In the robotics field, several grippers have been developed using SMA technologies, but, so far, SMA is only used as the actuating part of the mechanical device. However mechanical device requires assembly and in some cases this means friction. In the case of micro-grippers, this becomes a major problem due to the small size of the components. In this paper, a new monolithic concept of micro-gripper is presented. This concept is applied to the grasping of sub- millimeter optical elements such as Selfoc lenses and the fastening of optical fibers. Measurements are performed using a newly developed high precision 3D-computer vision tracking system to characterize the spatial positions of the micro-gripper in action. To characterize relative motion of the micro-gripper the natural texture of the micro-gripper is used to compute 3D displacement. The microscope image CCD receivers high frequency changes in light intensity from the surface of the ripper. Using high resolution camera calibration, passive auto focus algorithms and 2D object recognition, the position of the micro-gripper can be characterized in the 3D workspace and can be guided in future micro assembly tasks.
There is a high requirement for research for the growing demand in micro-assembly technology, especially in the area of gripping technology. By observing the specific requirements of the micro-world, a spectrum of different grippers will be developed. By the experimental examination of the prototypes, an evaluation of the potentials of utilization of the different gripping principles is carried out. Thus, in particular grippers adjusted to micro-assembly requirements working according to conventional principles of efficiency show promising results.
Shape memory alloys have the potential to become a material of great importance for miniature actuators that can be applied to the handling of sub-mm parts, biological engineering, and microsurgery. This paper reports on two shape memory microactuator systems under development in our laboratories, namely microgrippers and artificial muscle actuators.
For microassembly tasks uncertainty exists at many levels.Single static sensing configuration are therefore unable to provide feedback with the necessary range and resolution for accomplishing many desired tasks. In this paper we present experimental results that investigate the integration of two disparate sensing modalities, force and vision, for sensor-based microassembly. By integrating these sensing modes, we are able to provide feedback in a task- oriented frame of reference over a broad range of motion with an extremely high precision. An optical microscope is used to provide visual feedback down to micro resolutions, while an optical beam deflection technique is used to provide nanonewton level force feedback or nanometric level position feedback. Visually served motion at speeds of up to 2mm/s with a repeatability of 0.17 micrometers are achieved with vision alone. The optical beam deflection sensor complements the visual feedback by providing positional feedback with a repeatability of a few nanometers. Based on the principles of optical beam deflection, this is equivalent to force measurements on the order of a nanonewton. The value of integrating these two disparate sensing modalities is demonstrated during controlled micropart impact experiments. These results demonstrate micropart approach velocities of 80 micrometers /s with impact forces of 9nN and final contact forces of 2nN. Within our microassembly system this level of performance cannot be achieved using either sensing modality alone. This research will aid in the development of complex hybrid MEMS devices in two ways; by enabling the microassembly of more complex MEMS prototypes; and in the development of automatic assembly machines for assembling and packaging future MEMS devices that require increasingly complex assembly strategies.
In this article we describe the use of 3D computer vision for microassembly stations and future microfabrication. 3D measurements are performed using a newly developed high precision 3D computer vision system to characterize the spacial positions of the microrobots or microgrippers in action. To describe relative motion of the microrobots or microactuators, the natural texture of the micropart is used to compute 3D displacement. The microscope image CCD receives high frequency changes in light intensity from the surface of the gripper in focus. Using depth of focus, high resolution camera calibration, passive auto focus algorithms and 2D object recognition, the position and the displacement of the microrobot can be characterized in the 3D workspace and can be guided in micro-assembly tasks. Newly developed microgripper with integrated tracking structures will be presented to illustrate and explain the approach. Several other examples like chip manipulation and micromotor assembly will be presented and discussed.
A new and simple actuator principle is proposed and developed for microassembly. It allows to produce positioning with high resolution on a large motion ranges with the same element. It cumulates the advantages of classical mechanical elements such as linear rolling guides and screw-nut devices driven by DC motors with the elastic structures as guide and demagnification lever. The submicronic positioning is realized in two phases, coarse and fine, each other ensured by the same drive unit. A prototype with one linear DOF has been realized and characterized with a motion range of 45mm, a resolution of 0.1 (Mu) m and a motive force better than 20N. A second prototype with 2DOF X-Y table based on the same principle has also been developed with success, with 0.1micrometers for the resolution and 19mm for the motion range. This paper describes the new actuator principle, the realization and the result of the one and two degrees-of-freedom devices. The last section deals with the integration of this kind of actuator in a 6 degrees-of-freedom parallel structure dedicated to the microassembly of optical components.
There is an increasing interest in performing microsystem assembly using flexible microrobots. A new concept of a flexible robot-based micro-assembly desktop station and tow prototypes of piezoelectric microassembly robots, MINIMAN and PROHAM, were already presented at the last year's SPIE meeting. In this paper, the motion control approach of these robots is discussed. This control approach is based on the geometric description of the robot platform and aims at following the optimal motion trajectory to minimize the operation time and to keep the robot end effector under microscope supervision. Besides excellent abilities both robots have some disadvantages such as the relatively high drive voltage of the piezoactuators or the instability of grasp-and-hold operations. For this reason, several new piezoelectric microrobots that employ different locomotion and object handling principle have lately been developed. The design and functions of these microrobots are shown.
Developments in microelectronics, micromechanics and microelectromechanical systems require significant improvements in manufacturing tools for mass productions. Especially the assembling tools have to become feaster and more precise. Many assembly devices use XY stages driven by DC servomotors with ball screws or parallel structures; others use linear drives with traditional ball bearings. Only a few devices use linear drives together with air bearings, but always together with an angular guide for X and Y direction. The novel approach present in this paper is based on linear drives together with a planar air bearing. In contrast to other stages, it does not need any angular guide. This reduces the moved mass and leads to higher accelerations. It consists of an arrangement of four identical moving-coils attached to a slide, which is suspended by a planar air bearing. This new configuration allows a workspace of 60 X 60 mm2 and an acceleration exceeding 10 g1 with a resolution better than 100 nm. This paper gives an overview of the system, describes the design of the moving coils and shows first experimental result of the controller.
Physiological hand tremor and other manual positioning errors limit precision in microsurgical procedures. Our research has involved development of adaptive algorithms and neural network methods for real-time compensation of such errors. This paper presents a novel design for an active hand-held microsurgical instrument to implement these algorithms, particularly during vitreoretinal microsurgery. The basic vitreoretinal instrument consists of a handle fitted with a narrow freedom inertial sensing to determine the 3D position of the instrument tip. The intraocular shaft is attached to the instrument handle via a miniature parallel manipulator with three degrees of freedom, controlled by three piezoelectric elements. The manipulator actuates the intraocular shaft in pitch, yaw, and axial extension, allowing the system to perform active compensation of errors in the position of the tip of the intraocular shaft. The paper includes the formulation of the inverse kinematics of the instrument in a manner suitable for on-line computation. A discussion of practical design considerations and the methods and results of preliminary experiments are also presented.
This paper discusses recent experiments in the manipulation and assembly of parts with 100 micron outside dimensions and submicron tolerances. The objective of this work is to develop a micromanipulation workcell which can automatically assemble LIGA parts using an assembly plan and a CAD drawing of each of the components. The workcell consists of an AdeptOne robot, precision stages, and long distance microscope, and a high aspect ratio molded polysilicon tweezers for picking up the parts. Fourier optics methods are used to generate synthetic microscope magnifications and depths of field. They also provide reference image features which are used to visually servo the true part to the desired position.
This paper describes an automated microassembly system for the dynamic, flexible handling of 3D microobjects by means of visually guided manipulation unit. We propose a coarse- fine approach to microassembly, where a medium-resolution and a high-resolution monitoring device are used for coarse measurements within a large field of view and for fine sensing at high precision, respectively. A coarse motion device with large working area serves as parts supply and medium-resolution transport unit; the microassembly tasks are executed by a high-resolution fine manipulator. System supervision and control is base don parameter extraction from the visual information acquired by the two monitoring devices. The use of vision systems as external sensors for the control of micromanipulators in assembly tasks allows to directly determine the position of the end-effector and the parts to be manipulated. A relative motion control strategy is proposed for executing the microassembly tasks.
In the field of microsystem technologies one future trend is recognized. Manufacturing microsystems monolithically is becoming less reasonable and practicable with increasing applications and complexity. Assembly processes will be needed for the majority of microsystems due to difficulties arising in manufacturing complex structure out of one piece, the need for components to be manufactured by different processes, or simply to connect the microsystem with the macroscopic environment. Additionally, high production output at competitive costs is attainable only by replacing manual assembly with new automatic handling, positioning and joining technologies. To assist in development of microassembly processes, techniques from macroassembly technology may be transferred. Especially in microoptics existing know-how from macroscopic lens-assemblies might be transferred. The microsystem presented a microoptical beam forming system consisting of one SELFOC- and two GRIN- microlenses joined by adhesive bonding, fixed in a protection-mount, which serves additionally as a coupling unit of a multimode fiber, and finally adjusted to a laser diode at a defined distance according to an optical design. Besides complications due to the sensitive optical surfaces and the small and varying geometries of the system components, there is the additional requirement of high accuracies, of 0.1 to 2 micrometers and down to 1 arcsec, needed to realize the optical function of the microsystem. The assembly system, based on a six-axis-precision robot accurate to less than 1 micrometers , consists of a modular designed tool changing system, specially-adapted, self- adjusting grippers, several sensors to monitor positioning, dosage devices to dispense measured quantities of adhesive, in the range of nanoliters, and a specially designed assembly platform to clamp microparts of different geometries.
During the past few years, remarkable affords have been made for the realization of microscale sensors, actuators and microelectromechanical system. Due to advances in solid state and micromachining technologies, significant advances in designing, fabricating and testing of microminiaturized devices have been achieved at laboratory level. However, the technical and economical realization of microelectromechanical systems is considerably impeded by the lack of satisfying device technology for their industrial production. A production concept for the industrial production of hybrid microelectromechanical systems was developed and investigated. The concept is based on the resources and requirements of medium-sized enterprises and is characterized by its flexibility. Microsystem fabrication is separated into microfabrication steps performed in-house and technological steps performed by external technology providers. The modularity of the concept allows for a gradual increase in the degree of automation and the in-house production depth, depending on market capacity and financial resources. To demonstrate the feasibility of this approach, the design and realization of a microfabrication process center, which includes tasks like transport and handling, processing, cleaning, testing and storing are discussed. Special attention is given to the supply and feeding of microparts, to the necessary magazines, trays and transport systems, to the implementation of homogeneous mechanical, environmental and information interfaces, to the employment of advanced control, scheduling, and lot tracking concepts, and to the application of highly modular and cost-efficient clean production concepts.
Pumps utilizing electric traveling waves as the conveyor of liquids have already been presented in various publications. In those considerations, a dielectric liquid has been chosen as the media to propel. Inversely, it is conceivable to use pumps as propulsion motors for tiny vessels. Hereinafter, the proposed electrohydrodynamic (EHD) propulsion motor is based on the electric tube device which has been introduced in earlier papers by the first author for the tasks of particle mass transportation. The device is made by winding 6 parallel and insulated wires to a cylindrical tube. In the present work, the employed wires have a diameter in the range of 56 micrometers - 236 micrometers . Upon the application of multi-phase voltages to the monolayer-electrodes, the created traveling electric field wave carries the charged liquid in the same direction. Various EHD propulsion motors have been fabricated and optimized through a series of experiments. Optimizing parameters involve electrode- dimensions, fabrication materials, applied voltages and frequencies. As evaluative parameters, the propulsion pressure and the rate of liquid flow is determined. Constant and precise liquid propulsion is achieved. It is further shown that this tube structure has a high potential for miniaturization.
Practical micromachines, such as magnetic heads or endoscopic tools, can not be made only by shaping processes; they require post-machining processes such as assembling, wiring, piping, etc. The authors have developed an integrated manufacturing system, 'nano manufacturing world' (NMW). It performs shaping, post-machining or transferring like a factory. In this paper, we introduce a microwork transfer system, which functions a) steady transfer of a workpiece, b) non-release chucking of the workpiece during production and c) individual rotation of the workpiece using a preloaded microslide bearing on the pallet. Developed transfer system could realize the functions: less positioning error due to accurate pallet positioning by taper pins, high transfer yield of the workpieces due to no missing by a micro chuck, sub-micron rotational fluctuation due to a roller pallet by a preloaded micro slide bearing. Through the fabrication demonstrations of a sub-1 mm3 micro-house or micro force sensor block of 125 X 100 X 500 micrometers , it has been confirmed that this transfer system improved the performance of integrated manufacturing in NMW.
Microassembly and microadjustment techniques are key technologies in the industrial production of hybrid microelectromechanical systems. One focal point in current microproduction research and engineering is the design and development of high-precision microassembly and microadjustment equipment capable of operating within the framework of flexible automated industrial production. As well as these developments, suitable microassembly tools for industrial use also need to be equipped with interfaces for the supply and delivery of microcomponents. The microassembly process necessitates the supply of microparts in a geometrically defined manner. In order to reduce processing steps and production costs, there is a demand for magazines capable of providing free accessibility to the fixed microcomponents. Commonly used at present are feeding techniques, which originate from the field of semiconductor production. However none of these techniques fully meets the requirements of industrial microassembly technology. A novel modular magazine set, developed and tested in a joint project, is presented here. The magazines are able to hold microcomponents during cleaning, inspection and assembly without nay additional handling steps. The modularity of their design allows for maximum technical flexibility. The modular magazine fits into currently practiced SEMI standards. The design and concept of the magazine enables industrial manufacturers to promote a cost-efficient and flexible precision assembly of microelectromechanical systems.
In an earlier paper by the authors, down-scaled devices for microparts handling utilizing an AC electric field boundary wave were proposed. Devices that instantly generate contactless microparts driving forces through electric field creation have been designed and fabricated. In a further attempt, the mechanisms behind microparts conveyance are here subsequently validated in experiments and simulations. Particles as micropart substitute are actuated. On a thin protecting insulation-film above a series of encased and insulated parallel field electrodes, particles become either triboelectrically or induction charged through the application of balanced multi-phase voltages. The created non-uniform traveling field-wave conveys the charged particles perpendicular to the electrodes confined in electric filed traps from electrode to electrode. A series of particle materials with diameters up to 400 micrometers has been examined; metal, glass, and plastic spheres showed the best performances. Simulations of the potential distribution underline the experimental findings on the electric panel and dots device. One further result, which could ave been shown by experiments, is the pre-oscillation of a moving particle caused by gravity.
This paper discusses new technologies suited for application sin micro assembly. The discourse a new class of robots, based on closed kinematic chains and their advantages for applications in high precision applications with a focus on micro assembly. The discussion continues on design considerations for parallel robots focused on design methods concerning the kinematic aspects as well as for the design of the robot components. The paper presents two concepts for parallel robots focused on design methods concerning the kinematic aspects as well as for the design of the robot components. The paper presents two concepts for parallel robots with three and six degrees of freedom, covering the transformation algorithms including the kinematic characteristics of these robots. Finally the paper introduces micro gripper principles and specific design suggestions.
Many projects developing the miniaturized autonomous robot have been carried out in the whole world. This paper deals with our challenges developing a miniaturized autonomous robot. The miniaturized autonomous robot is defined as the miniaturized closed-loop system with micro processor, microactuators and microsensors. We have developed the micro autonomous robotic system (MARS) consisting of the microprocessor, microsensors, microactuators, communication units and batteries. The MARS controls itself by the downloaded program supplied through the IR communication system. In this paper, we demonstrate several performance of the MARS, and discuss the properties of the miniaturized autonomous robot.
In this paper, a system for measuring adhesive forces acting on micro objects under SEM and the obtained experimental results are discussed. In order to manipulate micro objects as small as 0.1 to 100 micrometers under scanning electron microscope (SEM) reliably, it is necessary to examine microadhesive forces acting on the objects by direct measurement. This is because adhesive forces acting on micro objects such as electrostatic force, surface tension force and van der Waals force are affected by various factors not considered in idealized theories. We have constructed an in situ micro force measurement system under SEM with a resolution of 1nN. The system is attached to the micro object handling system under SEM developed by the authors. The forces are obtained by measuring the displacement of a V-shaped parallel leaf cantilever with the laser interferometer. A worktable is attached to the cantilever is calculated from the change of its natural frequency, which is caused when a known mass is added at the tip. Utilizing this system, we have measured adhesive forces acting on micro solder spheres of 25 micrometers in diameter in situ while manipulating them and found the magnitude of the force is several 100nN. Besides, we proved the effectiveness of the micro object handling skills modifying facing area proposed by the authors.
This paper describes a detailed study of the behavior of the parallel spring stage having four circular flexure hinges of very thin cross-sections manufactured by wire electro- discharge machining. The state of the art recalls the abundant literature published on the parallel leaf spring stage, and presents the few articles found dealing with the parallel spring stages. The theoretical modeling for the calculation of the linear stiffness of the parallel spring stage is described. The starting point of the discussion is the observation that the theoretical model which is valid when applied to stages of large dimensions produces large errors when applied to wire-EDM machined flexures of very thin cross-sections. As an explanation of this observation, a hypothesis is put forward: on the surface of each neck a thin layer affected by the EDM process is not playing any mechanical role in the bending of the flexure and the thickness of this layer is related to the roughness of the surface. The experimental results show that the hypothesis is true to a large extent but that roughness is probably not the only factor affecting the neutral zone. The 'white layer' and the microstructural homogeneity of the material used could also be determinant.
Autonomous nanorobots with overall dimensions in the micrometer domain promise fascinating applications in fields ranging from nanofabrication on the molecular scale to minimal invasive surgery in hard-to-reach places - yet, they are beyond the reach of current technology. IN contrast, scanning probe microscopes, despite their macroscopic overall dimensions, have amply proved their versatility in accessing the nanometer scale and providing the user an interface to interact with structures down to single atoms directly. To explore and evaluate control strategies for future nanorobots, we extended the capabilities of an atomic force microscope beyond its intrinsic nanometer-resolution surface-imaging function. To this end, we implemented an additional control loop which automatically guides a multifunctional nanoprobe to user-specified features on integrated circuits, tracks their structure, and acquires multichannel information about their local geometric and electric properties.
In this paper, we propose and experimentally demonstrate 'molecular surgery of DNA', where DNA strand is stretched straight and immobilized on a solid surface, to which an enzyme-labeled micro particle is brought into contact, to make chemical modifications at an arbitrary position on the strand. An electrode array, whose spacing is made equal to the length of DNA, is micro-patterned on a glass surface. The electrodes are energized by a high frequency power supply, to create >= 1 MV/m, approximately equals 1 MHz electrostatic field in the gap. DNA supplied in the gap is stretched straight by the high-intensity field and both termini of the DNA strand are pulled into the electrode edges. As a result, the strand is anchored at both molecular ends bridging over two adjacent electrodes, but the middle part is free, so that the enzyme can bind and react. An enzyme-labeled micro bead, 1-3 micrometers in diameter, is laser-manipulated, and contacted on the immobilized DNA. Using DNase II and HhaI as the enzyme, cutting of DNA is experimentally demonstrated.