A bending sensor for monitoring human breathing and its preparation method

Abstract

The present invention discloses a bending sensor that can be used to monitor human breathing and a preparation method thereof. The sensor comprises a flexoelectric film made by electrostatic spinning technology, wherein the upper and lower surfaces of the flexoelectric film are provided with electrode layers, and both are covered by a packaging film. The relationship between the polarization intensity of the flexoelectric effect and the strain gradient is used to characterize the strength of breathing, and the frequency of the output voltage signal is used to monitor the speed of breathing. That is, the airflow intensity generated by different breathing patterns causes the sensor to produce different bending deformations, thereby generating a response voltage; the breathing frequency corresponds to the frequency of the response voltage signal, so the human breathing frequency can be judged accordingly. It can meet the sensitivity requirements and realize the monitoring of breathing intensity and frequency in a flexible and portable manner.

Description

Technical Field

[0001] The present invention relates to the fields of electronic science and biomedicine, and in particular to a bending sensor that can be used to monitor human breathing and a preparation method thereof. Background Art

[0002] Respiratory intensity and rate are important vital signs of the human body. These can indicate the onset of conditions such as heart failure, arrhythmias, hypertension, and respiratory obstruction. Currently, non-contact respiratory monitoring methods such as thermal imaging, camera imaging, and microwave Doppler radar are commonly used in clinical treatment. However, these devices are bulky, making them difficult to implement for real-time personal monitoring.

[0003] Self-powered wearable sensors have emerged, generally based on piezoelectric (PENG), triboelectric (TENG) nanogenerators or piezoelectric-triboelectric (PTENG) hybrid nanogenerators, which convert external mechanical energy into electrical energy. However, most PENG-based sensors require direct contact to form piezoelectric deformation. TENG-based sensors require high external resistance and air gap. The flexoelectric effect is different from piezoelectric or triboelectric nanogenerators. It is an electric polarization response generated by a bending strain gradient. Flexoelectric has a "small size effect". The smaller the device size, the larger the bending strain gradient, and the more significant the flexoelectric effect. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a bending sensor that can be used to monitor human breathing and a preparation method thereof.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A bending sensor that can be used to monitor human breathing includes a flexoelectric film made by electrostatic spinning technology. The upper and lower sides of the flexoelectric film are provided with electrode layers, and both are covered by a packaging film.

[0007] Electrode layers are provided on both the upper and lower sides of the flexoelectric film and assembled into a sandwich structure.

[0008] The electrode layer is a conductive metal film such as copper foil or silver foil.

[0009] The packaging film is a PDMS or PI film.

[0010] A method for preparing a curved sensor for monitoring human respiration comprises the following steps:

[0011] 1) Place the flexoelectric material in a sample bottle, add an organic solvent, and place it in an ultrasonic cleaner for ultrasonic cleaning to evenly disperse the flexoelectric material in the organic solvent;

[0012] 2) dissolving the base polymer material in the solution prepared in step 1), stirring the solution magnetically to obtain a precursor solution, and allowing the solution to stand for degassing.

[0013] 3) Using the precursor solution for electrospinning to prepare a composite film;

[0014] 4) Electrodes are attached to the upper and lower surfaces of the composite film to assemble a sandwich-structured bending sensor;

[0015] 5) Encapsulate with packaging film.

[0016] The flexoelectric material in step 1) is manganese tetraoxide or molybdenum sulfide, and the organic solvent is N,N-dimethylformamide or ethanol.

[0017] The mass fraction of the flexoelectric material is 10-15wt%, and the ultrasonic time is 0.5-2h.

[0018] In step 2), the base polymer is polyacrylonitrile or polyvinylidene fluoride.

[0019] The mass fraction of the base polymer is 8-12wt%, the magnetic stirring time is 3-5h, and the standing time is 0.5-3h.

[0020] In step 3), the electrospinning process parameters are as follows: a 19-24 gauge flat-head needle is selected as the spinning nozzle, the needle-receiver distance is 10-15 cm, the syringe pump push speed is 0.8-1.5 mL / h, the spinning voltage is 10-18 kV, and the drum speed is 200-500 r / min.

[0021] The present invention has the beneficial effects of utilizing the relationship between the polarization intensity of the flexoelectric effect and the strain gradient to characterize breathing intensity, and utilizing the frequency of the output voltage signal to monitor breathing rate. Specifically, the airflow intensity generated by different breathing patterns causes the sensor to produce different bending deformations, thereby generating a response voltage. The breathing frequency corresponds to the frequency of the response voltage signal, allowing the human respiratory rate to be determined. This device meets sensitivity requirements while providing flexible and portable monitoring of breathing intensity and frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the preparation method of the present invention.

[0023] Figure 2 Schematic diagram of the electrical signal response under different breathing intensities of the present invention.

[0024] Figure 3 Schematic diagram of the electrical signal response under different breathing pattern deformations of the present invention.

[0025] Figure 4Schematic diagram of the electrical signal response under different breathing pattern deformations of the present invention. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0028] As shown in the figure, the present invention discloses a bending sensor that can be used to monitor human breathing. The sensor comprises a flexoelectric film made by electrospinning technology. An electrode layer is provided on either side of the flexoelectric film, and both sides are covered by an encapsulation film. This thin film-shaped breathing sensor is very thin and can be easily placed at the breathing area. The airflow generated by breathing causes the flexoelectric film to produce a flexoelectric effect, which is then converted into an electrical signal for subsequent circuit processing to obtain the corresponding breathing signal.

[0029] Electrode layers are provided on both the upper and lower sides of the flexoelectric film and assembled into a sandwich structure.

[0030] The electrode layer is a conductive metal film such as copper foil or silver foil, and is used to transmit electrical signals to the outside.

[0031] The packaging film is a PDMS or PI film, which plays a role in protecting the internal circuit and is convenient for storage.

[0032] The relationship between the polarization intensity of the flexoelectric effect and the strain gradient is used to characterize breathing intensity, while the frequency of the output voltage signal is used to monitor breathing rate. Different breathing patterns generate different airflow intensities, causing the sensor to bend differently, generating a response voltage. The frequency of the response voltage signal corresponds to the frequency of the breathing frequency, allowing the human respiratory rate to be determined.

[0033] A method for preparing a curved sensor for monitoring human respiration comprises the following steps:

[0034] 1) Place the flexoelectric material in a sample bottle, add an organic solvent, and place it in an ultrasonic cleaner for ultrasonication to uniformly disperse the flexoelectric material in the organic solvent; the flexoelectric material is manganese tetraoxide or molybdenum sulfide, the organic solvent is N,N-dimethylformamide or ethanol, the mass fraction of the flexoelectric material is 10-15wt%, and the ultrasonication time is 0.5-2h.

[0035] 2) dissolving the base polymer material in the solution prepared in step 1), stirring the solution by magnetic force to obtain a precursor solution, and allowing the solution to stand for degassing. The base polymer is polyacrylonitrile or polyvinylidene fluoride.

[0036] The mass fraction of the base polymer is 8-12wt%, the magnetic stirring time is 3-5h, and the standing time is 0.5-3h.

[0037] 3) Electrospinning the precursor solution to prepare a composite film; the electrospinning process parameters are as follows: a 19-24 gauge flat-tip needle as the spinning nozzle, a needle-receiver distance of 10-15 cm, a syringe pump speed of 0.8-1.5 mL / h, a spinning voltage of 10-18 kV, and a drum speed of 200-500 rpm.

[0038] 4) Electrodes are attached to the upper and lower surfaces of the composite film to assemble a sandwich-structured bending sensor;

[0039] 5) Encapsulate with packaging film.

[0040] Example

[0041] 1.76g of Mn3O4 was added to 10g of DMF and ultrasonicated in an ultrasonic cleaner for 2h. Then, 1.36g of PVDF was added and magnetically stirred at 60°C for 3h to prepare the spinning precursor solution. Electrospinning was performed using a 19-gauge flat-head needle as the spinning nozzle, a needle-receiver distance of 12cm, a syringe pump speed of 1mL / h, a spinning voltage of 15kV, and a drum speed of 400r / min. The prepared film sample was as shown in FIG. Figure 1 As shown in . Copper foil is used as the electrode material to assemble a sandwich structure bending sensor, which is encapsulated by PI film.

[0042] The response electrical signals of the bending sensor under different breathing intensities and frequencies are as follows: Figure 2 、 3 As shown in the figure, the change of voltage can accurately reflect the intensity and frequency of breathing. Figure 4The figure shows the response characteristics of the flex sensor under three different breathing patterns: normal breathing, breathing after exercise, and coughing. After exercise, the airflow intensity increases, along with the respiratory rate. During a cough, the respiratory intensity changes significantly, and the frequency increases. Therefore, the sensor's flexoelectric signals can be used to determine respiratory intensity and frequency, thereby identifying breathing patterns.

[0043] The embodiments should not be regarded as limiting the present invention, but any improvements based on the spirit of the present invention should be within the scope of protection of the present invention.

Claims

1. A bending sensor for monitoring human respiration, characterized by: The invention comprises a flexoelectric film made by electrospinning technology, wherein the upper and lower sides of the flexoelectric film are provided with electrode layers, and both are covered by a packaging film. The preparation method comprises the following steps: 1) Place the flexoelectric material in a sample bottle, add an organic solvent, and place it in an ultrasonic cleaner for ultrasonic cleaning to evenly disperse the flexoelectric material in the organic solvent; 2) dissolving the base polymer material in the solution prepared in step 1), stirring the solution magnetically to obtain a precursor solution, and allowing the solution to stand for degassing. 3) Using the precursor solution for electrospinning to prepare a composite film; 4) Electrodes are attached to the upper and lower surfaces of the composite film to assemble a sandwich-structured bending sensor; 5) Encapsulate with packaging film, The flexoelectric material in step 1) is manganese tetraoxide or molybdenum sulfide, and the organic solvent is N,N-dimethylformamide or ethanol. In step 2), the base polymer is polyacrylonitrile or polyvinylidene fluoride.

2. The bending sensor for monitoring human breathing according to claim 1, characterized in that: Electrode layers are provided on both the upper and lower sides of the flexoelectric film and assembled into a sandwich structure.

3. The bending sensor for monitoring human breathing according to claim 1, characterized in that: The electrode layer is a conductive metal film such as copper foil or silver foil.

4. The bending sensor for monitoring human breathing according to claim 1, characterized in that: The packaging film is a PDMS or PI film.

5. The bending sensor for monitoring human breathing according to claim 1, characterized in that: The mass fraction of the flexoelectric material is 10-15wt%, and the ultrasonic time is 0.5-2h.

6. The bending sensor for monitoring human breathing according to claim 1, characterized in that: The mass fraction of the base polymer is 8-12wt%, the magnetic stirring time is 3-5h, and the standing time is 0.5-3h.

7. The bending sensor for monitoring human breathing according to claim 1, characterized in that: In step 3), the electrospinning process parameters are as follows: a 19-24 gauge flat-head needle is selected as the spinning nozzle, the needle-receiver distance is 10-15 cm, the syringe pump push speed is 0.8-1.5 mL / h, the spinning voltage is 10-18 kV, and the drum speed is 200-500 r / min.

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