Preparation method of Ni / Fe3O4 composite nano three-dimensional array strain sensor based on tunneling effect and sensor

Abstract

The invention relates to a preparation method of a Ni / Fe3O4 composite nano three-dimensional array strain sensor based on a tunneling effect and the sensor. The preparation method comprises the following steps: preparing a PDMS substrate layer through a spin coater; spraying a nano Pt particle conductive layer with a certain thickness on the PDMS substrate layer by using a metal spraying instrument; a copper conduction band is pasted on the PDMS substrate layer in an evaporation mode to serve as an electrode; depositing a nickel nanowire; depositing a nickel nanowire array on the surface of the PDMS substrate layer sprayed with the nano Pt electronic layer, and deviating the deposition position of the nickel nanowire array from the central axis in the width direction of the PDMS substrate layer; growing Fe3O4 nano particles on the surface of the nickel nanowire array to form a Ni / Fe3O4 composite nano three-dimensional array sensing layer; and packaging the Ni / Fe3O4 composite nano three-dimensional array strain sensing layer. The device can respond to triple anisotropic strain signals, has the precise decoupling characteristic, and has the capability of detecting the multi-dimensional strain amplitude and direction.

Description

Technical Field

[0001] The present application relates to the technical field of tunnel detectors, and in particular to a method for preparing a Ni / Fe3O4 composite nano three-dimensional array strain sensor based on the tunnel effect and a sensor. Background Art

[0002] Tunnels are usually subjected to complex geological, environmental and traffic loads. Tunnel construction faces many uncertain factors, such as geological conditions, various loads and construction methods, which may cause deformation and damage to the tunnel structure, and it is urgent to monitor its strain state. Tunnel strain takes various forms and various strains affect each other, which need to be considered comprehensively to ensure the safety and stability of the tunnel.

[0003] For single-dimensional strain detection of tunnels, strain sensors need to detect the amplitude (or angle) of tunnel displacement; for multi-dimensional strain detection, in addition to amplitude, strain sensors also need to detect the direction of displacement. In actual monitoring and analysis, multiple sensors are usually used to measure different forms of strain to obtain comprehensive tunnel health status information. However, current strain sensors are often not sensitive enough to provide sufficient sensitivity at low strains, making it difficult to detect small deformations in real time; the measurement range is limited, and the measurement range of strain sensors may sometimes not meet the needs of high-strain applications. Especially in high-frequency vibration or fast dynamic change environments, strain sensors cannot respond quickly, affecting the accuracy of real-time monitoring results. At the same time, strain sensors can often only monitor one-dimensional or two-dimensional strains and cannot accurately respond to three-dimensional strains; and the coupling effect between strain sensors of different forms is poor, resulting in large deviations in strain monitoring.

[0004] There are four main types of strain sensors for monitoring tunnel displacement: resistive, capacitive, piezoelectric, and triboelectric. Piezoelectric and triboelectric sensors are limited in their application in tunnel monitoring because they work in high-frequency environments and have fast charge transfer speeds, which makes them unable to capture static strains. Considering the multidimensional characteristics of tunnel structural strains, sensors are required to be able to detect anisotropic displacement strains. However, capacitive sensors are difficult to achieve due to structural limitations. In contrast, resistive sensors are favored by researchers in the field of multidimensional displacement strain detection due to their structural diversity. These sensors reflect structural movement by monitoring changes in electrical signals, and have the advantages of high sensitivity, scalability, fast response, stability, low cost, and easy manufacturing. However, how to apply resistive sensors to tunnel detection to solve the above technical problems still requires creative efforts. Summary of the invention

[0005] We hope to solve the above-mentioned technical problems existing in traditional uniaxial strain sensors and provide a preparation process and sensor for tunnel three-dimensional strain sensors with excellent sensitivity, linearity, accuracy, and good frequency response characteristics, so as to facilitate the monitoring of multi-dimensional dynamic deformation of tunnel structures.

[0006] In the first aspect, the present application provides a method for preparing a Ni / Fe3O4 composite nano three-dimensional array strain sensor based on the tunnel effect, which adopts the following technical solution: A method for preparing a Ni / Fe3O4 composite nano three-dimensional array strain sensor based on tunneling effect, comprising the steps of: Prepare the PDMS base layer by a gel spinning machine; Use a gold spraying device to spray a 30-80 nm thick nano Pt particle conductive layer on the PDMS substrate layer; Copper conductive strips are deposited and pasted on both ends of the PDMS substrate layer in the length direction as electrodes; Sequential nickel nanowires were prepared by electrochemical deposition; An ordered nickel nanowire array is deposited on the surface of the PDMS substrate layer sprayed with a nano-Pt electronic layer, and the deposition position of the nickel nanowire array is deviated from the central axis in the width direction of the PDMS substrate layer; Growing Fe3O4 nanoparticles on the surface of the nickel nanowire array to form a Ni / Fe3O4 composite nano three-dimensional array sensing layer; Encapsulating the Ni / Fe3O4 composite nano three-dimensional array strain sensing layer: using thermoplastic polyimide resin as a raw material, adding a plasticizer and a stabilizer to mix, kneading and melting, and preparing a TPI film by a casting method, placing the TPI film on the Ni / Fe3O4 composite nano three-dimensional array sensing layer, and performing hot pressing welding to bond and seal the TPI film to the Ni / Fe3O4 composite nano three-dimensional array sensing layer.

[0007] By adopting the above technical solution, the nano Pt particle conductive layer is a nano platinum particle conductive layer, which can enhance the frequency response characteristics of the sensor and improve the response capability of dynamic strain, with a response time between 2-7s. The Ni / Fe3O4 composite nano three-dimensional array has high sensing accuracy, and its minimum resolution of strain detection response reaches 0.2%; Fe3O4 nanoparticles grown on the surface of the nickel nanowire array improve the sensitivity of the sensor, which can reach more than 300. Thermoplastic polyimide is used as the packaging film of the packaging layer, thermoplastic polyimide is TPI, and PDMS is polydimethylsiloxane.

[0008] In the width direction of the substrate layer, the deposition position of the nickel nanowire array sensing layer is deviated from the central axis, so that the sensor presents asymmetry in the width direction, and further has the ability to detect the amplitude and direction of the bending strain in the plane. The entire sensor has three-dimensional spatial dimension asymmetry in the three-dimensional spatial structure, can respond to triple anisotropic strain signals, has precise decoupling characteristics, and has the ability to detect multi-dimensional strain amplitude and direction.

[0009] In addition, the base layer and the packaging layer are made of different materials, and the thickness of both can be adjusted, so that an asymmetric structure can be formed in the thickness direction of the sensor; further, this asymmetric structure is anisotropic when responding to out-of-plane bending strain, so that it has the ability to detect the amplitude and direction of out-of-plane bending strain.

[0010] Optionally, the step of preparing the PDMS base layer by a gelling machine includes: Weigh the PDMS two-component liquid, select the substrate and clean it with plasma water or anhydrous ethanol, place the evenly stirred PDMS prepolymer at the center of the substrate and spin-coat the PDMS prepolymer using a coater, and then place the substrate spin-coated with the PDMS prepolymer in a constant temperature oven for heating and curing.

[0011] By adopting the above technical solution, a proper amount of PDMS two-component liquid, namely the curing agent and the silicone rubber main agent, is weighed and stirred in a certain proportion to remove bubbles. PDMS films of different thicknesses can be prepared by adjusting the speed and time of the glue mixing.

[0012] Optionally, the PDMS base layer after heating and curing is treated with oxygen plasma to increase the surface hydrophilicity.

[0013] By adopting the above technical solution, the surface of the PDMS film is modified by oxygen plasma treatment to increase its surface viscosity, so that the Ni / Fe3O4 composite nano three-dimensional array strain sensor prepared by the present invention has good adhesion between the base layer, the sensing layer and the packaging layer, good linearity, acid and alkali corrosion resistance, good stability and high reliability.

[0014] Optionally, the step of preparing nickel nanowires by electrochemical deposition includes: An anodized aluminum film with regular pores is selected as a deposition template, and a layer of metal back electrode is sputtered on the back of the anodized aluminum film in a vacuum sputtering chamber. The sputtering time is 5-20 minutes and the sputtering power is 60-250W. A nickel ion electrolyte solution with a certain concentration is prepared, and an anodized aluminum film is placed in the nickel ion electrolyte solution, and a constant current is passed for electrochemical deposition. The anodized aluminum film with deposited nickel nanowires is immersed in a 5-10% mass fraction NaOH solution, and allowed to stand at 60-80° C. for 2.5-7 hours until the anodized aluminum film is completely dissolved to obtain nickel nanowires. The nickel nanowires are cleaned and placed in anhydrous ethanol, and the nickel nanowires are uniformly dispersed by ultrasound to form a suspension.

[0015] By adopting the above technical solution, AAO, or anodized aluminum oxide, plays the role of a template in the process of preparing nickel nanowires. Its pores are evenly distributed, with high pore density, and the diameter and length of the pores can be manually controlled, which enables the AAO template to provide regular pores for the growth of nickel nanowires, thereby preparing nickel nanowires with uniform size and consistent morphology.

[0016] The deposited nickel nanowire / AAO composite film is immersed in a 5-10% mass fraction NaOH solution and allowed to stand at 60-80° C. for 2.5-7 hours until the AAO template is completely dissolved.

[0017] Optionally, the step of depositing an ordered nickel nanowire array on the surface of the PDMS substrate layer sprayed with the nano Pt electronic layer, and deviating the deposition position of the nickel nanowire array from the central axis in the width direction of the PDMS substrate layer comprises: A double-pass polymethyl methacrylate square box container is placed on the PDMS substrate layer, and the contact part is sealed. It is then placed in a parallel magnetic field with the direction of the magnetic field consistent with the width direction of the PDMS substrate layer. A pipette is used to transfer the evenly dispersed nickel nanosuspension into the double-pass polymethyl methacrylate square box container and let it stand to deposit a highly ordered nickel nanowire array on the PDMS substrate.

[0018] By adopting the above technical solution, the position at the bottom of the double-pass polymethyl methacrylate square box container is placed at the position where the ordered array of nickel nanowires in the sensing layer is deposited. The uniformly dispersed nickel nanosuspension is transferred into the container with a pipette and allowed to stand until the anhydrous ethanol is completely evaporated, thereby depositing a highly ordered nickel nanowire array on the PDMS substrate.

[0019] Optionally, the surface of the anodized aluminum film is cleaned using ultrasound; The nickel nanowires were washed repeatedly with deionized water and anhydrous ethanol.

[0020] By adopting the above technical solution, the surface of the AAO anode film is cleaned by ultrasonic wave to remove impurities and obtain a pure AAO film. The nickel nanowires are repeatedly cleaned with deionized water and anhydrous ethanol to obtain pure nickel nanowires.

[0021] Optionally, the nickel nanowire array is asymmetric in a direction orthogonal to the stretching surface.

[0022] By adopting the above technical solution, the nickel nano ordered array sensing layer is asymmetric in the direction orthogonal to the stretching surface, making it anisotropic in the stretching surface, and further capable of detecting the strain amplitude in different directions in the stretching surface. The nickel nano ordered array sensing layer has good linearity, reaching more than 95%.

[0023] Optionally, the step of growing Fe3O4 nanoparticles on the surface of the nickel nanowire array to form a Ni / Fe3O4 composite nano three-dimensional array sensing layer includes: A mixed solution of ferric chloride hexahydrate and ferrous chloride tetrahydrate is added to a highly ordered nickel nanowire array deposited in a double-pass polymethyl methacrylate square box container, and ammonia water is added to adjust the pH of the solution to 10-12. The mixed solution undergoes a precipitation reaction, and Fe3O4 nanoparticles adhere and grow on the surface of the nickel nanowire array to form a Ni / Fe3O4 composite nano three-dimensional array sensing layer.

[0024] By adopting the above technical scheme, weigh an appropriate amount of ferric chloride hexahydrate (FeCl3·6H2O) and ferrous chloride tetrahydrate (FeCl2·4H2O) with a molar ratio of 2:1, dissolve the two in plasma water, and stir evenly. Add an appropriate amount of a mixed solution of ferric chloride hexahydrate (FeCl3·6H2O) and ferrous chloride tetrahydrate (FeCl2·4H2O) into the container deposited with the nickel nanowire array, add ammonia (NH3·H2O) to adjust the pH of the solution to 10-12, and the mixed solution undergoes a precipitation reaction, and Fe3O4 nanoparticles adhere to and grow on the surface of the nickel nanowire array. After the reaction is completed, wash with plasma water and anhydrous ethanol, and place in a vacuum oven for drying to obtain a Ni / Fe3O4 composite nano three-dimensional array. Growing Fe3O4 nanoparticles on the surface of the nickel nanowire array improves the sensitivity of the sensor, which can reach more than 300.

[0025] Optionally, the substrate is any one of glass, quartz, polyethylene terephthalate (PET), and nickel substrate.

[0026] In the second aspect, the present application provides a Ni / Fe3O4 composite nano three-dimensional array strain sensor based on the tunnel effect, using the aforementioned preparation method and adopting the following technical solution: A Ni / Fe3O4 composite nano three-dimensional array strain sensor based on tunnel effect, using the above preparation method, comprises: a substrate layer, a nano film layer, a Ni / Fe3O4 composite nano three-dimensional array sensing layer and a packaging layer.

[0027] By adopting the above technical solution, the sensor base layer and the packaging layer are made of different materials, the thickness of both can be adjusted, and an asymmetric structure can be formed in the thickness direction of the sensor.

[0028] In summary, the present application includes at least one of the following beneficial technical effects: 1. The preparation process of the present invention is simple and the preparation cost is low. The sensor prepared by the present invention can monitor three-dimensional strain, has excellent sensitivity, linearity and accuracy, and has good frequency response characteristics, which is convenient for monitoring the multi-dimensional dynamic deformation of the tunnel structure. At the same time, it has mechanical flexibility, can fit tightly to the surface of the tunnel structure to be detected, and is not affected by the adverse conditions of the tunnel such as temperature and humidity changes. It is resistant to acid and alkali corrosion and has good durability. It has broad application prospects in the field of strain response detection of tunnel construction and operation structures.

[0029] 2. The thickness of the base layer and packaging layer of the Ni / Fe3O4 composite nano three-dimensional array sensor and the density of the ordered array of nickel nanowires prepared by the invention can be controlled, and the control method is precise and the process is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart of the preparation of the Ni / Fe3O4 composite nano three-dimensional array strain sensor of the present application; Figure 2 is a SEM image of a highly ordered nickel nanowire array embodying the present application; Figure 3 It is a schematic diagram of the asymmetric structure of the Ni / Fe3O4 composite nano three-dimensional array strain sensor of the present application; Figure 4 It is an optical microscopic image of the Ni / Fe3O4 composite nano three-dimensional array embodying the present application; Figure 5 It is a sample diagram of a Ni / Fe3O4 composite nano three-dimensional array strain sensor embodying the present application; Figure 6 It is a schematic diagram of the asymmetric structure in the thickness direction of the Ni / Fe3O4 composite nano three-dimensional array strain sensor of the present application. DETAILED DESCRIPTION

[0031] The following will be combined with the attached examples of the present application Figure 1-Figure 6 , describe the technical solutions in the embodiments of the present application.

[0032] In order to help those skilled in the art better understand the present invention, specific embodiments will be described in detail below in conjunction with the accompanying drawings. It should be noted that the described embodiments represent only a part of the present invention, not all of it. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present invention.

[0033] In addition, in this article, when a certain element is described as being “disposed on” another element, it may be directly disposed or there may be an intermediate element. When a certain element is described as being “connected to” another element, it may be directly connected or there may be an intermediate connector.

[0034] In addition, the terms used in the text regarding orientation or position relationships, such as "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", and "outside", are merely for the convenience of description and simplification of illustration, and do not mean that the device or element referred to must have a specific orientation or position.

[0035] Unless otherwise specified, all technical and scientific terms used herein are the same as those commonly understood by those skilled in the art. The terms used herein are only used to describe specific embodiments and are not intended to limit the present invention. The term "and / or" means any combination of the listed items.

[0036] The Ni nanowire ordered array is designed based on the tunnel effect conductive mechanism. The theoretical basis of the tunnel effect conductive mechanism is as follows: R_t=V / AJ=(h^2 d) / (Ae^2 √2mγ) exp(4πd / h √2mγ) Where R_t represents the tunnel resistance, A is the lateral cross-sectional area of ​​the tunnel junction, V represents the electrode potential, J is the tunnel current density, d represents the distance between neighboring nanomaterials, e is the electron charge, h is the Planck constant, γ is the non-conductive energy barrier height, and m is the mass of a single electron.

[0037] The tunnel effect means that when the conductive nanomaterials are not in contact but the gap is very small, the electrons will undergo quantum tunneling, thereby making the non-conductive materials conductive. Based on this, the Ni nanowire ordered array (i.e., nickel nanowire array) prepared by the present invention will experience a tunnel effect in the strain expansion plane, causing the resistance to change. Further, due to the tunnel effect, the resistance of the sensing layer of the Ni nanowire sensing array has different relative change rates in the orthogonal direction of strain expansion. This difference gives the sensing layer a decoupling characteristic to the strain direction response signal in the expansion plane, and further the sensor has the ability to detect the strain amplitude and direction in the expansion plane.

[0038] The following are specific embodiments. It should be noted that these embodiments are preferred examples of the present invention and are used for those skilled in the art to understand the present invention, but the present invention is not limited to these embodiments.

[0039] like Figure 1 As shown in the figure, a method for preparing a Ni / Fe3O4 composite nano three-dimensional array strain sensor based on the tunnel effect includes preparing a PDMS flexible substrate layer, spraying a nano film layer (i.e., a nano Pt particle conductive layer), preparing an ordered array of nickel nanowires, and growing Fe3O4 nanoparticles on the surface thereof, and finally encapsulating the ordered array of nickel nanowires grown with Fe3O4 nanoparticles with TPI. PDMS is polydimethylsiloxane, and thermoplastic polyimide is TPI.

[0040] A method for preparing a Ni / Fe3O4 composite nano three-dimensional array strain sensor based on the tunnel effect of this embodiment includes the following steps: Step S1, prepare the PDMS base layer by a glue machine: weigh an appropriate amount of PDMS two-component liquid (curing agent and silicone rubber main agent), stir it thoroughly in a ratio of 1:10 between the curing agent and the silicone rubber main agent to remove bubbles. Select a glass substrate and clean it with plasma water or anhydrous ethanol. Place the evenly stirred PDMS prepolymer in the center of the substrate, set the glue machine speed to 150r / min, and the time to 5min. Place the substrate with PDMS coated in a constant temperature oven at 80℃ for heating and curing for 0.5h. After curing, modify the surface of the PDMS film by oxygen plasma treatment to prepare a PDMS base layer.

[0041] Step S2: Use a gold spraying device to spray a 30 nm thick nano Pt particle conductive layer on the PDMS base layer.

[0042] Step S3, evaporating and pasting copper conductive tapes on both ends of the PDMS substrate layer in the length direction as electrodes.

[0043] Step S4, preparing nickel nanowires by electrochemical deposition: an anodic aluminum oxide (AAO) film with a thickness of 100µm and a pore size of 250nm is selected as a deposition template. A metal back electrode of a certain thickness is sputtered on the back of the AAO film in a vacuum sputtering chamber. The sputtering time is set to 20min, and the sputtering power is set to 150W. A 0.5 mol / L nickel chloride (NiCl) electrolyte solution is prepared, and the AAO anode film is placed in the NiCl electrolyte solution, and a constant current of 7 milliamperes (mA) is passed for electrochemical deposition, and the deposition time is set to 1.5 hours (h). The deposited nickel nanowire / AAO composite film is immersed in a 10% mass fraction NaOH solution and allowed to stand at 75°C for 7h until the AAO template is completely dissolved, thereby obtaining nickel nanowires. The nickel nanowires are cleaned and placed in anhydrous ethanol, and the nickel nanowires are uniformly dispersed by ultrasound to form a suspension.

[0044] Step S5, depositing an ordered Ni nanowire array on the surface of the PDMS substrate layer sprayed with a nano-Pt electronic layer: place a double-pass polymethyl methacrylate (PMMA) square box container on the PDMS substrate layer and seal the contact part. Place the double-pass polymethyl methacrylate (PMMA) square box container in a parallel magnetic field, and the direction of the magnetic field is consistent with the width direction of the PDMS substrate film. Use a pipette to transfer the evenly dispersed nickel nanosuspension into the double-pass polymethyl methacrylate (PMMA) square box container, and let it stand until the anhydrous ethanol is completely evaporated, thereby depositing a highly ordered nickel nanowire array on the PDMS substrate. Figure 2 , the SEM image of Ni nanowire array shows a highly ordered arrangement structure.

[0045] Further, such as Figure 3 In the width direction of the PDMS substrate layer, the deposition position of the nickel nanowire array sensing layer is deviated from the central axis of the PDMS substrate layer by a certain distance, so that the sensor presents asymmetry in the width direction and further has the ability to detect the amplitude and direction of in-plane bending strain.

[0046] Step S6, growing Fe3O4 nanoparticles on the surface of the nickel nanowire array: weigh 20g of ferric chloride hexahydrate (FeCl3·6H2O) and ferrous chloride tetrahydrate (FeCl2·4H2O) in a molar ratio of 2:1, dissolve them in 1L of plasma water, and stir evenly. Add 50ml of a mixed solution of ferric chloride hexahydrate (FeCl3·6H2O) and ferrous chloride tetrahydrate (FeCl2·4H2O) into the above-mentioned double-pass polymethyl methacrylate (PMMA) square box container deposited with the nickel nanowire array, add ammonia water (NH3·H2O) to adjust the pH of the solution to 11, and the mixed solution undergoes a precipitation reaction, and Fe3O4 nanoparticles adhere and grow on the surface of the nickel nanowire array. After the reaction is completed, wash with plasma water and anhydrous ethanol, and place in a vacuum oven for drying to obtain a Ni / Fe3O4 composite nano three-dimensional array, such as Figure 4 .

[0047] Step S7, encapsulating the Ni / Fe3O4 composite nano three-dimensional array sensing layer: select thermoplastic polyimide resin as the raw material, add plasticizer and stabilizer to mix, and prepare TPI film by film casting after mixing and melting. Place the TPI film on the Ni / Fe3O4 composite nano three-dimensional array sensing layer, perform hot pressing welding under a certain temperature and pressure, and bond and seal it to the surface of the Ni / Fe3O4 composite nano three-dimensional array sensing layer. The plasticizer can be any one of phthalates, aliphatic dibasic acid esters or polyethylene glycol (PEG). The stabilizer can be any one of triethanolamine, antioxidant or ultraviolet absorber. Thus, a Ni / Fe3O4 composite nano three-dimensional array sensor with a complete structure is obtained, such as Figure 5 .

[0048] Further, such as Figure 6 The base layer and packaging layer of the sensor are made of different materials, and the thickness of the base layer is greater than that of the packaging layer, so that an asymmetric structure can be formed in the thickness direction of the sensor; further, this asymmetric structure has anisotropy when responding to out-of-plane bending strain, so that it has the ability to detect the amplitude and direction of out-of-plane bending strain.

[0049] Compared with the prior art, the present invention has at least the following beneficial technical effects: (1) The Ni / Fe3O4 composite nano three-dimensional array strain sensor based on the tunnel effect prepared by the present invention has good adhesion between the base layer, the sensing layer and the packaging layer, good linearity, acid and alkali corrosion resistance, good stability and high reliability.

[0050] (2) The thickness of the base layer and the encapsulation layer of the Ni / Fe3O4 composite nano three-dimensional array strain sensor based on the tunnel effect prepared by the present invention, as well as the density of the ordered array of nickel nanowires, can be controlled, and the control method is accurate and the process is simple.

[0051] (3) The conductive layer of nano-Pt particles in the Ni / Fe3O4 composite nano-three-dimensional array strain sensor based on the tunnel effect prepared by the present invention enhances the frequency response characteristics of the sensor and improves the response capability of dynamic strain, with a response time of 2-7s; the Ni / Fe3O4 composite nano-three-dimensional array strain sensing has high accuracy, and its minimum resolution of strain detection response reaches 0.2%; the Fe3O4 nanoparticles grown on the surface of the nickel nanowire array improve the sensitivity of the sensor, which can reach more than 300.

[0052] (4) The Ni / Fe3O4 composite nano three-dimensional array strain sensor based on the tunnel effect prepared by the present invention has asymmetry in the three-dimensional spatial structure, can respond to triple anisotropic strain signals, has precise decoupling characteristics, and has the ability to detect multi-dimensional strain amplitude and direction.

[0053] The embodiment of the present application also discloses a Ni / Fe3O4 composite nano three-dimensional array strain sensor using the above-mentioned method for preparing the Ni / Fe3O4 composite nano three-dimensional array strain sensor based on the tunnel effect.

[0054] A Ni / Fe3O4 composite nano three-dimensional array strain sensor based on tunnel effect comprises a substrate layer, a nano film layer, a Ni / Fe3O4 composite nano three-dimensional array sensing layer and a packaging layer.

[0055] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a Ni / Fe3O4 composite nano three-dimensional array strain sensor based on tunneling effect, characterized in that: Includes steps: Prepare the PDMS base layer by a gel spinning machine; Use a gold spraying device to spray a 30-80 nm thick nano Pt particle conductive layer on the PDMS substrate layer; Copper conductive strips are deposited and pasted on both ends of the PDMS substrate layer in the length direction as electrodes; Well-aligned nickel nanowires were prepared by electrochemical deposition; An ordered nickel nanowire array is deposited on the surface of the PDMS substrate layer sprayed with a nano-Pt electronic layer, and the deposition position of the nickel nanowire array is deviated from the central axis in the width direction of the PDMS substrate layer; Growing Fe3O4 nanoparticles on the surface of the nickel nanowire array to form a Ni / Fe3O4 composite nano three-dimensional array sensing layer; Encapsulating the Ni / Fe3O4 composite nano three-dimensional array strain sensing layer: using thermoplastic polyimide resin as a raw material, adding a plasticizer and a stabilizer to mix, kneading and melting, and preparing a TPI film by a casting method, placing the TPI film on the Ni / Fe3O4 composite nano three-dimensional array sensing layer, and performing hot pressing welding to bond and seal the TPI film to the Ni / Fe3O4 composite nano three-dimensional array sensing layer.

2. The method for preparing a Ni / Fe3O4 composite nano three-dimensional array strain sensor based on tunneling effect according to claim 1, characterized in that: The step of preparing the PDMS base layer by a gelling machine comprises: Weigh the PDMS two-component liquid, select the substrate and clean it with plasma water or anhydrous ethanol, place the evenly stirred PDMS prepolymer at the center of the substrate and spin-coat the PDMS prepolymer using a coater, and then place the substrate spin-coated with the PDMS prepolymer in a constant temperature oven for heating and curing.

3. The method for preparing the Ni / Fe3O4 composite nano three-dimensional array strain sensor based on the tunnel effect according to claim 2 is characterized in that: The PDMS substrate layer after heating and curing is modified by oxygen plasma to increase the surface hydrophilicity.

4. The method for preparing a Ni / Fe3O4 composite nano three-dimensional array strain sensor based on tunneling effect according to claim 1, characterized in that: The steps of preparing nickel nanowires by electrochemical deposition include: An anodized aluminum film with regular pores is selected as a deposition template, and a layer of metal back electrode is sputtered on the back of the anodized aluminum film in a vacuum sputtering chamber. The sputtering time is 5-20 minutes and the sputtering power is 60-250W. A nickel ion electrolyte solution with a certain concentration is prepared, and an anodized aluminum film is placed in the nickel ion electrolyte solution, and a constant current is passed for electrochemical deposition. The anodized aluminum film with deposited nickel nanowires is immersed in a 5-10% mass fraction NaOH solution, and allowed to stand at 60-80° C. for 2.5-7 hours until the anodized aluminum film is completely dissolved to obtain nickel nanowires. The nickel nanowires are cleaned and placed in anhydrous ethanol, and the nickel nanowires are uniformly dispersed by ultrasound to form a suspension.

5. The method for preparing the Ni / Fe3O4 composite nano three-dimensional array strain sensor based on the tunnel effect according to claim 4, characterized in that: The step of depositing an ordered nickel nanowire array on the surface of the PDMS substrate layer sprayed with a nano Pt electronic layer, and deviating the deposition position of the nickel nanowire array from the central axis in the width direction of the PDMS substrate layer comprises: A double-pass polymethyl methacrylate square box container is placed on the PDMS substrate layer, and the contact part is sealed. It is then placed in a parallel magnetic field with the direction of the magnetic field consistent with the width direction of the PDMS substrate layer. A pipette is used to transfer the evenly dispersed nickel nanosuspension into the double-pass polymethyl methacrylate square box container and let it stand to deposit a highly ordered nickel nanowire array on the PDMS substrate.

6. The method for preparing a Ni / Fe3O4 composite nano three-dimensional array strain sensor based on tunneling effect according to claim 4 or 5, characterized in that: Use ultrasonic waves to clean the surface of anodized aluminum film; The nickel nanowires were washed repeatedly with deionized water and anhydrous ethanol.

7. The method for preparing a Ni / Fe3O4 composite nano three-dimensional array strain sensor based on tunneling effect according to claim 5, characterized in that: The nickel nanowire array exhibits asymmetry in the direction orthogonal to the stretching surface.

8. The method for preparing a Ni / Fe3O4 composite nano three-dimensional array strain sensor based on tunneling effect according to claim 5, characterized in that: The step of growing Fe3O4 nanoparticles on the surface of the nickel nanowire array to form a Ni / Fe3O4 composite nano three-dimensional array sensing layer comprises: A mixed solution of ferric chloride hexahydrate and ferrous chloride tetrahydrate is added to a highly ordered nickel nanowire array deposited in a double-pass polymethyl methacrylate square box container, and ammonia water is added to adjust the pH of the solution to 10-12. The mixed solution undergoes a precipitation reaction, and Fe3O4 nanoparticles adhere and grow on the surface of the nickel nanowire array to form a Ni / Fe3O4 composite nano three-dimensional array sensing layer.

9. The method for preparing a Ni / Fe3O4 composite nano three-dimensional array strain sensor based on tunneling effect according to claim 2, characterized in that: The substrate can be any one of glass, quartz, polyethylene terephthalate (PET), and nickel substrate.

10. A Ni / Fe3O4 composite nano three-dimensional array strain sensor based on tunneling effect, using the preparation method according to any one of claims 1 to 9, characterized in that: It includes a base layer, a nano film layer, a Ni / Fe3O4 composite nano three-dimensional array sensing layer and a packaging layer.

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