the zinc oxide nano sheet layer (c) is completed.

10. The method according to claim 9, wherein the concentration of zinc acetate in the first mixed solution is 5mmol/L to 15mmol/L; the alkali concentration is 20 mmol/L-50 mmol/L; in the second mixed solution, the zinc salt is zinc nitrate or zinc chloride, and the concentration of the zinc salt is 20 mmol/L-50 mmol/L; the aluminum salt is aluminum nitrate or aluminum chloride, and the concentration of the aluminum salt is 6 mmol/L-8 mmol/L; the concentration of the hexamethylene tetramine is 20 mmol/L-50 mmol/L.