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Micro Electro Mechanical Systems, 1992, MEMS '92, Proceedings. An Investigation of Micro Structures, Sensors, Actuators, Machines and Robot. IEEE

Date 4-7 Feb. 1992

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Displaying Results 1 - 25 of 44
  • Proceedings. IEEE Micro Electro Mechanical Systems. An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots(Cat. No.92CH3093-2)

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    Freely Available from IEEE
  • Micro-gravity research and application of micromechanical devices

    Page(s): 158 - 161
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    A brief survey of flight opportunities in the German space program currently available to the user community is presented. Experiment facilities developed at MBB/ERNO are described. The possible future demands of micromechanical devices in space applications are assessed View full abstract»

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  • A comparative study of bearing designs and operational environments for harmonic side-drive micromotors

    Page(s): 171 - 176
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    The authors report the development of flange bearing harmonic side-drive (referred to as wobble) micromotors and the results from a comparative study of the operation of flange and center-pin bearing micromotors in different gas environments. Both the flange and center-pin wobble micromotors have been operated with excitation as low as 30 V across 1.5 μm rotor/stator gaps. In contrast to the center-pin bearing wobble micromotors it was found that the performance of the flange bearing wobble micromotors is not significantly affected by the operational environment. A convenient experimental procedure to characterize friction in wobble micromotors has been developed. Additionally, the requisite wobble micromotor dynamic model for extracting the bearing and bushing/flange frictional parameters from the experimental data is discussed View full abstract»

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  • E-beam induced fabrication of microstructures

    Page(s): 168 - 170
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    E-beam-induced deposition of metal from a metal organic gas has been used for the formation of microstructures of various geometries. Three examples, line deposition, needle growth and bridge formation, have been selected for demonstration. Important parameters of the tungsten (W) deposition process from W(CO)6 gas, such as minimum feature size, positional accuracy and growth rate, are given View full abstract»

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  • Helical microstructures grown by laser assisted chemical vapor deposition

    Page(s): 162 - 167
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    It is reported that laser-assisted chemical vapor deposition (LCVD) was used for growth in free space of microscale rods and helical structures of silicon. Using a newly developed rotable goniometer stage, the LCVD technique was also used for fabrication of a tungsten coil on a cylindrical silicon substrate, i.e. a simple microsolenoid was realized. The microstructure of the silicon deposits was investigated by cross-sectional transmission electron microscopy (TEM), and their mechanical strength was evaluated by micromechanical testing in situ in an SEM. The resistivity of the tungsten coil is measured, and the magnetic properties of the microsolenoid are investigated by means of SQUID equipment View full abstract»

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  • Epitaxial regrowth in surface micromachining of GaAs

    Page(s): 83 - 86
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    The authors demonstrate a complete surface micromachining procedure including a several steps of epitaxial regrowth in the fabrication of a laterally mobile GaAs structure (a wheel), as well as a sensor structure (a bridge). The enormous etch selectivity and the lack of internal stresses in the AlGaAs-GaAs system, combined with the excellent thickness control provided by MOCVD, make it possible to manufacture micromechanical structures that are similar to structures previously micromachined in the polysilicon-silica system. However, it is noted that economic factors and processing difficulties make the potential for GaAs micromechanics much more limited than for polysilicon View full abstract»

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  • Electrostatic film actuator with a large vertical displacement

    Page(s): 1 - 5
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    A microvalve actuator driven by electrostatic force and suitable for a rarefied gas flow control system is proposed. The actuator consists of a pair of planar electrodes sandwiching a conductive film. The film has an S-shaped bend in the middle. The S-bend moves back and forth as voltage is applied between the film and each of the electrodes alternately. The actuator makes possible the large valve seat lift that is necessary to allow a certain amount of gas flow. A macro model of the actuator allowed investigation of motion in the system. A film 5-μm thick and 12 mm wide was successfully operated between electrodes separated by 2.5 mm. The observed propagation speed was 4.0 m/s when the applied voltage was 150 V View full abstract»

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  • Lithography with high depth of focus by an ion projection system

    Page(s): 67 - 71
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    It is reported that ion projection lithography has been developed to generate structures with minimum feature sizes in the 100-nm range with a high pixel transfer rate. The high depth-of-focus resulting from the telecentric beam path concept is noted. A silicon wafer exhibiting 200-μm-deep cavities, which were fabricated by anisotropic etching, was patterned with a grating of 0.6-μm periodicity running with identical spacings from the bottom to the top. SiO2 served as an inorganic ion sensitive resist. Exposed to 73 keV helium ions, the SiO2 showed an enhanced etching rate in hydrofluoric acid, the structure developing agent. The application of patterning techniques considered is thought to be promising for the fabrication of two-dimensional reflecting mirrors or sensoric elements distributed on spherical surfaces View full abstract»

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  • Integration of the anisotropic-silicon-etching program ASEP within the CAEMEMS CAD/CAE framework

    Page(s): 133 - 139
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    The authors describe the inclusion, within a microelectromechanical-system (MEMS)-specific computer-aided-design/computer-aided-engineering (CAD/CAE) framework, of a MEMS-related CAD tool that was developed independently of the framework. The tool, ASEP (anisotropic silicon etching program), simulates the etching of (100)-oriented silicon by aqueous solutions of KOH, based on user-specified mask and etch-depth information. The framework is CAEMEMS (computer-aided engineering of microelectromechanical systems), which is a developing UNIX- and Motif-based system for MEMS designers. The operation of the integrated software is demonstrated with the design of a torsional resonator View full abstract»

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  • A new electrostatic actuator providing improved stroke length and force

    Page(s): 6 - 11
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    The electrostatic actuator considered consists of a silicon membrane bonded to a glass plate by anodic bonding. On the glass plate a circular gold electrode is made and a thin oxide layer is grown on the silicon membrane before bonding. A pressure is applied to the cavity between the membrane and the glass plate causing the membrane to deflect away from the electrode. When a voltage is applied between the gold electrode and the membrane, high electrostatic forces acting along the membrane periphery will pull the membrane into contact with the glass plate. Experimental results are presented demonstrating a stroke length of 18 μm working against a pressure of 2200 Pa using a voltage of 41 V. The actuator performance has in addition been investigated by means of mathematical analysis and numerical simulations, and a model relating the principal design parameters is presented View full abstract»

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  • An integrated lateral tunneling unit

    Page(s): 214 - 219
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    A micromachined device developed to perform displacement-controlled tunneling is described. Its performance was experimentally confirmed. The lateral tunneling unit (LTU), composed of a comb-drive actuator, a tunneling tip, and an opposing wall integrated on the same wafer was fabricated using surface micromachining with only one photomask. Integration of the tip and its opposing wall eliminated coarse positioning of the specimen, and realized a fully micromachined tunneling unit. The lateral configuration is easy to fabricate and suitable for integrating other structures such as an atomic force microscope (AFM) tip. The LTU can be used as an extremely sensitive position detector. Possible applications, such as an accelerometer and an integrated AFM/LTU chip, are discussed View full abstract»

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  • High aspect ratio electroplated microstructures using a photosensitive polyimide process

    Page(s): 87 - 92
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    A polymide-based process for the fabrication of high-aspect ratio microstructures is presented. The process exploits the sharp-sidewall characteristics of photosensitive polyimide to create the electroplating form through which the high-aspect-ratio structures are electroplated. Although the resolution of this process is inferior to the synchrotron-based process, this process has several advantages: it is simple and can be carried out using commercially available materials and common clean room equipment; the excellent chemical and thermal resistance of polyimide allows plating to take place in a variety of environments; and multiple coats of polyimide can be used to fabricate vertically integrated structures which have variation in the third dimension. The process is completely compatible with surface micromachining sacrificial layer techniques to create released electroplated microstructures View full abstract»

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  • Precision machine design: macromachine design philosophy and its applicability to the design of micromachines

    Page(s): 37 - 42
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    Macromachine design philosophies that may be of use to micromachining designs are reviewed. Definitions are provided for the precision engineering terms accuracy, repeatability, resolution, and Abbe error. Topics covered include predicting errors to mechanical systems, such as linear motion system errors, axis of rotation errors, and thermal growth errors, as well as issues relating to bearings, position measurement systems, and kinematic and elastically averaged design View full abstract»

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  • Current induced light emission from nanocrystalline silicon structures

    Page(s): 99 - 103
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    The photoluminescence and electroluminescence of light emitting porous silicon (LEPOS) are described. The porous silicon is made by anodic dissolution of silicon in HF with an applied electrical current and illumination with visible light. Photoluminescence is observed using ultraviolet light, and visible electroluminescence is achieved by applying a voltage to a solid-state contact on top of the porous layer. The luminescence, the structure, and the composition of LEPOS are studied View full abstract»

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  • Polysilicon micro vibromotors

    Page(s): 177 - 182
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    Two types of polysilicon microvibromotors have been designed, fabricated, and successfully operated in air and in vacuum. Each of these two types utilizes an electrostatically driven vibrating structure (the converter) to actuate a circular microrotor by means of oblique mechanical impact. Oscillatory linear motion is consequently converted into continuous angular motion. The microrotors are fabricated both 60 and 100 μm in diameter and are restrained at the center by a polysilicon hub. The converter tips are retracted by electrostatic comb drives and are propelled forward toward the rotor by elastic forces generated by folded beam flexures at frequencies ranging from 10 kHz to 20 kHz. A coupled, three-degree-of-freedom dynamic model successfully predicts both the two mode shapes and the frequency ranges of the bimodal converter observed in the experiment. An impact dynamics model of the vibromotor system is constructed to understand and estimate the dynamics between converter and rotor View full abstract»

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  • Photo-induced preferential anodization for fabrication of monocrystalline micromechanical structures

    Page(s): 56 - 61
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    Photo-induced preferential anodization (PIPA) for fabrication of monocrystalline micromechanical structures is presented. P-type silicon formed in an n-type substrate is preferentially anodized in an aqueous solution of hydrofluoric acid under illumination. This technology is based on anodization and the photovoltaic effect. In experiments, dependence on light intensity, HF concentration, and the ratio of the pn-junction area to the entrance area of the HF solution was investigated. It was found that porous silicon conditions depend on light intensity and HF concentration and that anodic current density provided by a pn-junction is the most important factor for controlling PIPA. A monocrystalline microbridge structure 1 μm thick, 20 μm wide, and 300 μm long was formed using this technology View full abstract»

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  • Micromachined thermoelectrically driven cantilever structures for fluid jet deflection

    Page(s): 12 - 18
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    The design, fabrication, and performance of bimorph cantilever structures for direction control of laminar jet flow are reported. The fabrication process comprises standard IC technologies and additional silicon micromachining techniques. The design parameters for the structures are obtained using analytical approximations and numerical simulations. Forced convection as the decisive cooling mechanism proves to be very effective, resulting in an excellent dynamic response of the thermoelectrically activated structures. Experimental testing confirmed the predicted stationary and transient behavior of 1-mm-long and 1-mm-wide actuators, which are able to control hydraulic power at pressure levels of up to 4 bar, flow rates of up to 150 ml/min, and time constants of about 1 ms View full abstract»

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  • Structure and mechanism of two types of micro-pump using polymer gel

    Page(s): 110 - 115
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    Micropumps using polymer gel actuators are proposed and two prototypes developed are described. One is actuated by a highly water absorbing polymer gel, while the other is actuated by a thermoresponsive polymer gel. The first type, the micro-capsule pump using the highly water absorbing polymer gel, consists structurally of an inlet with a semipermeable membrane, an outlet with a one-way valve, and a storage tank controlled by the water absorbing polymer gel. The gel rests within a thin film, and the semipermeable membrane is located on the inlet side. The important feature of this actuator is that an external driving power supply is not required in this micropump. The second type, the micropump using the thermoresponsive polymer gel, has two one-way valves which make use of the highly water absorbing polymer gel as a blocking ball. The polymer gel actuator used is constituted of polyvinyl methyl ether (PVME) atatic polymer gel. Repeating the heating and cooling processes causes, the PVME to repeat its shrinking and swelling motions. The micropump was tested on switching heating by a nichrome wire with electric current View full abstract»

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  • High-precision micronozzle fabrication

    Page(s): 116 - 121
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    A process for fabricating a high-precision micronozzle with irregular inner shapes (at its end) and high aspect ratio (at its main part) was developed. Micronozzles 3 mm long with slit-type openings of 100×10 μm, triangular openings of 50 μm, and circular openings of 6 μm were successfully obtained. By using a WEDG (wire electrodischarge grinding) polishing technology, a core with a smooth mirrorlike surface was prepared, improving the precision and inner surface quality of the micronozzles produced. The core preparation process with WEDG and WECG can be carried out using common low-conductivity water. This makes the fabricating process simple and effective. Stainless steel was suitable as the core material for WECG operation. A micropipe with an inner diameter of 50 μm and aspect ratio of 40 was successfully manufactured without using parting film View full abstract»

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  • Microelectromechanical filters for signal processing

    Page(s): 226 - 231
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    Microelectromechanical (MEM) filters based on coupled, lateral microresonators are demonstrated. This class of MEM systems has potential signal-processing applications for filters which require narrow bandwidth (high Q), good signal-to-noise ratio (SNR) and stable temperature and aging characteristics. Both series and parallel filters were fabricated and tested using an off-chip modulation technique. The frequency range of these filters is from approximately 5 kHz to on the order of 1 MHz, for polysilicon microstructures with suspension beams having a 2-μm-square cross section. A series-coupled resonator pair, designed for operation at atmospheric pressure, has a measured center frequency of 18.7 kHz and a bandwidth of 1.2 kHz View full abstract»

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  • Pumping of water solutions in microfabricated electrohydrodynamic systems

    Page(s): 25 - 30
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    A microfabricated electrohydrodynamic pump without moving parts driven by low voltages with high-frequency traveling waves is presented. Micron-size scale systems without moving parts fabricated in planar silicon technology are presented and quantitatively described. The operating principle to pump water and weak electrolyte solutions is outlined. It is shown that conductive liquids such as water solutions can be pumped opposite to the direction of the traveling wave. Typical parameters characterizing the advantages and limitations of the pumping principle are discussed. Opportunities for optimization of the micropump in terms of further miniaturization and an increased number of electrodes are noted View full abstract»

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  • Creation of an insect-based microrobot with an external skeleton and elastic joints

    Page(s): 190 - 195
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    The concept of making a microrobot with an external skeleton, like an insect, and its implementation using rigid plates and elastic joints is described. A large-scale model consisting of plastic plates and solenoids is shown to demonstrate this motion. Several microsized models using polysilicon plates and polyimide joints have been built on silicon wafers. By folding these at the joints, just like paper, three-dimensional structures can be constructed. These structures can be actuated by electrostatic force View full abstract»

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  • Microelectromechanical tuning of electrooptic devices

    Page(s): 154 - 157
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    The wavelengths of separate-confinement quantum-well heterostructure semiconductor lasers have been tuned by applying mechanical stress through a piezoelectric transducer. In addition, photoluminescence measurements have been made on GaAs samples stressed with piezoelectric bimorphs. It is shown that measurable shifts in the energy gap can be obtained by mechanically stressing the semiconductor with a microelectromechanical system (MEMS) transducer. The authors demonstrate MEMS-induced wavelength tuning with four independent phenomena: photoluminescence, photoresponse, lasing, and electroluminescence View full abstract»

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  • Microfabrication of submicron nozzles in silicon nitride

    Page(s): 150 - 153
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    A microfabrication process for obtaining nanometer apertures in highly cusped nozzle-like structures fabricated in silicon nitride and having apex angles of up to a few degrees is described. The process is based on a sacrificial etch technology using single-crystal silicon as the mold and silicon nitride as the material for the nozzle. The nitride coating on the apex of the pyramid shaped mold is selectively etched off using a polymer layer as the etch mask, which leaves the tip of the silicon mold protruding from the masked nitride, thus defining the aperture of the nozzles. The silicon mold is then removed in an alkaline etchant which leaves the free standing nozzles View full abstract»

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  • Theoretical and experimental results of an electrostatic micro motor with large gear ratio fabricated by the LIGA process

    Page(s): 139 - 140
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    It is known that the extension of the LIGA process by a sacrificial layer technique allows the fabrication of movable microstructures with great structural height without the need to assemble individual components. With this technique an electrostatic stepping micro motor has been fabricated and tested. The design of the motor has been optimized with regard to large torque by finite-element-method calculations. The radii of the rotor and the axle have been adjusted to the step width of the motor in order to realize a rolling movement of the rotor on the axle, which minimizes the friction View full abstract»

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