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 μm. 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 fspof 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 fspwas found and subsequently became one of the most important parameters in the new sensor design.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
An electronic-nose is developed based on eight quartz-crystal-microbalance (QCM) gas sensors in a sensor box, and is used to detect Chinese liquors at room temperature. Each sensor is a highly-accurate and highly-sens...An electronic-nose is developed based on eight quartz-crystal-microbalance (QCM) gas sensors in a sensor box, and is used to detect Chinese liquors at room temperature. Each sensor is a highly-accurate and highly-sensitive oscillator that has experienced airflow disturbances under the condition of varying room temperatures due to unstable flow-induced forces on the sensors surfaces. The three-dimensional (3D) nature of the airflow inside the sensor box and the interactions of the airflow on the sensors surfaces at different temperatures are studied by computational fluid dynamics (CFD) tools. Higher simulation accuracy is achieved by optimizing meshes, meshing the computational domain using a fine unstructural tetrahedron mesh. An optimum temperature, 30 ℃, is obtained by analyzing the distributions of velocity streamlines and the static pressure, as well as the flow-induced forces over time, all of which may be used to improve the identification accuracy of the electronic-nose for achieving stable and repeatable signals by removing the influence of temperature.展开更多
An unexpected frequency response for a piezoelectric quartz crystal (PQC) sensor to liquid density and viscosity was reported. For a PQC oscillating in a liquid phase, the frequency shifts (?f ) show a wave-shape re...An unexpected frequency response for a piezoelectric quartz crystal (PQC) sensor to liquid density and viscosity was reported. For a PQC oscillating in a liquid phase, the frequency shifts (?f ) show a wave-shape response to liquid density (ρ) and viscosity (η) in fine structure, if the longitudinal wave effect was not eliminated. This result is different from the well-known linear relationship between of ?f and (ρη)1/2. An oscillating frequency-temperature curve of the sensor was observed and explained.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
n oscillation condition was proposed and experimentally verified for an elec-troderaeparated piezoelectric sensor (ESPS) in non-electrolyte liquid, it was ex-pressed as , where C_s is the solution capaci-tance , R_q, ...n oscillation condition was proposed and experimentally verified for an elec-troderaeparated piezoelectric sensor (ESPS) in non-electrolyte liquid, it was ex-pressed as , where C_s is the solution capaci-tance , R_q, C_o and w are the motional resistance , static capacitance and resonant an-gle frequency of the crystal , respectively. And Y-tgθ, where θ is the phase shift inthe oscillator. The relationships between the minimum cell constant needed for ES-PS to oscillate and each of the following parameters, permittivity, density and vis-cosity of the liquid as well as the oscillator phase shift were discussed. The″ cease-to-oscillate″ frequency of ESPS was measured. The oscillation ability of ESPS in-creases with increasing permittivity or decreasing density and viscosity of the liq-uid. An oscillator with a larger Y value is helpful to drive ESPS.展开更多
A multimode-quartz-crystal oscillator was developed to excite stable dual-mode resonance at different frequencies: The oscillation of the 3rd harmonic resonance of the principle C-mode and an additional resonance B-mo...A multimode-quartz-crystal oscillator was developed to excite stable dual-mode resonance at different frequencies: The oscillation of the 3rd harmonic resonance of the principle C-mode and an additional resonance B-mode of SC-cut crystal. Harmonic combinations of the 3rd and fundamental mode of B-mode with the 3rd harmonics of C-mode are demonstrated. The measurement of the temperature dependence of the oscillation frequency is demonstrated along with the stability determined by root Allan variance. Dependence on the open conductance of the active circuit and the dependence on the coupling capacitors are discussed.展开更多
Quartz optical fibers are of great significance in many fields. For example,they can be used to fabricate strain sensors and temperature sensors.If the surface of optical fibers is metal-coated by the electroless plat...Quartz optical fibers are of great significance in many fields. For example,they can be used to fabricate strain sensors and temperature sensors.If the surface of optical fibers is metal-coated by the electroless plating method, the measuring precision and stability of the optical fiber sensors can be improved remarkably, additionally the life-span of sensors can be prolonged.In this work, an electroless nickel-phosphor plating process for optical fibers was presented.The influences of the content of NaH 2PO 2·H 2O, bath pH value and temperature and the plating deposition rate on the quality of the plating coatings were studied with orthogonal testing.The results indicated that the content of NaH 2PO 2·H 2O was the key factor, which influenced the adhesion force of the plating coatings.The nickel-phosphor plating bath presented in this work possessed excellent stability and the plating deposition rate could be accelerated.Using the process described in this work, nickel-phosphor coatings with great brightness and high adhesion force can be prepared successfully.Optimum conditions were: NiSO 4 30 g·L -1, NaH 2PO 2·H 2O 20 g·L -1, C 3H 6O 3 4 ml·L -1, Na 2CO 3 3 g·L -1, NH 4Cl 4 g·L -1, saccharin 1 mg·L -1, temperature 84 ℃, pH 4.6.展开更多
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 μm. 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 fspof 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 fspwas 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(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Project supported by the National Natural Science Foundation of China(Nos.61876059 and U1501251)
文摘An electronic-nose is developed based on eight quartz-crystal-microbalance (QCM) gas sensors in a sensor box, and is used to detect Chinese liquors at room temperature. Each sensor is a highly-accurate and highly-sensitive oscillator that has experienced airflow disturbances under the condition of varying room temperatures due to unstable flow-induced forces on the sensors surfaces. The three-dimensional (3D) nature of the airflow inside the sensor box and the interactions of the airflow on the sensors surfaces at different temperatures are studied by computational fluid dynamics (CFD) tools. Higher simulation accuracy is achieved by optimizing meshes, meshing the computational domain using a fine unstructural tetrahedron mesh. An optimum temperature, 30 ℃, is obtained by analyzing the distributions of velocity streamlines and the static pressure, as well as the flow-induced forces over time, all of which may be used to improve the identification accuracy of the electronic-nose for achieving stable and repeatable signals by removing the influence of temperature.
基金supported by the National Natural Science Foundation of China(No.20275021)
文摘An unexpected frequency response for a piezoelectric quartz crystal (PQC) sensor to liquid density and viscosity was reported. For a PQC oscillating in a liquid phase, the frequency shifts (?f ) show a wave-shape response to liquid density (ρ) and viscosity (η) in fine structure, if the longitudinal wave effect was not eliminated. This result is different from the well-known linear relationship between of ?f and (ρη)1/2. An oscillating frequency-temperature curve of the sensor was observed and explained.
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.
文摘n oscillation condition was proposed and experimentally verified for an elec-troderaeparated piezoelectric sensor (ESPS) in non-electrolyte liquid, it was ex-pressed as , where C_s is the solution capaci-tance , R_q, C_o and w are the motional resistance , static capacitance and resonant an-gle frequency of the crystal , respectively. And Y-tgθ, where θ is the phase shift inthe oscillator. The relationships between the minimum cell constant needed for ES-PS to oscillate and each of the following parameters, permittivity, density and vis-cosity of the liquid as well as the oscillator phase shift were discussed. The″ cease-to-oscillate″ frequency of ESPS was measured. The oscillation ability of ESPS in-creases with increasing permittivity or decreasing density and viscosity of the liq-uid. An oscillator with a larger Y value is helpful to drive ESPS.
文摘A multimode-quartz-crystal oscillator was developed to excite stable dual-mode resonance at different frequencies: The oscillation of the 3rd harmonic resonance of the principle C-mode and an additional resonance B-mode of SC-cut crystal. Harmonic combinations of the 3rd and fundamental mode of B-mode with the 3rd harmonics of C-mode are demonstrated. The measurement of the temperature dependence of the oscillation frequency is demonstrated along with the stability determined by root Allan variance. Dependence on the open conductance of the active circuit and the dependence on the coupling capacitors are discussed.
文摘Quartz optical fibers are of great significance in many fields. For example,they can be used to fabricate strain sensors and temperature sensors.If the surface of optical fibers is metal-coated by the electroless plating method, the measuring precision and stability of the optical fiber sensors can be improved remarkably, additionally the life-span of sensors can be prolonged.In this work, an electroless nickel-phosphor plating process for optical fibers was presented.The influences of the content of NaH 2PO 2·H 2O, bath pH value and temperature and the plating deposition rate on the quality of the plating coatings were studied with orthogonal testing.The results indicated that the content of NaH 2PO 2·H 2O was the key factor, which influenced the adhesion force of the plating coatings.The nickel-phosphor plating bath presented in this work possessed excellent stability and the plating deposition rate could be accelerated.Using the process described in this work, nickel-phosphor coatings with great brightness and high adhesion force can be prepared successfully.Optimum conditions were: NiSO 4 30 g·L -1, NaH 2PO 2·H 2O 20 g·L -1, C 3H 6O 3 4 ml·L -1, Na 2CO 3 3 g·L -1, NH 4Cl 4 g·L -1, saccharin 1 mg·L -1, temperature 84 ℃, pH 4.6.
