Active composite multi-sensor device based on micro-nano structure and interface and preparation method thereof

Abstract

The application discloses an active composite multi-sensor device based on micro-nano structures and interfaces and a preparation method, and belongs to the technical field of sensors, and comprises a surface microstructure sensitized electrode layer, a dense fiber type functional layer and an interdigital electrode layer in sequence; the surface microstructure sensitized electrode layer comprises a polyvinyl alcohol / silk fibroin composite film with micro-nano structures on the surface, and a metal electrode layer sprayed on the micro-nano structure side of the polyvinyl alcohol / silk fibroin composite film; the mass ratio of polyvinyl alcohol to silk fibroin is x:(1-x), and x=72% to 90%; the metal electrode layer is arranged towards the dense fiber type functional layer side; the dense fiber type functional layer is a silk fibroin / conductive material composite film, and the mass ratio of silk fibroin to conductive material is 30:(1 to 4). The application realizes the sensing identification of multi-sensing parameters such as pressure, temperature and humidity, has excellent flexibility and high sensitivity, and improves the stress transmission efficiency through the setting of micro-nano structures.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology, specifically relating to active composite multi-sensor devices based on micro-nano structures and interfaces, and their fabrication methods. Background Technology

[0002] To adapt to the development trend of wearable electronic devices and intelligent human-machine interfaces, various flexible sensors have been proposed to detect changes in physical signals from the human body and environmental conditions such as temperature, pressure, and strain. However, most traditional sensors are based on a single mechanism to detect a specific physical quantity, limiting the types of physical parameters that can be detected, and they require a power supply unit to continuously power them. For example, traditional piezoresistive sensors can only detect external static pressure and require an external power supply, which limits their application in different scenarios and under long-term monitoring requirements.

[0003] Furthermore, wearable sensors should possess excellent flexibility and high sensitivity, and the materials should be non-toxic and relatively inexpensive. Traditional silicon-based electronics have physical rigidity and cannot meet the requirements for flexibility; while traditional flexible materials can improve the flexibility of sensors, they limit the detection sensitivity to some extent. Moreover, common polymer materials such as PDMS (polydimethylsiloxane) and PI (polyimide) have low permeability, are non-biodegradable, and will impact the environment, making it difficult to meet the comfort requirements of wearable electronic devices.

[0004] Silk fibroin, a widely used and researched natural polymer, possesses high mechanical strength and toughness. It exhibits good shape retention with human skin, biocompatibility, and adjustable degradability, and is abundant and cost-effective. More importantly, silk fibroin is easily chemically modified and can be processed into various forms using deionized water or organic solvents, laying the foundation for its application in flexible electronic devices.

[0005] Therefore, it is of great significance to realize a multi-sensor composite, active, high-performance flexible sensor based on silk fibroin. Summary of the Invention

[0006] To address the problems in the prior art, this invention provides an active composite multi-sensor device based on micro-nano structures and interfaces, and its fabrication method, which can realize the sensing and identification of multiple sensing parameters such as pressure, temperature, and humidity.

[0007] The technical solution adopted in this invention is as follows:

[0008] An active composite multi-sensor based on micro-nano structures and interfaces, comprising a surface microstructure sensitizing electrode layer, a dense fiber-type functional layer, and an interdigitated electrode layer in sequence.

[0009] The surface microstructure-enhanced electrode layer includes a polyvinyl alcohol / silk protein composite film with a micro / nano structure on its surface, and a metal electrode layer sprayed on the micro / nano structure side of the polyvinyl alcohol / silk protein composite film; wherein, the mass ratio of polyvinyl alcohol to silk protein is x:(1-x), x=72%~90%; the metal electrode layer is disposed on the side facing the dense fiber-type functional layer.

[0010] The dense fiber-type functional layer is a silk fibroin / conductive material composite film, with a mass ratio of silk fibroin to conductive material of 30:(1-4).

[0011] Furthermore, the silk protein / conductive material composite film is prepared by electrospinning, and the spinning solvent is hexafluoroisopropanol, formic acid or hexafluoroacetone, preferably hexafluoroisopropanol.

[0012] Furthermore, the sum of the mass fractions of silk fibroin and conductive material in the spinning mixture is 8% to 10%.

[0013] Furthermore, the voltage used in the electrospinning process is 16–20 kV.

[0014] Furthermore, the conductive material is silver, specifically silver nanowires.

[0015] Furthermore, the material of the metal electrode layer is silver, specifically silver nanowires.

[0016] Furthermore, the micro-nano structure is a periodic array structure composed of several micro-nano units, wherein the depth of the micro-nano units is 20-50 μm and the maximum width is 40-80 μm.

[0017] Furthermore, the micro / nano structure is formed by molding using a mold with a periodic array structure, wherein the mold is one of a silicon template, a 3D-printed polyethylene template, or sandpaper.

[0018] Furthermore, the interdigitated electrode layer comprises N interdigitated structural units, where N is an integer greater than 1, and the width of each interdigitated structural unit is 2 mm; the gap width between adjacent interdigitated structural units is 0.5 mm, and the effective overlap length is 14.5–14.9 mm; the interdigitated electrode layer also includes two lead-out electrodes with an area of ​​2.5 × 2.5 mm. 2 The distance between the lead-out electrode and the interdigital structure unit is 2.5 mm.

[0019] The fabrication method of active composite multi-sensor based on micro / nano structures and interfaces includes the following steps:

[0020] Step 1: Prepare a silk protein solution with a mass fraction of 3-5 wt%;

[0021] Step 2: Add polyvinyl alcohol to deionized water, stir and disperse at room temperature for 30-50 minutes, then heat and stir at 60-70℃ for 1-2 hours to obtain a polyvinyl alcohol solution with a mass fraction of 9-18 wt%.

[0022] Step 3: Mix the silk fibroin solution with the polyvinyl alcohol solution and stir at room temperature for 30-40 minutes to obtain a polyvinyl alcohol / silk fibroin solution with a mass ratio of polyvinyl alcohol to silk fibroin of x:(1-x) and x = 72%-90%.

[0023] Step 4: Obtain a mold with a periodic array structure, pour the polyvinyl alcohol / silk protein solution into the mold to make a mold, and place it on a heating table at 45℃~60℃ to dry for 3~4 hours to obtain a polyvinyl alcohol / silk protein composite film with micro-nano structure on the surface.

[0024] Step 5: Using mask spraying technology, conductive metal is sprayed onto one side of the micro / nano structure of the polyvinyl alcohol / silk protein composite film. After heating and drying, a metal electrode layer is obtained.

[0025] Step 6: Drop casting and drying of the silk protein solution to obtain a pure silk protein film. After weighing, cut it into fragments and dissolve it in the spinning solvent. Stir to obtain a transparent silk protein solution.

[0026] Step 7: Disperse the conductive material in anhydrous ethanol, dry it, add spinning solvent, and ultrasonically disperse for 10-15 minutes to obtain a conductive material dispersion.

[0027] Step 8: Add the conductive material dispersion to the silk fibroin transparent solution to obtain a silk fibroin / conductive material spinning mixture solution; wherein, the mass ratio of silk fibroin to conductive material is 30:(1~4), and the sum of the mass fractions of silk fibroin and conductive material in the spinning mixture solution is 8%~10%;

[0028] Step 9: The spinning mixture solution is electrospinned to form a silk protein / conductive material composite film, and left at room temperature until the spinning solvent has completely evaporated;

[0029] Step 10: Using mask spraying technology, conductive metal is sprayed onto the surface of the silk protein / conductive material composite film, and after heating and drying, an interdigitated electrode layer is obtained.

[0030] Step 11: Encapsulate the interdigitated electrode layer, the silk fibroin / conductive material composite film, and the polyvinyl alcohol / silk fibroin composite film in sequence to obtain an active composite multi-sensor device based on micro-nano structures and interfaces.

[0031] Furthermore, the specific process of step 1 is as follows:

[0032] Step 1.1: Remove sericin from silkworm cocoons: Pour the chopped silkworm cocoons into a boiling 0.02M sodium carbonate solution, boil and stir for 45-60 minutes, remove the silkworm cocoons after removing sericin, wash them several times with deionized water, and dry them to obtain degummed silk.

[0033] Step 1.2, Dissolving silk protein: Dissolve lithium bromide in deionized water to prepare a 9.3M lithium bromide solution; dissolve degummed silk in the lithium bromide solution and heat in a 60℃ oven for 4 hours to obtain a silk protein / lithium bromide solution; wherein the mass ratio of degummed silk to the volume of lithium bromide solution is 1:5;

[0034] Step 1.3: Dialysis and filtration of silk protein: The silk protein / lithium bromide solution is injected into a dialysis bag and sealed. It is then placed in deionized water for 48 hours of stirring and dialysis to remove lithium bromide. The resulting dialysis solution is then filtered to remove impurities with larger particle sizes. The microporous filter used has a pore size of 5 μm. After repeating the filtration 3 times, a silk protein solution with a mass fraction of 3-5 wt% is obtained.

[0035] Furthermore, in steps 5 and 10, the spray gun is placed 20 cm above the film to be sprayed, and spraying is repeated 30 to 40 times. Afterward, it is heated and dried at 45°C to 60°C for 30 to 40 minutes.

[0036] Furthermore, the specific parameters of the electrospinning process in step 9 are: a voltage of 16-20kV, a syringe capacity of 10mL, a needle specification of 18-20G, a feed rate of 1.0-1.5cm / h, and a collection distance of 10-14cm.

[0037] The working principle of the active composite multi-sensor device based on micro / nano structures and interfaces provided by this invention is as follows:

[0038] The silk fibroin / silver nanowire composite film is prepared through electrospinning under a high-voltage electric field, resulting in an ordered arrangement of the silk fibroin polymer chains and a consistent orientation of the dipoles within the fibers, thus achieving a high dipole moment. Simultaneously, the added silver nanowire conductive material increases the local electric field strength, enhancing the polarization effect of the dipoles under the same voltage. When an external force perpendicular to the plane is applied to the active composite multi-sensor based on micro / nano structures and interfaces, the silk fibroin / silver nanowire composite film deforms, causing a change in the high dipole moment and separation of positive and negative charge centers, generating a potential output. This potential is then extracted through the interdigitated electrode layer and the surface microstructure-enhanced electrode layer, achieving piezoelectric sensing. Furthermore, during the application of external force, the micro / nano structure of the polyvinyl alcohol / silk fibroin composite film is compressed against the silk fibroin / silver nanowire composite film, causing greater deformation under the same pressure, further enhancing the piezoelectric output.

[0039] When an electric field is applied to the active composite multi-sensor device through the interdigitated electrode layer, the arrangement of molecular dipoles within the silk fibroin changes. On one hand, since the molecular activity within the silk fibroin increases with temperature, the increased molecular activity and the greater change in the arrangement of molecular dipoles lead to a larger dielectric constant of the silk fibroin, thus increasing the capacitance of the active composite multi-sensor device and achieving capacitive temperature sensing. On the other hand, because silk fibroin has very strong water absorption properties, its relative dielectric constant is 2.5–3.5, while the relative dielectric constant of water is approximately 81.5. Therefore, in environments with high relative humidity, silk fibroin will absorb water molecules, leading to an increase in the dielectric constant of the silk fibroin, which in turn increases the capacitance of the active composite multi-sensor device and achieves capacitive humidity sensing.

[0040] The beneficial effects of this invention are as follows:

[0041] 1. The active composite multi-sensor device based on micro-nano structure and interface proposed in this invention can achieve active piezoelectric sensing by applying external force to it, and can also achieve capacitive sensing of temperature and humidity by applying an electric field to the interdigital electrode layer. In this way, it can realize the perception and recognition of multiple sensing parameters such as pressure, temperature and humidity. It has excellent flexibility and high sensitivity and can be applied to the detection of finger tapping, joint bending and breathing related to human activities. It is of great significance for medical and health monitoring and other applications.

[0042] 2. In this invention, the polyvinyl alcohol / silk protein composite film has a micro-nano structure on the side facing the dense fibrous functional layer, and the resulting metal electrode layer also has a micro-nano structure. Compared with planar electrodes, the deformation caused by the same pressure will be greater, which increases the stress transfer efficiency between the metal electrode layer and the dense fibrous functional layer, thereby giving the device a higher piezoelectric sensing response and effectively solving the problem of small piezoelectric response of ordinary silk protein films.

[0043] 3. This invention uses silk protein as one of the materials for the dense fiber functional layer and the surface microstructure sensitive electrode layer, which has natural biodegradability; polyvinyl alcohol itself has good water solubility and, as an environmentally friendly material, helps to reduce the generation of electronic waste; other metal electrodes and conductive materials all have high biocompatibility and are suitable for long-term wear by the human body, and have broad development prospects in the field of wearable devices. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the active composite multi-sensor device based on micro-nano structures and interfaces proposed in Embodiment 1 of the present invention;

[0045] Figure 2This is the pressure response curve of the active composite multi-sensor device based on micro-nano structures and interfaces proposed in Embodiment 1 of the present invention.

[0046] Figure 3 This is the temperature response curve of the active composite multi-sensor device based on micro-nano structures and interfaces proposed in Embodiment 1 of the present invention.

[0047] Figure 4 This is the response curve of the active composite multi-sensor device based on micro-nano structure and interface proposed in Embodiment 1 of the present invention to humidity.

[0048] The labels in the attached diagram are explained as follows:

[0049] 1-Surface microstructure-enhanced electrode layer, 2-Dense fiber-type functional layer, 3-Interdigitated electrode layer. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0051] Example 1

[0052] This embodiment provides an active composite multi-sensor device based on micro / nano structures and interfaces, the structure of which is as follows: Figure 1 As shown, it includes, in sequence, a surface microstructure-enhancing electrode layer 1, a dense fiber-type functional layer 2, and an interdigitated electrode layer 3.

[0053] The surface microstructure-enhanced electrode layer 1 includes a polyvinyl alcohol / silk protein composite film with a micro / nano structure on its surface, and a silver electrode layer sprayed on the micro / nano structure side of the polyvinyl alcohol / silk protein composite film; wherein, the mass ratio of polyvinyl alcohol to silk protein is 9:1; the silver electrode layer is disposed on the side facing the dense fiber-type functional layer 2; the micro / nano structure is a periodic array structure composed of several micro / nano units, wherein the depth of the micro / nano unit is 20 μm and the width is 40 μm.

[0054] The dense fibrous functional layer 2 is a silk protein / silver nanowire composite film, with a mass ratio of silk protein to silver nanowires of 30:1.

[0055] The interdigitated electrode layer 3 is made of conductive silver nanowires and includes 14 interdigitated structural units. The width of each interdigitated structural unit is 2 mm, the gap width is 0.5 mm, and the effective overlap length is 14.5 mm.

[0056] The fabrication method of the active composite multi-sensor based on micro / nano structures and interfaces provided in this embodiment specifically includes the following steps:

[0057] Step 1: Prepare a 4 wt% silk protein solution, specifically as follows:

[0058] Step 1.1: Remove sericin from silkworm cocoons: Pour the chopped silkworm cocoons into a boiling 0.02M sodium carbonate solution, boil and stir for 45 minutes, remove the silkworm cocoons after removing sericin, wash them several times with deionized water, and dry them to obtain degummed silk.

[0059] Step 1.2, Dissolving silk protein: Dissolve lithium bromide in deionized water to prepare a 9.3M lithium bromide solution; dissolve degummed silk in the lithium bromide solution and heat in a 60℃ oven for 4 hours to obtain a silk protein / lithium bromide solution; wherein the mass ratio of degummed silk to the volume of lithium bromide solution is 1:5;

[0060] Step 1.3: Dialysis and filtration of silk protein: The silk protein / lithium bromide solution was injected into a dialysis bag and sealed. It was then placed in deionized water for 48 hours of stirring and dialysis to remove lithium bromide. The resulting dialysis solution was then filtered to remove impurities with larger particle sizes. The microporous filter used had a pore size of 5 μm. After repeating the filtration three times, a silk protein solution with a mass fraction of 4 wt% was obtained.

[0061] Step 2: Add polyvinyl alcohol to deionized water, stir and disperse at room temperature for 30 minutes, then heat and stir for 1 hour to obtain a polyvinyl alcohol solution with a mass fraction of 9 wt%.

[0062] Step 3: Mix the silk fibroin solution and the polyvinyl alcohol solution, and stir at room temperature for 30 minutes to obtain a polyvinyl alcohol / silk fibroin solution with a mass ratio of 9:1.

[0063] Step 4: Design and draw a photomask with a periodic array structure using L-edit software, and then prepare a silicon mold with a periodic array structure. Pour the polyvinyl alcohol / silk protein solution into the silicon mold to cast the film, and place it on a 45°C heating stage to dry for 4 hours to obtain a polyvinyl alcohol / silk protein composite film with micro-nano structure on the surface.

[0064] Step 5: Using mask spraying technology, place the spray gun 20cm above the micro-nano structure side of the polyvinyl alcohol / silk protein composite film, spray repeatedly 30 times, and then heat and dry at 45℃ for 40min to obtain the silver electrode layer.

[0065] Step 6: Drop casting and drying of the silk protein solution to obtain a pure silk protein film. After weighing, cut it into fragments and dissolve it in the spinning solvent. Stir to obtain a transparent silk protein solution.

[0066] Step 7: Disperse the silver nanowires in anhydrous ethanol, dry them, add hexafluoroisopropanol, and sonicate for 10 min to obtain a silver nanowire dispersion.

[0067] Step 8: Add the silver nanowire dispersion to the silk fibroin transparent solution to obtain a silk fibroin / silver nanowire hexafluoroisopropanol mixed solution; wherein, the mass ratio of silk fibroin to silver nanowire is 30:1, and the sum of the mass fractions of silk fibroin and silver nanowire in the hexafluoroisopropanol mixed solution is 8%;

[0068] Step 9: Prepare a silk protein / silver nanowire composite film by electrospinning the hexafluoroisopropanol mixed solution and leave it at room temperature for 24 hours until the hexafluoroisopropanol evaporates completely. The specific parameters of the electrospinning process are: 20kV voltage, 10mL syringe capacity, 18G needle specification, 1.5cm / h feed rate, aluminum foil wrapping the rotating roller to collect the ejected fibers, and a collection distance of 14cm.

[0069] Step 10: Using mask spraying technology, conductive metal is sprayed onto the surface of the silk protein / silver nanowire composite film, and after heating and drying, interdigitated electrode layer 3 is obtained.

[0070] Specifically, a mask pattern complementary to the interdigitated electrode layer is designed and drawn using SOLIDWORKS software, and then the required mold is printed using a 3D printer. The mask and the silk protein / silver nanowire composite film are fixed on the spraying platform. Preferably, the spray gun is about 20cm above the platform. Then, the silver nanowires are sprayed onto the silk protein / silver nanowire composite film under high pressure, and then dried at 45°C for 40 minutes on a heating platform to obtain the interdigitated electrode layer 3.

[0071] Step 11: Encapsulate the interdigitated electrode layer 3, the silk fibroin / silver nanowire composite film, and the polyvinyl alcohol / silk fibroin composite film in sequence to obtain an active composite multi-sensor device based on micro-nano structures and interfaces.

[0072] The following performance tests were performed on the active composite multi-sensor device based on micro / nano structures and interfaces prepared in this embodiment:

[0073] I. Piezoelectric sensing test:

[0074] The fabricated active composite multi-sensor was measured using an oscilloscope. To facilitate measurement, the silver electrode layers of the interdigital electrode layer 3 and the surface microstructure sensitizing electrode layer 1 were led out using silver wires through the electrode lead-out area before measurement.

[0075] At room temperature, the active composite multi-sensor to be measured is placed on a test platform. The signal frequency and amplitude are set using a signal generator, and a vibration table connected to it applies a certain pressure to the active composite multi-sensor in a regular manner. The real-time voltage output changes of the active composite multi-sensor can then be observed on an oscilloscope. For example... Figure 2 As shown, during the reciprocating motion on the vibration table, the active composite multi-sensor device exhibits a significant response to the applied pressure. When pressure is applied to the active composite multi-sensor device, the voltage output increases rapidly, and when the pressure is removed, the voltage returns to its initial level. Furthermore, with other structural elements of the device remaining unchanged, the voltage amplitude of the active composite multi-sensor device based on the surface microstructure-enhanced electrode layer 1 with micro / nano structures is significantly improved compared to a planar electrode layer.

[0076] II. Temperature-capacitance sensing test based on LCR bridge:

[0077] In this embodiment, a heating plate is selected as the temperature measurement platform. To reduce temperature measurement errors, the active composite multi-sensor device needs to be placed in close contact with the heating platform. When the temperature rises from room temperature (25°C) to 50°C, the capacitance response of the active composite multi-sensor device is as follows: Figure 3 As shown, within the time frame of 0 to 8 seconds, the capacitance change rate of the active composite multi-sensor device increases rapidly with increasing temperature, and the increase slows down after 8 seconds.

[0078] III. Humidity capacitive sensing test based on LCR bridge:

[0079] In this embodiment, a commercial ultrasonic humidifier is selected as the test platform. It uses ultrasonic waves generated by high-frequency oscillation to throw water off the water surface and generate tiny water mist particles through the high-frequency vibration of the atomizing plate. These particles are evenly dispersed and suspended in the air to achieve the purpose of rapid humidification.

[0080] The active composite multi-sensor to be measured is placed in a transparent, sealed box. To expand the humidity detection range, preferably, a desiccant is used to reduce the humidity in the sealed test box to 30% beforehand. Then, a humidifier is used to humidify the sealed environment, such as... Figure 4 As shown, within the first 40 seconds, the humidity rose from 30% to 80%, during which time the capacitance change rate of the active composite multi-sensor device increased rapidly. After 40 seconds, the lid of the sealed box was opened, and the water mist quickly dispersed, causing the capacitance value of the active composite multi-sensor device to decrease rapidly. During the process of opening the lid, a slight fluctuation in capacitance change was observed.

[0081] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An active composite multi-sensor device based on micro / nano structures and interfaces, characterized in that, It includes a surface microstructure sensitizing electrode layer, a dense fiber-type functional layer and an interdigitated electrode layer stacked sequentially; The surface microstructure-enhanced electrode layer includes a polyvinyl alcohol / silk protein composite film with a micro / nano structure on its surface, and a metal electrode layer sprayed on the micro / nano structure side of the polyvinyl alcohol / silk protein composite film; wherein, the mass ratio of polyvinyl alcohol to silk protein is x:(1-x), x=72%~90%; the metal electrode layer is disposed on the side facing the dense fiber-type functional layer. The dense fiber-type functional layer is a silk fibroin / conductive material composite film, with a mass ratio of silk fibroin to conductive material of 30:(1~4).

2. The active composite multi-sensor device based on micro / nano structures and interfaces according to claim 1, characterized in that, The silk protein / conductive material composite film is prepared by electrospinning, and the spinning solvent is hexafluoroisopropanol, formic acid or hexafluoroacetone.

3. The active composite multi-sensor device based on micro / nano structures and interfaces according to claim 2, characterized in that, The electrospinning process uses a voltage of 16~20 kV.

4. The active composite multi-sensor device based on micro / nano structures and interfaces according to claim 1, characterized in that, The micro-nano structure is a periodic array structure composed of several micro-nano units, wherein the depth of the micro-nano units is 20~50 μm and the maximum width is 40~80 μm.

5. The active composite multi-sensor device based on micro / nano structures and interfaces according to claim 1, characterized in that, The micro / nano structure is formed by molding using a mold with a periodic array structure, wherein the mold is one of a silicon template, a 3D-printed polyethylene template, or sandpaper.

6. The active composite multi-sensor device based on micro / nano structures and interfaces according to claim 1, characterized in that, The conductive material is silver, specifically silver nanowires.

7. The fabrication method of the active composite multi-sensor device based on micro / nano structures and interfaces as described in claim 1, characterized in that, Includes the following steps: Step 1: Prepare a silk protein solution with a mass fraction of 3-5 wt%; Step 2: Add polyvinyl alcohol to deionized water, stir and disperse at room temperature for 30-50 min, then heat and stir at 60-70℃ for 1-2 h to obtain a polyvinyl alcohol solution with a mass fraction of 9-18 wt%. Step 3: Mix the silk fibroin solution and the polyvinyl alcohol solution, and stir at room temperature for 30-40 minutes to obtain a polyvinyl alcohol / silk fibroin solution with a mass ratio of x:(1-x) and x=72%~90%. Step 4: Obtain a mold with a periodic array structure, pour the polyvinyl alcohol / silk protein solution into the mold to make a mold, and place it on a heating table at 45℃~60℃ to dry for 3~4 hours to obtain a polyvinyl alcohol / silk protein composite film with micro-nano structure on the surface. Step 5: Using mask spraying technology, conductive metal is sprayed onto one side of the micro / nano structure of the polyvinyl alcohol / silk protein composite film. After heating and drying, a metal electrode layer is obtained. Step 6: Drop casting and drying of the silk protein solution to obtain a pure silk protein film, dissolve it in spinning solvent and stir to obtain a transparent silk protein solution; Step 7: Disperse the conductive material in anhydrous ethanol, dry it, add spinning solvent, and ultrasonically disperse for 10-15 min to obtain a conductive material dispersion. Step 8: Add the conductive material dispersion to the silk fibroin transparent solution to obtain a silk fibroin / conductive material spinning mixture solution; wherein, the mass ratio of silk fibroin to conductive material is 30:(1~4), and the sum of the mass fractions of silk fibroin and conductive material in the spinning mixture solution is 8%~10%; Step 9: The spinning mixture solution is electrospinned to form a silk protein / conductive material composite film, and left at room temperature until the spinning solvent has completely evaporated; Step 10: Using mask spraying technology, conductive metal is sprayed onto the surface of the silk protein / conductive material composite film, and after heating and drying, an interdigitated electrode layer is obtained. Step 11: Encapsulate the interdigitated electrode layer, the silk fibroin / conductive material composite film, and the polyvinyl alcohol / silk fibroin composite film in sequence to obtain an active composite multi-sensor device based on micro-nano structures and interfaces.

8. The preparation method according to claim 7, characterized in that, The specific process of step 1 is as follows: Step 1.1: Remove silkworm cocoon sericin: Pour the chopped silkworm cocoons into a boiling 0.02 M sodium carbonate solution, boil and stir for 45-60 minutes, wash repeatedly with deionized water, and dry to obtain degummed silk. Step 1.2, Dissolving silk protein: Dissolve lithium bromide in deionized water to prepare a 9.3 M lithium bromide solution; Degummed silk was dissolved in lithium bromide solution and heated in a 60°C oven for 4 hours to obtain silk protein / lithium bromide solution; Step 1.3: Dialysis and filtration of silk protein: The silk protein / lithium bromide solution was injected into a dialysis bag and sealed. It was then placed in deionized water and dialyzed with stirring for 48 h to remove lithium bromide. The resulting dialysis solution was then filtered using a microporous filter with a pore size of 5 μm. After filtration was repeated 3 times, a silk protein solution with a mass fraction of 3-5 wt% was obtained.

9. The preparation method according to claim 7, characterized in that, The specific parameters for the electrospinning process in step 9 are: a voltage of 16~20 kV, a syringe capacity of 10 mL, a needle specification of 18~20 G, and a collection distance of 10~14 cm.

10. The preparation method according to claim 7, characterized in that, In steps 5 and 10, the spray gun is placed 20 cm above the film to be sprayed, and the spray is repeated 30 to 40 times. After that, it is heated and dried at 45℃ to 60℃ for 30 to 40 minutes.

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