RESUMO
The microgripper plays a critical role in micromanipulation systems; however, the handling accuracy of traditional driving microgrippers suffers from external vibration due to requiring connecting wires for an external power supply. By contrast, light driving has many advantages of remote non-contact manipulation, wireless energy transfer and no induced electromagnetic noise. In this study, an opto-electrostatic repulsive combined driving mechanism was proposed, and then a novel light-operated microgripper that used an opto-electrostatic repulsive actuator was designed and simulated. The static performance of the light-operated microgripper was investigated via simulation and numeric calculation results. The overall size of the microgripper was 1.3 mm × 0.7 mm × 1.027 mm, and the micro-objects ranging from 0 to 1000 µm in size could be manipulated and held using light. The proposed microgripper had many outstanding characteristics, such as a larger stroke, high response speed, remote non-contact manipulation, easy to integrate with an integrated circuit (IC) process and free from external interference. In addition, the dynamic control experiments of the photo-induced voltage of the PbLaZrTi (PLZT) ceramic were carried out, which shows that a stable electrical field could be obtained using the effective control methods that were developed.
RESUMO
With the increased application of ultrasonic motors, it is necessary to put forward higher demand for the adaptability to environment. Impact, as a type of extreme environment, is widespread in weapon systems, machinery and aerospace. However, there are few reports about the influence of impact on an ultrasonic motor. This article aimed to study the reasons for the performance degradation and failure mechanism of an ultrasonic motor in a shock environment. First, a finite element model is established to observe the dynamic response of ultrasonic motor in a shock environment. Meanwhile, the reasons of the performance degradation in the motor are discussed. An impact experiment is carried out to test the influence of impact on an ultrasonic motor, including the influence on the mechanical characteristic of an ultrasonic motor and the vibration characteristic of a stator. In addition, the protection effect of rubber on an ultrasonic motor in a shock environment is verified via an experimental method. This article reveals the failure mechanism of ultrasonic motors in a shock environment and provides a basis for the improvement of the anti-impact property of ultrasonic motors.
RESUMO
The coupled thickness-twist and face-shear vibrations of the lateral-field-excitation (LFE) two-unit resonator array are analyzed, and the frequency interference and shift of LFE resonator arrays are both studied. Different from most of the quartz resonator arrays based on thickness-field-excitation, the resonator array in this study operates with LFE generated by a pair of electrodes on the top surface of the resonator. By using Mindlin's first-order theory of piezoelectric plates, the electrically forced vibrations are analyzed. The effects of various structural parameters on the frequency interference and shift are examined; furthermore, the corresponding mechanisms are discussed. Varying trends of the frequency interference and shift with various structural parameters are verified by the finite element method. The results are crucial for avoiding frequency interferences between two adjacent units in parameter design of the resonator array operating on LFE.
RESUMO
The double-mode lateral-field-excitation (LFE) bulk acoustic wave characteristics of Ca3TaGa3Si2O14 (CTGS) crystals are investigated. It is found that LFE devices based on (yxl)-57° CTGS crystals can work on both pure-LFE and pseudo-LFE modes when the driving electric field direction is normal to the crystallographic x axis of the piezoelectric substrate. Several double-mode LFE bulk acoustic wave devices based on CTGS crystals are designed and tested. The experimental results conform to the theoretical prediction well. Being able to operate in pure-LFE and pseudo-LFE modes, the double-mode LFE sensors show high sensitivity to both mechanical and electrical property changes of analytes. The results provide the crystal cut for double-mode LFE sensors, which is a critical basis of designing high-performance chemical and biological sensors by using double-mode LFE devices.