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Micro Electro Mechanical Systems, 2007. MEMS. IEEE 20th International Conference on

Date 21-25 Jan. 2007

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Displaying Results 1 - 25 of 228
  • Oral presentations

    Page(s): ix - xxiv
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  • Technical digest

    Page(s): c1
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  • Author and keyword indexes

    Page(s): A - A-16
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  • Preface

    Page(s): ii - viii
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  • Process compensated micromechanical resonators

    Page(s): 183 - 186
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    Manufacturability and yield are the major challenges prior to adoption of micromechanical resonators as frequency references. In this paper, a design for manufacturability (DFM) technique to achieve absolute frequency accuracy is presented. Non-idealities of a deep reactive ion etching process are examined and determined to be random. The variations in resonator geometry are assumed to be locally systematic and are represented as a process bias. The effect of process bias on resonator center frequency is modeled and the procedure for optimizing for zero sensitivity is explained. Process bias on a 10 MHz optimized design was replicated with electron-beam lithography and supporting data demonstrating DFM is reported. View full abstract»

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  • Accuracy of Quasi-static simulation methods as compared to full-dynamic analysis of nonlinear electrostatic MEMS actuators

    Page(s): 187 - 190
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    Quasi-static numerical methods are much wider used for simulating MEMS devices as compared to full-dynamic analysis. Quasi-static models are uncomplicated to set up and have shorter simulation times. Furthermore, it is assumed that the inertia of moving masses can be neglected in MEMS devices because of their tininess. This paper investigates whether kinetic energies plays an important role in elastomechanics/electrostatics coupled-domain analysis since especially electrostatic actuators are characterized by very large actuation and thus acceleration forces. It is found that for certain actuator configurations, the dynamic behavior affects even apparently static parameters such as the pull-in threshold voltage of electrostatic actuators, especially when considering their high degree of nonlinearity. The paper identifies the most relevant device parameters and investigates their influence on the accuracy of the simulation results of quasi-static methods as compared to full-dynamic analysis. Based on these findings, the paper provides with practical guidelines on the choice of the appropriate simulation method depending on the device configuration. Moreover, the paper provides an error estimation of the simulation results obtained by quasi-static methods, using full-dynamic analysis as the reference. View full abstract»

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  • Development of micro mechanical parts utilized extra fine wires

    Page(s): 191 - 194
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    A micro screw, a micro nut, an outer micro gear, an internal micro gear, a helical micro gear, a micro turbine-impeller and other micro mechanical parts are developed by utilizing extra fine wires. The extra fine wires are metallic wires or synthetic fibers which diameters are as small as 30 to 200 micrometers like a stainless wire, a tungsten wire, a copper wire, and a fluorocarbon thread. The micro screw is produced by coiling a pair of these wires around a needle pin without spacing, and by brazing the wires on the pin; besides, by peeling one wire from the brazed pin. Its pitch is less than 100 micrometers, and its major diameter is less than 600 micrometers. Other micro mechanical parts are also produced by same processes. In this paper, a novel manufacturing method for the micro mechanical parts utilized extra fine wires is developed, and several micro mechanical parts are produced as prompt products. Moreover, a micro positioning stage and reduction micro gear systems are developed as trial manufactures, and the micro turbine system is proposed as a new engine for the micro systems without electrostatic or magnetic drives. View full abstract»

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  • LF55GN photosensitive flexopolymer as a new material for ultra-thick and high aspect-ratio MEMS fabrication

    Page(s): 219 - 222
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    We present the photosensitive flexopolymer LF55GN as a new material for the realisation of thick three-dimensional microstructures. The latter can be realised with a thickness up to 4 millimetres and with an aspect ratio of 10 using only a single UV exposure step. LF55GN is a unique material that allows fabricating thick components of optical quality that easily absorb stress due to the elastic nature of the material. View full abstract»

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  • Mechanical characterization of silicon nitride thin-films using microtensile specimens with integrated 2D diffraction gratings

    Page(s): 223 - 226
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    This paper reports on the mechanical characterization of microtensile specimens made of silicon nitride (SiNx) thin-films with integrated 2D reflective gratings. By applying an axial force, the structures respond mechanically with an elongation and contraction in the longitudinal and transversal directions, respectively. The corresponding variations of both periods of the grating are monitored in real time by measuring the diffraction pattern resulting from the illumination of the grating with monochromatic light. The strain components are thus evaluated locally in the structure. By integrating such an optical technique with an efficient test structure previously developed, the extraction of materials' Young's modulus E, Poisson's ratio nu, residual strain epsivres and stress sigmares and fracture strength sigma0 is in principle made possible from the measurement of a single test structure. Here we demonstrate the extraction of E, epsivres, sigmares and sigma0 of the nitride films. View full abstract»

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  • Mechanical calibration of MEMS spring with 0.1-μn force resolution

    Page(s): 227 - 230
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    The direct calibration of MEMS springs made of single crystal silicon was carried out using a mechanical force measurement tool. The spring device for calibration fabricated from silicon on insulator (SOI) wafer contains four folded-beam springs. The spring constants of different-length devices were directly measured using electromagnetic force-feedback balance, whose force resolution was about 0.2 muN. The spring constants of the two types of folded-beam springs, whose designed constant was 0.3 and 0.7 N/m, were 0.18 and 0.57 N/m, respectively. The spring constants were successfully calibrated, which shows that this tool can calibrate various kinds of MEMS flexible structures. View full abstract»

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  • Pyrolyzed polymer mesh electrode integrated into fluidic channel for gate type sensor

    Page(s): 271 - 274
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    This paper presents a novel means of introducing conductive pyrolyzed polymer structures into a muTAS platform. Insulation structures of polymer materials can be transformed into conductive structures through pyrolysis, and MEMS structures consisting of pyrolyzed polymer can be formed by a dual process of micromachining and pyrolysis. This work focuses on gate type sensing by a three-dimensional pyrolyzed polymer electrode. The three-dimensional SU-8 original structure was micromachined by multi-angle inclined lithography. Three-dimensional structures of pyrolyzed SU-8, which have meshes of 10 mum times 20 mum in dimension, could be obtained by pyrolysis in N2 atmosphere. Furthermore, the structures were integrated into the SU-8 fluidic channel with the 100 mum in height and 200 mum in width by a post-pyrolysis process. We will demonstrate the cross sectional sensing in electrochemical detection by making the best use of the three-dimensional mesh structure to overcome the restriction of planar electrode. View full abstract»

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  • Low temperature ion beam sputter deposition of amorphous silicon carbide for wafer-level vacuum sealing

    Page(s): 275 - 278
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    This paper presents a novel low temperature, wafer-level vacuum sealing method that uses line-of-sight deposition of amorphous SiC with ion beam sputter deposition. The ion beam sputter deposition system allows substrate tilting for off-normal deposition and operates with a pressure of approximately 3 times 10-6 torr during deposition. The amorphous SiC films have demonstrated compressive intrinsic stresses for growth rates between 0.06 - 0.13 nm/min test scaffold structures were fabricated by etching holes and trenches into bare Si wafers. The topography of sealing films deposited on the test scaffold structures shows that the film growth is directional with no visible down-hole deposition. The termination of the seal and the chemical resistance of the sealing films have been confirmed with a hot KOH immersion experiment. View full abstract»

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  • A new fabrication process for micro optical elements using drie and oxidation

    Page(s): 279 - 282
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    We have developed a new fabrication process of micro optical elements by applying DRIE (Deep Reactive Ion Etching) process and thermal oxidation, which enables us to make micro lenses and prisms on a silicon substrate without assembling. This process can also form other optical elements, such as light wave-guides by changing mask pattern. View full abstract»

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  • Fabrication and characteristics of MEMS vertical type probe tip for micro sized pads measurement

    Page(s): 283 - 286
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    In this research we proposed, designed, fabricated, and measured a novel micro electro mechanical system (MEMS) based vertical probe tips which differs from conventional cantilever probe tips. The main idea of the vertical probe design was how to distribute the total forces vertically concentrated on the probe tip in measuring semiconductor devices. To solve the problem, we designed the vertical probe tip with meander structure which could provide enough displacements so that the vertical probe tips could distribute the forces acting on the tips. The structural analyses of the probe tip were accomplished using finite element method (FEM) and compared with actual measurement values. The primary fabrication processes were surface micromachining, wafer bonding technology, and electroplating. The material of the electro-plated probe tip was an Ni-Co alloy. In this study, we demonstrated the potential of the vertical probe tip that could apply to a small area with the over drive (O.D.) of 10~40 mum and the contact force of 1~8 gf. The measured contact resistance was less than 2 Omega and little noise was observed. View full abstract»

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  • High aspect ratio nano-scale CFX structures fabricated by deep-rie

    Page(s): 287 - 290
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    High aspect ratio (>500) nano-scale CFx (fluorocarbon) "tube" and "test-tube" arrays were realized using Deep Reactive Ion Etching (RIE). Sidewall CFx nano structures of 200 nm in thickness formed during Deep RIE passivation process were used for the purpose. The film thickness of CFx was controlled from 200 nm to 500 nm, and the height more than 100 mum was available. As a result, the aspect ratio is larger than 500. This fluorocarbon tube and test-tube array are useful tools for chemical and biological applications. View full abstract»

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  • SU-8 surface-micromachining process utilizing PMGI as a sacrificial material

    Page(s): 291 - 294
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    This work presents a novel surface micromachining process based on the SU-8 polymer that uses the resist PMGI as a sacrificial layer as well as a lift-off resist for metal patterning. The process is capable of independent patterning of the structural and metal layers which decouples the mechanical and electrical properties of the resulting structures. The process uses inexpensive equipment and materials and can be completed in a single day, making this process ideal for proof of concept prototyping. View full abstract»

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  • A novel fabrication method of flexible micro electrode array for neural recording

    Page(s): 295 - 300
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    We present in this paper a novel fabrication method of making flexible micro electrode array for neural probing. We have successfully produced micro electrode needles array and their corresponding wirings on a flexible polymer membrane through an ingenious variation of UV-LIGA process. This process is suitable for mass production. The first prototype was designed to have sixteen neural probes (4 times 4) with a needle height of 200 mum. Because of the process flexibility, the micro electrodes have the potential to be fabricated on different kinds of polymer membranes, which would be very useful in various targets, especially when "compliance" and "fracture tolerance" are desired. We will introduce our fabrication approach, preparation methods and fabricated results in this paper. View full abstract»

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  • A novel intelligent textile technology based on silicon flexible skins

    Page(s): 301 - 304
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    This paper reports the successful prototype development of a novel intelligent textile technology based on the integration of silicon flexible skins with regular textiles. This novel approach enables the embedding of sensing and computational components into textiles without compromising the flexibility of the textiles. Silicon flexible skins comprising of arrays of silicon islands integrated with boron doped strain gauges and metal pads were successfully fabricated using micromachining techniques. Prototypes of intelligent textiles were developed by stitching the silicon flexible skins onto the surface of textiles. The preliminary test demonstrated excellent durability of the prototypes. The strain experienced by the silicon islands was monitored in real-time using the integrated strain gauge when the prototype was mechanically deformed. These strain data provide valuable information for the further optimization and the next stage development of the intelligent textile technology. View full abstract»

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  • Biodegradable polymer needle with various tip angles and effect of vibration and surface tension on easy insertion

    Page(s): 397 - 400
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    This paper proposes a fabrication method of microneedles with various tip angles made of biodegradable polymer (polylactic acid, referred to herein as PL A). It was confirmed by finite element method (FEM) simulation that stress concentration occurs more severely at the tip area, as the needle becomes thin, and tip angle becomes sharp. Masks for silicon cavities (negative dies for micromolding) with various tip angles are designed. The fabrication process involves etching a groove on the surface of a silicon die, molding the polymer into this groove, and then releasing it. The resistance force during inserting a fabricated needle to an artificial skin of silicone rubber was investigated. Effectiveness of sharp tip angle and thin shank for easy insertion is confirmed. Imitating mosquito's needle, the effectiveness of vibrating needle, and giving surface tension to object surface was also confirmed. View full abstract»

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  • Virtual components for droplet control using marangoni flows: Size-selective filters, traps, channels, and pumps

    Page(s): 401 - 404
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    This paper describes several microfluidic components, including channels, filters, traps, and pumps, for manipulating aqueous droplets suspended in a film of oil on blank, unpatterned substrates. These "virtual" devices have no physical structure; they accomplish their function entirely by localized Marangoni flows created in a non-contact manner by heat sources suspended just above the liquid surface. Various flow patterns can be engineered through the geometric design of the heat sources on size scales ranging from 10-1,000 mum. Channels and circular traps, emulated by linear and annular heat fluxes respectively, demonstrate nearly 100% selectivity for droplets ranging from 300-1,000 mum. A pump, emulated by a triangular heat flux with a 10deg taper, translates droplets of about the same range at speeds up to 200 mumls. View full abstract»

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  • Microprobe microsystem platform inserted during early metamorphosis to actuate insect flight muscle

    Page(s): 405 - 408
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    Following from early work demonstrating that early pupal- stage inserts are accepted by insects [9], a microprobe based microsystem platform was designed with respect to the position of the muscle bundles, and was inserted into the thorax at 4 days of the pupal stage. The platform is roughly 8times7times1.5 mm3 in size with probe thickness of 200 mum and weighs 500 mg, which the moth is able to successfully carry in the adult stage. In addition to the microsystem, an anchor to easily manipulate the adults was successfully formed in the insect by placing a glass-capillary through the pupae. The pupae emerged successfully, and the microsystem was used to characterize the potential for flight control. As part of the work to determine the microplatform design, we determined the strength-interval profiles of the pulses needed for direct muscle actuation. Two sets of flight muscles, which are symmetrically present on either side of the thorax, were differentially electrically actuated, which potentially influences the individual wing beat frequency and amplitude resulting in controlled turning behavior during flight. View full abstract»

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  • Shape control of filamentous motor proteins for bio-nano driving units

    Page(s): 409 - 412
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    This paper describes a technique for controlling the shape of filamentous motor proteins for the bio-nano driving units in MEMS devices. In this experiment, we have used Actin, a protein to construct cytoskeleton actin monomers (G-actin) polymerize in high salt condition and form filaments (F-actin); the filaments move when they bind with the motor protein (Myosin) in ATP (adenosine tri-phosphate) solution. Fascin, a putative bundling protein, tightly bundles several F-actins together to form tight bundles of actin [1]. When G-actin and the fascin solution was confined and polymerized in the polydimethylsiloxane (PDMS) or parylene micro chambers, we found that the polymerized actin bundles followed the geometry of chambers, and then formed several shapes, such as circles, rods, triangles or squares. Since the bundled actins still have motility, we believe this technique is useful for forming a desired pattern of bio-molecular motors toward the actuation of MEMS/NEMS devices. View full abstract»

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  • Pillar size effect on DNA electrophoresis in microchips with sub-micron pillar arrays

    Page(s): 413 - 416
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    This paper presents a systematic study of DNA electrophoresis in microchannels integrated with sub-micron pillar arrays. Electrophoretic mobility of different DNA fragments in channels having pillars of various dimensions is measured. In addition to confirming a previously observed nonlinear relationship with applied electric field following the Biased Reptation with Fluctuations Model, the mobility dependence on DNA size and pillar spacing is characterized and discussed. Similar to conventional slab-gel electrophoresis, short DNA molecules have higher migration mobility. However, a "band inversion"-like phenomenon is observed for larger DNA molecules. The pillar array significantly affects the electric field distribution in the separation channel and, consequently, the resulting mobility. Although this leads to a higher mobility in more closely packed pillars, excessive reduction of the pillar spacing generates a large retarding force. This counteracts the effect of electric field on the overall DNA mobility. View full abstract»

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  • A miniaturised integrated QCM-based electronic nose microsystem

    Page(s): 417 - 420
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    We designed, fabricated and successfully tested an integrated miniaturised quartz crystal microbalance (QCM) based electronic nose microsystem. The microsystem is an assembly of four parts: 1. a micromachined gas-liquid interface with integrated fluid channels and electrical conductors, 2. an anisotropically conductive double-sided adhesive film, 3. a QCM crystal and 4. a polymer cap with fluid and electrical ports. The choice of the multifunctional materials and the geometric features of the four-component microsystem allow a functional integration of a QCM crystal, electrical contacts, fluidic contacts and a sample interface in a single system with minimal assembly effort, a potential for low-cost manufacturing, and a few orders of magnitude reduction in system size (12* 12*4 mm3) and weight compared to commercially available instruments. The system detected ecstasy in the 100 ng range within 30 seconds. View full abstract»

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  • Miniaturized HPLC column with nano-pore beads for protein separation on flexible medical implants

    Page(s): 421 - 424
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    This paper reports a miniaturized HPLC (high performance liquid chromatography) column packed with nano-pore beads for flexible medical implants applications. The all-flexible-polymer column capable of integrating with micro/nano-devices on a chip separates biological entities to relax stringent requirements on subsequent detectors and to enable parallel detection in a detector array. The fabricated device has successfully separated a protein mixture using nano-pore beads in a miniaturized column. According to HPLC analysis, the intensity ratio of large to small protein varies significantly, more than a factor of 300, over sample collecting time, ~12mins, suggesting very high separation performance. View full abstract»

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