803 results about "Piezoelectric thin films" patented technology

The invention discloses a temperature and humidity adaptive control system and method for drying flower traditional Chinese medicinal materials, and the system comprises a humidity gradient monitoring module which is used for deploying a 12-channel capacitive humidity sensor spiral array and a laser radar, generating a three-dimensional humidity field thermodynamic diagram in combination with a Kriging interpolation method, calculating a humidity gradient change rate in real time, and carrying out the early warning of local abnormality; the heat-humidity ratio regulation and control module is used for integrating humidity gradient monitoring data and a real-time result of the evaporation latent heat calculation module based on a fuzzy PID algorithm, dynamically adjusting the heating power and the rotating speed of a dehumidification fan, and meanwhile, integrating a PVDF piezoelectric film sensor to monitor petal stress; the evaporation latent heat calculation module is used for predicting a future evaporation rate by combining an LSTM neural network based on an edge calculation unit and providing key parameters for the energy supply matching module; the energy supply matching module is used for outputting a combined control instruction of the heating power and the air door opening degree; and the air volume balance optimization module is used for dynamically adjusting air volume distribution according to the humidity gradient monitoring data.

The invention relates to the technical field of stoma nursing devices, and discloses an AI visual stoma leakage early warning system, which comprises a plurality of passive piezoelectric film sensors embedded in a stoma chassis and used for capturing acoustic signals generated by adhesion interface structure instability; the edge calculation unit periodically collects an electric signal sequence and calculates an information entropy value, and through comparison with a self-adaptive resting entropy baseline, the structural instability risk is judged and early warning is generated when the entropy value continuously and abnormally rises. The risk orientation is accurately identified in combination with a multi-sensor cooperative positioning technology, body movement interference is avoided by using a dynamic compensation mechanism, and the early warning accuracy and clinical practicability are improved.

The invention relates to the technical field of pipeline detection, and provides a non-contact pipeline fluid flow velocity measurement method based on a frequency wavenumber domain spatial spectrogram, and the method comprises the steps: collecting a turbulence signal in a pipeline through a piezoelectric film sensor; carrying out snapshot number segmentation on the turbulence signal to obtain a plurality of segmented turbulence time domain signals; fourier transform and narrowband signal processing are carried out on the segmented turbulence time domain signals, and a spatial spectrum corresponding to each narrowband signal component is obtained; constructing a three-dimensional frequency-wave number domain spectrogram according to the spatial spectrum function; and according to the three-dimensional frequency-wavenumber domain spectrogram, calculating the flow velocity of the pipeline fluid. According to the method, a three-dimensional spectrogram characteristic space is constructed through conjoint analysis of the frequency and the wave number, the angle, distance and frequency characteristics of the turbulence signals are decoupled through spatial spectrum estimation methods such as the MUSIC algorithm, multipath interference and noise are effectively restrained, the flow speed of fluid in a pipeline can be accurately estimated, and limitation in a traditional method is overcome.

A film bulk acoustic wave resonator comprising a piezoelectric film having a central region defining a main active domain in which a main acoustic wave is generated during operation, an upper electrode disposed on a top surface of the piezoelectric film, a lower electrode disposed on a lower surface of the piezoelectric film, a dielectric material layer disposed on a lower surface of the lower electrode, and lower recessed frame regions disposed laterally on opposite sides of the central region, the lower recessed frame regions defined by regions of one of the dielectric material or of the lower electrode having a lesser thickness than the thickness of the one of the dielectric material layer or of the lower electrode in the central region.

The invention discloses a micro-fluidic liquid cooling heat dissipation module integrated with piezoelectric driving, a chip and application, and belongs to the technical field of chip liquid cooling heat dissipation. The micro-fluidic liquid cooling heat dissipation module comprises a micro-fluidic substrate and a piezoelectric film, the piezoelectric film covers the surface of one side of the microfluidic substrate; a groove channel is formed in the surface of one side, facing the piezoelectric film, of the micro-fluidic substrate; a loop cavity defined by the piezoelectric film and the groove channel forms a micro-channel; a metal electrode layer, a heat source area and a heat exchange area are respectively arranged at different positions, corresponding to the micro-channel, on the surface of one side, deviating from the micro-fluidic substrate, of the piezoelectric film. The micro-fluidic liquid cooling heat dissipation module can actively drive the cooling liquid to flow to a heat source area, and compared with a traditional micro-channel heat dissipation mode, the micro-fluidic liquid cooling heat dissipation module has very high flexibility in fluid driving, does not need an external driving pump, can greatly reduce the size of a packaged chip, and is beneficial to development of chip integration and microminiaturization.

An acoustic wave device includes a piezoelectric film and an IDT electrode on the piezoelectric film. The IDT electrode includes first and second busbars, at least one first electrode finger, and at least one second electrode finger. When an overlap region is defined as a region in which the first and second electrode fingers overlap each other in an acoustic wave propagation direction, points A2, B2, C2, and D2, defined as follows, are all outside the cavity when, at the points A2, B2, C2, and D2, xa>about 25 μm, ya>about 25 μm, xb>about 25 μm, yb>about 25 μm, xc>about 25 μm, yc>about 25 μm, xd>about 25 μm, and yd>about 25 μm.

The invention discloses a piezoelectric film partition dynamic focusing system and method for intelligent glasses. The piezoelectric film partition dynamic focusing system comprises an optical modulation layer, a sensing layer, a control engine, a hybrid driving layer and a closed loop verification module. The optical modulation layer is integrated with an N * M piezoelectric film array, each subarea is provided with an independent electrode and a gradient thickness structure, and intervals are filled with low-modulus insulating polymers. The sensing layer is used for acquiring fixation point, diopter, temperature and head movement information of a wearer; and the control engine executes voltage mapping, temperature drift compensation and resonance suppression according to the sensing data, and drives the hybrid driving layer to complete deformation and displacement compensation. And the closed-loop verification module outputs a defocusing error in real time and feeds back a correction voltage. According to the invention, high-response, low-power-consumption and stable dynamic focusing is realized, and the visual adaptability is improved.

The invention discloses a piezoelectric air cooling device based on a piezoelectric film PZT technology, and relates to the technical field of MEMS. The device adopts a two-layer packaging structure of a piezoelectric cantilever beam MEMS chip and a PCB (Printed Circuit Board) with a vent hole. A cantilever beam of the MEMS chip is integrated with an SOI top silicon layer and an ultrathin PZT driving stack, low rigidity and high driving force are achieved, and the surface of the cantilever beam is covered with a PDMS flexible sealing layer to achieve dynamic sealing. When the device works, the cantilever beam is driven to resonate in an ultrasonic frequency band, and efficient synthetic jet is generated at the vent hole by periodically changing the volume of the pump cavity. The technical bottleneck that miniaturization and high performance are difficult to consider at the same time is broken through, and the device has the advantages of being compact in structure, mute and efficient and is suitable for precise heat dissipation of miniature electronic equipment.

The invention discloses a piezoelectric cantilever beam energy collector, and the collector comprises a fixed part 1 which is used for fixing the collector at a certain position; the supporting beam and the fixing piece 1 are connected into a whole, the supporting beam comprises a bionic bamboo joint structure 2 close to one end of the fixing piece 1 and a mass structure 3 far away from one end of the fixing piece 1, and at least one micropore 6 penetrating through the upper surface and the lower surface of the supporting beam is formed in the bionic bamboo joint structure 2 and used for forming alternate rigid segments and flexible nodes on the bionic bamboo joint structure 2; the supporting beam swings with the end close to the fixing piece 1 as the circle center in the vibration environment. The mass block 5 is arranged on the mass structure 3; the number of the piezoelectric films 4 is two, the two piezoelectric films 4 are arranged on the upper surface and the lower surface of the bionic bamboo joint structure 2 respectively, and the piezoelectric films 4 cover the micropores 6 formed in the bionic bamboo joint structure 2.

The invention discloses a two-phase-driven piezoelectric traveling wave micro-motor structure and a preparation method, and belongs to the field of micro-motors, the two-phase-driven piezoelectric traveling wave micro-motor structure comprises piezoelectric ceramic films arranged in partitions, upper electrodes arranged in partitions and lower electrodes arranged in partitions, and in corresponding partitions, the upper electrodes and the lower electrodes of the corresponding partitions are connected with the corresponding piezoelectric ceramic films respectively; the polarization characteristics of the piezoelectric ceramic films can be the same or different; when the same conditions are met, the first piezoelectric ceramic film is connected with an upper electrode and a sin signal, the lower electrode is connected with GND, the second piezoelectric ceramic film is connected with an upper electrode and a cos signal, the lower electrode is connected with GND, the third piezoelectric ceramic film is connected with an upper electrode and a GND, the lower electrode is connected with a sin signal, the fourth piezoelectric ceramic film is connected with an upper electrode and a GND, and the lower electrode is connected with a cos signal; the wiring of the four piezoelectric films in one period is the same, and the arrays in other periods are repeated and are the same in sequence. The size and power consumption of the driving circuit are reduced, and batch manufacturing is easy.

The invention relates to a preparation method of a single-crystal piezoelectric film bulk acoustic resonator, and relates to the field of semiconductor device production processes, and the preparation method comprises the following steps: S1, preparing a single-crystal piezoelectric film and an electrode layer on a first substrate; s2, patterning the single crystal piezoelectric film and the electrode layer; s3, temporarily bonding the supporting slide glass with the first substrate through the adhesion layer; s4, removing the first substrate; s5, etching a photoetching through hole in the thin film body; s6, depositing metal to form a connecting part and a lower electrode; s7, processing a cavity structure on the second substrate; s8, preparing a transition layer on the surface of the second substrate; s9, removing the first part; s10, preparing a bonding layer on the second substrate; s11, processing a communication hole in the bonding layer and removing the second part; s12, bonding the lower electrode and the second substrate; and S13, removing the supporting slide glass and the adhesion layer. The method has the advantages that the bonding material uniformly covers the surface of the second substrate and the cavity structure, weak points are prevented from being formed at the cavity structure, and the reliability and stability of the bonding process are remarkably improved.

The invention relates to the technical field of photovoltaic module manufacturing, in particular to a photovoltaic module vacuum laminating system based on dynamic pressure feedback. The dynamic pressure adjusting module comprises a piezoelectric film sensor and a servo motor, the piezoelectric film sensor is used for detecting the pressure borne by the photovoltaic module, and the control module calculates and obtains the real-time optimal pressure and then controls the servo motor to act so as to achieve the real-time optimal pressure; the heating control module comprises a heating plate, a thermal infrared imager and a PID temperature control unit, the heating plate is used for heating the photovoltaic module, the thermal infrared imager is used for detecting the surface temperature distribution of the photovoltaic module, and the PID temperature control unit is used for controlling the temperature of the heating plate; the vacuum control module comprises a plurality of air chambers which are independently arranged, each air chamber is provided with an air inlet pipeline and an air outlet pipeline which are communicated with the laminating machine cavity, and micro electromagnetic valves are arranged on the air inlet pipelines and the air outlet pipelines.

An acoustic wave device (10) using a surface acoustic wave, comprising: a substrate (11) containing 70 mass% or more of silicon dioxide (SiO2); a piezoelectric thin film (12) formed of LiTaO3 crystal or LiNbO3 crystal disposed on the substrate (11); and an interdigital transducer electrode (13) arranged in contact with the piezoelectric thin film (12); wherein Euler angle of the substrate (11) and Euler angle of the piezoelectric thin film (12) are selected such that a phase velocity of the surface acoustic wave propagating along the substrate (11) is greater than a phase velocity of the surface acoustic wave propagating along the piezoelectric thin film (12).

The invention discloses a digital stethoscope system based on a piezoelectric film, and relates to the technical field of medical electronics and biomedical engineering. An existing digital stethoscope based on a piezoelectric film has the challenges of signal noise and interference, limitation of a signal processing algorithm, nonlinear response and time migration, insufficient diagnosis accuracy and automation and the like. A piezoelectric film and microphone dual audio acquisition mode is fused, various physiological signals such as low-frequency vibration and high-quality heart and lung sound are captured, and background noise is removed through a self-adaptive filter and a frequency spectrum subtraction technology; an MFCC feature extraction and dynamic time warping algorithm is utilized to carry out fine feature analysis and time axis alignment on the preprocessed audio signal, and high-precision matching with a storage template is realized; different physiological states are accurately distinguished through intelligent feature processing, real-time and visual diagnosis feedback is achieved through wireless transmission and state indication, and the reliability and efficiency of medical detection are improved.

The invention relates to an acoustic resonator device and a forming method thereof, and a radio frequency filter. The acoustic resonator device comprises a substrate layer; the sacrificial layer is located on the substrate layer and comprises a cavity; the piezoelectric film layer is located on the sacrificial layer and comprises at least one strip-shaped piezoelectric film and etching grooves located in the two sides of each strip-shaped piezoelectric film, and the etching grooves are communicated with the cavity; the bottom conductor layer is located below the piezoelectric film layer and comprises a bottom bus bar and at least one bottom finger bar electrode suspended in the cavity; the top conductor layer is located on the piezoelectric film layer and comprises a top bus bar, a top terminal, a bottom terminal and at least one top finger bar electrode; the top finger strip electrodes, the bottom finger strip electrodes and the strip-shaped piezoelectric films are in one-to-one correspondence. In the embodiment of the invention, the suspended top finger strip electrode, the strip-shaped piezoelectric film and the bottom finger strip electrode are arranged in the device to support a mode of double shear bulk acoustic waves excited by a vertical electric field, so that the device meets the requirements of higher frequency and larger bandwidth.

Electric generators are described herein integrating thermoelectric and piezoelectric components. In some embodiments, an electric generator comprises a thermoelectric film having a plurality of lateral p-n junctions across a face of the film, the lateral p-n junctions established at interfaces between p-type regions and n-type regions. A piezoelectric film is coupled to the thermoelectric film and an electrode is coupled to the piezoelectric film.

The invention discloses piezoelectric catalysis-Fenton self-coupling staged underground water treatment equipment, and relates to the technical field of underground water pollution abatement, the piezoelectric catalysis-Fenton self-coupling staged underground water treatment equipment comprises a reactor main body, a piezoelectric-aeration water treatment module and a PVDF-HFP piezoelectric film array, the piezoelectric-aeration water treatment module is fixedly arranged in a piezoelectric-aeration catalysis reaction zone, and the PVDF-HFP piezoelectric film array is fixedly arranged in the reactor main body; the PVDF-HFP piezoelectric film array is fixedly arranged in the Fenton-piezoelectric catalysis enhanced reaction zone; the piezoelectric-aeration water treatment module comprises a micro-nano bubble generator, a micro-nano diaphragm and a piezoelectric composite filler, a filler containing cavity is formed between the micro-nano bubble generator and the micro-nano diaphragm, and the piezoelectric composite filler is filled in the filler containing cavity; the micro-nano bubble generator is connected with the dissolved air pump through a first air inlet pipe; and a Fenton filler is loaded on the surface of the PVDF-HFP piezoelectric film array. According to the invention, high-efficiency and low-consumption remediation and treatment of the water body can be realized in an underground water environment.

The invention discloses a lower limb movement monitoring and guiding method. A hardware part comprises a flexible induction sheet array, a smart phone, a built-in RGB-D camera of the smart phone and an edge calculation module. The flexible induction sheet array comprises five flexible induction sheets, each flexible induction sheet comprises a skin contact layer, a sensor layer, a flexible FPC substrate and a protective layer, the sensor layer is provided with a three-axis MEMS acceleration sensor, a PVDF piezoelectric film sensor, a flexible FPC substrate integrated signal conditioning module and a Bluetooth communication module; the flexible induction sheet is provided with an anatomical positioning mark; the lower limb movement monitoring and guiding method comprises the following steps: S1, cleaning; s2, a step of attaching a flexible induction sheet; s3, an automatic positioning calibration step; s4, a data transmission step; s5, a data fusion and calculation analysis step; s6, a normalization evaluation step; and S7, a feedback and optimization step. Quantitative assessment of lower limb movement can be effectively achieved, and the monitoring and guiding effect is good.

The invention discloses a high-temperature strain film sensor for detecting thermal stress of a small square billet crystallizer, and relates to the technical field of sensors, the high-temperature strain film sensor comprises a composite system formed by fiber structures, the fiber structures are interwoven and interspersed, and the composite system sequentially comprises a substrate layer, a high-temperature insulating layer, a piezoelectric film layer and a multifunctional composite layer from bottom to top; a channel is arranged in the piezoelectric film layer, the channel penetrates to the high-temperature insulating layer and the multifunctional composite layer, and the channel is connected with external equipment through a lead electrode. The multifunctional composite layer comprises a thermocouple array and a sensitive grid unit which are distributed in parallel and interwoven, and the thermocouple array is used for superposing the thermoelectric effect and increasing the output situation; the sensitive grid unit is used for converting strain of the crystallizer steel pipe into electric signals through sensitive grid deformation and outputting the electric signals, and real-time measurement of stress and strain on the surface or in the crystallizer is achieved. The sensor designed by the invention is good in high temperature resistance, good in structural stability, long in service life and high in measurement precision.

The invention relates to the field of microelectronic devices, in particular to a bulk acoustic wave resonator with a double-layer piezoelectric film structure, a preparation method and a filter, the bulk acoustic wave resonator comprises a cap wafer, and a dry film, a passivation layer, a silicon oxide layer, a high-resistance silicon wafer and RDL metal are sequentially arranged on the cap wafer; the dry film and the cap wafer form a dry film cavity, the passivation layer located above the dry film cavity extends into the dry film cavity, and a top electrode, a first piezoelectric film, a middle electrode, a second piezoelectric film and a bottom electrode are sequentially arranged on the passivation layer; the top electrode and the bottom electrode are used as first ports of the resonator; and the middle electrode is a second port. According to the resonator, the excitation mode of the resonator is changed through cooperation of the two layers of piezoelectric films with the same polarization direction and the intermediate electrode, a high-order resonance mode is jointly excited, meanwhile, a high electromechanical coupling coefficient is kept, and a wide fractional bandwidth is achieved at high frequency through the relatively thick piezoelectric films; the problems that a high-frequency resonator is weak in power bearing capacity, narrow in bandwidth, low in quality factor and poor in stability are solved.

The invention relates to the technical field of piezoelectric micropumps, in particular to an ultrasonic traveling wave piezoelectric micropump which comprises a semiconductor substrate and further comprises a piezoelectric film arranged on the semiconductor substrate. The plurality of driving electrodes are arranged on the piezoelectric film; the micro-channel cavity is bonded with the piezoelectric film to form a sealed channel for liquid flowing, and the micro-channel cavity is provided with a liquid inlet / outlet; wherein the plurality of driving electrodes are configured to input alternating current electric signals with fixed phase difference, so as to excite ultrasonic traveling waves used for driving liquid in the sealed flow channel to directionally flow in the piezoelectric film. The invention aims to solve the technical problems that the piezoelectric micropump is low in directional driving efficiency and difficult to adapt to complex working conditions.

The invention belongs to the technical field of biological signal processing and monitoring, and particularly relates to a multi-mode-based non-contact heart rate intelligent monitoring method which comprises the steps that a ballistocardiogram signal of a user is collected through a piezoelectric film sensor, meanwhile, a photoelectric volume pulse wave signal of the user is collected through a photoelectric sensor, and a multi-mode physiological signal is formed; performing space-time alignment processing on the multi-modal physiological signal, eliminating low-frequency breathing interference and motion noise by adopting an adaptive filtering algorithm, and outputting a pre-processed signal; inputting the preprocessed signal into a space-time coupling feature analysis engine, extracting time sequence features through a bidirectional long-short-term memory network, and extracting spatial features through a full convolutional network; adopting a multi-head self-attention mechanism to carry out dynamic weight fusion on the time sequence features and the spatial features to obtain fusion features; and calculating a real-time heart rate value based on the fused features, and judging a heart rate abnormal state. The problem that the heart rate monitoring difficulty is large is well solved.

The invention discloses a bimodal pressure sensor array and device.The bimodal pressure sensor array comprises a piezoelectric actuator, an elastic piezoresistive substrate array and a pressure sensor unit which are arranged from inside to outside, and the pressure sensor unit comprises a piezoelectric film array layer; the pressure measurement is realized based on the piezoelectric response of the piezoelectric film array layer and the vibration of the piezoelectric actuator; based on the piezoelectric response of the piezoelectric film array layer, the vibration of the piezoelectric actuator and the deformation of the elastic piezoresistive substrate array, the direction and angle measurement is realized. Pressure measurement and bending angle measurement can be simultaneously realized on a single device, and the unique dual-function sensing technology has huge application potential in the medical field.

The present invention relates to the fields of ferroelectric single crystal technology and acousto-optical device technology, particularly to a silicon-based lead magnesium niobate (PbMn) single crystal piezoelectric wafer structure, preparation method, and application. The structure comprises a silicon substrate on which a silicon dioxide layer and a single crystal piezoelectric thin film layer are sequentially disposed; the single crystal piezoelectric thin film layer is a PbMn-PT single crystal, including a binary PMN-PT single crystal thin film or a ternary PIN-PMN-PT single crystal thin film. This piezoelectric wafer structure on a silicon substrate can be used to fabricate various high-performance piezoelectric MEMS sensors, actuators, and electro-optical modulator devices. The resulting surface acoustic wave (SAW) filters and thin film bulk acoustic wave (BAW) filters exhibit a relative bandwidth increase of over 50%, and the resulting electro-optical modulators exhibit lower half-wave voltage and higher electro-optical modulation efficiency. The device volume can be reduced by 10 times, better meeting the future 6G communication requirements for higher efficiency, higher integration, and miniaturization of MEMS devices. This provides a novel multilayer piezoelectric wafer structure for the miniaturization and integration of piezoelectric MEMS and optoelectronic devices.

The invention discloses a road surface state recognition method based on machine vision and force feedback. The method comprises the following steps: S1, continuously shooting a front road surface image flow by using a vehicle front-end image acquisition device; s2, automatically segmenting a road surface abnormal region by adopting an arbitrary target segmentation model; s3, arranging a piezoelectric film vibration sensing unit in the contact surface of the vehicle tire and the road surface to collect tiny vibration signals in real time; s4, extracting time domain and frequency domain features of the vibration signals; s5, performing vision and force feedback feature multi-scale coding; s6, dynamically adjusting the weights of the two modal features, and generating fusion decision features; and S7, outputting a road surface state recognition result. The method is used for improving automatic driving safety.

The invention relates to the fields of information electronic material technology, information communication, wireless radio frequency communication and the like, in particular to a surface acoustic wave device and a preparation method thereof.The preparation method comprises the steps that after a metal film is deposited, patterned stripping is conducted on an interdigital electrode layer, and when patterned stripping is conducted on the interdigital electrode layer, a non-closed release window is formed; partially overlapping the thickened electrode layer from the direction of the non-closed release window to form a closed release window; etching the piezoelectric film exposed in the closed release window to form a release hole; and the sinking material is further released through the release holes so as to form a suspended piezoelectric film. According to the invention, by optimizing the patterning design and the processing flow of the resonator membrane structure, the release window in the bus bar region is efficiently stripped, the stripping processing difficulty of the bus bar electrode is reduced, and the stripping success rate of the bus bar electrode is improved.

The invention discloses an AlScN thin film with a lattice matching buffer layer, the AlScN thin film is of a stacked structure formed by a substrate, an intermediate lattice matching buffer layer and a piezoelectric thin film surface layer, an intrinsic AlN thin film is grown on the substrate in situ to serve as the intermediate lattice matching buffer layer, and AlScN is deposited on the intermediate lattice matching buffer layer to serve as the piezoelectric thin film surface layer; an intrinsic AlN thin film is grown on a substrate in situ to serve as a lattice matching intermediate layer, then an AlScN thin film is prepared through magnetron sputtering double-target co-sputtering, the AlScN thin film of a laminated structure is formed, the crystal quality and lattice matching performance of the AlScN thin film can be remarkably improved, the matching performance is beneficial to reduction of crystal defects and reduction of the phase separation phenomenon in the thin film, and the performance of the AlScN thin film is improved. According to the preparation method, the structural integrity and stability of the material are enhanced, the prepared AlScN film is more compact, more uniform and high in quality, the physical and electrical properties of the material are remarkably improved, and meanwhile, the economic cost is saved.

The invention relates to the technical field of psychological health monitoring, and particularly discloses a psychological risk dynamic assessment system and method based on sleep HRV characteristics, the system comprises a signal acquisition module, the signal acquisition module is integrated with a piezoelectric film sensor, a signal amplification circuit, an MCU and a data transmission module, the piezoelectric film sensor is arranged under a mattress, and the signal amplification circuit is connected with the signal acquisition module; the signal acquisition module is used for acquiring a BCG signal; the data processing module is used for processing the BCG signal and converting the BCG signal into an HRV (High Rate Voltage) characteristic value; the risk assessment module is used for generating a dynamic psychological risk assessment result through an HRV-emotion index mapping model on the basis of the HRV feature value; the user interaction module is used for displaying the dynamic psychological risk assessment result through a man-machine interaction device; bCG signals during sleep are collected in a non-contact mode, and HRV features are extracted based on the BCG signals, so that dynamic assessment of psychological risks is achieved.

A piezoelectric actuator comprises a stack of a plurality of piezoelectric films, a piezoelectric element having electrodes disposed between the piezoelectric films and at both end surfaces, and a drive circuit. Each of the plurality of piezoelectric films has asymmetric polarization-voltage hysteresis characteristics with two different absolute values of coercive voltage. The drive circuit applies a unipolar voltage waveform that generates an electric field in the same direction as the direction of spontaneous polarization in at least one layer from among the plurality of piezoelectric films and generates an electric field in the direction opposite to the direction of spontaneous polarization in the other piezoelectric films. A minimum voltage value V1 having a minimum absolute value in the unipolar voltage waveform is set such that the ratio of the slope T0 at 0 [V] to the slope T1 at the minimum voltage value V1 [V] in a hysteresis curve indicating bipolar polarization-hysteresis characteristics in another piezoelectric film satisfies |T0 / T1| ≥ 1.5.

Through the multi-sensor fusion design of the microphone, the millimeter wave radar sensor and the piezoelectric film sensor, compared with an existing single or double-sensor sleep monitoring technology, the monitoring precision, the function dimension, the environmental adaptability and the like are remarkably improved. According to the method, a weighted voting decision fusion mechanism and an improved random forest model are adopted, and after a microphone acoustic monitoring dimension is newly added, the apnea detection sensitivity is improved; acoustic characteristics such as snore, breath sound rhythm, cough and dream can be accurately captured; health risk assessment dimensions are richer, preliminary screening of diseases such as sleep apnea syndrome and periodic limb dyskinesia can be realized, snore indexes and breathing stability are newly increased, and a multi-dimensional sleep quality report is provided for a user; in the whole process, an electrode plate or a wrist strap does not need to be worn, the three sensors all adopt non-intrusive design, no foreign body sensation exists after the piezoelectric film is embedded into the mattress, the problem of wearing discomfort of traditional monitoring is solved, and the user compliance is improved.