Motion state intelligent monitoring system and method based on flexoelectric polarization

Abstract

The invention discloses an intelligent motion state monitoring system and method based on flexoelectric polarization, the intelligent motion state monitoring system integrates the idea of microstructure design in a metamaterial into the design of a sensor module, and the sensor module which takes a sensing layer as a main body and covers two electrode layers is prepared. Meanwhile, the sensing layer and the electrode layer are both formed by unit cell structures, and antisymmetric snake-shaped structures with initial curvatures are introduced into the unit cell structures, so that the sensor module can be designed in a customized manner according to contact parts, has sufficiently strong conformal capability, and has the characteristics of being ultrathin, low in modulus, light and flexible. Meanwhile, the sensor module can transmit a charge signal generated by mechanical deformation of the sensing layer caused by movement of each part of the body to the intelligent monitoring module through the control module, and various movement postures can be accurately judged through a machine learning framework.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wearable electronic devices, and particularly relates to a motion state intelligent monitoring system and method based on flexoelectric polarization. BACKGROUND

[0002] With the rapid development of wearable electronic devices, flexible sensors are widely used in biological signal acquisition, health monitoring and human-computer interaction fields and play an increasingly important role. Traditional sensors are mainly based on piezoelectric effect and triboelectric effect to realize mechanical energy to electric energy conversion. However, the sensors prepared by using triboelectric effect often have problems such as low energy density, high internal resistance, Young's modulus much higher than human skin, and easy mechanical mismatch. At the same time, piezoelectric sensors usually have high mass density and poor flexibility, and materials with high piezoelectric coefficient often contain lead, which does not meet the biological compatibility and is not suitable for preparing wearable sensors.

[0003] In contrast, flexoelectric effect as a new mechanism has unique advantages: it does not depend on the structural symmetry requirement of the material and almost exists in all dielectric materials, and its flexoelectric characteristics provide a new path for preparing high-sensitivity, lightweight and skin-friendly sensors. However, most of the existing sensors based on flexoelectricity have simple structure, low sensitivity, lack of systematic structural design strategy, and are difficult to meet the comprehensive performance requirements of high sensitivity, high flexibility and good conformability at the same time. SUMMARY

[0004] The present application proposes a motion state intelligent monitoring system and method based on flexoelectric polarization to solve the problems of low sensitivity, poor flexibility and insufficient adhesion of existing sensors. The system has good conformability and excellent force-electric coupling ability, and can realize high-accuracy recognition and real-time monitoring of various motion postures.

[0005] In the first aspect, the present application provides a motion state intelligent monitoring system based on flexoelectric polarization, which comprises a sensor module, a control module, an intelligent monitoring module and an energy supply module. The sensor module is used to collect data and transmit the data to the intelligent monitoring module through the control module for motion state monitoring. The energy supply module is used to supply power for the control module and the intelligent monitoring module.

[0006] The sensor module comprises a first electrode layer, a sensing layer and a second electrode layer which are sequentially stacked; the first electrode layer, the sensing layer and the second electrode layer each comprise a functional part and a packaging part arranged on both sides of the functional part; the first electrode layer and the second electrode layer outside the sensing layer are fixed through the packaging part; the functional part of the sensing layer can generate spontaneous flexoelectric polarization when subjected to tensile deformation, and generate electric charges on the upper and lower surfaces and are transmitted into the functional parts of the first electrode layer and the second electrode layer respectively; the packaging parts on the same side of the first electrode layer and the second electrode layer are connected with the control module, and are used for transmitting the electric charges in the functional parts into the control module.

[0007] Preferably, the functional parts of the first electrode layer, the sensing layer and the second electrode layer have the same structure and each comprise a plurality of unit cell structures arranged sequentially; the unit cell structure comprises three serpentine structures connected in sequence; the serpentine structure is composed of two curved beam structures spliced in different directions.

[0008] Preferably, the unit cell structures are arranged in the following manner: all the unit cell structures form a grid through the adhesion of the serpentine structures; the serpentine structures of adjacent unit cell structures in the grid are completely adhered, and each grid point is jointly converged by the vertices of six unit cell structures.

[0009] Preferably, the functional parts of the first electrode layer, the sensing layer and the second electrode layer have the same size.

[0010] Preferably, the control module comprises a signal amplification module and a communication module; the signal amplification module is used for receiving the electric charge signals output by the sensor module and converting the electric charge signals into voltage signals; and the communication module is used for transmitting the voltage signals to the intelligent monitoring module.

[0011] Preferably, the signal amplification module adopts a charge amplifier; and the sensing layer adopts a polydimethylsiloxane film.

[0012] Preferably, the side opposite to the first electrode layer and the second electrode layer of each of the first electrode layer and the second electrode layer is provided with a packaging layer; the two packaging layers are fixedly connected around; the packaging layers completely cover the first electrode layer and the second electrode layer, and the first electrode layer and the second electrode layer are fixedly connected with the packaging layers through the packaging parts.

[0013] In a second aspect, the application provides a motion state intelligent monitoring method based on flexoelectric polarization, which adopts the motion state intelligent monitoring system described above; the motion state intelligent monitoring method comprises the following steps:

[0014] The sensor module respectively collects the electric charge signals of different parts of the subject; the electric charge signals are transmitted to the control module through the electric leads, and the electric charge signals are converted into voltage signals by the control module and then input into the intelligent monitoring module; a data set is constructed based on the voltage signals collected by the intelligent monitoring module, and the data set is labeled.

[0015] The motion state monitoring model is constructed, and the motion state monitoring model is trained using a data set; the trained motion state monitoring model is used to monitor the motion state of a subject.

[0016] In a third aspect, the present application provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the memory stores the computer program; and the processor executes the motion state intelligent monitoring method described above.

[0017] In a fourth aspect, the present application provides a readable storage medium storing a computer program; when the computer program is executed by a processor, the motion state intelligent monitoring method described above is implemented.

[0018] The present application has the beneficial effects that:

[0019] 1. The present application constructs a sensor module formed by a unit cell structure, and introduces an anti-symmetrical snake structure with an initial curvature in the unit cell structure, so that the sensor module realizes excellent mechanical matching performance. At the same time, the sensor module in the present application utilizes the flexoelectric effect, and through structural design, the sensor module has a high transverse piezoelectric coefficient in a tensile state, and can output an electrical signal in real time with the user's movement.

[0020] 2. The present application uses a PDMS film as a sensing layer of the sensor module, so that the obtained sensing layer has good biocompatibility, low Young's modulus and excellent stretchability, and can realize electrical signal output by using the flexoelectric polarization in the tensile state; at the same time, the stress-strain curve of the sensor module in the present application presents a "J" shaped nonlinear response similar to biological tissues, and can be attached to the skin surface of different parts such as the back, wrist and leg, and realizes synchronous deformation during human movement, avoiding foreign body sensation. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0022] Figure 1 It is a schematic diagram of the overall structure of embodiment 1 of the present application.

[0023] Figure 2 It is a sensor module design diagram of embodiment 1 of the present application.

[0024] Figure 3The physical diagram of the sensor module in embodiment 1 of the present application.

[0025] Figure 4 The evolution flow chart of the single-cell structure in embodiment 1 of the present application.

[0026] Figure 5 The schematic diagram of the curved beam structure in embodiment 1 of the present application.

[0027] Figure 6 The simulated strain nephogram of the sensor module in embodiment 1 of the present application.

[0028] Figure 7 The stress-strain curve of the sensor module in embodiment 1 of the present application.

[0029] Figure 8 The overall flow chart of embodiment 2 of the present application.

[0030] Figure 9 The schematic diagram of the collection position of the voltage signal in embodiment 2 of the present application.

[0031] Figure 10 The schematic diagram of the voltage signal characteristics corresponding to different motion state types in embodiment 2 of the present application; wherein, (a) is the schematic diagram of the voltage signal characteristics corresponding to wrist bending; (b) is the schematic diagram of the voltage signal characteristics corresponding to running; (c) is the schematic diagram of the voltage signal characteristics corresponding to leg shaking; (d) is the schematic diagram of the voltage signal characteristics corresponding to twisting; (e) is the schematic diagram of the voltage signal characteristics corresponding to arm bending; (f) is the schematic diagram of the voltage signal characteristics corresponding to fist bending.

[0032] Figure 11 The flow chart of the motion state monitoring in embodiment 2 of the present application.

[0033] Figure 12 The t-distributed Stochastic Neighbor Embedding analysis schematic diagram corresponding to the motion state monitoring result in embodiment 2 of the present application.

[0034] Figure 13 The confusion matrix corresponding to the motion state monitoring result in embodiment 2 of the present application.

[0035] The figure legend: 1, first electrode layer; 2, sensing layer; 3, second electrode layer. DETAILED DESCRIPTION

[0036] The present application is further described below in combination with the drawings.

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1

[0039] like Figure 1 As shown, a motion state intelligent monitoring system based on flexural polarization can be attached to the skin surface of a user during movement and output electrical signals in real time. This intelligent motion state monitoring system includes a sensor module, a control module, an intelligent monitoring module, and a power supply module. The sensor module generates a charge signal after the monitored area is stretched and deformed, and this charge signal is transmitted to the control module through electrical wires. The control module includes a signal amplification module and a communication module. The signal amplification module receives the charge signal transmitted from the sensor module to the control module and converts this weak charge signal into a low-impedance voltage signal; the communication module transmits the converted voltage signal from the signal amplification module to the intelligent monitoring module. The intelligent monitoring module monitors the motion state of the monitored area based on the voltage signal transmitted from the communication module. The power supply module supplies power to the control module and the intelligent monitoring module.

[0040] In this embodiment, the signal amplification module uses a charge amplifier; the power supply module includes a first power supply module and a second power supply module; the first power supply module is used to supply power to the control module; and the second power supply module is used to supply power to the intelligent monitoring module.

[0041] like Figure 2 and Figure 3 As shown, the sensor module includes a first electrode layer 1, a sensing layer 2, and a second electrode layer 3, which are stacked and completely bonded together. Each of the first electrode layer 1, sensing layer 2, and second electrode layer 3 includes a functional section and encapsulation sections disposed on both sides of the functional section. The functional section of sensing layer 2 has the same dimensions as the functional sections of the first electrode layer 1 and the second electrode layer 3, and sensing layer 2 is fixed to the first electrode layer 1 and the second electrode layer 3 located outside sensing layer 2 by the encapsulation sections. When subjected to tensile deformation, the functional section of sensing layer 2 can undergo spontaneous flexural polarization, generating charges on its upper and lower surfaces, which are then transferred to the functional sections of the first electrode layer 1 and the second electrode layer 3, respectively. The encapsulation sections of the first electrode layer 1 and the second electrode layer 3 located on the same side are connected to the control module via electrical wires to transfer the charges located in the functional sections to the control module.

[0042] In this embodiment, the first electrode layer 1 and the second electrode layer 3 are both made of gold; and the sensing layer 2 is made of a PDMS (polydimethylsiloxane) film. The width of the packaging portion is 5 mm. The length of the first electrode layer 1, the sensing layer 2 and the second electrode layer 3 is 84 mm, and the width is 20 mm.

[0043] In this embodiment, the side opposite to the first electrode layer 1 and the second electrode layer 3 is provided with a packaging layer; the four sides of the two packaging layers are fixedly connected; the packaging layer completely covers the first electrode layer 1 and the second electrode layer 3, and the first electrode layer 1 and the second electrode layer 3 are fixedly connected with the packaging layer through the packaging portion. The packaging layer is made of a polyurethane film, and the electric wires are fixed on the packaging portion of the first electrode layer 1 and the second electrode layer 3 on the same side through the polyurethane film.

[0044] As shown in Figure 4 and Figure 5 , the functional portion of the first electrode layer 1, the sensing layer 2 and the second electrode layer 3 has the same structure, and each includes a plurality of unit cell structures arranged in sequence, and the unit cell structures in the first electrode layer 1, the sensing layer 2 and the second electrode layer 3 correspond one by one. Each unit cell structure is formed by sequentially connecting the heads and tails of three snake-shaped structures with the same size; the connection points of adjacent snake-shaped structures serve as the vertices of the unit cell structure, and the connecting line of the three vertices of the unit cell structure forms an equilateral triangle. The snake-shaped structure is formed by inversely splicing two curved beam structures with the same size; the span length L2 and the height H of the curved beam structure can be modified according to different monitoring areas.

[0045] In this embodiment, the unit cell structures in the functional portion are arranged in the following manner: all the unit cell structures form a grid through the adhesion of the snake-shaped structures; the snake-shaped structures of adjacent unit cell structures in the grid are completely adhered, and each grid point is jointly converged by the vertices of six unit cell structures.

[0046] In this embodiment, the span length L2 of the curved beam structure is 2 mm, and the height H is 0.2 mm.

[0047] The sensor module is respectively subjected to a simulation strain test and an actual uniaxial tensile test, and the results are shown in Figure 6 and Figure 7 . As can be seen from Figure 6 , the sensor module can adapt to different strains, and the maximum strain can reach about 60%. As can be seen from Figure 7 , the stress-strain curve of the sensor module as a whole presents a nonlinear J shape, which is consistent with the stress-strain curve law of the skin, is convenient for adhesion to the skin of the subject for monitoring the motion state, and improves the monitoring accuracy.

[0048] Embodiment 2

[0049] As shown in Figure 8As shown, a motion state intelligent monitoring method based on flexural polarization employs the motion state intelligent monitoring system described in Example 1. This motion state intelligent monitoring method includes the following steps:

[0050] like Figure 9 As shown, the sensor module collects electrical signals from different parts of the subject (including the wrist, arm, knee, ankle, and calf). Figure 9 The red circle indicates the attachment point for the sensor module. The electrical charge signal is transmitted to the control module via a wire, where it is converted into a voltage signal by a signal amplification module. This voltage signal is then transmitted to the intelligent monitoring module via a communication module for real-time voltage signal collection. A dataset is constructed based on the collected voltage signals and labeled accordingly. The dataset is labeled with the subject's motion state type, including wrist flexion, running, leg shaking, twisting, arm flexion, and fist clenching. The voltage signal characteristics corresponding to different motion state types are shown below. Figure 10 As shown.

[0051] Build a motion state monitoring model and train it using a dataset. For example... Figure 11 As shown, the trained motion state monitoring model was used to monitor the motion state of the subjects. The motion monitoring results are as follows: Figure 12 and 13 As shown. Figure 12 The six different colors and shapes of the symbols represent six different motion states, which are visualized through distributed random neighbor embedding analysis, showing a good classification of the six results. Figure 13 The confusion matrix in the figure shows the accuracy of the motion state monitoring model relative to the predicted data of the true category, demonstrating that the present invention can accurately identify the motion state type with 100% accuracy.

[0052] In summary, the FSMS in this invention can perfectly fit human skin, has a J-shaped stress-strain curve, and can output electrical signals. The system of this invention can accurately identify movement postures with 100% accuracy.

Claims

1. A motion state intelligent monitoring system based on flexoelectric polarization, comprising a sensor module, a control module, an intelligent monitoring module and an energy supply module; the sensor module is used to collect data and transmit it to the intelligent monitoring module through the control module for motion state monitoring; the energy supply module is used to supply power for the control module and the intelligent monitoring module; characterized in that: the sensor module comprises a first electrode layer (1), a sensing layer (2) and a second electrode layer (3) stacked in sequence; the first electrode layer (1), the sensing layer (2) and the second electrode layer (3) each comprise a functional part and a packaging part arranged on both sides of the functional part; the first electrode layer (1) and the second electrode layer (3) on the outside of the sensing layer (2) are fixed through the packaging part; the functional part of the sensing layer (2) can generate spontaneous flexoelectric polarization when subjected to tensile deformation, generating electric charges on the upper and lower surfaces and transmitting them into the functional part of the first electrode layer (1) and the second electrode layer (3) respectively; the packaging parts on the same side of the first electrode layer (1) and the second electrode layer (3) are connected with the control module, for transmitting the electric charges in the functional part to the control module. The functional parts of the first electrode layer (1), the sensing layer (2) and the second electrode layer (3) have the same structure and each comprise a plurality of unit cell structures arranged in sequence; the unit cell structure comprises three serpentine structures connected in sequence; the serpentine structure is composed of two curved beam structures spliced in different directions.

2. The motion state intelligent monitoring system based on flexoelectric polarization according to claim 1, characterized in that: The arrangement of the unit cell structures is as follows: all the unit cell structures form a grid by fitting the serpentine structures; the serpentine structures of adjacent unit cell structures in the grid are completely fitted, and each grid point is jointly converged by the vertices of six unit cell structures.

3. The motion state intelligent monitoring system based on flexoelectric polarization according to claim 2, characterized in that: The functional parts of the first electrode layer (1), the sensing layer (2) and the second electrode layer (3) have the same size.

4. The motion state intelligent monitoring system based on flexoelectric polarization according to claim 1, characterized in that: The control module comprises a signal amplification module and a communication module; the signal amplification module is used to receive the charge signal output by the sensor module and convert it into a voltage signal; the communication module is used to transmit the voltage signal to the intelligent monitoring module.

5. The motion state intelligent monitoring system based on flexoelectric polarization according to claim 1, characterized in that: The signal amplification module adopts a charge amplifier; the sensing layer (2) adopts a polydimethylsiloxane film.

6. The motion state intelligent monitoring system based on flexoelectric polarization according to claim 5, characterized in that: The side opposite to the first electrode layer (1) and the second electrode layer (3) is provided with a packaging layer; the two packaging layers are fixedly connected around; the packaging layer completely covers the first electrode layer (1) and the second electrode layer (3), and the first electrode layer (1) and the second electrode layer (3) are fixedly connected with the packaging layer through the packaging part.

7. The motion state intelligent monitoring system based on flexoelectric polarization according to claim 1, characterized in that: The motion state intelligent monitoring method comprises:

8. A method for monitoring the state of motion intelligently based on flexoelectric polarization, characterized in that: collecting the charge signals of different parts of the subject through the sensor module; transmitting the charge signals to the control module through the electric lead, and inputting the charge signals into the intelligent monitoring module after converting them into voltage signals through the control module; constructing a data set based on the voltage signals collected by the intelligent monitoring module, and performing label processing on the data set; constructing a motion state monitoring model and training it using the data set; using the trained motion state monitoring model to monitor the motion state of the subject. ​ 9. A computer device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that: The memory stores a computer program; and the processor executes the motion state intelligent monitoring method as claimed in claim 8.

10. A readable storage medium, storing a computer program; characterized in that: The computer program is executed by the processor to implement the motion state intelligent monitoring method as claimed in claim 8.

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