Preparation method of composite piezoelectric film, sensor and application of sensor in heart sound monitoring

Abstract

The invention provides a preparation method of a composite piezoelectric film, which comprises the following steps: adding a 0.5 Ba (Zr < 0.2 > Ti < 0.8 >) O < 3 >-0.5 (Ba0. 7Ca0. 3) TiO < 3 > nanowire into a buffer solution containing dopamine hydrochloride to obtain a 0.5 Ba (Zr < 0.2 > Ti < 0.8 >) O < 3 >-0.5 (Ba0. 7Ca0. 3) TiO < 3 > nanowire of which the surface is modified by dopamine; polyvinylidene fluoride and 0.5 Ba (Zr < 0.2 > Ti < 0.8 >) O < 3 >-0.5 (Ba < 0.7 > Ca < 0.3 >) TiO < 3 > nanowires with the surfaces modified with dopamine are dissolved in a spinning solvent respectively and mixed, and an electrostatic spinning solution is obtained; and carrying out electrostatic spinning by utilizing electrostatic spinning to obtain the composite piezoelectric film. The invention further provides a sensor prepared from the composite piezoelectric film, a preparation method of the sensor and application of the composite piezoelectric film sensor in heart sound monitoring.

Description

Technical Field

[0001] The invention belongs to the field of piezoelectric materials and biosensors, and in particular relates to a preparation method of a composite piezoelectric film, a sensor and application of the same in heart sound monitoring. Background Art

[0002] Currently, the diagnosis of cardiovascular disease is based on electrocardiogram (ECG), but it is not suitable for the diagnosis of certain organic heart diseases. From the perspective of cardiovascular disease prevention, in the early stages of certain cardiovascular diseases before obvious symptoms occur, changes in heart sound signals often herald the onset of certain diseases. Therefore, heart sound signals are an effective supplement to ECG signals.

[0003] Auscultation of heart sounds generally uses a mechanical stethoscope to listen to heart sounds directly through the ears of the relevant personnel, but this method relies on the subjective judgment of the relevant personnel and cannot be digitally recorded and subsequently analyzed.

[0004] Therefore, there is a need for a flexible and highly sensitive heart sound monitoring sensor that can be used in monitoring heart sounds, motion detection, and wearable motion monitoring equipment. Summary of the invention

[0005] In view of this, in order to at least partially solve at least one of the above-mentioned technical problems, the present invention provides a method for preparing a composite piezoelectric film, comprising:

[0006] 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 nanowires were added to a buffer solution containing dopamine hydrochloride to obtain 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 nanowires;

[0007] Polyvinylidene fluoride and 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 nanowires are dissolved in spinning solvents respectively, and mixed to obtain electrospinning solution;

[0008] Electrospinning is performed by electrostatic spinning to obtain a composite piezoelectric film.

[0009] According to an embodiment of the present invention, in the electrospinning solution, 0.5Ba(Zr 0.2 Ti 0.8)O3–0.5(Ba 0.7 Ca 0.3 )The mass ratio of TiO3 nanowires and polyvinylidene fluoride is (0.1~5):(10~50).

[0010] According to an embodiment of the present invention, the voltage of electrospinning is 10-18 kV.

[0011] According to another embodiment of the present invention, there is provided a composite piezoelectric film prepared according to the above preparation method.

[0012] According to an embodiment of the present invention, the thickness of the composite piezoelectric film is 50 μm-150 μm.

[0013] According to another embodiment of the present invention, there is provided a composite piezoelectric film sensor, comprising:

[0014] Composite piezoelectric film;

[0015] Polydimethylsiloxane, used as a substrate to support the composite piezoelectric film;

[0016] The first electrode and the second electrode are respectively arranged on two sides of a film-base layer formed by a composite piezoelectric film and polydimethylsiloxane.

[0017] According to another embodiment of the present invention, there is provided a method for preparing a composite piezoelectric film sensor, comprising:

[0018] pasting the composite piezoelectric film onto a polydimethylsiloxane substrate to obtain a film-substrate layer;

[0019] The first electrode and the second electrode are respectively pasted to the two sides of the film-substrate layer to obtain a composite piezoelectric film sensor.

[0020] According to another embodiment of the present invention, there is provided a method for preparing a composite piezoelectric film sensor, comprising:

[0021] Vapor-depositing a first metal on one side of the polydimethylsiloxane to form a first electrode;

[0022] The electrospinning solution is sprayed onto the other side of the polydimethylsiloxane to obtain a polydimethylsiloxane-composite piezoelectric film, wherein the electrospinning solution includes polyvinylidene fluoride, 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 nanowires and spinning solvent;

[0023] A second metal is evaporated on the polydimethylsiloxane-composite piezoelectric film to form a second electrode, thereby obtaining a composite piezoelectric film sensor.

[0024] According to another embodiment of the present invention, there is provided an application of a composite piezoelectric film sensor in heart sound monitoring.

[0025] According to an embodiment of the present invention, a composite piezoelectric film sensor is applied to the fifth intercostal space of the left chest; a charge signal amplifier, a filter and an oscilloscope are connected to the composite piezoelectric film sensor through a wire;

[0026] The heart sound monitoring data after being processed by the charge signal amplifier and filter is obtained through an oscilloscope.

[0027] According to an embodiment of the present invention, the lead-free nanomaterial 0.5Ba (Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 (BZT-BCT) and piezoelectric polymer polyvinylidene fluoride (PVDF) are composited by electrospinning to obtain a flexible porous composite piezoelectric film, and the BZT-BCT modified with dopamine (PDA) and PVDF have a stronger bonding ability; the composite piezoelectric film prepared by the mixed electrospinning solution has a uniform and stable structure. The electrospinning technology can effectively orient the PVDF molecular segments, increase the electric dipole moment in PVDF, increase the β-phase content in the nanofibers, and is beneficial to improve the piezoelectric properties of PVDF, so that the prepared composite piezoelectric film The membrane not only has good and stable piezoelectric properties but also has the dual effects of frictional energy. It has good stability and can remain unchanged for one year under tight sealing. It is lead-free, non-toxic and has good biocompatibility. It can be further used in flexible sensors for heart sound monitoring. It can convert the mechanical energy of slight changes in heart sounds into electrical signals, thereby monitoring heart sounds. In heart sound monitoring, it can reach a signal peak-to-peak value of 10mv~20mv, and the peak intensity is improved compared with related technologies. Moreover, the prepared composite piezoelectric film is soft and can be adhered to the body wall for wearable use. It can be used in wearable devices for monitoring heart sound signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0029] Figure 1 This is a flow chart of a method for preparing a composite piezoelectric film according to an embodiment of the present invention;

[0030] Figure 2This is a schematic diagram of the structure of a composite piezoelectric film sensor according to an embodiment of the present invention;

[0031] Figure 3 This is a transmission electron microscope image of BZT-BCT nanowires according to an embodiment of the present invention;

[0032] Figure 4 This is an X-ray diffraction diagram of BZT-BCT nanowires according to an embodiment of the present invention;

[0033] Figure 5 This is a comparison of infrared spectra of dopamine before and after BZT-BCT nanowires are modified in the embodiment of the present invention.

[0034] Figure 6 This is a scanning electron microscope image of a composite piezoelectric film according to an embodiment of the present invention;

[0035] Figure 7 This is an appearance diagram of a composite piezoelectric film sensor according to an embodiment of the present invention;

[0036] Figure 8 This is a graph showing the voltage output variation of the composite piezoelectric film sensor with different doping amounts according to an embodiment of the present invention;

[0037] Fig. 9 This is a circuit diagram of the composite piezoelectric film sensor for monitoring cardiac sounds, amplifying and filtering, and a physical diagram of the circuit board in accordance with an embodiment of the present invention;

[0038] Fig.10 This is the original waveform diagram of the pulse signal monitoring of the composite piezoelectric film sensor according to the embodiment of the present invention;

[0039] Fig.11 This is a waveform diagram of the pulse signal monitoring of the composite piezoelectric film sensor according to an embodiment of the present invention after being processed by an amplifying and filtering circuit;

[0040] Fig.12 This is the original waveform diagram of the heart sound monitoring of the composite piezoelectric film sensor according to the embodiment of the present invention;

[0041] Fig.13 This is a waveform diagram of the composite piezoelectric film sensor heart sound monitoring after being processed by the amplification and filtering circuit in an embodiment of the present invention;

[0042] Fig.14 This is a waveform diagram of heart sounds detected by a commercial sensor in the comparative example of the present invention, wherein A is the original waveform diagram after signal processing and B is the waveform diagram after signal processing after filtering. DETAILED DESCRIPTION

[0043] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0044] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The term "comprising" used herein indicates the existence of features, steps, operations, but does not exclude the existence or addition of one or more other features.

[0045] In the case of using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.). In the case of using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, or C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0046] The relevant terms in the present invention are explained as follows:

[0047] BZT-BCT: 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3.

[0048] PVDF: polyvinylidene fluoride.

[0049] PVDF / BZT-BCT@PDA: PVDF and BZT-BCT composite piezoelectric thin film material with dopamine modified on the surface of BZT-BCT.

[0050] In the process of realizing the concept of the present invention, it was found that the sensor probe of the electronic stethoscope is generally an electret microphone, a piezoresistance and a piezoelectric material. The electret microphone receives the heart sound signal through the air or a certain medium, and converts the sound signal into an electrical signal to realize the function of auscultating the heart sound. Piezoresistive material is a material that will cause its own resistance to change when subjected to pressure. The essence of heart sound is tissue vibration and sound. When this vibration acts on the piezoresistive material, its resistance will change. By designing a corresponding circuit to record this change, the waveform of the heart sound can be obtained. Piezoelectric material is a material that will generate an electric charge on the surface of the material when subjected to pressure, and form an electric potential difference on both sides of the material. It can convert mechanical energy into electrical signals and generate current under the action of external force. Therefore, the mechanical energy of heart sound can be converted into electrical signals by piezoelectric material for heart sound detection.

[0051] Furthermore, PVDF has excellent processing properties and can be processed into flexible films for use in wearable sensing devices. However, its piezoelectric constant (d 33 ) is lower than that of inorganic piezoelectric materials, which limits the further application of PVDF in the field of weak signal sensing. BZT-BCT nanomaterials have excellent piezoelectric properties. If block BZT-BCT piezoelectric materials are used, their hardness is large and the processing and thinning process is complicated, which is not suitable for the preparation of sensors for flexible electronic devices. In related technologies, adding nanofillers as nucleating agents to PVDF-based polymers can improve the piezoelectric properties of composite piezoelectric materials. Therefore, the composite of PVDF and BZT-BCT piezoelectric nanomaterials can achieve synergistic enhancement, which is conducive to the development of high-performance PVDF-based composite piezoelectric nano-power generation devices.

[0052] Figure 1 The figure is a flow chart of a method for preparing a composite piezoelectric film according to an embodiment of the present invention.

[0053] Specifically, according to an embodiment of one aspect of the present invention, a method for preparing a composite piezoelectric film is provided, such as Figure 1 As shown, it includes steps S1 to S3.

[0054] Step S1: 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 nanowires were added to a buffer solution containing dopamine hydrochloride to obtain 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 nanowires;

[0055] Step S2: Polyvinylidene fluoride and 0.5Ba(Zr 0.2 Ti0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 nanowires are dissolved in spinning solvents respectively, and mixed to obtain electrospinning solution;

[0056] Step S3: Perform electrospinning by electrospinning to obtain a composite piezoelectric film.

[0057] According to an embodiment of the present invention, the lead-free nanomaterial 0.5Ba (Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 (BZT-BCT) and piezoelectric polymer polyvinylidene fluoride (PVDF) are composited by electrospinning to obtain a flexible porous composite piezoelectric film, and the BZT-BCT modified with dopamine (PDA) and PVDF have a stronger bonding ability; the composite piezoelectric film prepared by the mixed electrospinning solution has a uniform and stable structure. The electrospinning technology can effectively orient the PVDF molecular segments, increase the electric dipole moment in PVDF, increase the β-phase content in the nanofibers, and is beneficial to improve the piezoelectric properties of PVDF, so that the prepared composite piezoelectric film The membrane not only has good and stable piezoelectric properties but also has the dual effects of frictional energy. It has good stability and can remain unchanged for one year under tight sealing. It is lead-free, non-toxic and has good biocompatibility. It can be further used in flexible sensors for heart sound monitoring. It can convert the mechanical energy of slight changes in heart sounds into electrical signals, thereby monitoring heart sounds. In heart sound monitoring, it can reach a signal peak-to-peak value of 10mv~20mv, and the peak intensity is improved compared with related technologies. Moreover, the prepared composite piezoelectric film is soft and can be adhered to the body wall for wearable use. It can be used in wearable devices for monitoring heart sound signals.

[0058] According to an embodiment of the present invention, in the electrospinning solution, 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )The mass ratio of TiO3 nanowires and polyvinylidene fluoride is (0.1~5):(10~50).

[0059] According to an embodiment of the present invention, 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3) The mass ratio of TiO3 nanowires to polyvinylidene fluoride can be 0.1:10, 1:10, 3:10, 5:10, 0.1:20, 0.1:20, 1:20, 3:20, 5:20, 0.1:30, 1:30, 3:30, 5:30, 0.1:40, 1:40, 3:40, 5:40, 0.1:50, 1:50, 3:50, 5:50, but is not limited to the values ​​listed, and other values ​​not listed in the numerical range are also applicable. By adjusting the ratio of nanowires to PVDF, the mechanical properties of the composite film, including flexibility and strength, can be improved. Appropriate nanowire content can enhance the structural stability of the film while maintaining the flexibility of PVDF. As the content of BZT-BCT nanomaterials increases, the piezoelectric sensitivity of the composite film will also increase, but too much BZT-BCT nanomaterials will lead to poor flexibility. Therefore, by adjusting the ratio, the response of the film in the electric field can be optimized, thereby affecting its piezoelectric and dielectric properties while ensuring the mechanical properties of the composite piezoelectric film.

[0060] According to an embodiment of the present invention, the voltage of electrospinning is 10-18 kV.

[0061] According to an embodiment of the present invention, the voltage of electrostatic spinning can be 10kV, 11kV, 12kV, 13kV, 14kV, 15kV, 16kV, 17kV, 18kV, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable. In the electrostatic spinning process, only when the electric field force overcomes the surface tension of the electrostatic spinning droplets, the electrostatic spinning solution can be ejected from the Taylor cone to form a jet and further form a fiber. The voltage range of 10~18kV is to ensure that the electric field force is large enough to enable the electrostatic spinning solution to be ejected from the spinneret and form a fiber.

[0062] According to an embodiment of the present invention, the volume flow rate of the electrospinning solution is 0.1-0.3 mL h −1 , which can be 0.1 mL h −1 , 0.2 mL h −1 , 0.3 mL h −1 , but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0063] According to an embodiment of one aspect of the present invention, a composite piezoelectric film PVDF / BZT-BCT@PDA prepared by steps S1 to S3 is also provided. PVDF and BZT-BCT piezoelectric nanomaterials are compounded into a nanofiber composite film by electrospinning technology, which not only has piezoelectric properties but also has a dual effect of triboelectric energy, which can effectively improve the sensitivity of the PVDF / BZT-BCT@PDA nanofiber film. The above-mentioned composite piezoelectric film can be used for high-sensitivity detection of weak signals such as pulse and heart sounds, etc., and has potential application prospects in the fields of biological sign monitoring and heart sound sensing.

[0064] According to an embodiment of the present invention, the thickness of the composite piezoelectric film is 50 μm-150 μm.

[0065] According to an embodiment of the present invention, the thickness of the composite piezoelectric film may be 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable. The thickness of the composite piezoelectric film directly affects the piezoelectric performance. The thickness of the composite piezoelectric film will affect its mechanical properties such as stiffness and flexibility, and thus affect the piezoelectric response. Thicker composite piezoelectric films may have better mechanical stability and durability, while thinner composite piezoelectric films may perform better in flexibility, but may be insufficient in mechanical strength. Therefore, it is necessary to select a composite piezoelectric film thickness that can ensure both mechanical properties and good piezoelectric properties.

[0066] Figure 2 This is a schematic diagram of the structure of a composite piezoelectric film sensor according to an embodiment of the present invention.

[0067] Another aspect of the present invention discloses a composite piezoelectric film sensor. Figure 2 As shown, including:

[0068] Composite piezoelectric film;

[0069] Polydimethylsiloxane, used as a substrate to support the composite piezoelectric film;

[0070] The first electrode and the second electrode are respectively arranged on two sides of a film-base layer formed by a composite piezoelectric film and polydimethylsiloxane.

[0071] In some specific embodiments of the present invention, Figure 2 As shown, polydimethylsiloxane (PDMS) is divided into an encapsulation layer for encapsulating the composite piezoelectric film, the first electrode and the second electrode, and a base layer for supporting the composite piezoelectric film.

[0072] According to an embodiment of the present invention, polydimethylsiloxane (PDMS) is a common material with good biocompatibility, certain elasticity and good insulation. The composite piezoelectric film is connected to other oscilloscopes, signal processing and other equipment through electrodes and wires, and supported and packaged by PDMS. It not only has good biocompatibility but also has insulation that will not cause harm to the subject. The composite piezoelectric film sensor can be used to monitor relevant signs of the organism, such as heart sound signals.

[0073] Another aspect of the present invention discloses a method for preparing a composite piezoelectric film sensor, including steps S11 and S12.

[0074] Step S11: pasting the composite piezoelectric film onto a polydimethylsiloxane substrate to obtain a film-substrate layer;

[0075] Step S12: Paste the first electrode and the second electrode to the two sides of the film-substrate layer respectively to obtain a composite piezoelectric film sensor.

[0076] According to an embodiment of the present invention, by pasting the composite piezoelectric film onto a polydimethylsiloxane substrate and then applying the first electrode and the second electrode, simple packaging and wire connection can be performed through waterproof insulating materials, thereby simply and conveniently completing the preparation of the composite piezoelectric film sensor.

[0077] Another embodiment of the present invention discloses another method for preparing a composite piezoelectric film sensor, including steps S21 to S23.

[0078] Step S21: evaporating a first metal on one side of the polydimethylsiloxane to form a first electrode;

[0079] Step S22: Spraying the electrospinning solution onto the other side of the polydimethylsiloxane to obtain a polydimethylsiloxane-composite piezoelectric film, wherein the electrospinning solution includes polyvinylidene fluoride, 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 nanowires and spinning solvent;

[0080] Step S23: evaporating a second metal on the polydimethylsiloxane-composite piezoelectric film to form a second electrode to obtain a composite piezoelectric film sensor.

[0081] According to an embodiment of the present invention, a composite piezoelectric thin film sensor can be formed by first vapor-depositing a layer of metal on PDMS as an electrode, then directly spraying the aforementioned material on PDMS using an electrospinning method, and finally vapor-depositing a layer of electrode on the surface of the material. The composite piezoelectric thin film material and PDMS can be more closely fitted, so that the prepared composite piezoelectric thin film sensor has higher sensitivity and stability.

[0082] Another aspect of the present invention provides an application of a composite piezoelectric film sensor in heart sound monitoring.

[0083] According to the embodiments of the present invention, the composite piezoelectric film sensor has a simple structure and high sensitivity, and can accurately measure weak heart sound signals. At the same time, because the composite piezoelectric film sensor is soft and can fit closely to the body wall, and its acoustic impedance is close to that of human tissue, it is suitable for monitoring heart sound signals. Furthermore, heart sound monitoring is a non-diagnostic and therapeutic monitoring, and is not directly used to obtain the health status of the monitored person. The composite piezoelectric film sensor can realize heart sound monitoring by converting the mechanical signals in the heart sounds into electrical signals, which can be intuitively displayed through related equipment such as an oscilloscope.

[0084] According to an embodiment of the present invention, in heart sound monitoring, a specific method may include:

[0085] Apply the composite piezoelectric film sensor to the fifth intercostal space of the left chest;

[0086] Connecting the charge signal amplifier, the filter and the oscilloscope to the composite piezoelectric film sensor through wires;

[0087] The heart sound monitoring data after being processed by the charge signal amplifier and filter is obtained through an oscilloscope.

[0088] According to an embodiment of the present invention, since the charge of the heart sound signal received by the composite piezoelectric film sensor is weak, the charge signal amplifier can be used to amplify the received charge signal. In the received signal, there is an interference signal, and it is necessary to obtain the required signal through a low-pass circuit constructed by basic circuit components such as capacitors, inductors, and resistors for filtering. Since the signal amplified by the charge amplifier circuit is very small, it will be further amplified by the charge signal amplifier at the terminal of the signal to obtain a processed, complete, and interference-free heart sound signal, and then the specific waveform will be displayed through an oscilloscope to obtain the heart sound monitoring signal information. By connecting the composite piezoelectric film sensor to an oscilloscope, a complete detection device can be formed, and the stability and sensitivity can reach a high level.

[0089] The methods in the following examples are all conventional methods unless otherwise specified, and the reagents and raw materials used can be obtained from public commercial channels unless otherwise specified.

[0090] Example 1 Preparation of BZT-BCT Nanowires

[0091] 1.845 g of titanium isopropoxide (Aldrich, 97%) and 0.3275 g of zirconium propoxide (Aldrich, 70% in 1-propanol) were added to 70 ml of isopropanol and stirred vigorously for 1 h.

[0092] Mix 2 ml of deionized water (boil deionized water for 15 min) and 15 ml of isopropanol evenly, stir for 2-3 min, slowly add the mixed liquid to a mixture of titanium isopropoxide (Aldrich, 97%), zirconium propoxide (Aldrich, 70% in 1-propanol) and isopropanol, stir for 10 min, and precipitate Zr 0.1 Ti 0.9 O2·8H2O gel.

[0093] Zr 0.1 Ti 0.9 The O2·8H2O precipitate was centrifuged at 6000 rpm in a centrifuge, repeated 5 times, 10 min each time, washed with pure water, and then separated from the solution to obtain Zr 0.1 Ti 0.9 O2·8H2O gel. 0.1 Ti 0.9 The O2·8H2O gel was dispersed in a reactor containing 20 ml of 10 M NaOH solution, and the reactor was heated to 230 °C for 24 h.

[0094] The resulting reaction product was immersed in 0.2 M hydrochloric acid (Fisher, 37%) for 4 h to obtain H2Zr 0.1 Ti 0.9 O3 nanowires. H2Zr 0.1 Ti 0.9 The O3 nanowires were centrifuged at 6000 rpm in a centrifuge, and the centrifugation was repeated 5 times, each time for 10 min, washed with pure water, and then separated from the solution, and finally dried at 60°C for 12 h to obtain the nanowires.

[0095] The nanowires were dissolved in a mixed solution of 0.051M Ba(OH)2 and 0.09M Ca(OH)2 with a molar ratio of Ba:H2Zr 0.1 Ti 0.9 O3=2:1, ensuring complete conversion.

[0096] After the solution was ultrasonically treated for 5 min, the solution was transferred to a reactor with a filling factor of 0.7, purged with nitrogen, and then placed in an oven at 210° C. and heated for 1.5 h.

[0097] The solution was added to a 0.2M hydrochloric acid solution and reacted with the hydrochloric acid solution for 4 hours. The obtained nanowires were centrifuged at 6000 rpm for 5 times, each time for 4 minutes, washed with pure water, and then dried at 60°C for 12 hours. The nanowires were heated at 600°C for 2 hours to remove impurities generated by the hydrothermal reaction, and BZT-BCT nanowires were obtained and characterized. The structure of the nanowires was characterized as follows Figure 3 and Figure 4 shown.

[0098] BZT-BCT modified dopamine: 0.00968 g of tris (hydroxymethyl) aminomethane (Tris) was dissolved in 80 mL of water, hydrochloric acid was added dropwise to a pH of 8.5, and 0.4 g of BZT-BCT was mixed with it. High-power ultrasound was used to mix for 1 h, and then 0.04 g of dopamine hydrochloride was added and stirred for 6 h to obtain BZT-BCT@PDA.

[0099] Figure 3 This is a transmission electron microscope image of BZT-BCT nanowires according to an embodiment of the present invention; Figure 4 This is an X-ray diffraction diagram of BZT-BCT nanowires according to an embodiment of the present invention; Figure 5 This is a comparison of infrared spectra of dopamine before and after modification with BZT-BCT nanowires in an embodiment of the present invention.

[0100] according to Figure 3 and Figure 4 It can be seen that BZT-BCT nanowires were successfully prepared. The prepared nanowires are all short wires with a length of micrometer level and a width of nanometer level. Figure 5 The comparison shows that dopamine was successfully modified on BZT-BCT nanowires.

[0101] Example 2 Preparation of composite piezoelectric film

[0102] 0.15 g of BZT-BCT@PDA prepared in Example 1 was uniformly dispersed in 5 mL of DMF / acetone, and 0.85 g of PVDF was dissolved in 5 mL of DMF / acetone. The two were ultrasonically treated, mixed together and stirred with a magnetic stirrer for 1 to 3 h, and then electrospun in an electrostatic field of 15 kV to obtain a composite piezoelectric film. Figure 5 shown.

[0103] Figure 6 This is a scanning electron microscope image of the composite piezoelectric film according to an embodiment of the present invention.

[0104] according to Figure 6 It can be seen that the prepared composite piezoelectric film fibers are uniform in thickness and uniform in void distribution, which provides a basis for stable piezoelectric conversion.

[0105] Example 3 Preparation of composite piezoelectric film sensor

[0106] Step S21: evaporating a first metal on one side of the polydimethylsiloxane to form a first electrode;

[0107] Step S22: Spraying the electrospinning solution onto the other side of the polydimethylsiloxane to obtain a polydimethylsiloxane-composite piezoelectric film, wherein the electrospinning solution includes polyvinylidene fluoride, 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 nanowires and spinning solvent;

[0108] Step S23: evaporating a second metal on the polydimethylsiloxane-composite piezoelectric film to form a second electrode, thereby obtaining a composite piezoelectric film sensor, such as Figure 7 shown.

[0109] The prepared composite piezoelectric film sensor was dried at 40°C to further volatilize DMF. After the volatilization was completed, an adhesive tape was used to stick to the film surface to protect the sprayed film.

[0110] Figure 7 This is an appearance diagram of a composite piezoelectric film sensor according to an embodiment of the present invention.

[0111] Example 3 Performance test of composite piezoelectric film sensors with different doping amounts

[0112] Composite piezoelectric film sensors with different BZT-BCT nanowire doping amounts were prepared using the methods of Example 1, Example 2 and Example 3, and were placed under the same mechanical force to measure the output voltage. Figure 8 shown.

[0113] Figure 8 This is a graph showing the voltage output variation of composite piezoelectric film sensors with different doping amounts according to an embodiment of the present invention.

[0114] according to Figure 8 It can be seen that with the increase of the doping amount of BZT-BCT nanowires, the output voltage gradually increases, but after 15%, the output voltage decreases instead. This proves that the more doping amount is not necessarily better. 15% BZT-BCT nanowire doping amount is appropriate. Too little piezoelectric performance cannot be achieved, and too much will also lead to increased dielectric loss and deteriorate piezoelectric performance.

[0115] Example 4 Composite piezoelectric film sensor heart sound monitoring

[0116] The composite piezoelectric film sensor prepared in Example 3 is attached to the wrist and the mitral valve area, i.e., the fifth intercostal space of the left chest, and the wire is connected to the oscilloscope to record the current heart sound waveform. However, due to the interference of sounds emitted by other tissues and organs in the human body, environmental noise, and electromagnetic noise, filtering is required to obtain the desired waveform. The heart sound band is 20Hz-200Hz, which can be filtered by the digital filtering function of the wave processing software.

[0117] Fig. 9 This is a circuit diagram and a physical diagram of a circuit board for monitoring and amplifying filtering of cardiac sounds of a composite piezoelectric film sensor according to an embodiment of the present invention.

[0118] according to Fig. 9 It can be seen that the amplification and filtering circuit printed by the FPC flexible circuit (Flexible Printed Circuit) can amplify and filter the monitored heart sound signals, thereby improving the sensitivity of heart sound monitoring.

[0119] Fig.10 This is the original waveform diagram of the pulse signal monitoring of the composite piezoelectric film sensor according to the embodiment of the present invention; Fig.11 This is a waveform diagram of the pulse signal monitoring of the composite piezoelectric film sensor according to an embodiment of the present invention after being processed by an amplifying and filtering circuit; Fig.12 This is the original waveform diagram of the heart sound monitoring of the composite piezoelectric film sensor according to the embodiment of the present invention; Fig.13 This is a waveform diagram of the composite piezoelectric film sensor heart sound monitoring after being processed by the amplification and filtering circuit in an embodiment of the present invention.

[0120] according to Figure 10~Figure 13 It can be seen that the composite piezoelectric film sensor can monitor pulse signals and heart sound signals with large amplitudes. At the same time, the amplification and filtering circuit can amplify and filter weak pulse signals and heart sound signals, thereby improving the sensitivity of the composite piezoelectric film sensor in pulse signal monitoring and heart sound monitoring.

[0121] Comparative Example 1 Commercial sensor detects heart sound signals

[0122] The same monitoring method as in Example 4 is used, except that the sensor used is a commercially available HKY-06B heart sound sensor in the related art. The measurement results are shown in FIG. Fig.14 shown.

[0123] Fig.14 This is a waveform diagram of heart sounds detected by a commercial sensor in the comparative example of the present invention, wherein A is the original waveform diagram after signal processing and B is the waveform diagram after signal processing after filtering.

[0124] according to Fig.14It can be seen that the peak value of the heart sound signal measured by the commercial sensor is lower, so the monitoring accuracy is also lower. Fig.12 and Fig.13 It can be seen that the composite piezoelectric film sensor of the present invention can detect signal peaks with a peak value of 10mv~20mv and has higher sensitivity.

[0125] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a composite piezoelectric film, comprising: 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 nanowires were added to a buffer solution containing dopamine hydrochloride to obtain 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 nanowires; Polyvinylidene fluoride and the surface modified dopamine 0.5Ba (Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 nanowires are dissolved in spinning solvents respectively, and mixed to obtain electrospinning solution; The electrostatic spinning is performed by using the electrostatic spinning method to obtain a composite piezoelectric film.

2. The preparation method according to claim 1, wherein In the electrospinning solution, 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )The mass ratio of TiO3 nanowires to the polyvinylidene fluoride is (0.1~5):(10~50).

3. The preparation method according to claim 1, wherein The electrospinning voltage is 10-18 kV; the volume flow rate of the electrospinning solution is 0.1-0.3 mL h −1 .

4. A composite piezoelectric film prepared by the preparation method according to any one of claims 1 to 3.

5. The composite piezoelectric film according to claim 4, wherein: The thickness of the composite piezoelectric film is 50 μm to 150 μm.

6. A composite piezoelectric film sensor, comprising: The composite piezoelectric film according to any one of claims 4 to 5; Polydimethylsiloxane, as a substrate, used to support the composite piezoelectric film; The first electrode and the second electrode are respectively arranged on two sides of a film-base layer formed by the composite piezoelectric film and the polydimethylsiloxane.

7. A method for preparing a composite piezoelectric film sensor, comprising: Pasting the composite piezoelectric film according to any one of claims 4 to 5 onto a polydimethylsiloxane substrate to obtain a film-substrate layer; The first electrode and the second electrode are respectively adhered to the two sides of the film-substrate layer to obtain a composite piezoelectric film sensor.

8. A method for preparing a composite piezoelectric film sensor, comprising: Vapor-depositing a first metal on one side of the polydimethylsiloxane to form a first electrode; The electrospinning solution is sprayed onto the other side of the polydimethylsiloxane to obtain a polydimethylsiloxane-composite piezoelectric film, wherein the electrospinning solution includes polyvinylidene fluoride, 0.5Ba(Zr 0.2 Ti 0.8 )O3–0.5(Ba 0.7 Ca 0.3 )TiO3 nanowires and spinning solvent; A second metal is evaporated on the polydimethylsiloxane-composite piezoelectric film to form a second electrode, thereby obtaining a composite piezoelectric film sensor.

9. Use of the composite piezoelectric thin film sensor according to claim 6 or the composite piezoelectric thin film sensor prepared by the preparation method according to claim 7 or 8 in heart sound monitoring.

10. The use according to claim 9, wherein: The applications include: Apply the composite piezoelectric film sensor to the fifth intercostal space of the left chest; Connecting the charge signal amplifier, filter and oscilloscope to the composite piezoelectric film sensor through wires; The heart sound monitoring data processed by the charge signal amplifier and the filter is obtained through an oscilloscope.

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