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Micro-LEDs (μLEDs) have advantages in terms of brightness, power consumption, and response speed. In addition, they can also be used as micro-sensors implanted in the body via flexible electronic skin. One of the key techniques involved in the fabrication of μLED-based devices is transfer printing. Although numerous methods have been proposed for transfer printing, improving the yield of μLED arrays is still a formidable task. In this paper, we propose a novel method for improving the yield of μLED arrays transferred by the stamping method, using an innovative design of piezoelectrically driven asymmetric micro-gripper. Traditional grippers are too large to manipulate μLEDs, and therefore two micro-sized cantilevers are added at the gripper tips. A μLED manipulation system is constructed based on the micro-gripper together with a three-dimensional positioning system. Experimental results using this system show that it can be used successfully to manipulate μLED arrays. ARTICLE HIGHLIGHTS: HIGHLIGHTS • A piezoelectrically driven asymmetric micro-gripper is proposed. • A μLED manipulation system is constructed based on the micro-gripper together with a three-dimensional positioning system. • A single μLED array is manipulated by the proposed micro-gripper-based system. [ABSTRACT FROM AUTHOR]

As regards to daily developments in micro/nano technology and very special intricate missions in micro/nano scale, many researches focused on manipulation and movement in correspond scales. Micro-grippers are end effectors of micro/nano manipulation systems which perform some duties such as holding, picking up, moving and cutting. In this research a micro-gripper has been introduced which consists of two perpendicular Micro-beams. Each Micro-beam has an elastic layer and two piezoelectric layer. One of these piezoelectric layers is used for actuation and another one for sense and feedback control. First static equations of Micro-beam presented. Kinematics of Micro-gripper including direct and inverse kinematics and static displacement has been presented. Eventually Micro-gripper workspace for a Micro-beam’s ultimate displacement has been specified. The results have been verified by FEM software. The difference between the analytical results of displacements in different directions with the corresponding results of finite element software output is about 2 percent. Therefore, the results indicate the accuracy and efficiency of the proposed method and the current research can be a framework and foundation for the analysis of similar systems with more complex geometry.

A robotic system for the automatic wire pulling of coreless motor winding is designed, including the design of an opening-closing control system and a micro-gripper's tip structure with a double-armed elastic-beam structure for the support part and an enveloping clamping structure for the tip part. The micro-gripper captures the electrode wire from the root, encircles the wire after the envelope region is closed, and the thin and flexible electrode wire is pulled to the top of the electrode pad by the movement of the micro-gripper and released. The mechanical index of the micro-gripper is simulated to obtain the optimal structural parameters. The experimental results show that the electrode wire's maximum bearing force is about 0.3 N. Under this reaction force, the deformation of the tip-envelope region of the micro-gripper is about 27.5 μm, which is sufficient for electrode wire pulling micro-manipulation. By comparison with the steel micro-gripper, the silicon micro-gripper has more advantages in shape integrity, machinability and mechanical properties. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Donghua University (Natural Science Edition) is the property of Journal of Donghua University (Natural Science) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A robotic system for the automatic wire pulling of coreless motor winding is designed, including the design of an opening-closing control system and a micro-gripper’s tip structure with a double-armed elastic-beam structure for the support part and an enveloping clamping structure for the tip part. The micro-gripper captures the electrode wire from the root, encircles the wire after the envelope region is closed, and the thin and flexible electrode wire is pulled to the top of the electrode pad by the movement of the micro-gripper and released. The mechanical index of the micro-gripper is simulated to obtain the optimal structural parameters. The experimental results show that the electrode wire’s maximum bearing force is about 0.3 N. Under this reaction force, the deformation of the tip-envelope region of the micro-gripper is about 27.5 μm, which is sufficient for electrode wire pulling micro-manipulation. By comparison with the steel micro-gripper, the silicon micro-gripper has more advantages in shape integrity, machinability and mechanical properties.

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper proposes a new compliant gripper with integrated position and force sensors dedicated to automated microassembly tasks. The uniqueness of the gripper is that it possesses a large gripping range with a bidirectional drive, and it is capable of detecting grasping force and environmental interaction forces in horizonal and vertical axes, respectively. This is enabled by a mechanism design based on a rotary flexure bearing. Moreover, a compliant mechanism with two-stage stiffness is designed to provide the force sensing with dual sensitivities and measuring ranges to accommodate the grasp of objects with different sizes and weights. Analytical models are derived to predict the grasping range, force sensing sensitivities, and ranges. These models are verified by conducting finite-element analysis simulations. A proof-of-concept prototype gripper is developed for experimental calibration and performance testing. Results reveal that the single set of strain-gauge force sensor is able to detect both grasping and interaction forces in an alternate manner. The dual-sensitivity, dual-range force sensor provides a solution to large-range gripper with finer and coarser force sensing in a small and large ranges, respectively . [ABSTRACT FROM PUBLISHER]

Micro-particle is hard to be observed as small scale and hard to be gripped as micro-force from substrate, an automatic approach and grip method of micro-particle in the guide of microscopic vision systems is proposed in the paper to grip micro-particle. First, the micro-gripper driven by electrostatic force is introduced and forces in gripping process are analyzed. Second, a micro-assembly robot composed of two microscopic vision systems is established to monitor micro-operation process and to operate micro-particle. Image features of micro-particle and micro-gripper end-effector are extracted by image feature extraction method to calculate relative position of micro-particle and micro-gripper in image space. Last, a movement control strategy in 3D space based on image Jacobian matrix is studied to control micro-gripper approach and align with micro-particle. Experimental results verified the effectiveness of proposed methods. [ABSTRACT FROM AUTHOR]

This paper presents a triple-finger gripper driven by a piezoceramic (PZT) transducer for multi-target micromanipulation. The gripper consists of three fingers assembled on adjustable pedestals with flexible hinges for a large adjustable range. Each finger has a PZT actuator, an amplifying structure, and a changeable end effector. The moving trajectories of single and double fingers were calculated and finite element analyses were performed to verify the reliability of the structures. In the gripping experiment, various end effectors of the fingers such as tungsten probes and fibers were tested, and different micro-objects such as glass hollow spheres and iron spheres with diameters ranging from 10 to 800 μm were picked and released. The output resolution is 145 nm/V, and the driven displacement range of the gripper is 43.4 μm. The PZT actuated triple-finger gripper has superior adaptability, high efficiency, and a low cost. [ABSTRACT FROM AUTHOR]

This paper proposes a rapid fabrication process for miniaturized electro-thermal grippers by using silver-nickel composite ink. Thick resistive structures are dispensed on a silicon wafer by a dispenser, and the parameters of the dispenser can be controlled for different thicknesses of hot and cold arms in a micro-gripper. The fabricated single layer structures are almost symmetric about a central plane of symmetry, thus largely suppressing the out-of-plane deflection. Due to cross-sectional area difference of the cold and hot arms, the micro-gripper can be driven by applying dc voltages. Electrical and mechanical behaviors of the micro-grippers are simulated and tested, and the simulation results are in accordance with the experiment results. The simulated maximum temperature is 155 °C, and occurs at the hot arms with an input voltage of 1.54 V. The measured displacement of the micro-gripper is observed to be 311 μm for an applied current of 0.26 A with maximum power dissipation of 0.4 W. The fabricated micro-gripper can grip a small styrofoam ball with a diameter of 1.3 mm between both tips. [ABSTRACT FROM AUTHOR]

In-plane shape memory alloy (SMA) actuators operated in agonist-antagonist mode are integrated on silicon micro-grippers. The actuator elements are cut out of sheet material in a femtosecond laser ablation process. The assembly process is carried out on wafer-level, and the fixation realized by galvanic riveting. The initial deformation of the differential actuators needed to access their actuation potential is implemented during the gripper connection to energy supply.

The aim of this study is to investigate the mechanical behavior of an electrostatically actuated functionally graded piezoelectric micro-gripper. The presented micro-gripper includes two clamped–clamped microbeams symmetrically located against each other in vertical direction. The microbeams are composed of silicon and Piezoelectric Material based on Lead Zirconate Titanate. The mechanical properties, including elasticity modulus, density, and piezoelectricity coefficient are varied exponentially along the height of the microbeam based on power law distribution. The microbeams undergo simultaneous electrostatic and piezoelectric excitations. Two main sources of nonlinearities including geometrical nonlinearity and electrostatic force dominate the dynamics of the gripper. The temporal response is determined by numerically integrating the motion equations and verified by means of method of multiple scales. The contact with the particle is modeled as linear spring which increases the overall stiffness of the grippers. The stability analysis is performed and the pull-in voltage of the device is determined. [ABSTRACT FROM AUTHOR]

This paper presents a novel micro-gripper design with the dual functions of manipulation and force sensing. The device consists of two parallel plates, each mounted on torsion bars, which can be made to rotate towards or away from each other by use of a pneumatically- or hydraulically-actuated elastic membrane. The plates can be conveniently fabricated using photo-etching and the design allows for a range of ratios between actuation pressure and tip opening displacement and force. The elastic gripping tips can be designed to provide sufficient compliance that their strain can be used to monitor and control the gripping force. An exemplar device has been fabricated and its behaviour characterised by a series of mechanical measurements of force and displacement. These measurements have been rationalised using a simple analytical model, backed up with finite element analysis to emphasise the design variables and scalability. This exemplar device, with a maximum tip opening amplitude of 1 mm and maximum force output of 50 mN, has also been demonstrated to perform pick-and-place operations with 200 μm micro-beads. [ABSTRACT FROM AUTHOR]

Single-cell analysis and manipulation methods are becoming increasingly important for fundamental research, as well as practical applications, such as in vitro fertilization (IVF) and pharmaceutical research and development. The need for adequate handling tools is reflected in a large number of publications discussing grippers, injection automation, or cell immobilization. Endeavors toward the improvement of existing devices focus on the continuous monitoring of multiple parameters, such as gripping force, constitution of the medium, or recording of video sequences, enabling the operator or the operating system to verify proper functioning of the method and the success of the operation. The approach described in this conceptual study unifies the steps of cell positioning, immobilization, tool alignment, manipulation, and analysis by integrating the necessary devices into a single monolithic tool based on a micromechanical gripper. The critical mechanical and fluidic aspects of the new design are investigated by analytical calculations and finite-element analysis to evaluate the feasibility of the micro-gripper. In doing so, local critical stresses inside the oocytes have been determined, allowing conclusions on the micro-gripper design. Furthermore, the monolithic micro fabrication route is described, and the first results of the process development for integrated injection and immobilization channels are presented. [ABSTRACT FROM AUTHOR]

This paper develops a monolithic compliant SPCA-driven micro-gripper for micro-assembly and describes the mechanism design, kinematic model, static model, control strategy and experimental verification of micro-gripper. The paper includes the following points: (1) the MCM integrates the lever mechanism and parallelogram mechanism so as to magnify the SPCA input and transform the linear input of SPCA into the clamping movement of gripping jaw. In addition, the kinematic model of the MCM is established to describe the relationship between the SPCA input and the output displacement of gripping jaw. (2) The static model of movement jaw is established to analyze the inherent relationship between the gripping force and the strain angle of flexible hinge. (3) The control strategy based on the incremental PID algorithm is applied to control the gripping manipulation of micro-gripper. The control strategy selects the visual or force feedback signal according to the contacting condition between the gripping jaw and clamped micro-object. Finally, a series of experiments were performed to validate the kinematic model, static model and control strategy of micro-gripper. In addition, a glassy micro-tube with 150 μm diameter was clamped non-destructively by the developed micro-gripper. [ABSTRACT FROM AUTHOR]

Meso-scale parts are widely used in the complex miniature weapon systems. On account of a large dimension range, a variety of shapes and vulnerable structures of the meso-scale parts, the weapon systems are mainly assembled by hand, bringing poor efficiency and reliability. A challenging issue in the precision assembly of miniature weapon systems is how to safely and reliably grip the meso-scale parts in the automatic handling and assembly. A micro-gripper for gripping the sub-millimeter and millimeter scale shafts and parts is developed, including a pair of rigid and flexible gripping jaws and a precision linear motion stage. A Wheatstone bridge, which consists of strain gauges stuck on the flexible gripping jaw, is used to detect a clamping force on a part in real time. The structural parameters of flexible gripping jaw are designed optimally, and an optimal design model of gripping jaws is proposed. A simulation analysis is carried out to determine the best sticking positions of the gauges. A strain-force model for the special shape of flexible gripping jaw is derived. Grip-release experiments indicate that the micro-gripper is capable to grip the meso-scale parts stably and nondestructively. [ABSTRACT FROM AUTHOR]

This paper describes an experimental approach to the adaptive positioning of a MEMS production system with nano - scale resolution. It is known that accurate positioning within nano - scale requires higher move resolutions which cause drastic speed reductions. Production processes which are running within such production systems are therefore very time consuming or very limited due to their working spaces. We are proposing an adaptive approach to the positioning within nano - scale, which will help us extend the size of the system's working space in such a way that it will not be time consuming. The basic idea of our approach is that the move resolution and the move speed are adapted according to the size of positioning error. Large positioning error sets the system to low resolution and high speed. As a separate axis approaches the target point, positioning error decreases, move resolution increases, and move speed decreases. The so called adaptive approach was tested on the positioning system with five axes based on Piezo LEGS© linear motors, with the use of bang-bang, fuzzy and polynomial control techniques. The results of the experiments with these techniques, and the practical implementation of them, are given in this paper. The practical use of such a system with three different micro-grippers is also presented. [ABSTRACT FROM AUTHOR]

This paper describes the design and simulation of an integrated micro-electro-mechanical system (MEMS) to be used for micromanipulation. Electrothermal micro-grippers were designed for micro-tensile tests of biological materials which require relatively low force and temperature. Finite element analysis (FEA) was performed to examine gripper opening displacements, tip temperature and stresses. The feasibility of various materials including silicon, plated nickel and SU-8 was examined for applications in biological environment. The paper looks at fabrication techniques employed to allow a cheaper, wet etching solution, to the fabrication of SU-8 micro-grippers. The structure was successfully fabricated and tested. The results showed that the micro-gripper could be actuated by fairly low voltage. [ABSTRACT FROM AUTHOR]

A novel micro-gripper is designed and fabricated to manipulate the micro-sized object like a cell. In order to grip the cell, the micro-gripper should be operated in the liquid environment. Since the mechanical type micro-gripper is rarely affected by the surroundings, it is suitable to treat the cell. The other consideration for manipulating the cell is properties of the cell such as the bursting force and the maximum deformation of the cell for the applied force. Thus, the sensor system is needed to measure the force on the cell during the gripping. On this micro-gripper, a piezoresistive sensor is integrated for sensing the gripping force. Using the fabricated micro-gripper, micro-glass beads are successfully manipulated in the water. The resistance in the piezoresistor is changed by 0.06∼ 0.07% for each 10 μ N of the applied force. Therefore, since the proposed micro-gripper satisfies the requisite conditions, it can be utilized for manipulation of the cell. [ABSTRACT FROM AUTHOR]

Abstract: Worldwide, many micro-actuators have been developed for various applications in biotechnology, biochemistry, micro-sensors, etc. However, most of these actuators have been made using 2D-based micro-electro-mechanical systems (MEMS) technology, so they cannot perform long-travel 3D motion. This substantially limits the applications of these actuators. In this study, we developed a new bellows-shaped micro-actuator using micro-stereolithography (MSTL) technology, which makes it possible to fabricate complex 3D microstructures. The total travel and 3D motion of the new actuator could be easily adjusted during the design process. Using a finite element method (FEM) simulation, the actuation characteristics were analyzed and compared with experimental results. The analysis verified the adjustability of the total travel. In addition, to demonstrate the feasibility of the actuation principle in 3D space, two different kinds of micro-gripper were successfully demonstrated. [Copyright &y& Elsevier]

This paper presents a micro-pneumatic actuator utilizing a new actuation principle for micro-mechanical systems. As a first application, a micro-gripper driven by two bellow-type micro-pneumatic actuators, is described. The basic structures of the micro-pneumatic actuator and the micro-gripper are fabricated by silicon dry etching in a single etching step. The device consists of a Pyrex–silicon–Pyrex sandwich structure which was assembled by anodic bonding. Alternatively, an SU8 UV-depth lithography process was used to realize the pneumatically driven micro-gripper. [Copyright &y& Elsevier]

A microelectromechanical systems (MEMS) rotary microgripper incorporating electrothermal force sensors is reported. The device is fabricated using a standard SOI-MEMS process and achieves a stroke of (90 μm) m) at a relatively low voltage (<;80 V). The electrothermal force sensor has a small footprint, is quite linear, and operates with a high accuracy. Being fabricated from biocompatible material (silicon) with sufficiently long gripping arms, the gripper can be used to manipulate living cells, tissues, and other biologically relevant samples. A pick-and-place experiment on a soft cell is conducted to verify performance of the proposed rotary microgripper. [ABSTRACT FROM PUBLISHER]