Design of a Piezoelectric-actuated microgripper with a three-stage flexure-based amplification

This paper presents a novel microgripper mechanism for micromanipulation and assembly. The microgripper is driven by a piezoelectric actuator, and a three-stage flexure-based amplification has been designed to achieve large jaw displacements. The kinematic, static and dynamic models of the microgripper have been established and optimized considering the crucial parameters that determine the characteristics of the microgripper. Finite element analysis was conducted to evaluate the characteristics of the microgripper, and wire electro discharge machining technique was utilized to fabricate the monolithic structure of the microgripper mechanism. Experimental tests were carried out to investigate the performance of the microgripper and the results show that the microgripper can grasp microobjects with the maximum jaw motion stroke of 190 μm corresponding to the 100-V applied voltage. It has an amplification ratio of 22.8 and working mode frequency of 953 Hz

A flexure-based kinematically decoupled micropositioning stage with a centimeter range dedicated to micro/nano manufacturing

Precision positioning stages with large strokes and high positioning accuracy are attractive for high-performance micro/nano manufacturing. This paper presents the dynamic design and characteristic investigation of a novel XY micropositioning stage. Firstly, the mechanism of the stage was introduced. The XY stage was directly driven by two linear motors, and the X- and Y- axes kinematic decoupling was realized through a novel flexible decoupling mechanism based on flexure hinges and preloaded spring. The dynamic model of the XY stage was established, and the influences of the rotational stiffness of the flexure hinge and the initial positions of the working table on the dynamic rotation of the positioning stage were investigated. The stiffness and geometric parameters of the flexure hinges were determined at the condition that the angular displacements of the working table were within ±0.5° with a motion stroke of ±25 mm. Finally the stage performance was investigated through simulation and experiments, the X- and Y-axes step responses, the rotation angular and positioning accuracy of the stage were obtained. The results show that the stage exhibits good performance and can be used for micro/nano manufacturing

Design of high frequency ultrasonic transducers with flexure decoupling flanges for thermosonic bonding

This paper presents the design of high frequency ultrasonic transducers for micro/nano device thermosonic bonding. The transducers are actuated by piezoelectric ceramics and decoupled with their connecting parts through novel flexure decoupling flanges. Firstly, the initial geometric dimensions of the transducers were calculated using electromechanical equivalent method, then dynamic optimization design was carried out based on 3D finite element method (FEM), and the geometric dimensions of the transducer were finally determined. Flexure decoupling flanges were presented, and the decoupling principle of the flanges was explained through compliance modeling using compliance matrix method and FEM. After that the dynamic characteristics of the transducers were analyzed through finite element analysis (FEA). The vibration frequencies and modes of the piezoelectric converter, concentrators and transducers were obtained through modal analysis, and the displacement nodes were determined. The longitudinal ultrasonic energy transmission was presented and the decoupling effects of the flexure flanges were compared. Finally, the transducers were manufactured and experimental tests were conducted to examine the transducer characteristics using an impedance analyzer. The experimental results match well with the FEA. The results show that the longitudinal vibration frequencies of the transducers with ring, prismatic beam and circular notched hinge based flanges are 126.6 kHz, 125.8 kHz and 125.52 kHz, respectively. The decoupling flange with circular notched hinges shows the best decoupling effect among the three types of flanges

Dynamic modeling and control of a novel XY positioning stage for semiconductor packaging

This paper presents the dynamic modeling and controller design of an XY positioning stage for semiconductor packaging. The XY stage is directly driven by two linear voice coil motors, and motion decoupling between the X and Y axes is realized through a novel flexible decoupling mechanism based on flexure hinges and preloaded spring. Through bond graph method, the dynamic models of X- and Y-axes servomechanisms are established, respectively, and the state space equations are derived. A control methodology is proposed based on force compensations and the performance of the XY stage is investigated by simulations and experimental tests. The results show that the XY stage has good performance. When the reference displacements are defined as 2 mm, the settling time of the X-axis movement is 64 ms, and the overshoot is 0.7%. Y-axis settling time is 62 ms, and the overshoot is 0.8%. X-axis positioning accuracy is 1.85 μm and the repeatability is 0.95 μm. Y-axis positioning accuracy and repeatability are 1.75 μm and 0.9 μm, respectively. In addition, the stage can track linear, circular and complex trajectories very well

A novel actuator-internal micro/nano positioning stage with an arch-shape bridge type amplifier

This paper presents a novel actuator-internal two degree-of-freedom (2-DOF) micro/nano positioning stage actuated by piezoelectric (PZT) actuators, which can be used as a fine actuation part in dual-stage system. To compensate the positioning error of coarse stage and achieve a large motion stroke, a symmetrical structure with an arch-shape bridge type amplifier based on single notch circular flexure hinges is proposed and utilized in the positioning stage. Due to the compound bridge arm configuration and compact flexure hinge structure, the amplification mechanism can realize high lateral stiffness and compact structure simultaneously, which is of great importance to protect PZT actuators. The amplification mechanism is integrated into the decoupling mechanism to improve compactness, and to produce decoupled motion in X- and Y- axes. An analytical model is established to explore the static and dynamic characteristics, and the geometric parameters are optimized. The performance of the positioning stage is evaluated through finite element analysis (FEA) and experimental test. The results indicate that the stage can implement 2-DOF decoupled motion with a travel range of 55.4×53.2 μm2, and the motion resolution is 8 nm. The stage can be used in probe tip-based micro/nano scratching

A novel monolithic piezoelectric actuated flexure-mechanism based wire clamp for microelectronic device packaging

A novel monolithic piezoelectric actuated wire clamp is presented in this paper to achieve fast, accurate, and robust microelectronic device packaging. The wire clamp has compact, flexure-based mechanical structure and light weight. To obtain large and robust jaw displacements and ensure parallel jaw grasping, a two-stage amplification composed of a homothetic bridge type mechanism and a parallelogram leverage mechanism was designed. Pseudo-rigid-body model and Lagrange approaches were employed to conduct the kinematic, static, and dynamic modeling of the wire clamp and optimization design was carried out. The displacement amplification ratio, maximum allowable stress, and natural frequency were calculated. Finite element analysis (FEA) was conducted to evaluate the characteristics of the wire clamp and wire electro discharge machining technique was utilized to fabricate the monolithic structure. Experimental tests were carried out to investigate the performance and the experimental results match well with the theoretical calculation and FEA. The amplification ratio of the clamp is 20.96 and the working mode frequency is 895 Hz. Step response test shows that the wire clamp has fast response and high accuracy and the motion resolution is 0.2 μm. High speed precision grasping operations of gold and copper wires were realized using the wire clamper

Design of a novel 3D tip-based nanofabrication system with high precision depth control capability

The design, analysis, and experimental investigation of a novel 3D tip-based nanofabrication system with high precision depth control capability is presented in this paper. Based on this system, a new depth control method, namely tip displacement-based closed-loop (DC) depth control methodology is proposed to improve the depth control capability. As the force-depth prediction with the commonly-used depth control method, i.e. the normal force-based closed-loop (FC) method, may depend on the machining speed, the machining direction, and the material properties, etc. Compared with the FC method, the DC method decreases the complexity and the high uncertainty. The tip feed system utilizes a non-contact force, i.e. the electromagnetic force, to adjust the tip displacement. Therefore, the tip support mechanism can be used to accomplish the tip-sample contact detection. Additionally, an active compensation method is proposed to eliminate the tilt angle between the sample surface and the horizontal plane. Otherwise the machining depth will change gradually, i.e. getting deeper or lower. Furthermore, a series of patterns have been fabricated on silicon sample surface with the proposed system and method. The maximum machining depth of a single scan reaches 300 nm, which is much larger than that of an atomic force microscope (AFM)-based nanofabrication system. The experimental results demonstrate that the system has advantages of distinguished depth control capability, high machining accuracy, and excellent repeatability, which diminishes the influence of above-mentioned factors on the machining depth. Also, the method has the potential of machining arbitrary 2D/3D patterns with well-controlled depth and high accuracy