Cantilever beam microactuators with electrothermal and electrostatic drive

Microfabrication provides a powerful tool for batch processing and miniaturization of mechanical systems into dimensional domain not accessible easily by conventional machining. CMOS IC process compatible design is definitely a big plus because of tremendous know-how in IC technologies, commercially available standard IC processes for a reasonable price, and future integration of microma-chined mechanical systems and integrated circuits. Magnetically, electrostatically and thermally driven microactuators have been reported previously. These actuators have applications in many fields from optics to robotics and biomedical engineering. At NJIT cleanroom, mono or multimorph microactuators have been fabricated using CMOS compatible process. In design and fabrication of these microactuators, internal stress due to thermal expansion coefficient mismatch and residual stress have been considered, and the microactuators are driven with electro-thermal power combined with electrostatical excitation. They can provide large force, and in- or out-of-plane actuation. In this work, an analytical model is proposed to describe the thermal actuation of in-plane (inchworm) actuators. Stress gradient throughout the thickness of monomorph layers is modeled as linearly temperature dependent Δσ. The nonlinear behaviour of out-of-plane actuators under electrothermal and electrostatic excitations is investigated. The analytical results are compared with the numerical results based on Finite Element Analysis. ANSYS, a general purpose FEM package, and IntelliCAD, a FEA CAD tool specifically designed for MEMS have been used extensively. The experimental results accompany each analytical and numerical work. Micromechanical world is three dimensional and 2D world of IC processes sets a limit to it. A new micromachining technology, reshaping, has been introduced to realize 3D structures and actuators. This new 3D fabrication technology makes use of the advantages of IC fabrication technologies and combines them with the third dimension of the mechanical world. Polycrystalline silicon microactuators have been reshaped by Joule heating. The first systematic investigation of reshaping has been presented. A micromirror utilizing two reshaped actuators have been designed, fabricated and characterized

A Review of Cooperative Actuator and Sensor Systems Based on Dielectric Elastomer Transducers

This paper presents an overview of cooperative actuator and sensor systems based on dielectric elastomer (DE) transducers. A DE consists of a flexible capacitor made of a thin layer of soft dielectric material (e.g., acrylic, silicone) surrounded with a compliant electrode, which is able to work as an actuator or as a sensor. Features such as large deformation, high compliance, flexibility, energy efficiency, lightweight, self-sensing, and low cost make DE technology particularly attractive for the realization of mechatronic systems that are capable of performance not achievable with alternative technologies. If several DEs are arranged in an array-like configuration, new concepts of cooperative actuator/sensor systems can be enabled, in which novel applications and features are made possible by the synergistic operations among nearby elements. The goal of this paper is to review recent advances in the area of cooperative DE systems technology. After summarizing the basic operating principle of DE transducers, several applications of cooperative DE actuators and sensors from the recent literature are discussed, ranging from haptic interfaces and bio-inspired robots to micro-scale devices and tactile sensors. Finally, challenges and perspectives for the future development of cooperative DE systems are discussed

Design and realization of a microassembly workstation

With the miniaturization of products to the levels of micrometers and the recent developments in microsystem fabrication technologies, there is a great need for an assembly process for the formation of complex hybrid microsystems. Integration of microcomponents made up of different materials and manufactured using different micro fabrication techniques is still a primary challenge since some of the fundamental problems originating from the small size of parts to be manipulated, high precision necessity and specific problems of the microworld in that field are still not fully investigated. In this thesis, design and development of an open-architecture and reconfigurable microassembly workstation for efficient and reliable assembly of micromachined parts is presented. The workstation is designed to be used as a research tool for investigation of the problems in microassembly. The development of such a workstation includes the design of: (i) a manipulation system consisting of motion stages providing necessary travel range and precision for the realization of assembly tasks, (ii) a vision system to visualize the microworld and the determination of the position and orientation of micro components to be assembled, (iii) a robust control system and necessary fixtures for the end effectors that allow easy change of manipulation tools and make the system ready for the desired task. In addition tele-operated and semi-automated assembly concepts are implemented. The design is verified by implementing tasks in various ranges for micro-parts manipulation. The versatility of the workstation is demonstrated and high accuracy of positioning is shown

Intelligent Systems

This book is dedicated to intelligent systems of broad-spectrum application, such as personal and social biosafety or use of intelligent sensory micro-nanosystems such as "e-nose", "e-tongue" and "e-eye". In addition to that, effective acquiring information, knowledge management and improved knowledge transfer in any media, as well as modeling its information content using meta-and hyper heuristics and semantic reasoning all benefit from the systems covered in this book. Intelligent systems can also be applied in education and generating the intelligent distributed eLearning architecture, as well as in a large number of technical fields, such as industrial design, manufacturing and utilization, e.g., in precision agriculture, cartography, electric power distribution systems, intelligent building management systems, drilling operations etc. Furthermore, decision making using fuzzy logic models, computational recognition of comprehension uncertainty and the joint synthesis of goals and means of intelligent behavior biosystems, as well as diagnostic and human support in the healthcare environment have also been made easier

Progettazione, sviluppo e test per il microassemblaggio di microcomponenti

In questa tesi viene studiata una stazione di microlavorazione composta da un microgripper, un microavvitatore ed un micromanipolatore per realizzare un collegamento tra due oggetti di materiale plastico utilizzando una micro-rosetta ed una micro-vite autofilettante. Lo studio si articola in tre parti. La prima parte consiste nella progettazione e realizzazione di un dispositivo capace di rilevare la forza di contatto durante le operazioni di pick and place, installato su un microgripper precedentemente realizzato presso il Dipartimento di Ingegneria Meccanica e Nucleare. La seconda parte della tesi ha previsto la progettazione e la realizzazione di un avvitatore azionato da un attuatore piezoelettrico. Lo spostamento generato dall’attuatore comprime una molla progettata e realizzata sulle specifiche fornite da questa tesi al fine di trasformare l'azione lineare dell'attuatore in una coppia torcente capace d’avvitare micro-viti. L'ultimo elemento studiato riguarda un innovativo manipolatore capace di afferrare micro-oggetti dalle svariate dimensioni e geometrie. L'afferraggio sfrutta le forze capillari generate da una gocci d’acqua, ed il rilascio dei micro-oggeti invece è basato sulle doti di idrofilia ed idrofobia di un particolare tessuto realizzato dall'università danese "DTU" che costituisce il fulcro del manipolatore. Tutti i componenti sono stati realizzati presso i laboratori del Dipartimento di Ingegneria Meccanica dell'Università di Pisa. Ad eccezione dell'avvitatore per il quale non è stato possibile reperire un generatore sufficientemente potente per farlo azionare, sono stati testati sperimentalmente tutti i componenti ottenendo ottimi risultati. __________________________________________________ In this thesis we studied a micro station composed by a micro-gripper, a micro-screwdriver and a micromanipulator for making a link between two objects of plastic materials using a micro-washer and a micro-screw. The study is composed of three parts. The first part is about the design and implementation of a device able to detect the contact force during the pick and place operations. The device was installed in a micro-gripper previously realized by the Department of Mechanical and nuclear Engineering. In the second part of the thesis it was designed and completed a screwdriver driven by a piezoelectric actuator. The movement generated by the actuator compresses a spring, which was designed and built thanks to the specifications provided by this thesis, in order to transform the linear action of the actuator in a torque able to screw micro-screws. The last studied element is an innovative manipulator able to grip micro-objects with a variety of sizes and geometries. This grip exploits capillary forces generated by a drop of water, and the release of micro-objects is based on the qualities of hydrophilic and hydrophobic properties of a particular material ,made by the Danish University "DTU", that constitutes the core of the manipulator. All components have been manufactured in the laboratories of the Department of Mechanical Engineering of the University of Pisa. All components were tested with good results, with the exception of the screwdriver, because it was not possible to find a generator powerful enough to operate it