Halide perovskites with excellent piezoelectric properties,but their poor stability hinders their largescale application.Herein,a sandwich-structured halide perovskite flexible sensor with good stability was developed...Halide perovskites with excellent piezoelectric properties,but their poor stability hinders their largescale application.Herein,a sandwich-structured halide perovskite flexible sensor with good stability was developed according to a three-step procedure as follows:(ⅰ) in-situ growth of wool keratinCsPbBr_(3)(WK-CsPbBr_(3)) using wool keratin in interfacial passivation and coating,(ⅱ) electrospinning of a wool keratin-CsPbBr_(3)/polyacrylonitrile(WCP) nanofiber film,and(ⅲ) coating of the WCP nanofiber with polydimethylsiloxane(PDMS) to obtain a sensor(WCPP).The sensor could generate a piezoelectric voltage of 7.8 V at a pressure of 6 kPa in the stages of pressing and releasing,and the output characteristics did not decline even after 10,000 cycles.Compared to the 4-month stability of the perovskite sensor,WCPP sensor exhibited the output performance even after 16 months,which indicated that wool keratin as a multidentate improved the stability of the halide perovskite.Additionally,the sensor displayed a self-cleaning property and could also light up 14 commercial LEDs.The close-loop recycling of the lead halide perovskite was achieved by dissolving the WCP nanofiber film in DMF and then reelectrospinning.Therefore,the method proposed is a step forward for achieving the commercialization of WK-CsPbBr_(3) and providing new avenues for further utilization of wool waste.展开更多
The exact thermoelastic analysis of a functionally graded piezoelectrical (FGP) rotating cylinder is investigated analytically. The cylinder is subjected to a com- bination of electrical, thermal, and mechanical loa...The exact thermoelastic analysis of a functionally graded piezoelectrical (FGP) rotating cylinder is investigated analytically. The cylinder is subjected to a com- bination of electrical, thermal, and mechanical loads simultaneously. The structure is a simplified model of a rotational sensor or actuator. The basic governing differential equation of the system is obtained by using the energy method. A novel term, named as the additional energy, is introduced to exact the evaluation of the energy functional. The solution to the governing differential equation is presented for two types of boundary conditions including free rotating and rotating cylinders exposed to the inner pressure. The effect of the angular velocity is investigated on the radial distribution of various components. The mentioned structure can be considered as a sensor for measuring the angular velocity of the cylinder subjected to the pressure and temperature. The obtained results indicate that the electrical potential is proportional to the angular velocity.展开更多
We present a new polymer quartz piezoelectric crystal sensor that takes a quartz piezoelectric crystal as the basal material and a nanometer nonmetallic polymer thin film as the surface coating based on the principle ...We present a new polymer quartz piezoelectric crystal sensor that takes a quartz piezoelectric crystal as the basal material and a nanometer nonmetallic polymer thin film as the surface coating based on the principle of quartz crystal microbalance (QCM). The new sensor can be used to detect the characteristic materials of a volatile liquid. A mechanical model of the new sensor was built, whose structure was a thin circle plate composing of polytef/quartz piezoelectric/polytef. The mechanical model had a diameter of 8 mm and a thickness of 170 ~tm. The vibration state of the model was simulated by software ANSYS after the physical parameters and the boundary condition of the new sensor were set. According to the results of experiments, we set up a frequency range from 9.995850 MHz to 9.997225 MHz, 17 kinds of frequencies and modes of vibration were obtained within this range. We found a special frequency fsp of 9.996358 MHz. When the resonant frequency of the new sensor's mechanical model reached the special frequency, a special phenomenon occurred. In this case, the amplitude of the center point O on the mechanical model reached the maximum value. At the same time, the minimum absolute difference between the simulated frequency based on the ANSYS software and the experimental measured stable frequency was reached. The research showed that the design of the new polymer quartz piezoelectric crystal sensor perfectly conforms to the principle of QCM. A special frequency value fsp was found and subsequently became one of the most important parameters in the new sensor design.展开更多
Two-dimensional material has been widely investigated for potential applications in sensor and flexible electronics.In this work,a self-powered flexible humidity sensing device based on poly(vinyl alcohol)/Ti_(3)C_(2)...Two-dimensional material has been widely investigated for potential applications in sensor and flexible electronics.In this work,a self-powered flexible humidity sensing device based on poly(vinyl alcohol)/Ti_(3)C_(2)Tx(PVA/MXene)nanofibers film and monolayer molybdenum diselenide(MoSe2)piezoelectric nanogenerator(PENG)was reported for the first time.The monolayer MoSe_(2)-based PENG was fabricated by atmospheric pressure chemical vapor deposition techniques,which can generate a peak output of 35 mV and a power density of42 mW m^(-2).The flexible PENG integrated on polyethylene terephthalate(PET)substrate can harvest energy generated by different parts of human body and exhibit great application prospects in wearable devices.The electrospinned PVA/MXene nanofiber-based humidity sensor with flexible PET substrate under the driven of monolayer MoSe_(2) PENG,shows high response of~40,fast response/recovery time of 0.9/6.3 s,low hysteresis of 1.8%and excellent repeatability.The self-powered flexible humidity sensor yields the capability of detecting human skin moisture and ambient humidity.This work provides a pathway to explore the high-performance humidity sensor integrated with PENG for the self-powered flexible electronic devices.展开更多
We report for the first time a cleavage phenomenon in the resonant peak of a piezoelectric quartz crystal(PQC) in liquid phase.In the presence of a strong longitudinal wave effect,an additional resonant peak appears i...We report for the first time a cleavage phenomenon in the resonant peak of a piezoelectric quartz crystal(PQC) in liquid phase.In the presence of a strong longitudinal wave effect,an additional resonant peak appears in the conductance-frequency curve.With gradually increasing liquid density,the additional peak moves from low to high frequency region then disappears.The frequency of the additional resonant peak is sensitive to the change in liquid density.The frequency shift of the additional peak is linear with the liquid density in a given range.For a 5 MHz PQC with a reflection distance of 16 mm for longitudinal wave,the sensitivity to liquid density is 2.61×10^6 Hz g^-1 cm^3.The overlap between the primary resonant peak and the additional resonant peak causes a decrease in the intensity of the former and an increase in the intensity of the latter.In a combined impedance analysis method,the changes in surface mass loading,density and viscosity of the liquid were monitored simultaneously by a PQC sensor.展开更多
The capability of embedded piezoelectric wafer active sensors(PWAS)to perform in-situ nondestructive evaluation(NDE)for structural health monitoring(SHM)of reinforced concrete(RC)structures strengthened with fiber rei...The capability of embedded piezoelectric wafer active sensors(PWAS)to perform in-situ nondestructive evaluation(NDE)for structural health monitoring(SHM)of reinforced concrete(RC)structures strengthened with fiber reinforced polymer(FRP)composite overlays is explored.First,the disbond detection method were developed on coupon specimens consisting of concrete blocks covered with an FRP composite layer.It was found that the presence of a disbond crack drastically changes the electromecfianical(E/M)impedance spectrum lneasurcd at the PWAS terlninals.The spectral changes depend on the distance between the PWAS and the crack tip.Second,large scale experiments were conducted on a RC beam strengthened with carbon fiber reinforced polymer(CFRP)composite overlay.The beam was subject to an accelerated fatigue load regime in a three-point bending configuration up to a total of 807,415 cycles.During these fatigue tests,the CFRP overlay experienced disbonding beginning at about 500,000 cycles.The PWAS were able to detect the disbonding before it could be reliably seen by visual inspection.Good correlation between the PWAS readings and the position and extent of disbond damage was observed.These preliminary results demonstrate the potential of PWAS technology for SHM of RC structures strengthened with FRP composite overlays.展开更多
The micro touch sensor which is designed to be used in the blood vessels isproposed. Using this touch sensor, the risk of injuring blood vessels can be reduced. A prototype ofmicro touch sensor using PZT (lead zircona...The micro touch sensor which is designed to be used in the blood vessels isproposed. Using this touch sensor, the risk of injuring blood vessels can be reduced. A prototype ofmicro touch sensor using PZT (lead zirconate titanate) thin film synthesized by hydrothermal methodis made. The basic properties of the micro touch sensor are studied. In order to analyse theproperties of the micro touch sensor, a mathematical model is set up.展开更多
For traditional piezoelectric sensors based on poled ceramics,a low curie tem-perature(T_(c))is a fatal flaw due to the depolarization phenomenon.However,in this study,we find the low T_(c) would be a benefit for flex...For traditional piezoelectric sensors based on poled ceramics,a low curie tem-perature(T_(c))is a fatal flaw due to the depolarization phenomenon.However,in this study,we find the low T_(c) would be a benefit for flex-ible piezoelectric sensors because small alterations of force trig-ger large changes in polarization.BaTi_(0.88)Sn_(0.12)O_(3)(BTS)with high piezoelectric coefficient and low T_(c) close to human body temperature is taken as an example for materials of this kind.Continuous piezo-electric BTS films were deposited on the flexible glass fiber fabrics(GFF),self-powered sensors based on the ultra-thin,superflexible,and polarization-free BTS-GFF/PVDF composite piezoelectric films are used for human motion sensing.In the low force region(1-9 N),the sensors have the outstanding performance with voltage sensitivity of 1.23 V N^(−1) and current sensitivity of 41.0 nA N^(−1).The BTS-GFF/PVDF sensors can be used to detect the tiny forces of falling water drops,finger joint motion,tiny surface deformation,and fatigue driving with high sensitivity.This work provides a new paradigm for the preparation of superflexible,highly sensitive and wearable self-powered piezoelectric sensors,and this kind of sensors will have a broad application prospect in the fields of medical rehabilitation,human motion monitoring,and intelligent robot.展开更多
In this paper, an oscillation frequency equation for a pizoelectric sensor with two separated-electrodes is theoretically derived and experimentally verified. The correlatione of the oscillation frequency and the liqu...In this paper, an oscillation frequency equation for a pizoelectric sensor with two separated-electrodes is theoretically derived and experimentally verified. The correlatione of the oscillation frequency and the liquid properties are investigated.展开更多
ZnO films on R-sapphire substrates are prepared and characterized by x-ray diffraction and scanning electron microscopy, which indicate that the thin films are well crystallized with (1120) texture. Love wave and Ra...ZnO films on R-sapphire substrates are prepared and characterized by x-ray diffraction and scanning electron microscopy, which indicate that the thin films are well crystallized with (1120) texture. Love wave and Rayleigh wave are used for fabrications of humidity sensors, which are excited in [1100] and [0001] directions of the (1120) ZnO piezoelectric films, respectively. The experimental results show that both kinds of sensors have good humidity response and repeatability, and the performances of the Love wave sensors are better than those of the Rayleigh wave sensors at room temperature. Moreover, the theoretical calculations of the mass sensitivity of the sensors are a/so carried out and the calculated results are in good agreement with the experimental measurements.展开更多
A novel cement matrix smart piezoelectric composite and its application as sensing element are presented.A cement matrix smart piezoelectric composite piece encapsulated in a cement mortar formed a practical sensor, a...A novel cement matrix smart piezoelectric composite and its application as sensing element are presented.A cement matrix smart piezoelectric composite piece encapsulated in a cement mortar formed a practical sensor, and it was tested on material test system with cyclic loading.According to the theoretical analysis, the function of the cement matrix piezoelectric sensor output voltage was expressed in terms of the magnitude of the input cyclic loading amplitude and frequency.The curve fitting of gain function that is defined as sensor′s gain factor under different frequencies of input loading was carried out. From the results of curve fitting, it is found that the cement matrix smart piezoelectric composite has a simple relationship between input loading and output voltage.Therefore the cement matrix piezoelectric composite sensor is suitable to be applied in structural health monitoring.展开更多
PSN-PZN-PZT + x wt. %Cr2O3, X = 0.0-0-9, were prepared by conventional mixed oxide techniques at sintering temperatures of 1220 degrees C-1300 degrees C for 2 h. The effect of sintering temperature on the microstructu...PSN-PZN-PZT + x wt. %Cr2O3, X = 0.0-0-9, were prepared by conventional mixed oxide techniques at sintering temperatures of 1220 degrees C-1300 degrees C for 2 h. The effect of sintering temperature on the microstructure and the piezoelectric properties was investigated by XRD, SEM, and other conventional measurement. The result indicated that with temperature increasing, the valence of Cr ion from Cr5+ or Cr6+ changes into C3+, and the piezoelectric properties turn hard. With increasing Cr2O3 content, the amount of rhombohedral phases increases and the morphotropic boundary phase is correspondingly shifts to rhombohedral phase. A uniform microstructure and excellent comprehensive properties were obtained at 1240 degrees C as the amount of Cr2O3 is 0.5 wt.%.展开更多
PZT nanocrystalline powder was prepared by a stearic acid gel method. Thecrystallization process from the precursor was monitored by infrared spectroscopy, differentialthermal analysis, and thermogravimetric analysis....PZT nanocrystalline powder was prepared by a stearic acid gel method. Thecrystallization process from the precursor was monitored by infrared spectroscopy, differentialthermal analysis, and thermogravimetric analysis. The nano-sized PZT powder was characterized byX-ray diffraction and transmission electron microscopy. It shows that pure single-phase PZT powdercould be obtained at 450 deg C for 1 h, and the particle size is about 20 nm. With an increase inthe calcination temperature, the PZT crystallite size increased.展开更多
In this paper, the dependences of the frequeucy-temperature coefficient (df/dt) of an electrode-sepa-rated piezolectric sensor(ESPS) on desity, viscosity, permittivity and conductivity of the solution to be tested wer...In this paper, the dependences of the frequeucy-temperature coefficient (df/dt) of an electrode-sepa-rated piezolectric sensor(ESPS) on desity, viscosity, permittivity and conductivity of the solution to be tested were investigated’ A comparison of the frequency -temperature coefficient between the ESPS and a conwentioal piezoelectric quartz crystal was made, In a nou-electrolyte liquid, the df/dt)walwe of the ESPS increases with the increase of viscosity, density and permittivity of the liquid There is df/dt>0 in low or high conductivity solutions, but df/dt>0 in middle conductivity solution.And two zoues where df/dt is approximately equal to zero are observed in electrolyte展开更多
Based on the analysis of one-dimension inertial accelerometer movement model,from which the resolution of the accelerometer inertial mass displacement equation was derived,the response of the sensor sensing element to...Based on the analysis of one-dimension inertial accelerometer movement model,from which the resolution of the accelerometer inertial mass displacement equation was derived,the response of the sensor sensing element to vibration and impact of various frequencies was studied.The theoretical and experimental results show that a reasonable configuration among the sensing element inherent frequency,environmental exciting frequency and the damp factors of the sensor is the key to prevent the sensor from damage.The sensor has good anti-vibrating impact ability when the relative damp factor is 0.7,and the environmental interferential vibrating frequency is less than 0.35 times of the inherent frequency of the sensing element.展开更多
Based on the needs of the oscillation equation and frequency stability, three oscillation conditions are proposed and have been experimentally verified for an electrode-separated piezoelectric sensor (ESPS ) in electr...Based on the needs of the oscillation equation and frequency stability, three oscillation conditions are proposed and have been experimentally verified for an electrode-separated piezoelectric sensor (ESPS ) in electrolyte solutions. The present paper covers the dependence of the minimum cell constant needed for the ESPS on solution conductivity. The oscillation conditions of the classical liquid piezoelectric sensor are discussed. The 'cease-to-oscillate' frequencies of the ESPS were measured.展开更多
基金funded by the National Natural Science Foundation of China (22178210)the Innovation Capability Support Program of Shaanxi (2021TD-16)+1 种基金Key Project of Natural Science Basic Research Program of Shaanxi Province (2023JC-XJ-12)the Shaanxi Provincial “Special Support Plan for High-level Talents”。
文摘Halide perovskites with excellent piezoelectric properties,but their poor stability hinders their largescale application.Herein,a sandwich-structured halide perovskite flexible sensor with good stability was developed according to a three-step procedure as follows:(ⅰ) in-situ growth of wool keratinCsPbBr_(3)(WK-CsPbBr_(3)) using wool keratin in interfacial passivation and coating,(ⅱ) electrospinning of a wool keratin-CsPbBr_(3)/polyacrylonitrile(WCP) nanofiber film,and(ⅲ) coating of the WCP nanofiber with polydimethylsiloxane(PDMS) to obtain a sensor(WCPP).The sensor could generate a piezoelectric voltage of 7.8 V at a pressure of 6 kPa in the stages of pressing and releasing,and the output characteristics did not decline even after 10,000 cycles.Compared to the 4-month stability of the perovskite sensor,WCPP sensor exhibited the output performance even after 16 months,which indicated that wool keratin as a multidentate improved the stability of the halide perovskite.Additionally,the sensor displayed a self-cleaning property and could also light up 14 commercial LEDs.The close-loop recycling of the lead halide perovskite was achieved by dissolving the WCP nanofiber film in DMF and then reelectrospinning.Therefore,the method proposed is a step forward for achieving the commercialization of WK-CsPbBr_(3) and providing new avenues for further utilization of wool waste.
文摘The exact thermoelastic analysis of a functionally graded piezoelectrical (FGP) rotating cylinder is investigated analytically. The cylinder is subjected to a com- bination of electrical, thermal, and mechanical loads simultaneously. The structure is a simplified model of a rotational sensor or actuator. The basic governing differential equation of the system is obtained by using the energy method. A novel term, named as the additional energy, is introduced to exact the evaluation of the energy functional. The solution to the governing differential equation is presented for two types of boundary conditions including free rotating and rotating cylinders exposed to the inner pressure. The effect of the angular velocity is investigated on the radial distribution of various components. The mentioned structure can be considered as a sensor for measuring the angular velocity of the cylinder subjected to the pressure and temperature. The obtained results indicate that the electrical potential is proportional to the angular velocity.
基金Project supported by the National High Technology Research and Developmem Program of China ~Grant No. 2013AA030901).
文摘We present a new polymer quartz piezoelectric crystal sensor that takes a quartz piezoelectric crystal as the basal material and a nanometer nonmetallic polymer thin film as the surface coating based on the principle of quartz crystal microbalance (QCM). The new sensor can be used to detect the characteristic materials of a volatile liquid. A mechanical model of the new sensor was built, whose structure was a thin circle plate composing of polytef/quartz piezoelectric/polytef. The mechanical model had a diameter of 8 mm and a thickness of 170 ~tm. The vibration state of the model was simulated by software ANSYS after the physical parameters and the boundary condition of the new sensor were set. According to the results of experiments, we set up a frequency range from 9.995850 MHz to 9.997225 MHz, 17 kinds of frequencies and modes of vibration were obtained within this range. We found a special frequency fsp of 9.996358 MHz. When the resonant frequency of the new sensor's mechanical model reached the special frequency, a special phenomenon occurred. In this case, the amplitude of the center point O on the mechanical model reached the maximum value. At the same time, the minimum absolute difference between the simulated frequency based on the ANSYS software and the experimental measured stable frequency was reached. The research showed that the design of the new polymer quartz piezoelectric crystal sensor perfectly conforms to the principle of QCM. A special frequency value fsp was found and subsequently became one of the most important parameters in the new sensor design.
基金supported by the National Natural Science Foundation of China(51777215)National Natural Science Foundation of China(51775306)+1 种基金Beijing Municipal Natural Science Foundation(4192027)the Graduate Innovation Fund of China University of Petroleum(YCX2020097)。
文摘Two-dimensional material has been widely investigated for potential applications in sensor and flexible electronics.In this work,a self-powered flexible humidity sensing device based on poly(vinyl alcohol)/Ti_(3)C_(2)Tx(PVA/MXene)nanofibers film and monolayer molybdenum diselenide(MoSe2)piezoelectric nanogenerator(PENG)was reported for the first time.The monolayer MoSe_(2)-based PENG was fabricated by atmospheric pressure chemical vapor deposition techniques,which can generate a peak output of 35 mV and a power density of42 mW m^(-2).The flexible PENG integrated on polyethylene terephthalate(PET)substrate can harvest energy generated by different parts of human body and exhibit great application prospects in wearable devices.The electrospinned PVA/MXene nanofiber-based humidity sensor with flexible PET substrate under the driven of monolayer MoSe_(2) PENG,shows high response of~40,fast response/recovery time of 0.9/6.3 s,low hysteresis of 1.8%and excellent repeatability.The self-powered flexible humidity sensor yields the capability of detecting human skin moisture and ambient humidity.This work provides a pathway to explore the high-performance humidity sensor integrated with PENG for the self-powered flexible electronic devices.
基金supported by the National Natural Science Foundation of China(Nos.20775045,20975063)open foundation of the State Key Laboratory of Chemo/Biosensing and Chemometrics,Hunan University(No.2008012)
文摘We report for the first time a cleavage phenomenon in the resonant peak of a piezoelectric quartz crystal(PQC) in liquid phase.In the presence of a strong longitudinal wave effect,an additional resonant peak appears in the conductance-frequency curve.With gradually increasing liquid density,the additional peak moves from low to high frequency region then disappears.The frequency of the additional resonant peak is sensitive to the change in liquid density.The frequency shift of the additional peak is linear with the liquid density in a given range.For a 5 MHz PQC with a reflection distance of 16 mm for longitudinal wave,the sensitivity to liquid density is 2.61×10^6 Hz g^-1 cm^3.The overlap between the primary resonant peak and the additional resonant peak causes a decrease in the intensity of the former and an increase in the intensity of the latter.In a combined impedance analysis method,the changes in surface mass loading,density and viscosity of the liquid were monitored simultaneously by a PQC sensor.
基金the National Seienee Foundation through grants NSF#CMS-9908293 and NSF INT-9904493the Federal Highway Administration and the South Carolina Department of TransPortation(projeet Number 614)
文摘The capability of embedded piezoelectric wafer active sensors(PWAS)to perform in-situ nondestructive evaluation(NDE)for structural health monitoring(SHM)of reinforced concrete(RC)structures strengthened with fiber reinforced polymer(FRP)composite overlays is explored.First,the disbond detection method were developed on coupon specimens consisting of concrete blocks covered with an FRP composite layer.It was found that the presence of a disbond crack drastically changes the electromecfianical(E/M)impedance spectrum lneasurcd at the PWAS terlninals.The spectral changes depend on the distance between the PWAS and the crack tip.Second,large scale experiments were conducted on a RC beam strengthened with carbon fiber reinforced polymer(CFRP)composite overlay.The beam was subject to an accelerated fatigue load regime in a three-point bending configuration up to a total of 807,415 cycles.During these fatigue tests,the CFRP overlay experienced disbonding beginning at about 500,000 cycles.The PWAS were able to detect the disbonding before it could be reliably seen by visual inspection.Good correlation between the PWAS readings and the position and extent of disbond damage was observed.These preliminary results demonstrate the potential of PWAS technology for SHM of RC structures strengthened with FRP composite overlays.
基金This project is supported by National Natural Science Foundation of China (No.90207003) Scientific Research Foundation of Ministry of Education and Dalian City for the Returned Overseas Chinese Scholars, China.
文摘The micro touch sensor which is designed to be used in the blood vessels isproposed. Using this touch sensor, the risk of injuring blood vessels can be reduced. A prototype ofmicro touch sensor using PZT (lead zirconate titanate) thin film synthesized by hydrothermal methodis made. The basic properties of the micro touch sensor are studied. In order to analyse theproperties of the micro touch sensor, a mathematical model is set up.
基金This work is financially supported by the basic research project of science and technology of Shanghai(No.20JC1415000)National Natural Science Foundation of China(Nos.11874257 and 52032012)the Fund for Science and Technology Innovation of Shanghai Jiao Tong University.
文摘For traditional piezoelectric sensors based on poled ceramics,a low curie tem-perature(T_(c))is a fatal flaw due to the depolarization phenomenon.However,in this study,we find the low T_(c) would be a benefit for flex-ible piezoelectric sensors because small alterations of force trig-ger large changes in polarization.BaTi_(0.88)Sn_(0.12)O_(3)(BTS)with high piezoelectric coefficient and low T_(c) close to human body temperature is taken as an example for materials of this kind.Continuous piezo-electric BTS films were deposited on the flexible glass fiber fabrics(GFF),self-powered sensors based on the ultra-thin,superflexible,and polarization-free BTS-GFF/PVDF composite piezoelectric films are used for human motion sensing.In the low force region(1-9 N),the sensors have the outstanding performance with voltage sensitivity of 1.23 V N^(−1) and current sensitivity of 41.0 nA N^(−1).The BTS-GFF/PVDF sensors can be used to detect the tiny forces of falling water drops,finger joint motion,tiny surface deformation,and fatigue driving with high sensitivity.This work provides a new paradigm for the preparation of superflexible,highly sensitive and wearable self-powered piezoelectric sensors,and this kind of sensors will have a broad application prospect in the fields of medical rehabilitation,human motion monitoring,and intelligent robot.
文摘In this paper, an oscillation frequency equation for a pizoelectric sensor with two separated-electrodes is theoretically derived and experimentally verified. The correlatione of the oscillation frequency and the liquid properties are investigated.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11174142,11304160 and 11404147the National Basic Research Program of China under Grant No 2012CB921504+2 种基金the PAPD Projectthe Natural Science Foundation of Jiangsu Higher Education Institutions of China under Grant No 13KJB140008the Foundation of Nanjing University of Posts and Telecommunications under Grant No NY213018
文摘ZnO films on R-sapphire substrates are prepared and characterized by x-ray diffraction and scanning electron microscopy, which indicate that the thin films are well crystallized with (1120) texture. Love wave and Rayleigh wave are used for fabrications of humidity sensors, which are excited in [1100] and [0001] directions of the (1120) ZnO piezoelectric films, respectively. The experimental results show that both kinds of sensors have good humidity response and repeatability, and the performances of the Love wave sensors are better than those of the Rayleigh wave sensors at room temperature. Moreover, the theoretical calculations of the mass sensitivity of the sensors are a/so carried out and the calculated results are in good agreement with the experimental measurements.
文摘A novel cement matrix smart piezoelectric composite and its application as sensing element are presented.A cement matrix smart piezoelectric composite piece encapsulated in a cement mortar formed a practical sensor, and it was tested on material test system with cyclic loading.According to the theoretical analysis, the function of the cement matrix piezoelectric sensor output voltage was expressed in terms of the magnitude of the input cyclic loading amplitude and frequency.The curve fitting of gain function that is defined as sensor′s gain factor under different frequencies of input loading was carried out. From the results of curve fitting, it is found that the cement matrix smart piezoelectric composite has a simple relationship between input loading and output voltage.Therefore the cement matrix piezoelectric composite sensor is suitable to be applied in structural health monitoring.
文摘PSN-PZN-PZT + x wt. %Cr2O3, X = 0.0-0-9, were prepared by conventional mixed oxide techniques at sintering temperatures of 1220 degrees C-1300 degrees C for 2 h. The effect of sintering temperature on the microstructure and the piezoelectric properties was investigated by XRD, SEM, and other conventional measurement. The result indicated that with temperature increasing, the valence of Cr ion from Cr5+ or Cr6+ changes into C3+, and the piezoelectric properties turn hard. With increasing Cr2O3 content, the amount of rhombohedral phases increases and the morphotropic boundary phase is correspondingly shifts to rhombohedral phase. A uniform microstructure and excellent comprehensive properties were obtained at 1240 degrees C as the amount of Cr2O3 is 0.5 wt.%.
基金This work was financially supported by the Ministry of Science and Technology of China through 973-project (No. 2002CB613301).
文摘PZT nanocrystalline powder was prepared by a stearic acid gel method. Thecrystallization process from the precursor was monitored by infrared spectroscopy, differentialthermal analysis, and thermogravimetric analysis. The nano-sized PZT powder was characterized byX-ray diffraction and transmission electron microscopy. It shows that pure single-phase PZT powdercould be obtained at 450 deg C for 1 h, and the particle size is about 20 nm. With an increase inthe calcination temperature, the PZT crystallite size increased.
文摘In this paper, the dependences of the frequeucy-temperature coefficient (df/dt) of an electrode-sepa-rated piezolectric sensor(ESPS) on desity, viscosity, permittivity and conductivity of the solution to be tested were investigated’ A comparison of the frequency -temperature coefficient between the ESPS and a conwentioal piezoelectric quartz crystal was made, In a nou-electrolyte liquid, the df/dt)walwe of the ESPS increases with the increase of viscosity, density and permittivity of the liquid There is df/dt>0 in low or high conductivity solutions, but df/dt>0 in middle conductivity solution.And two zoues where df/dt is approximately equal to zero are observed in electrolyte
文摘Based on the analysis of one-dimension inertial accelerometer movement model,from which the resolution of the accelerometer inertial mass displacement equation was derived,the response of the sensor sensing element to vibration and impact of various frequencies was studied.The theoretical and experimental results show that a reasonable configuration among the sensing element inherent frequency,environmental exciting frequency and the damp factors of the sensor is the key to prevent the sensor from damage.The sensor has good anti-vibrating impact ability when the relative damp factor is 0.7,and the environmental interferential vibrating frequency is less than 0.35 times of the inherent frequency of the sensing element.
文摘Based on the needs of the oscillation equation and frequency stability, three oscillation conditions are proposed and have been experimentally verified for an electrode-separated piezoelectric sensor (ESPS ) in electrolyte solutions. The present paper covers the dependence of the minimum cell constant needed for the ESPS on solution conductivity. The oscillation conditions of the classical liquid piezoelectric sensor are discussed. The 'cease-to-oscillate' frequencies of the ESPS were measured.