Papers by Keyword: Micro-Actuator

Abstract: In this study, capabilities of zinc oxide (ZnO) thin films in sensing and actuating were investigated using micromachined micro-cantilevers. A heterogeneous piezoelectric cantilever was modeled to study its response under voltage and/or external mechanical loading. A ZnO thin-film micro-cantilever was designed based on the developed theoretical model. Simulated tip deflections of the micro-cantilever were on the nanometer level under typical electrical and mechanical input. A prototype was fabricated with microfabrication techniques. The ZnO thin film was sputtered at room temperature and demonstrated good compatibility with common chemicals and processes in micromachining. The fabricated micro-cantilever was experimentally characterized for its actuating and sensing performance. For actuator characterization tip deflection of the micro-cantilever was detected by a laser Doppler vibrometer, while for sensor characterization the micro-cantilever was calibrated as an acceleration sensor using a reference accelerometer. The experimental resonant frequency, actuating and sensing sensitivities agreed well the design specifications.

Abstract: For the problems of the oversized voltage and undersized displacement in the electrostatic micro actuator of transverse loading recently, a silicon micro actuator model with characteristics of large-displacement and low-voltage is presented based on the principle of vertically-horizontally bending. The deflection equation of the micro actuator is derived. The axial static electricity, temperature stress and axial squeezing pressure on the deformation of micro-beam are analyzed. The simulation shows that the displacement is as big as 17.5μm when the driving voltage is as low as 5V. The displacement is much larger than the deformation of the current micro actuator.

Abstract: Micro-actuators using giant magnetostrictive material as the core of drive components are becoming more and more widely used in the field of precise micro-actuator. In order to improve the energy transfer efficiency of the micro-actuator, reduce energy losing as heat and improve the working accuracy of micro-actuator.The relationship of pre-compression stress, magnetoconducivity and electromechanical coupling factor has been analyzed in the theory; A reasonable composition form of bias magnetic field has been put out; The relationship between bias magnetic field and electromechanical coupling factor has been analyzed; The configuration and size of coils have been optimized; The relationship between bias magnetic field and electromechanical factor has been discussed and experiments on correlative fields have been accomplished. When GMM is driven by constant magnetic field, measures like optimizing pre-compression stress, configuration and size of coils can be taken to improve giant magnetostrictive energy transfer efficiency and working performance of micro-actuator so that the driving performance can reach the best.

Abstract: For the purpose of developing liquid crystalline micro-actuators, the transient behaviors of a nematic liquid crystal between two parallel plates have been computed for various parameters such as applied voltage, the gap between the plates, and the twist and tilt angles at the plates. The Leslie–Ericksen theory has been selected as a constitutive equation. As conclusion of this study, we can develop micro-actuators with arbitrary characteristics by suitably controlling the applied voltage, the size of the actuators, and the director anchoring conditions.

Abstract: As a purpose of developing micro-actuators driven by liquid crystals, transient behaviors of a nematic liquid crystal between two parallel plates under an electric field have investigated numerically by using the Leslie-Ericksen theory. Twist angle has been selected as computational parameters. Imposition of an electric field on a liquid crystal induces backflow whose profile and magnitude depend strongly on the twist angle of the director. When the twist angle is 0 degree, the induced flow is planar, and with increasing of the twist angle, the flow has an out of plane component, and finally the profile becomes unidirectional when the twist angle reaches 180 degrees.

Abstract: Micro-actuator technology is important base of design and fabrication MEMS. According to a kind of bimorph thermal actuator, this paper obtains the thermal deflection and temperature distribution of MEMS thermal actuator by using finite element analysis. The relationship between the thermal deflection and some parameter such as length of flexure are analyzed in detail. Through simulation comparison, the influences of the length of flexure on thermal deflection and fatigue life are verified, which provides a good guide for the design of MEMS thermal actuator further.

Abstract: This paper presents a novel microactuator driven by shape memory alloy (SMA). First, the helical spring-shaped SMA is fabricated from SMA wire (Ti50%-Ni45%-Cu5%) with one way shape memory effect and 0.6 mm in diameter. Subsequently, a compliant tube-type microactuator driven by helical spring-shaped SMA is developed. The performances of the helical spring-shaped SMA and the compliant tube-type microactuator, such as the response time, the recovery force and the surface temperature in terms of the driving currents, are investigated. The driving circuit system comprising a pulse width modulation (PWM) control circuit is used to drive the actuator. Experiments demonstrate that control of the SMA actuator using PWM effectively reduces the energy consumption and ensures a short cooling time to guarantee a high response time in actuating cycles. Finite element software (COSMOSWorks) is applied for the analysis of the compliant tube-type actuator, which aim is to demonstrate the agreement between the theoretical analysis and experiment as well as to improve the performance of the actuators.

Abstract: The paper present a type of nano and manipulators which are based on structure of the magnetic bacterium, which is described. There are presented a theoretical study and analisys of the micromechanic circuit with elastic and damper elements, the micromagnetic circuit ( with micromagnetic specific characteristics) and also the electromechanic analogy aspects of the magnetic bacterium. The authors propose some nano and micromanipulators based on the structure of the chain of magnetic bacterium which include the nano or micro magnetic particles. The calculus, electromechanical modeling and experiments of this nano or microstructure what work and in the fluid medium are presented. There are evidenced the possible aspects on microrobotics and application field.

Abstract: A novel piezoelectric micro-actuator with actuating range amplification structure has been proposed. This actuator is unique in that the leverage type amplification structure enables large actuating movement with low voltage. In case of general piezoelectric thin film actuator, applied voltage is low and almost zero power is consumed. Its switching time is very fast in comparison with electrostatic actuators and thermal actuators. However, the most drawback of piezoelectric actuator is short actuating range. A 100μm length PZT actuator can only make movement of 100
. In this research, we suggest an actuator which can provide geometric amplification of the PZT strain displacement in lateral direction. The lateral piezoelectric MEMS actuator was fabricated and its actuating range was measured. The actuator shows maximum lateral displacement of 1.1μm, and break-down-voltage of the thin film PZT actuator is above 16V.

Abstract: The shape memory effect and the high damping in shape memory alloys are based on the martensitic phase transformation, which takes place essentially without diffusion and any change of order have an influence on its side effects: the memory effect, the superelasticity and the high damping capacity of the martensitic phase. A new method to control the performance of shape memory alloys is presented, which is based on selective modification of specified parts of working components. In this research, ion irradiation has been used to introduce locally disorder into a crystal or even amorphise it. A pre-deformed Ni-Ti, 6μm thin film in its martensitic state has been irradiated with Ni-ions of energy of 5 MeV up to a dose of 1016 ions/cm2. By this treatment, a 2μm thin surface layer has been finally transformed into an amorphous state, in which the martensitic transformation is suppressed. During heating the underlying non-modified layer is contracting and an out-of-plane movement is observed. The amorphous layer is elastically deformed and its energy is used during cooling to bring the film in its original shape. In this way, a reversible movement of the film is created. This new technique not only allows us to design new types of micro-actuators, but also to influence locally the high damping, which can be of great importance for micro-engineering applications.