This paper studies the static deformation behavior of a piezoelectric micromachined ultrasonic transducer (PMUT) actuated by a strong external electric field. The transducer membrane consists of a piezoelectric laye...This paper studies the static deformation behavior of a piezoelectric micromachined ultrasonic transducer (PMUT) actuated by a strong external electric field. The transducer membrane consists of a piezoelectric layer, a passive layer and two electrode layers. The nonlinearities of the piezoelectric layer caused by electrostriction under a strong electric field are analyzed. Because the thickness of the transducer membrane is on the microscale, the size dependence of the deformation behavior is evaluated using the couple stress theory. The results show that the optimal ratio of the top electrode diameter and the membrane diameter is around 0.674. It is also found that this optimal value does not depend on any other parameters if the thicknesses of the two electrodes are negligible compared with those of the piezo- electric and passive layers. In addition, the nonlinearities of the piezoelectric layer will become stronger along with the increase of the electric field, which means that softening of the membrane stiffness occurs when a strong external electric field is applied. Meanwhile, the optimal thickness ratio for the passive layer and the piezoelectric layer is not equal to 1.0 which is usually adopted by previous researchers. Because there exists size dependence of membrane deforma-tion, the optimal value of this thickness ratio needs to be greater than 1.0 on the microscale.展开更多
A novel linear ultrasonic motor based on d15 effect of piezoelectric materials was presented. The design idea aimed at the direct utilization of the shear-induced vibration modes of piezoelectric material. Firstly, th...A novel linear ultrasonic motor based on d15 effect of piezoelectric materials was presented. The design idea aimed at the direct utilization of the shear-induced vibration modes of piezoelectric material. Firstly, the inherent electromechanical coupling mechanism of piezoelectric material was investigated, and shear vibration modes of a piezoelectric shear block was specially designed. A driving point’s elliptical trajectory induced by shear vibration modes was discussed. Then a dynamic model for the piezoelectric shear stator was established with finite element(FE) method to conduct the parametric optimal design. Finally, a prototype based on d15 converse piezoelectric effect is manufactured, and the modal experiment of piezoelectric stator was conducted with laser doppler vibrometer. The experimental results show that the calculated shear-induced vibration modes can be excited completely, and the new linear ultrasonic motor reaches a speed 118 mm/s at noload, and maximal thrust 12.8 N.展开更多
Conventional servomotor and stepping motor face challenges in nanometer positioning stages due to the complex structure, motion transformation mechanism, and slow dynamic response, especially directly driven by linear...Conventional servomotor and stepping motor face challenges in nanometer positioning stages due to the complex structure, motion transformation mechanism, and slow dynamic response, especially directly driven by linear motor. A new butterfly-shaped linear piezoelectric motor for linear motion is presented. A two-degree precision position stage driven by the proposed linear ultrasonic motor possesses a simple and compact configuration, which makes the system obtain shorter driving chain. Firstly, the working principle of the linear ultrasonic motor is analyzed. The oscillation orbits of two driving feet on the stator are produced successively by using the anti-symmetric and symmetric vibration modes of the piezoelectric composite structure, and the slider pressed on the driving feet can be propelled twice in only one vibration cycle. Then with the derivation of the dynamic equation of the piezoelectric actuator and transient response model, start-upstart-up and settling state characteristics of the proposed linear actuator is investigated theoretically and experimentally, and is applicable to evaluate step resolution of the precision platform driven by the actuator. Moreover the structure of the two-degree position stage system is described and a special precision displacement measurement system is built. Finally, the characteristics of the two-degree position stage are studied. In the closed-loop condition the positioning accuracy of plus or minus 〈0.5 μm is experimentally obtained for the stage propelled by the piezoelectric motor. A precision position stage based the proposed butterfly-shaped linear piezoelectric is theoretically and experimentally investigated.展开更多
The steady-state vibration amplitude is an important performance indicator of high-frequency ultrasonic transducers for ultrasonically assisted manipulating,machining,and manufacturing.This work aimed to develop a cal...The steady-state vibration amplitude is an important performance indicator of high-frequency ultrasonic transducers for ultrasonically assisted manipulating,machining,and manufacturing.This work aimed to develop a calculation model for the steady-state vibration amplitude of a new type of dual-branch cascaded composite structure-based ultrasonic transducer that can be used in the packaging of microelectronic chips.First,the steady-state vibration amplitude of the piezoelectric vibrator of the transducer was derived from the piezoelectric equation.Second,the vibration transfer matrices of the tapered ultrasonic horns were obtained by combining the vibration equation,the continuous condition of the displacement,and the equilibrium condition of the force.Calculation models for the steady-state vibration amplitude of the two working ends of the transducer were then developed.A series of exciting trials were carried out to test the performance of the models.Comparison between the calculated and measured results for steady-state vibration amplitude showed that the maximum deviation was 0.0221μm,the minimum deviation was 0.0013μm,the average deviation was 0.0097μm,and the standard deviation was 0.0046μm.These values indicated good calculation accuracy,laying a good foundation for the practical application of the proposed transducer.展开更多
A dual-excited full-wavelength piezoceramic ultrasonic transducer as a cascade of two half-wavelength sandwich piezoceramic transducers is studied.The relevant parameters' expressions of the figure of merit N for the...A dual-excited full-wavelength piezoceramic ultrasonic transducer as a cascade of two half-wavelength sandwich piezoceramic transducers is studied.The relevant parameters' expressions of the figure of merit N for the transducer are derived,and the effects of the structure and material parameters of the transducer on its characteristics are further analyzed by numerical calculation.The results show that when the two piezoceramic stacks are respectively located at the displacement nodes of their own half-wavelength transducers,or the two piezoceramic stacks have the same number of pieces in the case of a certain number of piezoceramic pieces,the figure of merit of the transducer can reach a maximum.With increasing of the number of piezoceramic pieces in a fairly large range,the figure of merit of the transducer slightly decreases,but the force factor of the transducer increases rapidly.The metal materials of the transducer have little effect on its figure of merit.Thus it can be seen that the dual-excited full-wavelength transducer can effectively increase the volumes of the piezoceramic stacks in the case of that the transducer's comprehensive performance has only a little bit of degradation,so it's power capacity and load capability can be dramatically improved,which means the transducer is more suitable for high power and heavy load applications.展开更多
This paper presents a 591×438-DPI ultrasonic fingerprint sensor.The sensor is based on a piezoelectric micromachined ultrasonic transducer(PMUT)array that is bonded at wafer-level to complementary metal oxide sem...This paper presents a 591×438-DPI ultrasonic fingerprint sensor.The sensor is based on a piezoelectric micromachined ultrasonic transducer(PMUT)array that is bonded at wafer-level to complementary metal oxide semiconductor(CMOS)signal processing electronics to produce a pulse-echo ultrasonic imager on a chip.To meet the 500-DPI standard for consumer fingerprint sensors,the PMUT pitch was reduced by approximately a factor of two relative to an earlier design.We conducted a systematic design study of the individual PMUT and array to achieve this scaling while maintaining a high fill-factor.The resulting 110×56-PMUT array,composed of 30×43-μm^(2) rectangular PMUTs,achieved a 51.7% fill-factor,three times greater than that of the previous design.Together with the custom CMOS ASIC,the sensor achieves 2 mV kPa^(−1) sensitivity,15 kPa pressure output,75μm lateral resolution,and 150μm axial resolution in a 4.6 mm×3.2 mm image.To the best of our knowledge,we have demonstrated the first MEMS ultrasonic fingerprint sensor capable of imaging epidermis and sub-surface layer fingerprints.展开更多
The mechanical characterization of a 4×4 air-coupled array of Piezoelectric Micromachined Ultrasonic Transducers(PMUTs)is pre-sented.The experimental campaign consists of three set of experi-mental tests,namely:t...The mechanical characterization of a 4×4 air-coupled array of Piezoelectric Micromachined Ultrasonic Transducers(PMUTs)is pre-sented.The experimental campaign consists of three set of experi-mental tests,namely:topography measurements,small signal dynamic measurements,and vibrometry in the non-linear dynamic regime.The behavior of three different kinds of PMUT are reported.They differ according to the thermo-electrical treatment that has been applied to the piezoelectric material.The presence of the fabrication induced residual stresses is investigated and the treat-ment effect is evaluated in terms of the initial deflected configura-tion.The results reported in this paper represent an experimental mechanical investigation useful for the design of PMUT structures with advanced functionalities in the linear and non-linear regime.展开更多
基金supported by the National Natural Science Foundation of China (11172138, 10727201)
文摘This paper studies the static deformation behavior of a piezoelectric micromachined ultrasonic transducer (PMUT) actuated by a strong external electric field. The transducer membrane consists of a piezoelectric layer, a passive layer and two electrode layers. The nonlinearities of the piezoelectric layer caused by electrostriction under a strong electric field are analyzed. Because the thickness of the transducer membrane is on the microscale, the size dependence of the deformation behavior is evaluated using the couple stress theory. The results show that the optimal ratio of the top electrode diameter and the membrane diameter is around 0.674. It is also found that this optimal value does not depend on any other parameters if the thicknesses of the two electrodes are negligible compared with those of the piezo- electric and passive layers. In addition, the nonlinearities of the piezoelectric layer will become stronger along with the increase of the electric field, which means that softening of the membrane stiffness occurs when a strong external electric field is applied. Meanwhile, the optimal thickness ratio for the passive layer and the piezoelectric layer is not equal to 1.0 which is usually adopted by previous researchers. Because there exists size dependence of membrane deforma-tion, the optimal value of this thickness ratio needs to be greater than 1.0 on the microscale.
基金Funded by the National Basic Research Program of China(973 Program,No.2015CB057501)the National Natural Science Foundation of China(Nos.50975135,51275235)+1 种基金the Fundamental Research Funds for the Central Universities(No.NJ20140024)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘A novel linear ultrasonic motor based on d15 effect of piezoelectric materials was presented. The design idea aimed at the direct utilization of the shear-induced vibration modes of piezoelectric material. Firstly, the inherent electromechanical coupling mechanism of piezoelectric material was investigated, and shear vibration modes of a piezoelectric shear block was specially designed. A driving point’s elliptical trajectory induced by shear vibration modes was discussed. Then a dynamic model for the piezoelectric shear stator was established with finite element(FE) method to conduct the parametric optimal design. Finally, a prototype based on d15 converse piezoelectric effect is manufactured, and the modal experiment of piezoelectric stator was conducted with laser doppler vibrometer. The experimental results show that the calculated shear-induced vibration modes can be excited completely, and the new linear ultrasonic motor reaches a speed 118 mm/s at noload, and maximal thrust 12.8 N.
基金Supported by National Basic Research Program of China(973 Program,Grant No.2015CB057500)National Natural Science Foundation of China(Grant Nos.50305035,51575259)Research Fund of State Key Laboratory of Mechanics and Control of Mechanical Structures,China(Grant No.0315K01)
文摘Conventional servomotor and stepping motor face challenges in nanometer positioning stages due to the complex structure, motion transformation mechanism, and slow dynamic response, especially directly driven by linear motor. A new butterfly-shaped linear piezoelectric motor for linear motion is presented. A two-degree precision position stage driven by the proposed linear ultrasonic motor possesses a simple and compact configuration, which makes the system obtain shorter driving chain. Firstly, the working principle of the linear ultrasonic motor is analyzed. The oscillation orbits of two driving feet on the stator are produced successively by using the anti-symmetric and symmetric vibration modes of the piezoelectric composite structure, and the slider pressed on the driving feet can be propelled twice in only one vibration cycle. Then with the derivation of the dynamic equation of the piezoelectric actuator and transient response model, start-upstart-up and settling state characteristics of the proposed linear actuator is investigated theoretically and experimentally, and is applicable to evaluate step resolution of the precision platform driven by the actuator. Moreover the structure of the two-degree position stage system is described and a special precision displacement measurement system is built. Finally, the characteristics of the two-degree position stage are studied. In the closed-loop condition the positioning accuracy of plus or minus 〈0.5 μm is experimentally obtained for the stage propelled by the piezoelectric motor. A precision position stage based the proposed butterfly-shaped linear piezoelectric is theoretically and experimentally investigated.
基金This work was supported by the National Natural Science Foundation of China(Grant No.52175110)Author Hongjie Zhang has received research support from the National Natural Science Foundation of China.
文摘The steady-state vibration amplitude is an important performance indicator of high-frequency ultrasonic transducers for ultrasonically assisted manipulating,machining,and manufacturing.This work aimed to develop a calculation model for the steady-state vibration amplitude of a new type of dual-branch cascaded composite structure-based ultrasonic transducer that can be used in the packaging of microelectronic chips.First,the steady-state vibration amplitude of the piezoelectric vibrator of the transducer was derived from the piezoelectric equation.Second,the vibration transfer matrices of the tapered ultrasonic horns were obtained by combining the vibration equation,the continuous condition of the displacement,and the equilibrium condition of the force.Calculation models for the steady-state vibration amplitude of the two working ends of the transducer were then developed.A series of exciting trials were carried out to test the performance of the models.Comparison between the calculated and measured results for steady-state vibration amplitude showed that the maximum deviation was 0.0221μm,the minimum deviation was 0.0013μm,the average deviation was 0.0097μm,and the standard deviation was 0.0046μm.These values indicated good calculation accuracy,laying a good foundation for the practical application of the proposed transducer.
基金supported by the National Natural Science Foundation of China(11304207)the Natural Science Foundation of Guangdong Province(S2012010010402)the Science and Technology R&D funds of Shenzhen(JC201006020762A)
文摘A dual-excited full-wavelength piezoceramic ultrasonic transducer as a cascade of two half-wavelength sandwich piezoceramic transducers is studied.The relevant parameters' expressions of the figure of merit N for the transducer are derived,and the effects of the structure and material parameters of the transducer on its characteristics are further analyzed by numerical calculation.The results show that when the two piezoceramic stacks are respectively located at the displacement nodes of their own half-wavelength transducers,or the two piezoceramic stacks have the same number of pieces in the case of a certain number of piezoceramic pieces,the figure of merit of the transducer can reach a maximum.With increasing of the number of piezoceramic pieces in a fairly large range,the figure of merit of the transducer slightly decreases,but the force factor of the transducer increases rapidly.The metal materials of the transducer have little effect on its figure of merit.Thus it can be seen that the dual-excited full-wavelength transducer can effectively increase the volumes of the piezoceramic stacks in the case of that the transducer's comprehensive performance has only a little bit of degradation,so it's power capacity and load capability can be dramatically improved,which means the transducer is more suitable for high power and heavy load applications.
文摘This paper presents a 591×438-DPI ultrasonic fingerprint sensor.The sensor is based on a piezoelectric micromachined ultrasonic transducer(PMUT)array that is bonded at wafer-level to complementary metal oxide semiconductor(CMOS)signal processing electronics to produce a pulse-echo ultrasonic imager on a chip.To meet the 500-DPI standard for consumer fingerprint sensors,the PMUT pitch was reduced by approximately a factor of two relative to an earlier design.We conducted a systematic design study of the individual PMUT and array to achieve this scaling while maintaining a high fill-factor.The resulting 110×56-PMUT array,composed of 30×43-μm^(2) rectangular PMUTs,achieved a 51.7% fill-factor,three times greater than that of the previous design.Together with the custom CMOS ASIC,the sensor achieves 2 mV kPa^(−1) sensitivity,15 kPa pressure output,75μm lateral resolution,and 150μm axial resolution in a 4.6 mm×3.2 mm image.To the best of our knowledge,we have demonstrated the first MEMS ultrasonic fingerprint sensor capable of imaging epidermis and sub-surface layer fingerprints.
基金This work was supported by the ECSEL JOINT UNDERTAKING[826452].
文摘The mechanical characterization of a 4×4 air-coupled array of Piezoelectric Micromachined Ultrasonic Transducers(PMUTs)is pre-sented.The experimental campaign consists of three set of experi-mental tests,namely:topography measurements,small signal dynamic measurements,and vibrometry in the non-linear dynamic regime.The behavior of three different kinds of PMUT are reported.They differ according to the thermo-electrical treatment that has been applied to the piezoelectric material.The presence of the fabrication induced residual stresses is investigated and the treat-ment effect is evaluated in terms of the initial deflected configura-tion.The results reported in this paper represent an experimental mechanical investigation useful for the design of PMUT structures with advanced functionalities in the linear and non-linear regime.