A silk fibroin-based piezoelectric sensing film induced by bto conformation transition and a preparation method thereof

Abstract

The application discloses a silk fibroin-based piezoelectric sensing film induced by BTO conformation transition and a preparation method thereof. The sensing film is composed of regenerated silk fibroin (SF) and tetragonal barium titanate (BaTiO3) nanoparticles by electrospinning technology. The core of the application is that the polar surface charge of BaTiO3 nanoparticles is used to in-situ induce the silk fibroin molecular chain to transform from random coil to beta sheet crystal phase with piezoelectric activity under the synergistic effect of high-voltage electric field in electrospinning, and a double piezoelectric synergistic system of organic crystal phase and inorganic ceramic phase is constructed. Experiments prove that the sensing film has excellent flexibility, biocompatibility and extremely high low-frequency sensitivity (0.25Hz-1Hz), and is stable under 10000 times of cyclic loading. The application has important application value in the fields of flexible self-powered physiological sensing such as heart sound monitoring and pulse recognition.

Description

Technical Field

[0001] This invention belongs to the field of biomass functional materials and flexible electronic devices, specifically relating to a piezoelectric sensing membrane based on barium titanate-induced conformational transition of silk fibroin and its preparation method. Background Technology

[0002] With the deep integration of flexible electronics technology and the Internet of Things (IoT), flexible sensors with biocompatibility, self-powering properties, and high sensitivity have become a research hotspot in the fields of assisted medical monitoring, human-computer interaction, and electronic skin. Among many materials, silk fibroin (SF), as a natural protein polymer, is considered an ideal matrix for constructing implantable or adhesive flexible devices due to its excellent mechanical strength, superior biodegradability, and good air and moisture permeability.

[0003] However, when pure silk fibroin is not specially treated, its molecular chains mainly exist in random coil or α-helix structures, resulting in its intrinsic piezoelectric constant (d 33 The piezoelectric coefficient is extremely low, making it difficult to meet the requirements for capturing weak physiological electrical signals. To improve the piezoelectric response, existing studies mostly use ferroelectric ceramic particles such as barium titanate (BaTiO3, BTO) and lead zirconate titanate (PZT) as active fillers. Among them, BTO has become the first choice for improving the performance of SF-based sensing films due to its lead-free and environmentally friendly nature and its high piezoelectric coefficient.

[0004] Although existing research has explored the combination of SF and BTO, the current technology still has the following significant limitations:

[0005] Interfacial interactions are often overlooked, limiting synergistic effects: In existing technologies, the composite of silk fibroin and barium titanate is mostly achieved through physical blending, relying primarily on the piezoelectricity of barium titanate itself, which fails to effectively stimulate the piezoelectric activity of silk fibroin. In fact, silk fibroin only exhibits significant piezoelectric activity after transforming into a β-sheet crystalline phase. How to utilize the interfacial energy of inorganic particles to actively induce phase transitions in protein molecules and achieve synergy between organic and inorganic dual piezoelectric phases remains a challenge, lacking systematic physicochemical mechanism demonstrations in currently published patents.

[0006] The unstable microstructure of the coating results in poor long-term stability: Due to the significant difference in modulus matching between ceramic particles and the polymer matrix, BTO particles are prone to agglomeration during mixing or spinning, or may only loosely adhere to the fiber surface. During long-term mechanical wear (such as breathing movements or muscle stretching), the particles are easily detached from the matrix, leading to a sharp decrease in sensitivity. Currently, there is a lack of a microstructure construction scheme that can achieve a stable "core-shell" coating without disrupting fiber continuity, which limits the reliability of the device in over 10,000 cycles.

[0007] The recognition rate of sub-Hz signals is low: key physiological signals of the human body (such as heart sounds S1 / S2, low-frequency pulse waves, and abdominal peristalsis sounds) are mostly concentrated in the extremely low frequency range of 0.1Hz to 20Hz. Traditional flexible piezoelectric materials are prone to severe signal distortion or charge leakage at extremely low frequencies due to charge relaxation effects. Most existing patents focus on wide-range pressure sensing (such as foot walking and joint flexion), while effective structural optimization schemes are still lacking for high-quality capture of sub-Hz level, extremely weak mechanical energy.

[0008] In summary, developing a silk fibroin / barium titanate piezoelectric sensing membrane that can enhance crystallinity through interface-induced effects, possesses a stable core-shell coating structure, and exhibits high-fidelity response to weak sub-Hertz signals is not only a major technological breakthrough in the field of flexible sensors, but also an urgent need to achieve self-powered and precise medical monitoring. Summary of the Invention

[0009] Objective: To address the shortcomings of existing silk fibroin-based sensors, such as weak piezoelectric output performance, poor interfacial bonding between inorganic fillers and the protein matrix, and insufficient sensitivity in detecting weak physiological signals, this invention provides a composite piezoelectric sensing membrane that utilizes BTO to induce a conformational transition in SF. Through microscopic phase modulation, the sensor achieves excellent low-frequency piezoelectric conversion efficiency and long-term cycling stability while maintaining high flexibility.

[0010] Technical solution: To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A BTO-induced conformational change silk fibroin-based piezoelectric sensing membrane comprises a nanofiber continuous phase matrix composed of a nanofiber matrix. The nanofibers use regenerated silk fibroin as the continuous phase matrix, and the regenerated silk fibroin is uniformly coated with barium titanate nanoparticles, that is, tetragonal barium titanate (BaTiO3) nanoparticles are uniformly embedded inside the regenerated silk fibroin matrix. In the continuous phase, the silk fibroin molecular chains undergo conformational changes at the interface of the barium titanate nanoparticles, forming a cross-linked network rich in β-sheet crystal regions. The β-sheet crystal regions and the barium titanate nanoparticles together constitute a piezoelectric response unit.

[0012] Furthermore, in the nanofiber continuous phase matrix, the barium titanate nanoparticles account for 5wt%-20wt% of the total mass of the matrix, and the average particle size is 100nm-200nm; the diameter of the nanofibers ranges from 400nm to 800nm.

[0013] Furthermore, the barium titanate nanoparticles have a core-shell encapsulation structure inside a single nanofiber; the encapsulation structure forms an interfacial bonding layer by the electric field-induced force in the electrospinning process, which causes silk fibroin to be encapsulated on the surface of the barium titanate particles.

[0014] In the above technical solution, the content of the β-folded crystal region of the silk fibroin is significantly increased compared with that of the pure silk fibroin nanofiber membrane; the existence of the β-folded crystal region is characterized by the enhanced intensity of the characteristic peak in the X-ray diffraction (XRD) spectrum between 19.2∘ and 20.5∘.

[0015] The preparation method of this silk fibroin-based piezoelectric sensing film includes the following steps:

[0016] (1) Preparation of spinning solution: Regenerated silk fibroin was dissolved in formic acid solvent, and barium titanate nanoparticles were added to prepare a blended spinning solution;

[0017] (2) Electrospinning: Using a high-voltage electrospinning device, a fiber membrane is obtained by spinning a blended spinning solution. The electric field induces the silk fibroin molecular chains in the blended spinning solution to be oriented and coated on the surface of barium titanate particles.

[0018] (3) Crystallization locking treatment: The fiber membrane prepared in step (2) is subjected to ethanol vapor post-treatment to further lock the β-fold crystal region structure.

[0019] In step (1), ultrasonic dispersion of the blended spinning solution allows the barium titanate particles to come into full contact with the silk fibroin molecular chains.

[0020] In step (1), the mass ratio of barium titanate nanoparticles to regenerated silk fibroin in the blended spinning solution is 5-20:80-95.

[0021] In step (2), the voltage of high-voltage electrospinning is 18kV-25kV.

[0022] In step (2), the spinning propulsion speed is set to 0.1 mL / h-0.5 mL / h, the receiving distance is 12 cm-18 cm, and the ambient humidity is controlled below 40%.

[0023] Preferably, in step (2), the spinning voltage is set to 22kV, the feed speed is 0.2mL / h, and the receiving distance is 15cm.

[0024] Preferably, the method for preparing the silk fibroin-based piezoelectric sensing film includes the following steps:

[0025] Spinning solution preparation: Dissolve the degummed silk fibroin in formic acid to prepare an SF solution with a mass fraction of 10%-15%; add surface-modified BaTiO3 particles and perform high-energy ultrasonic treatment to achieve stable dispersion by utilizing the electrostatic interaction between the polar groups on the BTO surface and the polar amino acid residues of SF.

[0026] Electrospinning: The mixture is placed in a syringe, the voltage is set to 18kV-25kV, and the receiving distance is 12cm-18cm to prepare the SF / BTO composite nanofiber membrane.

[0027] Post-treatment induction: The original membrane is placed in an ethanol vapor atmosphere for 30-60 minutes to further lock the β-fold structure of SF and improve the mechanical strength and electrical stability of the membrane.

[0028] This piezoelectric sensing film can be used in flexible, self-powered physiological monitoring devices.

[0029] The piezoelectric sensing diaphragm has a pressure load range of 5N-60N and a sensing frequency of 0.25Hz-1Hz. Specifically, within the pressure load range of 5N-60N, the voltage output of the sensing diaphragm exhibits a linear relationship with the pressure; and within the low-frequency range of 0.25Hz-1Hz, it possesses a complete piezoelectric voltage pulse response waveform.

[0030] In this application, a piezoelectric sensing film is attached to the surface of human skin for heart sound monitoring or pulse wave feature extraction.

[0031] Beneficial Effects: Compared with existing technologies, this invention has the following significant advantages: Mechanism Innovation (Synergistic Enhancement): This invention is not a simple physical doping, but rather discovers the inductive effect of BTO on the conformation of SF. XRD data proves that the addition of BTO significantly enhances the crystallization peak intensity of SF at 19.2 Å to 20.5 Å. This "induced phase transition" makes the total piezoelectric response of the film much higher than the linear sum of the components.

[0032] Robust Structure (Core-Shell Protection): TEM observation revealed that the BTO particles are completely encapsulated by SF fibers, forming a core-shell structure. This structure significantly enhances interfacial bonding, resolves the performance degradation caused by inorganic particle shedding, and supports high cycle stability of over 10,000 cycles.

[0033] Precise application (ultra-low frequency sensing): Thanks to the high sensitivity coupling between SF crystal phase and BTO, this sensing film can still output a high-quality voltage signal at sub-hertz (0.25Hz-1Hz) frequencies, which can accurately capture the weak mechanical vibration components in human heart sounds, and the signal-to-noise ratio is significantly better than that of similar flexible piezoelectric materials. Attached Figure Description

[0034] Figure 1 : Schematic diagram of the overall "sandwich" structure of the self-powered electronic skin, where 10 is the overall flexible piezoelectric sensing device; 11 is the upper electrode layer; 12 is the middle composite functional sensing layer; 121 is the silk fibroin (SF) nanofiber matrix; 122 is the barium titanate (BaTiO3) nanoparticles; and 13 is the lower electrode layer.

[0035] Figure 2 SEM images of SF+BTO composite fibers: (a) SF+BTO composite fibers, (b) SEM images of beads under 20kV process parameters.

[0036] Figure 3 XRD patterns of SF, BTO, and SF+BTO.

[0037] Figure 4 : TEM transmission electron microscopy and EDS elemental distribution of SF+BTO, (a) TEM transmission electron microscopy of SF+BTO; (b) EDS elemental scan.

[0038] Figure 5 Linear voltage output curve under 5N-60N load.

[0039] Figure 6 Low-frequency piezoelectric response diagram: 0.25-1Hz.

[0040] Figure 7 Stability test curve after 10,000 cycles. Detailed Implementation

[0041] This section will clearly and completely describe the technical solutions of the embodiments of the present invention with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0042] The raw materials used in this invention, such as regenerated silk fibroin (SF), barium titanate (BaTiO3) nanoparticles, and formic acid solvent, can all be obtained through commercial channels or prepared by standard biochemical processes known in the art, such as degumming, dissolution, and dialysis.

[0043] The core idea of ​​this invention lies in precisely controlling the interfacial interaction between inorganic piezoelectric particles and the natural protein matrix, and using the shear force of a high-voltage electric field to induce the directional rearrangement of protein molecular chains, thereby constructing a synergistic enhancement structure of "core-shell encapsulation" at the microscale. This structure not only solves the industrial problem of easy aggregation and detachment of inorganic particles in flexible matrices, but more importantly, it enhances the charge retention capability of the overall sensing film in the extremely low frequency environment of sub-Hertz (Sub-Hz) through phase transition induction.

[0044] The detection equipment and conditions involved in the following embodiments are described below:

[0045] Morphology characterization: The surface morphology and diameter distribution of the nanofibers were observed using field emission scanning electron microscopy (FE-SEM).

[0046] Phase analysis: X-ray diffraction (XRD) was used to analyze the crystal transformation of silk fibroin and the crystallization state of BaTiO3, with a scanning range of 5. ∘ Up to 60 ∘ ;

[0047] Compositional analysis: Transmission electron microscopy (TEM) combined with energy dispersive spectroscopy (EDS) was used to observe the coating of particles and elemental distribution inside a single fiber;

[0048] Electrical performance testing: A linear motor was used as the excitation source, and a digital oscilloscope and an electrometer were used to record the open-circuit voltage and short-circuit current signals of the sensor under different frequencies and pressures.

[0049] Example 1: Preparation of pure silk fibroin (SF) sensing membrane (0 wt.% BTO)

[0050] This embodiment provides a method for preparing a pure silk fibroin (SF) sensing membrane, including the following steps:

[0051] Preparation of spinning solution: Dissolve the degummed regenerated silk fibroin (SF) in a 98% formic acid solvent and stir at room temperature for 4 hours to prepare a spinning solution with a mass fraction of 13 wt.%.

[0052] Electrospinning: The above stock solution was loaded into a 5mL syringe and prepared using uniaxial electrospinning technology. The spinning voltage was set to 22kV, the feed speed to 0.2mL / h, the receiving distance to 15cm, the receiving device to be a roller collector (rotation speed 100rpm), the ambient temperature to be controlled at (25±2)℃, and the humidity to be (40±5)%.

[0053] Post-processing and crystallization locking: The prepared nanofiber membrane was placed in a vacuum drying oven to remove residual solvent. It was then placed above a sealed container containing 75% ethanol solution and fumigated with ethanol vapor for 45 minutes to induce the molecular chains to transform into a β-sheet structure, obtaining a pure SF sensing membrane. Testing showed that under a 50N load, the membrane's output voltage was 5.2V and its output current was 68nA.

[0054] Example 2: Preparation of a piezoelectric sensing film with a 5 wt.% BTO loading

[0055] This embodiment provides a method for preparing a silk fibroin-based piezoelectric sensing film based on BTO-induced conformational change, including the following steps:

[0056] Preparation of blending stock solution: Add barium titanate (BTO) nanoparticles to a 13 wt.% SF / formic acid solution, and control the mass ratio of BTO to SF to be 5:95.

[0057] Dispersion treatment: High-power ultrasonic waves are used to disperse the BTO particles in an ice-water bath for 30 minutes to ensure that the particles are uniformly suspended in the spinning solution.

[0058] Spinning and Post-treatment: The same electrospinning parameters and ethanol vapor post-treatment process as in Example 1 were used. During spinning, the SF molecular chains began to align under the induction of the BTO polar surface. Testing showed that under a 50N load, the output voltage of the membrane increased to 8.3V, and the output current was 87nA.

[0059] Example 3: Preparation of a piezoelectric sensing film with a 10 wt.% BTO loading

[0060] This embodiment provides a method for preparing a silk fibroin-based piezoelectric sensing film based on BTO-induced conformational change, including the following steps:

[0061] Preparation of blending stock solution: Adjust the mass ratio of BTO nanoparticles to SF to 10:90.

[0062] Process flow: Repeat the dispersion, spinning and post-processing process of Example 2.

[0063] Induced enhancement effect: At this point, the BTO particle distribution density and the contact area of ​​the SF molecular chains reach equilibrium, maximizing the generation of β-folded crystal regions and forming a highly efficient piezoelectric response network. Testing showed that under a 50N load, the film exhibited optimal electrical performance, with an output voltage of 14.6V and an output current of 144nA.

[0064] X-ray diffraction was performed on the pure SF film prepared in Example 1, the piezoelectric sensing film prepared in Example 3, and the pure BTO powder, respectively. The results are as follows: Figure 3 As shown in the figure. By comparison, it can be seen that the intensity of the β-sheet characteristic peak of silk fibroin at 19.2°~20.5° in Example 3 is significantly enhanced compared with that in Example 1, which confirms the inducing effect of BTO nanoparticles on the conformational transformation of SF.

[0065] Transmission electron microscopy (TEM) and EDS elemental distribution analysis of the SF / BTO composite nanofibers prepared in Example 3 were performed as follows: Figure 4 As shown. Figure 4 The data clearly shows that BTO particles are tightly coated with silk fibroin, forming a "core-shell" structure, and the elements are evenly distributed, proving that BTO achieves good dispersion and interfacial bonding inside the fiber.

[0066] The piezoelectric sensing film prepared in Example 3 was subjected to linear voltage output testing within a load range of 5N~60N. Figure 5 As shown, the test results indicate that the output voltage of the sensing membrane exhibits a good linear relationship with increasing pressure, with a correlation coefficient R²>0.99, making it suitable for quantitative pressure monitoring.

[0067] The piezoelectric sensing film prepared in Example 3 was subjected to piezoelectric response testing in the low-frequency range of 0.25Hz to 1Hz. Figure 6 As shown, even in the sub-hertz frequency band, the membrane can still output complete and clear voltage pulse signals, demonstrating its excellent ability to capture weak physiological vibrations.

[0068] The piezoelectric sensing film prepared in Example 3 was subjected to a stability test under 10,000 cycles of loading (30 N, 1 Hz). Figure 7 As shown, after 10,000 cycles, the output voltage retention rate exceeds 95% with no significant attenuation, indicating that the sensing film has excellent long-term working stability.

[0069] Example 4: Preparation of a piezoelectric sensing film with a 15 wt.% BTO loading

[0070] This embodiment provides a method for preparing a silk fibroin-based piezoelectric sensing film based on BTO-induced conformational change, including the following steps:

[0071] Preparation of blended stock solution: Adjust the mass ratio of BTO nanoparticles to SF to 15:85.

[0072] Process flow: Repeat the dispersion, spinning and post-processing process of Example 2.

[0073] Performance observation: Although the content of active particles continued to increase, a slight charge shielding effect began to appear in some areas due to the limited space inside the fibers. Testing showed that under a 50N load, the membrane's output voltage dropped to 12.7V, and the output current was 125nA.

[0074] Example 5: Preparation of a piezoelectric sensing film with a 20 wt.% BTO loading

[0075] This embodiment provides a method for preparing a silk fibroin-based piezoelectric sensing film based on BTO-induced conformational change, including the following steps:

[0076] Preparation of blended stock solution: The mass ratio of BTO nanoparticles to SF was further increased to 20:80.

[0077] Process flow: Repeat the dispersion, spinning and post-processing process of Example 2.

[0078] Performance observation: Under high loads, BTO particles exhibited slight agglomeration, disrupting the continuity of the nanofibers. Testing showed that under a 50N load, the membrane's output voltage dropped to 11.4V, and the output current was 124nA.

[0079] To quantitatively evaluate the effect of BTO content on the piezoelectric output performance of silk fibroin-based sensing membranes, the present invention conducted systematic electrical performance tests on the nanofiber membranes prepared in Examples 1-5 above (test conditions: external cyclic load 30N, frequency 1Hz, ambient humidity 45%).

[0080] By comparing the experimental data of each group (see Table 1 for details), it can be seen that as the BTO loading gradually increases, the output voltage and current of the sensing membrane both show a trend of first increasing and then decreasing. Among them, Example 3 (BTO content of 10 wt.%) exhibits the best overall electrical response, with its output voltage reaching a peak of 14.6V, which is about 180% higher than that of the pure SF membrane (Example 1).

[0081] Table 1. Comparison of electrical output performance of piezoresistive films with different BTO contents.

[0082] <![CDATA[BaTiO3]]> Voltage (V) Current(nA) 0% 5.2 68 5% 8.3 87 10% 14.6 144 15% 12.7 125 20% 11.4 124

[0083] This nonlinear enhancement reveals the core mechanism of the invention: at 10 wt.%, BTO nanoparticles form an optimal inducing interface with silk fibroin molecular chains, maximally driving the conformational transformation of the random coil to a β structure, thus macroscopically manifesting as a significant enhancement of polarization intensity; however, when the loading exceeds 15 wt.% (as in Example 5), excessive inorganic particles lead to physical barriers and microscopic aggregation within the fiber, which in turn inhibits the effective transmission of piezoelectric signals. Therefore, Example 3 represents the optimal formulation for achieving high-sensitivity sensing according to the present invention.

[0084] Example 6: Effects of electrospinning process parameters on nanofiber morphology and piezoelectric properties

[0085] To further investigate the influence of the preparation process on the microstructure of the sensing film, this embodiment, based on the formulation of Example 3 (10 wt.% BTO), conducted a comparative experiment by changing the voltage and feed speed of electrospinning.

[0086] 1. Optimized process conditions (as described in Example 3): The spinning voltage is set to 22kV, the feed speed is 0.2mL / h, and the receiving distance is 15cm.

[0087] Morphological observation: Reference Figure 2 In Figure a (preferred), the resulting nanofibers have a smooth surface, uniform diameter distribution, no beading, and are interwoven into a uniform network structure, providing a good matrix for uniform loading of BTO.

[0088] Performance: The output voltage is stable at 14.6V.

[0089] 2. Process Comparison Group A (Low Voltage Conditions): The voltage is reduced to 20kV, while other conditions remain unchanged.

[0090] Morphological observation: Reference Figure 2 In diagram b (poor morphology), the jet is extremely unstable due to insufficient electric field force to overcome the surface tension of the droplets, resulting in a large number of spindle-shaped beads appearing on the fiber surface.

[0091] Defect analysis: The beaded structure leads to stress concentration and disrupts the continuity of the fiber, making it difficult for the SF molecular chains to achieve efficient directional alignment during stretching and limiting the conformational transition to β-sheet.

[0092] 3. Process Comparison Group B (High Flow Rate Conditions): The feed rate was increased to 0.8 mL / h, and the voltage was maintained at 22 kV.

[0093] Morphological observation: Obvious fiber agglomeration and adhesion were observed. Due to incomplete solvent evaporation, the fibers physically fused on the collecting device.

[0094] Defect analysis: This dense, non-fibrous structure leads to a significant reduction in the porosity of the membrane, resulting in a substantial decrease in sensitivity compared to Example 3.

[0095] Example 7: Self-Powered Electronic Skin

[0096] like Figure 1 As shown, a self-powered electronic skin includes an integral flexible piezoelectric sensing device 10, comprising an upper electrode layer 11, an intermediate composite functional sensing layer 12, and a lower electrode layer 13 arranged sequentially from top to bottom. The intermediate composite functional sensing layer 12 includes a silk fibroin (SF) nanofiber matrix 121, in which barium titanate (BaTiO3) nanoparticles 122 are uniformly coated. In the matrix, the molecular chains of the regenerated silk fibroin undergo conformational transformation at the interface of the barium titanate nanoparticles under the induction of an electric field, forming a cross-linked network rich in β-folded crystal regions. The β-folded crystal regions and the barium titanate nanoparticles together constitute a piezoelectric response unit.

Claims

1. A silk fibroin-based piezoelectric sensing film, characterized in that, The invention includes a nanofiber continuous phase matrix, wherein the nanofibers use regenerated silk fibroin as the continuous phase matrix, and the regenerated silk fibroin is uniformly coated with tetragonal barium titanate nanoparticles; wherein, in the continuous phase matrix, the molecular chains of the regenerated silk fibroin undergo conformational transformation at the interface of the barium titanate nanoparticles under the induction of an electric field, forming a cross-linked network rich in β-sheet crystal regions, and the β-sheet crystal regions and the barium titanate nanoparticles together constitute a piezoelectric response unit.

2. The silk fibroin-based piezoelectric sensing film according to claim 1, characterized in that, In the continuous phase matrix of nanofibers, the mass of tetragonal barium titanate nanoparticles accounts for 5 wt% to 20 wt% of the total mass of the matrix; the average diameter of the nanofibers is 400 nm to 800 nm.

3. The silk fibroin-based piezoelectric sensing film according to claim 1, characterized in that, The barium titanate nanoparticles have a core-shell encapsulation structure inside a single nanofiber; the encapsulation structure forms an interfacial bonding layer by inducing the silk fibroin to coat the surface of the barium titanate particles through the electric field induction force in the electrospinning process.

4. A method for preparing a piezoelectric sensing film as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Dissolve regenerated silk fibroin in formic acid solvent, add barium titanate nanoparticles, and prepare a blended spinning solution; (2) Using a high-voltage electrospinning device, a fiber membrane is obtained by spinning a blended spinning solution, wherein the electric field induces the silk fibroin molecular chains in the blended spinning solution to be oriented and coated on the surface of barium titanate particles. (3) The fiber membrane prepared in step (2) is subjected to ethanol vapor post-treatment to further lock the β-fold crystal region structure.

5. The method for preparing the piezoelectric sensing film according to claim 4, characterized in that, In step (1), ultrasonic dispersion of the blended spinning solution allows the barium titanate particles to come into full contact with the silk fibroin molecular chains.

6. The method for preparing the piezoelectric sensing film according to claim 4, characterized in that, In step (1), the mass ratio of barium titanate nanoparticles to regenerated silk fibroin in the blended spinning solution is 5-20:80-95.

7. The method for preparing the piezoelectric sensing film according to claim 4, characterized in that, In step (2), the voltage of high-voltage electrospinning is 18kV-25kV.

8. The method for preparing the piezoelectric sensing film according to claim 4, characterized in that, In step (2), the spinning propulsion speed is set to 0.1 mL / h-0.5 mL / h, the receiving distance is 12 cm-18 cm, and the ambient humidity is controlled below 40%.

9. The application of the piezoelectric sensing membrane according to any one of claims 1 to 3 in a flexible self-powered physiological monitoring device.

10. The application according to claim 9, characterized in that, The pressure load range of the piezoelectric sensing film is 5N-60N, and the sensing frequency is 0.25Hz-1Hz.

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