Preparation method of composite piezoelectric film, sensor and application of sensor in physical sign monitoring

Abstract

The invention provides a preparation method of a composite piezoelectric film, which comprises the following steps: dissolving polyvinylidene fluoride-trifluoroethylene in a first solvent to obtain an electrostatic spinning solution; performing electrostatic spinning on the electrostatic spinning solution through an electrostatic spinning device to obtain a polyvinylidene fluoride-trifluoroethylene nanofiber film; dissolving trichlorocadmium acid trimethylchloromethyl ammonium in a second solvent to obtain an electrospray solution; and spraying an electrospray solution on the polyvinylidene fluoride-trifluoroethylene nanofiber film through an electrospray device 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 physical sign 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 thereof in vital sign monitoring. Background Art

[0002] Piezoelectric materials can be divided into inorganic piezoelectric materials, organic piezoelectric materials and composite piezoelectric materials; inorganic piezoelectric materials include piezoelectric ceramics and piezoelectric crystals. Piezoelectric crystals refer to asymmetric single crystals. Common piezoelectric crystals in nature include quartz, sphalerite, tourmaline, zincite, gallium arsenide, bismuth germanate, potassium sodium tartrate, etc.; but most crystals have weak piezoelectric properties and are not very practical. Piezoelectric ceramics is a general term for piezoelectric polycrystals. Common piezoelectric ceramics include barium titanate, lead zirconate titanate, etc.; piezoelectric ceramics have high piezoelectric constants and dielectric constants, and can be processed into a variety of shapes, but their stability is poor.

[0003] Vital sign detection involves monitoring and analyzing various physiological parameters of the human body, which can reflect the health status of an individual and provide important information for the prevention, diagnosis and treatment of diseases. Sensors for related vital sign detection are less comfortable and affect the user's daily activities, while invasive sensors may increase the risk of infection or cause discomfort to patients.

[0004] Piezoelectric materials can convert mechanical energy into electrical signals and can generate electric current under the action of external force. Therefore, piezoelectric materials can be used to convert the mechanical energy in vital signs into electrical signals for vital sign detection. However, not all piezoelectric materials are suitable for use in vital sign detection. Therefore, a piezoelectric material and vital sign detection sensor with higher sensitivity and higher user comfort is needed. 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, a sensor and application of the same in vital sign detection.

[0006] According to an embodiment of one aspect of the present invention, there is provided a method for preparing a composite piezoelectric film, comprising:

[0007] dissolving polyvinylidene fluoride-trifluoroethylene in a first solvent to obtain an electrospinning solution;

[0008] Electrospinning the electrospinning solution by an electrospinning device to obtain a polyvinylidene fluoride-trifluoroethylene nanofiber film;

[0009] dissolving trimethylammonium chlorocadmium trichloride in a second solvent to obtain an electrospray solution;

[0010] The electrospray solution is sprayed on the polyvinylidene fluoride-trifluoroethylene nanofiber film through an electrospray device to obtain a composite piezoelectric film.

[0011] According to an embodiment of the present invention, the first solvent includes at least one of N,N-dimethylformamide and acetone;

[0012] The second solvent includes at least one of deionized water and methanol.

[0013] According to an embodiment of another aspect of the present invention, a composite piezoelectric film prepared by the above preparation method is provided.

[0014] According to an embodiment of the present invention, the doping amount of trimethylammonium chlorocadmium trichloride in the composite piezoelectric film is 0.05-0.4 g / cm 2 .

[0015] According to an embodiment of the present invention, the thickness of the composite piezoelectric film is 50 μm-150 μm.

[0016] According to an embodiment of another aspect of the present invention, a composite piezoelectric film sensor is provided, comprising the above-mentioned composite piezoelectric film; a first electrode and a second electrode, respectively arranged on both sides of the composite piezoelectric film; and a packaging layer for packaging the composite piezoelectric film, the first electrode and the second electrode.

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

[0018] Depositing metal on both sides of the composite piezoelectric film to form a first electrode and a second electrode to obtain an electrode film layer;

[0019] The electrode film layer is packaged with a packaging material to obtain a composite piezoelectric film sensor.

[0020] According to another embodiment of the present invention, there is provided an application of a composite piezoelectric film sensor in vital sign monitoring.

[0021] According to an embodiment of the present invention, the vital sign detection includes heart sound monitoring.

[0022] According to an embodiment of the present invention, by spraying the organic-inorganic hybrid piezoelectric material trichlorocadmium trimethylammonium chloromethylammonium containing cadmium on the organic polymer substrate polyvinylidene fluoride-trifluoroethylene through an electrospray device, a lead-free molecular piezoelectric material trichlorocadmium trimethylammonium chloromethylammonium composite piezoelectric film can be prepared, and the spherical cation tetramethylammonium is structurally optimized by halogen. The prepared composite piezoelectric film is flexible, low in density and has a high piezoelectric coefficient, and the film prepared by the electrospinning device is evenly distributed and has high piezoelectric performance. It can be further applied to flexible sensors for vital sign detection, and the mechanical energy of vital signs is converted into electrical signals, thereby performing vital sign detection. In heart sound monitoring, a signal peak-to-peak value of 10mv~20mv can be achieved, and the peak intensity is improved compared with the related art. Moreover, in the absence of tight sealing, no attenuation can be achieved within one week, slight attenuation can be achieved within two weeks, and the performance can only be attenuated by half within three weeks. The performance is still higher than the sensor in the related art, and the stability is high. The material is safe and healthy, has good biocompatibility, and does not contain lead and is non-toxic to the human body. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] 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:

[0024] Figure 1 Schematic diagram of the steps of the method for preparing the composite piezoelectric film according to an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the structure of a composite piezoelectric film sensor according to an embodiment of the present invention;

[0026] Figure 3 This is a scanning electron microscope image of the white crystal of TMCM-CdCl3 in the embodiment of the present invention;

[0027] Figure 4 This is a transmission electron microscope image of the white crystal of TMCM-CdCl3 in the embodiment of the present invention;

[0028] Figure 5 This is a scanning electron microscope image of the PVDF-TrFE electrospun film of an embodiment of the present invention;

[0029] Figure 6 This is a scanning electron microscope image of the PVDF-TrFE / TMCM-CdCl3 electrospun film of an embodiment of the present invention;

[0030] Figure 7 This is a transmission electron microscopy image of the PVDF-TrFE / TMCM-CdCl3 electrospun film of an embodiment of the present invention;

[0031] Figure 8This is a cross-sectional scan of the PVDF-TrFE / TMCM-CdCl3 electrospun film according to an embodiment of the present invention;

[0032] Fig. 9 This is a physical picture of the composite piezoelectric film sensor according to an embodiment of the present invention;

[0033] Fig.10 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;

[0034] Fig.11 This is a graph showing the stability test results of the composite piezoelectric film sensor according to an embodiment of the present invention;

[0035] Fig.12 The waveform diagram of the heart sound of the composite piezoelectric film sensor according to the embodiment of the present invention, wherein A is the original waveform diagram of the heart sound, and B is the waveform diagram of the heart sound after filtering;

[0036] Fig.13 The waveform diagram of the heart sound after signal processing of the composite piezoelectric film sensor according to the embodiment 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;

[0037] Fig.14 The pulse signal waveform diagram of the composite piezoelectric film sensor according to the embodiment of the present invention, wherein A is the original pulse signal waveform diagram, and B is the pulse signal waveform diagram after filtering;

[0038] Fig.15 The waveform diagram of the pulse signal of the composite piezoelectric film sensor according to the embodiment of the present invention after signal processing, wherein A is the original waveform diagram after signal processing and B is the waveform diagram after signal processing after filtering;

[0039] Fig.16 The waveform diagram of the carotid artery signal of the composite piezoelectric film sensor according to the embodiment of the present invention after signal processing, wherein A is the original waveform diagram after signal processing, and B is the waveform diagram after signal processing after filtering;

[0040] Fig.17 The waveform diagram of the ankle signal of the composite piezoelectric film sensor after signal processing according to the embodiment 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;

[0041] Fig.18 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

[0042] 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.

[0043] 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.

[0044] 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.).

[0045] In the process of realizing the conception of the present invention, it was found that organic piezoelectric materials are also called piezoelectric polymers, such as PVDF films. Such materials are flexible, low in density and have a high piezoelectric coefficient. Furthermore, composite piezoelectric materials refer to a composite material composed of various finely divided inorganic or organic piezoelectric materials of unlimited shapes embedded in an organic polymer base material. This material can combine the advantages of inorganic and organic piezoelectric materials and has a high application potential.

[0046] Figure 1 Schematic diagram of the steps of the method for preparing the composite piezoelectric film according to an embodiment of the present invention.

[0047] Based on this, the present invention provides a method for preparing a composite piezoelectric film, such as Figure 1 As shown, it includes steps S1 to S4.

[0048] Step S1: dissolving polyvinylidene fluoride-trifluoroethylene in a first solvent to obtain an electrospinning solution;

[0049] Step S2: electrospinning the electrospinning solution by an electrospinning device to obtain a polyvinylidene fluoride-trifluoroethylene nanofiber film;

[0050] Step S3: dissolving trimethylammonium chlorocadmium trichloride in a second solvent to obtain an electrospray solution;

[0051] Step S4: spraying the electrospray solution onto the polyvinylidene fluoride-trifluoroethylene nanofiber film through an electrospray device to obtain a composite piezoelectric film.

[0052] According to an embodiment of the present invention, by spraying cadmium-containing organic-inorganic hybrid piezoelectric material trimethylammonium trichlorocadmium chloride (TMCM-MnCl3) on the organic polymer substrate polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) through an electrospray device, a lead-free molecular piezoelectric material trimethylammonium trichlorocadmium chloride composite piezoelectric film can be prepared, and the spherical cationic tetramethylammonium is structurally optimized by halogen. The prepared composite piezoelectric film is flexible, low in density and has a high piezoelectric coefficient. The film prepared by the electrospinning device is evenly distributed and has high piezoelectric performance. It can be further applied to flexible sensors for vital sign detection, converting the mechanical energy of vital signs into electrical signals, thereby performing vital sign detection. In heart sound monitoring, a signal peak-to-peak value of 10mv~20mv can be achieved, and the peak intensity is improved compared with the related art. Moreover, in the absence of tight sealing, no attenuation can be achieved within one week, slight attenuation can be achieved within two weeks, and the performance can be attenuated by half within three weeks. The performance is still higher than that of sensors in the related art, and the stability is high. The material is safe and healthy, has good biocompatibility, does not contain lead and is non-toxic to the human body.

[0053] According to an embodiment of the present invention, the first solvent includes at least one of N,N-dimethylformamide and acetone; the second solvent includes at least one of deionized water and methanol.

[0054] According to an embodiment of the present invention, N,N-dimethylformamide (DMF) or acetone can ensure that PVDF-TrFE is fully dissolved to form a uniform solution, thereby affecting the quality and morphology of the fibers spun during the electrospinning process. Moreover, the viscosity and surface tension of DMF and acetone are suitable for the requirements of electrospinning, which can ensure that the solution forms a stable jet under the action of the electric field, and the appropriate surface tension helps to form uniform fibers. Moreover, although DMF and acetone are organic solvents, they are relatively easy to handle and recycle in industrial applications.

[0055] According to the embodiment of the present invention, deionized water and methanol are used as the second solvent because they have good solubility for TMCM-MnCl3, and during the electrospraying process, the volatility, conductivity and interaction of the solvent with the sample will affect the spraying effect. The physicochemical properties of deionized water and methanol are suitable for the requirements of electrospraying, and can ensure the stability of the electrospraying solution and the smooth progress of the spraying process. Moreover, deionized water and methanol are more environmentally friendly and have less impact on the environment.

[0056] In some specific embodiments of the present invention, other common solvents having good solubility for TMCM-MnCl 3 may also be used.

[0057] According to the embodiment of the present invention, the composite piezoelectric film prepared through steps S1 to S4 forms a piezoelectric material having a special crystal structure and special ferroelectric properties that can convert mechanical energy into electrical energy by means of intermolecular forces such as hydrogen bonds and van der Waals forces. It also has strong flexibility and can be applied to curved and uneven surfaces such as skin.

[0058] According to an embodiment of the present invention, the doping amount of trimethylammonium chlorocadmium trichloride in the composite piezoelectric film is 0.05-0.4 g / cm 2 .

[0059] According to an embodiment of the present invention, the doping amount of TMCM-MnCl3 can be 0.05 g / cm 2 , 0.1g / cm 2 , 0.15g / cm 2 , 0.2g / cm 2 , 0.25g / cm 2 , 0.3g / cm 2 , 0.35g / cm 2 , 0.4g / cm 2 , but it is not limited to the listed values. Other values ​​not listed in this range are also applicable. Too much TMCM-MnCl3 doping may increase the dielectric loss of the material and affect its piezoelectric properties; too little doping may not fully utilize the piezoelectric properties of TMCM-MnCl3 and cannot form an effective piezoelectric response. The right amount of doping can ensure that there are enough active sites in the material to achieve the best piezoelectric effect. The control of the doping amount is also related to the stability and phase change of the piezoelectric material. Doping will increase the Curie temperature and promote the transition from the rhombohedral phase to the tetragonal phase. The appropriate doping amount helps to maintain its piezoelectric properties and stability at room temperature.

[0060] According to an embodiment of the present invention, the thickness of the composite piezoelectric film is 50 μm-150 μm.

[0061] 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.

[0062] Figure 2 This is a schematic diagram of the structure of a composite piezoelectric film sensor according to an embodiment of the present invention.

[0063] Another aspect of the present invention discloses a composite piezoelectric film sensor. Figure 2 As shown, including:

[0064] Composite piezoelectric film;

[0065] A first electrode and a second electrode are respectively arranged on two sides of the composite piezoelectric film;

[0066] The packaging layer is used to package the composite piezoelectric film, the first electrode and the second electrode.

[0067] According to an embodiment of the present invention, the molecular piezoelectric material trimethylammonium chlorocadmiumate composite piezoelectric film is composited with the piezoelectric polymer polyvinylidene fluoride-trifluoroethylene to obtain a thickness-controllable and high-performance nanocomposite piezoelectric material for the construction of a flexible pressure sensor. Electrodes are deposited on both sides of the piezoelectric film, connected with wires and packaged to complete a pressure or vibration sensor. The sensor can also be connected to an oscilloscope to form a complete detection device. The stability and sensitivity of the composite piezoelectric film sensor have reached a high level, providing a new method for vibration and pressure sensing.

[0068] According to an embodiment of the present invention, the thickness of the first electrode and the second electrode are respectively 50-100 nm.

[0069] According to an embodiment of the present invention, the thickness of the first electrode and the second electrode can be 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, respectively, but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable. If the thickness of the first electrode and the second electrode is too thin, the piezoelectric material may be broken down because it is a thin film material. If the thickness of the first electrode and the second electrode is too thick, the flexibility may be poor, which affects the use of the sensor and the overall flexibility, and cannot be better applied in the field of physical sign detection and other fields that require sticking detection.

[0070] In some specific embodiments of the present invention, the first electrode and the second electrode can be selected from at least one of a gold electrode, a platinum electrode, an aluminum electrode, and a copper electrode, respectively, and alloy materials of the above electrodes can also be used.

[0071] In some specific embodiments of the present invention, the encapsulation layer may use at least one of polydimethylsiloxane (PDMS), polyurethane elastomer (TPU), and polylactic acid (PLA). The encapsulation layer should be soft and insulating, biosafe, and can be applied to the surface of the skin. The thickness of the encapsulation layer should not be too thick, and should be able to be encapsulated and insulated. The thickness of the encapsulated sensor is 120μm~200μm.

[0072] Another aspect of the present invention discloses a method for preparing a composite piezoelectric film sensor, including steps S11 and S12.

[0073] Step S11: evaporating metal on both sides of the composite piezoelectric film to form a first electrode and a second electrode to obtain an electrode film layer;

[0074] Step S12: encapsulating the electrode film layer with a packaging material to obtain a composite piezoelectric film sensor.

[0075] In some specific embodiments of the present invention, a layer of metal can be evaporated on PDMS as a first electrode, and then polyvinylidene fluoride-trifluoroethylene and trimethylammonium chlorocadmium trichloride material can be directly sprayed on the PDMS using an electrospinning method, and finally a layer of second electrode can be evaporated on the surface of the material to form a composite piezoelectric film sensor.

[0076] According to the embodiments of the present invention, the composite piezoelectric film sensor prepared by the above method is closely attached to PDMS, and the piezoelectric material is evenly distributed, and has good piezoelectric conversion function, so that the prepared sensor has higher stability and sensitivity.

[0077] Another aspect of the present invention provides an application of a composite piezoelectric film sensor in vital sign monitoring.

[0078] According to the embodiments of the present invention, vital sign monitoring may include aspects such as respiration, blood pressure, pulse, blood flow, etc. Furthermore, vital sign detection is monitoring for non-diagnostic and therapeutic purposes and is not directly used to obtain the health status of the monitored person. The composite piezoelectric film sensor can realize vital sign monitoring by converting the mechanical signal in the vital sign into an electrical signal and displaying it visually through related equipment such as an oscilloscope.

[0079] According to an embodiment of the present invention, the vital sign detection includes heart sound monitoring.

[0080] According to an embodiment of the present invention, the composite piezoelectric film sensor is connected to a signal processing circuit, and the output end of the signal processing circuit is connected to an oscilloscope. The sensor is placed flat, and the oscilloscope is adjusted to ensure that the noise error is minimized. Then the sensor is placed on the wrist to measure the pulse signal; the sensor is placed on the fifth rib of the chest to clearly measure the heart sound signal.

[0081] 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 human body signals. At the same time, because the composite piezoelectric film sensor is soft and can be closely attached to the body wall, the acoustic impedance is close to the acoustic impedance of human tissue, and is suitable for detecting human body signals such as pulse and heart sounds.

[0082] 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.

[0083] Example 1 Preparation of TMCM-CdCl3

[0084] At room temperature, equimolar amounts of trimethylamine (30% aqueous solution) and dichloromethane were mixed in an acetonitrile solution and reacted for 24 hours to synthesize chloromethyltrimethylammonium chloride, and the obtained colorless solid was stored in a vacuum desiccator. The above chloromethyltrimethylammonium chloride (10 mmol) and anhydrous cadmium chloride (50 mmol) were added to a methanol solution (100 mL) and stirred thoroughly to dissolve. The solution was kept still in a beaker covered with a porous filter paper at room temperature, and white block crystals Me3NCH2ClMnCl3 (TMCM-CdCl3) were obtained by solvent evaporation method. The results are shown in Figure 3 , 4 shown.

[0085] Figure 3 This is a scanning electron microscope image of the white crystal of TMCM-CdCl3 in the embodiment of the present invention; Figure 4 This is a transmission electron microscopy image of the white crystals of TMCM-CdCl3 in the embodiment of the present invention.

[0086] according to Figure 3 and Figure 4It can be seen that TMCM-CdCl3 white crystals were successfully prepared.

[0087] Example 2 Preparation of composite piezoelectric film

[0088] Step S1: 0.75 g of PVDF-TrFE powder was dissolved in 2.5 mL of N,N-dimethylformamide (DMF) and 2.5 mL of acetone, i.e., the first solvent, and magnetic stirring was performed at room temperature to form a uniform and transparent electrospinning solution.

[0089] Step S2: The electrospinning solution is loaded into a 5 mL plastic syringe with a 25-gauge stainless steel needle, the electrospinning device is started, and the voltage is adjusted to spin the piezoelectric PVDF nanofibers. Figure 5 shown.

[0090] Step S3: Dissolve the single crystal TMCM-CdCl3 in a second solvent, deionized water or methanol, to obtain an electrospray solution.

[0091] Step S4: Treat PVDF nanofibers with oxygen plasma to obtain a hydrophilic surface. The RF plasma cleaner was operated at 118 W, 0.1 mbar, and a gas flow rate of 50 sccm O2 for 300 s. The electrospray solution was loaded into the electrospray device and quantitatively and uniformly sprayed onto the PVDF treated with oxygen plasma. The solvent was slowly evaporated to obtain a PVDF-TRFE / TMCM-CdCl3 film, such as Figures 6-8 shown.

[0092] Three different molecular ferroelectric doped films were prepared in the experiment, marked as 0.1 g / cm 2 , 0.2 g / cm 2 and 0.3 g / cm 2 .

[0093] Figure 5 This is a scanning electron microscope image of a PVDF electrospun film according to an embodiment of the present invention; Figure 6 This is a scanning electron microscope image of the PVDF / TMCM-CdCl3 electrospun film of an embodiment of the present invention; Figure 7 This is a transmission electron microscopy image of the PVDF / TMCM-CdCl3 electrospun film of an embodiment of the present invention; Figure 8 This is a cross-sectional scan of the PVDF-TrFE / TMCM-CdCl3 electrospun film according to an embodiment of the present invention.

[0094] pass Figures 6-8 It can be seen that the PVDF-TrFE / TMCM-CdCl3 electrospinning film was prepared with uniform fiber distribution and stratification.

[0095] Example 3 Preparation of composite piezoelectric film sensor

[0096] Step S11: using a thermal evaporation coating machine to deposit gold electrodes with a thickness of 50-100 nm on both sides of the three composite piezoelectric films prepared in Example 2.

[0097] Step S12: Use a commercial PU waterproof film to encapsulate the composite piezoelectric film-electrode, and then use a spin coating process to prepare PDMS as an encapsulation layer to protect and insulate the composite piezoelectric film-electrode. Use gold or copper wire electrodes to connect and encapsulate the composite piezoelectric film sensor after PDMS encapsulation. The result is as follows: Fig. 9 shown.

[0098] Fig. 9 This is a physical picture of the composite piezoelectric film sensor according to an embodiment of the present invention.

[0099] according to Fig. 9 It can be seen that the prepared composite piezoelectric film sensor has a length × width × thickness of 15 mm × 15 mm × 120 µm.

[0100] Example 4 Functional test of composite piezoelectric film sensor

[0101] The composite piezoelectric film sensors with three TMCM-CdCl3 doping amounts in Example 2 were placed under the same mechanical force, and the output voltage was measured. Fig.10 shown.

[0102] Fig.10 This is a graph showing the voltage output variation of a composite piezoelectric film sensor with different doping amounts according to an embodiment of the present invention.

[0103] according to Fig.10 It can be seen that in the range of 0~0.3g / cm 2 As the doping amount increases, the output voltage gradually increases, but at 0.3g / cm 2 The output voltage decreases instead, which proves that the more doping amount is not necessarily better. Too little doping amount cannot achieve piezoelectric performance, and too much doping amount will lead to increased dielectric loss and deteriorate piezoelectric performance.

[0104] The 0.3 g / cm 2 The stability experiment of the composite piezoelectric film sensor with TMCM-CdCl3 doping was carried out, and the curve of the voltage output was measured as time increased, such as Fig.11 shown.

[0105] Fig.11 This is a graph showing the stability test results of the composite piezoelectric film sensor according to an embodiment of the present invention.

[0106] according to Fig.11It can be seen that after working for three weeks, although the performance of the composite piezoelectric film sensor has slightly decayed, it can still ensure good piezoelectric performance, indicating that the composite piezoelectric film sensor prepared by the present invention has high stability.

[0107] Example 5: Composite piezoelectric film sensor for monitoring heart sounds

[0108] The copper wires from the composite piezoelectric film sensor prepared in Example 3 were connected to an oscilloscope, and the composite piezoelectric film sensor was attached to the mitral valve area of ​​the heart. The original heart sound waveform and the filtered heart sound waveform were recorded as shown in Fig. Fig.12 As shown in Figure A in Figure 12 and Figure B in Figure 12. Connect the prepared sensor to one end of the signal processing circuit and the other end to the oscilloscope. Place the sensor flat and adjust the oscilloscope to ensure that the noise error is minimal. Place the sensor in the same position on the left chest and the heart sound signal can be clearly measured as shown in Figure 12. Fig.13 As shown in A and B.

[0109] Fig.12 The composite piezoelectric film sensor heart sound waveform of the embodiment of the present invention A is the original heart sound waveform and B is the filtered heart sound waveform; Fig.13 This is a waveform diagram of the heart sound of the composite piezoelectric film sensor after signal processing according to an embodiment of the present invention. A is the original waveform diagram after signal processing, and B is the waveform diagram after signal processing after filtering.

[0110] according to Fig.12 and Fig.13 It can be seen that the composite piezoelectric film sensor of the present invention can detect clear heart sound signals, and the waveform after the signal processing circuit and filtering processing can more clearly reflect the heart sound monitoring signal.

[0111] Example 6 Composite piezoelectric film sensor pulse monitoring

[0112] The copper wire from the composite piezoelectric film sensor prepared in Example 3 was connected to an oscilloscope, and the sensor was attached to the wrist to record the original pulse signal and the filtered pulse signal. Fig.14 A, 14B. Connect the prepared sensor to one end of the signal processing circuit and the other end to the oscilloscope. Place the sensor in the same position and the pulse signal can be clearly measured. Fig.15 A, as shown in 15B.

[0113] Fig.14 The pulse signal waveform of the composite piezoelectric film sensor according to the embodiment of the present invention is shown in Figure A as the original pulse signal waveform and Figure B as the pulse signal waveform after filtering; Fig.15This is a waveform diagram of the pulse signal of the composite piezoelectric film sensor after signal processing in an embodiment of the present invention. A is the original waveform diagram after signal processing, and B is the waveform diagram after signal processing after filtering.

[0114] according to Fig.14 and Fig.15 It can be seen that the composite piezoelectric film sensor of the present invention can detect a clear pulse signal, and the waveform after the signal processing circuit and filtering processing can more clearly reflect the pulse monitoring signal.

[0115] Example 7 Composite piezoelectric film sensor carotid artery signal monitoring

[0116] The copper wire from the composite piezoelectric film sensor prepared in Example 3 was connected to an oscilloscope, and the sensor was attached to the cervical vertebrae. The original carotid artery signal and the filtered carotid artery signal were recorded. Fig.16 A, as shown in 16B.

[0117] Fig.16 This is a waveform diagram of the carotid artery signal of the composite piezoelectric film sensor after signal processing according to an embodiment of the present invention. A is the original waveform diagram after signal processing, and B is the waveform diagram after signal processing after filtering.

[0118] according to Fig.16 It can be seen that the signal monitored by the composite piezoelectric film sensor of the present invention can clearly reflect the carotid artery monitoring signal after being processed by the signal processing circuit and filtering.

[0119] Example 8 Composite piezoelectric film sensor ankle signal monitoring

[0120] The copper wire from the composite piezoelectric film sensor prepared in Example 3 was connected to an oscilloscope, and the sensor was attached to the bottom of the ankle. The original ankle signal and the filtered ankle signal were recorded as follows: Fig.17 A, as shown in 17B.

[0121] Fig.17 This is the waveform diagram of the ankle signal of the composite piezoelectric film sensor after signal processing in an embodiment of the present invention. A is the original waveform diagram after signal processing, and B is the waveform diagram after signal processing after filtering.

[0122] according to Fig.17 It can be seen that the signal monitored by the composite piezoelectric film sensor of the present invention can be processed by the signal processing circuit and filtered to clearly reflect the ankle monitoring signal.

[0123] Comparative Example 1 Commercial Sensor Detects Heart Sound Signals

[0124] The same monitoring method as in Example 5 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.18 shown.

[0125] Fig.18 The waveform of heart sounds detected by a commercial sensor is a comparative example of the present invention. A is the original waveform after signal processing, and B is the waveform after signal processing after filtering.

[0126] according to Fig.18 It 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.

[0127] 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: dissolving polyvinylidene fluoride-trifluoroethylene in a first solvent to obtain an electrospinning solution; Electrospinning the electrospinning solution by an electrospinning device to obtain a polyvinylidene fluoride-trifluoroethylene nanofiber film; dissolving trimethylammonium chlorocadmium trichloride in a second solvent to obtain an electrospray solution; The electrospray solution is sprayed on the polyvinylidene fluoride-trifluoroethylene nanofiber film through an electrospray device to obtain a composite piezoelectric film.

2. The preparation method according to claim 1, wherein The first solvent includes at least one of N,N-dimethylformamide and acetone; The second solvent includes at least one of deionized water and methanol.

3. A composite piezoelectric film prepared according to the preparation method according to any one of claims 1 to 2.

4. The composite piezoelectric film according to claim 1, wherein: In the composite piezoelectric film, the doping amount of trimethylammonium chlorocadmium trichloride is 0.05-0.4 g / cm 2 .

5. The composite piezoelectric film according to claim 3, 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 3 to 5; A first electrode and a second electrode are respectively arranged on two sides of the composite piezoelectric film; The packaging layer is used to package the composite piezoelectric film, the first electrode and the second electrode.

7. The composite piezoelectric film sensor according to claim 6, wherein: The thickness of the first electrode and the second electrode are 50-100 nm respectively.

8. A method for preparing a composite piezoelectric film sensor, comprising: Depositing metal on both sides of the composite piezoelectric film according to any one of claims 3 to 5 to form a first electrode and a second electrode to obtain an electrode film layer; The electrode film layer is packaged with a packaging material to obtain a composite piezoelectric film sensor.

9. Application of the composite piezoelectric film sensor according to any one of claims 6 to 8 in vital sign monitoring.

10. The use according to claim 9, wherein the vital sign detection comprises heart sound monitoring.

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