In order to improve the rectangle factor, the paper described the design of a hybrid structure SAW filter. By established simulate model, a hybrid structure of longitudinally coupled resonator filter cascading single resonator or multiple resonators are used, two kinds of SAW filters have been developed on 36°Y-X LiTaO3 and 41°Y-X LiNbO3 piezoelectric materials. The rectangle factor of the filters are 1.7 and 2, the test results are consistent with the simulation results.

In this paper an improved 3IDT-LCR structure was developed by theoretical simulation, and a low-loss SAW filter with small rectangular coefficients was successfully developed based on this structure. The device adopts 42°Y-X LiTaO3 piezoelectric substrate with nominal frequency 253.75 MHz, measured insertion loss 1.05 dB, lower-side stopband rejection nearly 80 dB, higher-side stopband rejection nearly 65 dB, -1 dB bandwidth 10.52 MHz, -3 dB bandwidth 12.54 MHz, -40 dB bandwidth 16.68 MHz, and rectangular coefficient 1.33. The measured results show that the SAW filter with improved 3IDT-LCR structure can achieve the performance characteristics of low insertion loss, small rectangular coefficient, and high stopband rejection at the same time.

In this paper, a phase demodulator based on surface acoustic wave (SAW) delay line is proposed. The basic idea is to demodulate a phase-modulated signal using the "delay addition" method after converting it to an amplitude-modulated (ASK) signal using a SAW delay line. The delay line achieves a delay time of 1 μs in the frequency range of 2.695 GHz to 3.00 GHz, and the proposed demodulator can demodulate BPSK-modulated signals with modulation rates of 500 kHz and 1 MHz.

In order to accurately design the SAW filter, it is necessary to extract accurate material parameters from the measured values of the reference SAW resonator. When measuring the SAW resonator, a single resonator cannot be directly tested, and a transmission line is required to contact the probe for measurement. The process of removing the influence of the transmission line is very important for the accurate extraction of SAW resonator material parameters. In this paper, several de-embedding methods of SAW resonators are introduced, including Open-Short algorithm, electromagnetic simulation method, segmented equivalent circuit model method, lumped parameter equivalent circuit method, and several commonly used de-embedding methods are verified and analyzed with examples.

In this paper, the resonator performance of a small hammer structure with the interdigital end of the total aperture length on an Incredible High-performance surface acoustic wave (I.H.P. SAW) substrate is researched. On the substrate structure of Y42°-lithium tantalate (Y42°-LT)/SiO2/polysilicon (Poly-Si)/Si, the corresponding 3D finite element simulation model was established. It was preliminarily concluded that the increase of the total aperture length with the hammer structure can suppress the stray in the transverse modes. The layouts of a single port resonator with a total aperture length of 7.5, 10, 15, 20, 25, 32.5, and 40 times of the period at 1.44, 2, and 2.56 m periods are drawn and taped out. According to the measured results, it is concluded that with the continuous increase of the total aperture length in different periods, the suppression of the transverse mode of the resonator will continue to increase, the electromechanical coupling coefficient will also continue to increase, and the impedance ratio is the highest near the period with a total aperture length of 20 times. The above simulation and measurement results show that the total aperture length has a great influence on the performance of I.H.P. SAW resonator, which provides design guidance for high-performance resonators used in I.H.P. SAW filters.

Based on FDTD numerical simulation method, the influence of the conductivity modulation on the resonant performance of ZnO bulk acoustic wave resonator, which provides guidance on the optimal design of the bulk acoustic wave amplifier, tunable filter and the detectors. The influence of the conductivity is introduced by the continuity equation. In order to improve the simulation accuracy, the fourth order Adams-Bashforth difference scheme was adopted in the continuity equation. The simulation results indicate that the resonant frequency of the ZnO bulk acoustic wave resonator can be significantly modulated by the conductivity when it is in the range of 1-30 mS/m.

This paper investigates the effect of the protective layer Al2O3 thickness on the acoustic characteristics and device performance in SAW high-temperature sensors with LGS as the piezoelectric substrate and Pt as the electrode using a multi-physics field coupled finite element model. The results show that the vibration displacement of the sound surface wave in the L-wave direction increases with the increase of the thickness of the Al2O3 protective layer. The vibration displacement in the SH and SV wave directions decreases.The diffusion of energy into the interior of the substrate at 6.25% of the normalized thickness of the protective layer. When the normalized layer thickness is 18.75%, the Rayleigh wave disappears and then the body wave BAW mode; increasing the Al2O3 protective layer, the wave velocity v and electromechanical coupling coefficient K2 increase significantly; First-order frequency temperature coefficient τf, 1 and conversion temperature increase with the increase of the protective layer thickness; using Al2O3 thin film for SAW temperature sensor structure optimization, in order to obtain good comprehensive performance normalized thickness should be around 0.94%.

In view of the problem that the receiving signal of the integrated piezoelectric micro mechanical ultrasonic transducer (PMUT) has a long tail, which makes it difficult to distinguish the near-field original echo and causes a blind area in measurement, a method to identify the echo signal in the tail section is proposed in this paper.The method uses demodulated logarithmic amplifier to compress the received signal nonlinearly and carry out envelope processing to obtain the envelope curve with obvious extremum point characteristics in the trailing section. The peak value of echo is identified by the extremum point of envelope curve. Eight groups of PMUT devices with different resonant frequencies were selected to test and verify the method. The results show that the measuring blind area is reduced to around 10 cm when the farthest distance is more than 300 cm, which demontrates that the proposed method has certain effectiveness and universality.

The relationship between the nonlinear effect of Lamb wave and temperature and stress of thermostat metal strip is studied, and the nonlinear ultrasonic testing system is established, and the stress value is determined by X-ray diffraction method. Heat the thermostat metal to 100 ℃, 200 ℃ and 310 ℃ respectively for one hour and then air cool it. Compare the influence of different temperatures on the nonlinear coefficient, and analyze the relationship between the nonlinear coefficient and the stress value of the thermostat metal under normal conditions and after stress reduction by heat treatment. The experimental results show that the nonlinear coefficient of the thermostat metal under normal temperature and after heating at 100 ℃ and 200 ℃ is basically unchanged, but after the stress reduction by heat treatment at 310 ℃. The nonlinear coefficient is significantly reduced. It is verified that the second-order and third-order nonlinear coefficients of Lamb wave in thermostat metal are sensitive to the stress value and increase with the increase of stress, which can be used to characterize the residual stress state. The fitting function can be obtained according to the relationship between the stress value and the nonlinear coefficient, and the feasibility of calculating the stress through the fitting function is verified, which provides a reference method for using the nonlinear coefficient to evaluate the stress.

The density detection of liquid products is one of the important means to audit product quality. Aiming at the problems of large volume, high power consumption and difficulty of online detection of the current traditional density detection device, a liquid density measurement sensor based on piezoelectric micromachined ultrasonic transducer (PMUT) was designed and fabricated in this paper. The sensor consists of two PMUTs (the radius is 500 μm, and the resonant frequency in air is 136 kHz), which are used as the transmitting end and the receiving end, respectively. The experimental test results show that the resonant frequency of the sensor has a linear relationship with the liquid density, it has a good response in the density range of 776 to 1 150 kg/m3, and the sensitivity is 17 Hz/kg/m3.

In this paper, W6+ doped 0.07Pb(Sc0.5Nb0.5)O3-0.93Pb(Hf0.47Ti0.53)O3 (PSN-PHT) ceramics were successfully synthesized by solid state reaction method, and the improvement of PSN-PHT ceramic properties was comprehensively analyzed from the aspects of microstructure, phase structure and electrical properties. The experimental results show that W6+ doping can increase the amount of rhombohedral in perovskite structure, effectively increase the grain size, and improve the piezoelectric coefficient. When the W6+ doping amount is 1.0 mol%, the sample has the best piezoelectric and dielectric properties, that is, d33=585 pC/N, TC=323 ℃, εr=2 088. More importantly, the d33 of PSN-PHT-1.0mol%WO3 ceramic still maintains a high value of 570 pC/N at the depolarization temperature of 200 ℃. After holding at 200 ℃ for 1 080 minutes, d33 can still reach 537 pC/N, with a change of only 5.7%. These results show that W6+ doping can improve the piezoelectric coefficient and enhance the temperature stability, so that it has a great application prospect in the field of high pressure-temperature service.

In order to obtain microwave dielectric ceramics sintered at low temperature, the Al2O3-SiO2-(Li2O-B2O3-SiO2-CaO-Al2O3) system microwave dielectric ceramic powders were prepared by the solid-state sintering method in this paper, and the Polyvinyl Butyral (PVB), glycerol, herring oil, ethanol and ethyl acetate were added to prepare the slurry, the microwave dielectric tape was obtained by the tape casting process. The surface morphology of the tape prepared at different proportions was analyzed by the scanning electron microscope (SEM). The results showed that the distribution of particles on the surface of the tape was more uniform when the mass ratio of PVB, glycerol,herring oil,ethanol and ethyl acetate was 25∶15∶2∶1∶7.The sintered density and sintered shrinkage ratio of the tape sample at different temperatures were measured and analyzed. The results showed that the density and shrinkage ratio of the tape samples reached the maximum at 870 ℃. In addition, the cross-section morphology of the tape sample after co-firing with Ag electrode was observed and analyzed by SEM, and the results showed that the tape was well co-fired with Ag electrode at 870 ℃.

In this paper, the barium titanate nanowires (BTO NWs) were prepared by two-step hydrothermal method, then compounding with the polyvinylidene fluoride (PVDF) by spin coating method to prepare the BTO NWs/PVDF composite films. The effects of different NaOH concentrations, different reaction times and different BTO NWs doping amounts on the piezoelectric output performance of BTO NWs/PVDF composite films in the hydrothermal reactions were systematically studied, and its piezoelectric properties were compared with those of BTO NPs/PVDF composite films prepared by the commercial barium titanate nanospheres (BTO NPs). The results show that when the NaOH concentration is 10 mol/L and the reaction time is 10 h, the open-circuit voltage and short-circuit current of BTO NWs/PVDF composite film can reach 5.42 V and 1.81 μA, respectively. When the doping amount of BTO NWs is 20wt%, the open-circuit voltage and short-circuit current of the composite piezoelectric film can reach 9.34 V and the short-circuit current can reach 2.15 μA, which is 1.92 and 1.49 times that of the BTO NPs/PVDF composite film, respectively. At a load resistance value of 5 MΩ, the output power of the BTO NWs/PVDF composite film can reach 1.44 μW. After 4 000 cycles of percussion test, the BTO NWs/PVDF piezoelectric composite film shows good mechanical stability. The prepared BTO NWs/PVDF piezoelectric composite film is expected to be widely used in self-powered devices and flexible wearable electronic devices.

In this paper, a simple and compact piezoelectric stick-slip rotary motor is proposed. The stator is designed by a force-coupled mechanism, and a double-stator piezoelectric stick-slip rotary motor is designed on this stator to improve the compactness of its structure. An asynchronous drive method is modified according to a typical sawtooth wave to enable the motor to achieve “increasing stickiness and reducing slippage”. An electromechanical-frictional coupling dynamics model of the motor is established, and a prototype motor is built and experimented accordingly. The experimental results show that the motor output displacement curve shows good stepping characteristics. The maximum single-step rotation angle and speed of the motor are 125 μrad and 6.3 (°)/s respectively when the driving voltage amplitude is 150 V and the frequency is 900 Hz, and its maximum load capacity is 30 g.

In this paper, an ultrasonic motor driven by piezoelectric stack is proposed, which takes advantage of the high output force of piezoelectric stack. The stator of the motor is composed of piezoelectric stack and metal elastic body structure. The stator generates traveling wave vibration under the alternating excitation signal, and drives the rotor to rotate through friction coupling. A prototype of the ultrasonic motor was fabricated and the experimental platform was set up. The test results show that there is a positive correlation between the motor speed and the driving voltage.speed within a certain range is positively correlated with the driving voltage. When the peak-to-peak value of the drive voltage is 310 V, the maximum output speed of the motor is 42.55 r/min and the output torque is 0.8 N·m.

A novel traveling wave ultrasonic motor having a stator with a square hole is proposed, designed, analyzed and experimented. The stator, which consists of a square-hole metal body and four piezoelectric ceramic plates, is elastically deformed by fitting with a rotor with a diameter greater than the inner length of the stator, thereby generating pre-pressure on the rotor for driving. The modal analysis of the stator is carried out by using the finite element method, and the third order mode is selected as the working mode. The relationships between the maximum amplitude of the stator and the excitation frequency, voltage, wall thickness, side length and corner radius are obtained, and the influence of frequency, voltage and pre-pressure on the output characteristics of the rotor is studied. A prototype is made and its output characteristics are tested. The experimental results show that under the signal excitation of 100 V and 31.5 kHz, the no-load speed can reach 215 r/min and the maximum stall torque is 1.58 mN·m.

The working frequency band width of piezoelectric vibrator is a key index that affects the efficiency of piezoelectric vibratory energy collector. In this paper, the modal frequency of an array piezoelectric vibration energy collector is analyzed, which can be used as a reference for the dynamic design of piezoelectric vibrators. Firstly, based on the vibration theory of the elastic beam, the dynamic equations of the saw-tooth piezoelectric beam are derived, and the factors affecting the modal frequency are analyzed. Then, the finite element model of the saw-tooth piezoelectric beam is established by COMSOL, and its frequency response, power and load impedance matching characteristic and acceleration dependence are analyzed. Finally, the voltage amplitude-frequency characteristic curve of the saw-tooth piezoelectric beam is tested by experimental research, which verifies the rationality of the theoretical analysis and simulation results. The results show that the saw-tooth array piezoelectric vibration energy collector can effectively broaden the working frequency band and improve the power generation efficiency.

The relationship between the thickness vibration resonant frequency and the size of 1-3-2 piezoelectric composites was studied in this paper. Using the theories of piezoelectricity and elastodynamics, the electromechanical equivalent diagram was established, the thickness vibration modes of 1-3-2 piezoelectric composites were analyzed by electromechanical theory, and the resonant frequency was calculated. The finite element simulation software was used to analyze the relationship among the resonant frequency, anti-resonant frequency and the dimensional variation of 1-3-2 piezoelectric composites in the thickness vibration mode. The results show that the frequency curve decreases when the longitudinal dimension ratio increases, the frequency curve increases when the transverse dimension ratio increases, the frequency curve decreases slowly when the ratio of transverse dimension to longitudinal dimension increases. The frequency curve decreases first and then increases when the thickness of the base increases. The longitudinal dimension ratio has the most significant influence on the overall resonant and anti-resonant frequencies in the four cases.

In this paper, the high frequency piezoelectric composite spherical transducer is simulated and designed. A finite element model is established by COMSOL software to calculate the acoustic radiation characteristics of the transducer. The influence of different piezoelectric ceramic materials and different primitive sizes on the acoustic radiation characteristics of the transducer is analyzed. The simulation results show that the spherical high-frequency transducer has the characteristics of high frequency, wide band and omnidirectional acoustic radiation, and can be widely used in underwater acoustic detection and imaging emission transducers and their arrays.

As an excellent multifunctional crystal material,lithiumtantalate has good piezoelectric, electro-optic and pyroelectric properties and is widely used in communication, electronics and other industries.This paper introduces the structure, defects and performance control methods of lithium tantalate crystal, summarizes the preparation methods, advantages and disadvantages of lithium tantalate crystal, analyzes the research progress of lithium tantalate crystal in various application fields at home and abroad, and prospects the development of lithium tantalate crystal, in order to provide assistance for the application and research of lithium tantalate crystals.

In order to achieve stable and accurate detection of methanol vapor concentration, a fiber Bragg grating (FBG) methanol sensor based on polymethyl methacrylate (PMMA) film was proposed. First, use hydrofluoric acid to etch part of the cladding layer, and coat a layer of PMMA film on the surface of the gate region. Then, a measurement system was constructed, and a theoretical model for the sensor to detect methanol vapor was established. Finally, a temperature compensation unit is introduced to eliminate the effect of temperature on the measurement of methanol vapor concentration. The effects of PMMA film thickness and temperature and humidity on the sensitivity of the sensor were experimentally studied, and the response time, selection sensitivity and detection limit of the sensor were tested. The results show that there is a linear relationship(R2=0.992) between the center wavelength drift of the sensor and the concentration in the methanol concentration range of 20-160 mg/L. In the temperature range of 20-40 ℃ and relative humidity of 40%-80%, the sensor can accurately detect the change of methanol vapor concentration with a sensitivity of 0.292 pm/(mg·L-1), a relative error of 9.3%, and a lower detection limit of 20 mg/L.

In this paper, a high-sensitivity fiber grating refractive index sensor based on direct femtosecond laser writing is proposed, and the temperature and axial strain characteristics of the sensor are also measured. A long-period grating with a period of 150 μm, a period number of 50, and a gate length of 7.5 mm was inscribed with a femtosecond laser at a wavelength of 800 nm. The sensitivity of the sensor in refractive index measurement experiment is up to 1 605 nm/RIU and a temperature sensitivity of 76.52 nm/℃ in the temperature range of 30 ℃ to 330 ℃. The sensor is stable and insensitive to strain with excellent robustness. This long-period fiber grating based on femtosecond laser direct writing with high refractive index sensitivity and high temperature resistance has a wide application prospect.

To accurately detect the H2 concentration in liquid phase, a H2 sensor was fabricated using palladium, silica superhydrophobic sol and tilted fiber grating. First, to respond the hydrogen concentration, a layer of dense Pd film was coated on the surface of the tilted fiber grating by using the magnetron sputtering method. Then, a layer of silicon oxide superhydrophobic film was coated on the surface of the Pd film by using a dip coater, which was used to prevent water molecules from entering into the palladium film, causing the palladium film to detach from the surface of the optical fiber, thereby enhancing the stability of the sensor in the liquid phase environment. The effect of the thickness of the Pd film on the hydrogen-sensitive response characteristics of the sensor was experimentally studied, and H2 concentration in the liquid phase was detected using the sensor. The study shows that the sensor can accurately respond to the change of the H2 concentration in liquid phase, and when the thickness of the Pd film is 120 nm, the sensitivity reached -15.29 pm/% and the maximum relative error is 8.67%.

Fast steering mirror (FSM) driven by piezoelectric ceramics has been widely used in the execution of adaptive optical systems. In order to accurately model its hysteresis effect, this paper proposes an IDE-BPNN modeling method for FSM. Based on Madelung’s rule, a symmetric hysteresis operator is constructed by least squares method as the basic description of hysteresis motion, and the training dataset is extended. The improved differential evolution algorithm (IDE) is used to train BP neural network (BPNN). The experiment shows that when a 30 Hz attenuated sine signal is input, the single-axis maximum error of the IDE-BPNN model is 0.745 μrad, the normalized maximum error is 0.87%, and the normalized root mean square error is 0.36%. Compared with the least squares model, the error of this model is greatly reduced and has good practical value.

Aiming at the difficulty of cable force monitoring in the construction and operation stages of large-span spatial cable structures, based on the strain-sensitive characteristics of fiber grating, an intelligent cable embedded with large range of fiber grating sensors is developed by using the "prestress principle" and groove packaging technology, which solves the defects of easy fracture and insufficient monitoring range of fiber Bragg grating sensors in engineering applications. On this basis, the main sensing performance indexes of the intelligent cable are verified by the tensioning test. The results show that the monitoring sensitivity of the fiber grating sensor is about 0.002 66 nm/kN and the linearity error is ≤2.86%, the hysteresis error is ≤1.53%, the repeatability error is ≤2.40%, the total accuracy is ≤4.03%, and the monitoring range can reach 80% of the ultimate bearing capacity of the cable. By using this technology, the construction tension of the cable network structure of a sports stadium is monitored in real-time by using fiber Bragg grating sensor, and the monitoring load of fiber Bragg grating sensor is compared with the tension load of the jack, and the error between the two is only 2.95% after the cable tension is completed. This technology enables high precision cable force monitoring through the full life cycle of the cable.

In order to realize the high precision and high stability measurement of wind speed and direction in complex environment, the closed-loop control scanning technology is adopted on the basis of the wind sensor system based on the acoustic resonance principle, and the performance index of the system is greatly improved. The linear scanning of ultrasonic transducer is realized by means of acoustic resonance, and frequency modulation and intensity modulation of the signal generated by the transducer. Frequency modulation solves the problem of resonance frequency shift caused by different environmental factors such as pressure and temperature, intensity modulation solves the problem of the performance of the transducer attenuation over time, and greatly improves the signal-to-noise ratio. The experimental results show that the wind speed and direction can be measured accurately by using the closed-loop control method. Wind speed measurement range 0-50 m/s, wind speed measurement accuracy ±0.5m/s (≤15 m/s) /±5% (> 15 m/s and 35 m/s). The improved system is less affected by environmental changes in complex environment, has high accuracy, good stability and strong anti-interference ability.

The radar attitude determination system is actually an inertial navigation system. If it is not calibrated for a long time, the zero position of the accelerometer will change, which will directly affect the accuracy of horizontal measurement. In order to solve this problem, this paper analyzes the system error mechanism and observability. According to the actual radar antenna motion range, a zero reference error compensation scheme of accelerometer without disassembly is proposed. The calibration method is simple and can effectively identify and estimate the zero error of three-axis accelerometer, and the dynamic horizontal reference accuracy after compensation is improved from 2′ to 0.5′, which is especially suitable for large equipment such as radar trucks that are inconvenient to disassemble.

The sensitivity mechanism of a thermal oscillator type biaxial MEMS angular velocity gyro was revealed. The temperature field inside the sensitive structure was calculated on the basis of the biaxial sensitivity principle, the vibration mode of the thermal oscillator and the gyroscopic effect. The results show that: A stable temperature field is formed inside the sensitive structure after 1.8 s of power-on. When there is angular velocity loading, the thermal oscillator moves with the input angular velocity, causing the temperature field to shift, and the temperature difference ΔTY(ΔTX)S between the two hot lines set symmetrically in the two orthogonal Y(X) directions shows a linear growth with the increase of the input angular velocity ax(ay), and the average temperature sensitivity of x and y axes is 121 mK/(°)/s. According to the input-output ωx-VYout and ωy-VXout characteristic curves, the mathematical model is obtained and the sensitive mechanism is revealed. The average sensitivity of x and y axes is 0.091 mV/(°)/s, the average nonlinearity is 1.86%, and the average cross-coupling is 2.3%. This paper provides a practical theoretical foundation for the optimized structure.

The storage life is one of the important assessment indicators for products with long service life and high reliability. In order to evaluate the storage life of a certain type of acceleration switch, the degradation process of acceleration switch was studied by using the constant stress acceleration test method with temperature stress four orders of magnitude. The reliability model was established by combining the Arrhenius acceleration model with the drift-Brownian motion. Finally, the maximum likelihood estimation and least square method were used to fit and analyze the experimental data. The results showed that the equivalent storage life of the acceleration switch was up to 33 years under the acceleration magnitude of 100 ℃, which met the requirements of effective storage life of the product.