A Comprehensive Survey on Microgrippers Design: Operational Strategy
01 Jul 2017-Journal of Mechanical Design (American Society of Mechanical Engineers Digital Collection)-Vol. 139, Iss: 7, pp 070801
About: This article is published in Journal of Mechanical Design.The article was published on 2017-07-01. It has received 66 citations till now.
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76 citations
TL;DR: A review of electrothermal micro-actuators and applications is presented in this paper, where the three main configurations of electro-thermal actuators are discussed: hot-and-cold-arm, chevron, and bimorph.
Abstract: This paper presents a review of electrothermal micro-actuators and applications. Electrothermal micro-actuators have been a significant research interest over the last two decades, and many different designs and applications have been investigated. The electrothermal actuation method offers several advantages when compared with the other types of actuation approaches based on electrostatic and piezoelectric principles. The electrothermal method offers flexibility in the choice of materials, low-cost fabrication, and large displacement capabilities. The three main configurations of electrothermal actuators are discussed: hot-and-cold-arm, chevron, and bimorph types as well as a few other unconventional actuation approaches. Within each type, trends are outlined from the basic concept and design modifications to applications which have been investigated in order to enhance the performance or to overcome the limitations of the previous designs. It provides a grasp of the actuation methodology, design, and fabrication, and the related performance and applications in cell manipulation, micro assembly, and mechanical testing of nanomaterials, Radio Frequency (RF) switches, and optical Micro-Electro-Mechanical Systems (MEMS).
66 citations
TL;DR: This paper is concentrated on reviewing the state-of-the-art research on complaint micro-/nano-positioning stage design in recent years and involves the major processes and components for designing a compliant positioning stage, e.g., actuator selection, stroke amplifier design, connecting scheme of the multi-DOF stage and structure optimization.
Abstract: Micromanipulation is a hot topic due to its enabling role in various research fields. In order to perform a high precision operation at a small scale, compliant mechanisms have been proposed and applied for decades. In microscale manipulation, micro-/nano-positioning is the most fundamental operation because a precision positioning is the premise of subsequent operations. This paper is concentrated on reviewing the state-of-the-art research on complaint micro-/nano-positioning stage design in recent years. It involves the major processes and components for designing a compliant positioning stage, e.g., actuator selection, stroke amplifier design, connecting scheme of the multi-DOF stage and structure optimization. The review provides a reference to design a compliant micro-/nano-positioning stage for pertinent applications.
59 citations
TL;DR: A CSFH has been analyzed with both theoretical and finite element methods, in order to obtain the relation between voltage and generated torque, and showed that CSFH performs better than linear flexure hinges in terms of larger rotations and less stress for given applied voltage.
Abstract: Progress in MEMS technology continuously stimulates new developments in the mechanical structure of micro systems, such as, for example, the concept of so-called CSFH (conjugate surfaces flexural hinge), which makes it possible, simultaneously, to minimize the internal stresses and to increase motion range and robustness. Such a hinge may be actuated by means of a rotary comb-drive, provided that a proper set of simulations and tests are capable to assess its feasibility. In this paper, a CSFH has been analyzed with both theoretical and finite element (FEM) methods, in order to obtain the relation between voltage and generated torque. The FEM model considers also the fringe effect on the comb drive finger. Electromechanical couple–field analysis is performed by means of both direct and load transfer methods. Experimental tests have been also performed on a CSFH embedded in a MEMS prototype, which has been fabricated starting from a SOI wafer and using D–RIE (deep reactive ion etching). Results showed that CSFH performs better than linear flexure hinges in terms of larger rotations and less stress for given applied voltage.
32 citations
TL;DR: In this article, the authors reviewed the recent advances on performance indices, classification, structural composition, optimization and modeling method, and control of PEACM and provided a guideline on further development of the micro gripper.
Abstract: The piezoelectric-actuated compliant microgripper (PEACM) plays an essential role in the application fields such as biomedical engineering, microelectronics, and optical engineering. As compared with other categories of grippers, PEACM exhibits the advantages of high accuracy of displacement, large power to weight ratio, low energy consumption, and fast response speed. This paper reviews the recent advances on performance indices, classification, structural composition, optimization and modeling method, and control of PEACM. First, the gripper's performance indices and classifications are elaborated, which is beneficial to determine the design goal. Then, the compliant mechanisms adopted in the microgripper design are discussed, including the flexible hinge, displacement amplifier, and guiding mechanism. In addition, the optimization and modeling methods of the microgripper are presented. Popular types of position/force sensors and different displacement/force control strategies employed in the microgripper are surveyed. Moreover, the prospect on future development trend of the PEACM is discussed. The paper provides the reader with an overview of the recent advances on PEACM design and also a guideline on further development of the microgripper.
32 citations
References
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01 Aug 2016-Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems
TL;DR: A thermomechanical behavior analysis of bimorph SMA structure and studies the effect of varying the SMA layer thickness, the type of stress layer and its thickness, and the processing temperature on the displacement of the microactuator is presented in this paper.
Abstract: Shape-memory-alloy (SMA) has attracted considerable attention in recent years as a smart and efficient material, due to its unique properties. SMA microactuators became one of the potential solutions for unresolved issues in microelectromechanical systems (MEMS). This paper presents a thermomechanical behavior analysis of bimorph SMA structure and studies the effect of varying the SMA layer thickness, the type of stress layer and its thickness, and the processing temperature on the displacement of the microactuator. Furthermore, the analyzed results were verified by experimental work, where the fabrication of the SMA microactuators followed the standards of the MEMS fabrication process. SiO2, Si3N4 and Poly-Si were used as stress layers. The fabrication results showed that the bimorph SMA structure achieved maximum displacement when SiO2 was used. The SMA structure with dimensions of 10 mm (length) × 2 mm (width) × 80 µm (thickness), had maximum displacement of 804 µm when 4.1 µm of SiO2 layer was deposited at a temperature of 400 °C.
26 citations
TL;DR: A chronological overview of gripping force measurement using two-fingered micromanipulation systems from the early 90s to the present, focusing in particular on the evolution of measurement technologies regarding the requirements of microrobotic applications.
Abstract: Two-fingered micromanipulation systems with an integrated force sensor are widely used in robotics to sense and control gripping forces at the micro and nano-scales. They became of primary importan...
26 citations
01 Jan 2014
TL;DR: A review of electrostatic, piezoelectric and electrothermal microactuators is presented in this paper, where three actuation principles and characteristics are briefly explained.
Abstract: Microactuators are emerging as important tools that are capable of performing the tasks of conventional tools in the macroworld, but they are much smaller and allow greater precision. A review of electrostatic, piezoelectric and electrothermal microactuators is presented. The basics of these three actuation principles and characteristics are briefly explained to highlight the motivation behind the selection of different microactuators. Various design models of electrostatic, piezoelectric and electrothermal microactuators are described and compared from the perspective of the mechanism and output performance. Limitations of existing designs are identified to improve some of these microactuators to gain better performance or reliability. Finally, key challenges in different microfabrication techniques associated with their process and compatibility with commercial foundries are highlighted, as this aspect decides the viability of microactuators commercially and economically.
26 citations
14 Jul 2009
TL;DR: In this article, a compliant two-fingered micro gripper was designed, fabricated, and demonstrated, which is distributively actuated by shape memory alloy (SMA) wires so that high gripping range to gripper length ratio and mechanical advantage are achieved.
Abstract: A compliant two-fingered microgripper was designed, fabricated, and demonstrated. To accommodate objects of various sizes and weights, the gripper is distributively actuated by shape memory alloy (SMA) wires so that high gripping range to gripper length ratio and mechanical advantage are achieved. A SMA actuated gripper model is presented to predict SMA strain and gripper deflection by using measurements from force sensors. Based on this model, design of finger shape and specification of SMA wire dimension are facilitated. Two grippers with different stiffness are prototyped and their motion characteristics demonstrated. Due to the large stress provided by SMA wires, high gripping force can be obtained. The SMA contraction force to deflect gripper and produce gripping force may be adjusted by changing the input power to SMA wire. We further investigate the feasibility of self-sensing contraction force by using SMA resistance signal. With the capabilities of the gripper shown, we expect that it can be applied for miniature robotic manipulations.
26 citations
01 Jan 2014-Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems
TL;DR: In this paper, a chevron actuator was used to grasp and transport nano tubes/wires and release them on a desired substrate by vibrating the gripper arms.
Abstract: In this study, we investigate a novel metallic microgripper which is able to grasp and transport nano particles (nano tubes/wires) and release them on desirable substrate by vibrating the gripper arms. This microgripper consists of a chevron actuator to grip nano object electrothermally and interdigited comb drive systems to generate vibration at the gripper arms electrostatically. Metallic (nickel) properties enable the chevron actuator to close the gap and pick the nano particle at low voltage and temperature. In order to reduce the out of plane bending during operation and also increase the gripping force, thickness of the nickel layer must be increased, hence electroplating process is proposed for deposition of nickel layer. To generate vibration at the end effectors, comb drive systems are stimulated by applying two voltage signals at desired resonant frequency to the stators. Practically, by sweeping the frequency of these signals around the resonant frequency the end effectors start vibrating. The vibration results in overcoming the adhesion forces due to inertial effects.
25 citations