We analyze thickness-shear vibration of an axially poled circular cylindrical tube with unattached electrodes and air gaps. Both free and electrically forced vibrations are studied. Exact solutions are obtained from t...We analyze thickness-shear vibration of an axially poled circular cylindrical tube with unattached electrodes and air gaps. Both free and electrically forced vibrations are studied. Exact solutions are obtained from the equations of linear piezoelectricity. Resonant frequencies and the impedance of the transducer are calculated from the solution. Results show that the resonant frequencies are sensitive to the dimensions of the air gaps when the gaps are thin. The impedance depends strongly on the air gaps.展开更多
The paper proposed a method to capture micron-sized particles in three-dimensional fluid space using bulk acoustic wave(BAW) microstreaming traps.Two types of BAW microstreaming trap arrays were prepared,and the finit...The paper proposed a method to capture micron-sized particles in three-dimensional fluid space using bulk acoustic wave(BAW) microstreaming traps.Two types of BAW microstreaming trap arrays were prepared,and the finite element method(FEM) was used to simulate them.The first-order and second-order acoustic fields were obtained by solving the Navier-Stokes equation.The movement of polystyrene particles in the flow field was simulated and analyzed.The experimental results showed that the BAW microstreaming traps could quickly and efficiently capture micron-sized particles in three-dimensional fluid space.The experimental results were in good agreement with the simulation results.Both cylindrical and circular hole BAW microstreaming traps could capture particles in three-dimensional space in tens of seconds.Moreover,the capture efficiency of the cylindrical BAW microstreaming traps was higher than that of circular hole BAW microstreaming traps.This method breaks the limitation that the surface acoustic wave(SAW) microstreaming traps cannot manipulate the particles in three-dimensional space,which improves the efficiency of capturing the particles.展开更多
To explore a more convenient method for measuring the focused ultrasound power, a piezoelectric ceramic plate was used to receive ultrasonic signal directly. Due to an acoustic force acts on the surface of piezoelectr...To explore a more convenient method for measuring the focused ultrasound power, a piezoelectric ceramic plate was used to receive ultrasonic signal directly. Due to an acoustic force acts on the surface of piezoelectric ceramic plate, the piezoelectric response was obtained by means of electromechanical analogy, which was composed of voltage response caused by forced vibration and high frequency attenuation response caused by natural vibration. The conversion relationship between output signal of piezoelectric ceramic plate and acoustic power of transducer was analyzed. The envelope of output piezoelectric signal was extracted in twice, and a voltage amplitude curve with sinusoidal distribution that could describe the changes of acoustic power was obtained. Under different drive voltage of transducer, the maximum peak voltage of envelope curve was found respectively. Their squared values were made a linear fitting with acoustic power measured by acoustic power meter, and then the proportional coefficient of theoretical relational expression was calibrated. The experimental results are in good agreement with the theory. The relative error between calibrated theoretical acoustic power and that measured by acoustic power meter was less than 8.7%. The paper can provide a guideline for measuring acoustic power of transducer by using piezoelectric signal.展开更多
基金Supported by the National Natural Science Foundation of China (Grant No. 50778179)
文摘We analyze thickness-shear vibration of an axially poled circular cylindrical tube with unattached electrodes and air gaps. Both free and electrically forced vibrations are studied. Exact solutions are obtained from the equations of linear piezoelectricity. Resonant frequencies and the impedance of the transducer are calculated from the solution. Results show that the resonant frequencies are sensitive to the dimensions of the air gaps when the gaps are thin. The impedance depends strongly on the air gaps.
基金supported by the Natural Scienceof Chongqing (cstc2019jcyjmsxmX0098)。
文摘The paper proposed a method to capture micron-sized particles in three-dimensional fluid space using bulk acoustic wave(BAW) microstreaming traps.Two types of BAW microstreaming trap arrays were prepared,and the finite element method(FEM) was used to simulate them.The first-order and second-order acoustic fields were obtained by solving the Navier-Stokes equation.The movement of polystyrene particles in the flow field was simulated and analyzed.The experimental results showed that the BAW microstreaming traps could quickly and efficiently capture micron-sized particles in three-dimensional fluid space.The experimental results were in good agreement with the simulation results.Both cylindrical and circular hole BAW microstreaming traps could capture particles in three-dimensional space in tens of seconds.Moreover,the capture efficiency of the cylindrical BAW microstreaming traps was higher than that of circular hole BAW microstreaming traps.This method breaks the limitation that the surface acoustic wave(SAW) microstreaming traps cannot manipulate the particles in three-dimensional space,which improves the efficiency of capturing the particles.
基金supported by the National Science Foundation of China(11274404,81201102)Municipal Education Commission Science Foundation of Chongqing(KJ1500204)
文摘To explore a more convenient method for measuring the focused ultrasound power, a piezoelectric ceramic plate was used to receive ultrasonic signal directly. Due to an acoustic force acts on the surface of piezoelectric ceramic plate, the piezoelectric response was obtained by means of electromechanical analogy, which was composed of voltage response caused by forced vibration and high frequency attenuation response caused by natural vibration. The conversion relationship between output signal of piezoelectric ceramic plate and acoustic power of transducer was analyzed. The envelope of output piezoelectric signal was extracted in twice, and a voltage amplitude curve with sinusoidal distribution that could describe the changes of acoustic power was obtained. Under different drive voltage of transducer, the maximum peak voltage of envelope curve was found respectively. Their squared values were made a linear fitting with acoustic power measured by acoustic power meter, and then the proportional coefficient of theoretical relational expression was calibrated. The experimental results are in good agreement with the theory. The relative error between calibrated theoretical acoustic power and that measured by acoustic power meter was less than 8.7%. The paper can provide a guideline for measuring acoustic power of transducer by using piezoelectric signal.
