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MEMS, NANO and Smart Systems, 2003. Proceedings. International Conference on

Date 20-23 July 2003

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Displaying Results 1 - 25 of 82
  • Transient electro-osmotic pumping in rectangular microchannels

    Page(s): 364 - 372
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    Two-dimensional Poisson-Boltzmann and momentum equations are solved simultaneously to study the transient characteristics of electro-osmotic pumping in a rectangular microchannel. A finite difference scheme with variable grid spacing is used to calculate electric potential distribution. Time variations of velocity profiles are obtained by using a combined ADI-TDMA technique. Numerical solutions show significant influences of the channel hydraulic diameter, the aspect ratio, and the applied voltage on the transient and steady state velocity fields and the resulting volumetric flow rates. As the channel hydraulic diameter is increased, it takes a longer period for the flow to reach steady state condition. On the other hand, as the channel aspect ratio deviates from the square, a steady-state flow field is reached in a shorter period, and a slightly larger flow can be obtained. The numerical results also show that the steady state channel throughput is linearly increasing with the applied voltage along the channel length. View full abstract»

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  • The emergence of high-density semiconductor-compatible spintronic memory

    Page(s): 321 - 326
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    After many years of research and development, megabit-density spintronic memory, also called magneto-resistive random-access memory (MRAM), may be on the verge of commercial production at several companies, including Honeywell International Inc., Cypress Semiconductor Corp., IBM Corporation, and Motorola Inc. MRAM has been touted as being a universal memory technology, with the high speed of SRAM, the nonvolatility of flash memory (but with much greater erase-write endurance than flash memory), and with storage densities approaching those of DRAM. MRAM is also promoted as being embeddable in conventional CMOS processes with as few as four additional mask steps. Similar advantages are also claimed by proponents of at least two other emerging candidate universal memories: ferroelectric memory and chalcogenide-based phase change memory. This paper focuses on MRAM, and briefly surveys the most promising MRAM technologies, including anisotropic MRAM, spin valve MRAM, pseudo spin valve MRAM, and magnetic tunnel junction MRAM (MTJ-MRAM). View full abstract»

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  • Understanding bitumen recovery from oil sands through Colloidal and interfacial phenomena

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    "Summary form only given". Canadian oil sands are unconsolidated sand deposits that are impregnated with heavy, viscous petroleum, normally referred to as bitumen. The total bitumen in place in Alberta is estimated at 1.7 to 2.5 trillion barrels and is clearly massive by world standards. Presently, 25% of the Canadian energy needs are derived from upgraded bitumen from mined oil sands. The oil sands are a complex mixture containing bitumen, mineral solids, clays, connate water and salts. The bitumen recovery from the oil sands using water extraction processes involves bitumen separation from the sand grains and air-bitumen attachment for subsequent flotation. Colloidal, interfacial and electrokinetic phenomena play a major role in bitumen recovery from oil sands using water based extraction processes. Through the use of basic scientific tools at the micro and molecular scales, we were able to understand the working of what is considered to be a mega scale industrial process. Electrophoretic and atomic force balance measurements were used to establish the reasons for the observed low bitumen recovery in the presence of fine solids and divalent ions. As well, impinging jet deposition experiments were utilized to ascertain the ability of air-bitumen attachment under different physicochemical environment. The behavior of the bitumen-water interface was studied to better understand the formation of stable water-in-bitumen emulsions. Langmuir trough and micro-pipette techniques were employed to elucidate the fundamental role of deemulsifiers. The presentation will illustrate how one can within a University environment study a complex industrial process that is of great importance to the Canadian Energy Sector. View full abstract»

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  • Terahertz wave propagation in multiwall carbon nanotubes

    Page(s): 430 - 434
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    This paper aims to study sound wave propagation in individual multiwall carbon nanotubes based on a multiple-elastic beam model. The present model predicts that there exist (N-1) critical frequencies (within terahertz range) for an N-wall carbon nanotube. Sound wave propagation in multiwall carbon nanotubes is almost coaxial only when the frequency is much below all critical frequencies, and becomes substantially non-coaxial when the frequency is higher than at least one of the (N-1) critical frequencies. In the latter case, the sound speeds predicted by the present model are significantly higher or lower than that given by the existing single-beam model. Hence, terahertz sound waves in multiwall carbon nanotubes exhibit complex new phenomena and are essentially non-coaxial. View full abstract»

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  • Electrostatic interactions between nanoparticles in confined spaces: influence of confining wall roughness

    Page(s): 263 - 268
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    Nanoparticles confined in capillaries is a commonly encountered system in a variety of micro and nano electromechanical devices. In this paper we study the influence of the confining geometry on the electrostatic-interaction forces between two nanoparticles. Predictions of electrostatic double layer interaction forces between two similarly charged smooth spherical colloidal particles inside a long "rough " capillary are presented. A simple numerical model of a rough surface is proposed, which assumes the capillary wall to be a periodic function of axial position. The nonlinear Poisson-Boltzmann equation governing the electrical potential distribution in the electrolyte is solved using finite element technique. The interaction force between the spheres was affected significantly by the proximity of the rough capillary wall. The influence of surface undulations on the particle-particle interaction force was most pronounced when the particle radius was comparable to the wavelength of the surface undulations of the capillary. According to present simulations, it seems possible to utilize this oscillation of electrostatic force to move a particle through micro-channels for controlled delivery of fluids in devices like micro-arrays and labs-on-a-chip. View full abstract»

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  • Parametric excitation of spin waves in bismuth-substituted yttrium iron garnet films using the first-order Suhl instability

    Page(s): 148 - 152
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    The first-order Suhl instability in a bismuth-substituted yttrium iron garnet (Bi-YIG) film is parametrically driven at the difference frequency of two microwave oscillators. Our results show that the onset of the instability occurs at lower threshold power when excited parametrically, and the power of the instability can be fed into other spin wave modes. Other nonlinear processes are also enhanced using parametric excitation. View full abstract»

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  • Performance improvement of a magnetically levitated microrobot using an adaptive control

    Page(s): 332 - 338
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    This paper deals with an application of an adaptive control to a magnetically levitated microrbot. Using an electromagnetic device, a microrobot is levitated and manipulated within a 3-D space inside a magnetic field. The microrobot has two fingers that can grasp and elevate objects. PID controls are applied for positioning of the microrobot in the three axes. However, as the microrobot deals with various payloads, a PID control may not be sufficient to maintain the microrobot on high performance in the vertical axis. To improve the performance, an adaptive control law is also examined for the positioning in the vertical axis so that the controller parameters become adjustable in real-time to cope with uncertainties and variations in payloads. A model-reference adaptive system (MRAS) based on the augmented error is designed, and simulations and experiments are conducted to verify the effectiveness of the control. The simulation and experimental results for PID and adaptive control are shown for comparison. View full abstract»

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  • Energetics and strain field of surface steps

    Page(s): 270 - 273
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (259 KB) |  | HTML iconHTML  

    Stability and surface morphology of a thin film deposited in ultrahigh vacuum condition depend on strain energy stored in the thin film. Predicting the stability and morphology of such surfaces is essential for understanding, e.g., (i) the formation and growth of nanocrystals (quantum dots) in semiconductor heteroepitaxial thin film deposition and (ii) the requirements to grow flat thin films despite the presence of surface steps. This work describes a novel, theoretical model that gives rise to modified mechanical force equilibrium equations and provides a new framework to model step energetics and dynamics in heteroepitaxial thin films. Specializing in two-dimensional thin films, strain fields and energetics of a solitary surface step will be presented. View full abstract»

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  • Three-dimensional square spiral photonic crystal nanostructures by glancing angle deposition

    Page(s): 165 - 171
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1784 KB) |  | HTML iconHTML  

    We demonstrate the fabrication of a three-dimensional photonic band gap nanostructure using the unique Glancing Angle Deposition (GLAD) thin film technique. This innovative photonic structure is based on a tetragonal, square spiral symmetry found in FCC and diamond lattices and can be implemented in a virtual single-step fabrication process using GLAD. A highly porous film with engineered nanostructure results from the implementation of advanced substrate motion during the deposition, and three-dimensional periodicity required for a photonic crystal can be obtained when a square spiral staircase is fabricated on a tetragonally seeded substrate. We present successful fabrication of three-dimensional square spiral structures along with some examples of the unique capabilities of these nanostructured thin films. View full abstract»

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  • Computational patent mapping: Intelligent agents for nanotechnology

    Page(s): 274 - 278
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (717 KB) |  | HTML iconHTML  

    Patents are an important source of technological intelligence that companies can use to gain strategic advantage and computational patent mapping is a methodology for the development and application of a technology knowledgebase for technology and competitive intelligence. The primary deliverables of patent mapping is in the form of knowledge visualization through landscape and maps. This paper applied computational patent mapping techniques in the area of nanoagent and several dominant nanoagent themes have been identified by the visualization of a patent dataset presented in the form of a patent landscape for nanoagents. This study reveal insights into nanoagents patent technology S-curves, patenting activities of various nanoagent players over time, the development in nanoagent enabling technologies over time and selected patent with high QS-lndex. View full abstract»

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  • First results in patterning of ultra high aspect ratio microstructures by a 4T wave length shifter at BESSY

    Page(s): 177 - 180
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    Both X-ray lithography beamlines at BESSY can be operated in three different modes: one coming from a dipole (1.3 T) is used for standard exposures for patterning PMMA and SU-8, while the other beamline, coming from a straight section of the storage ring, can be operated in soft wavelength mode (0.4 T) or alternatively in wave length shifter mode (4T). Using the soft wave length mode, copying processes for X-ray mask can be carried, while the very hard radiation generated in the wave length shifter (WLS) modes best for patterning ultra thick PMMA layers up to several mm in thickness. In WLS mode the higher magnetic field of 4T is shifting the critical photon energy to 7.7 keV compared to a standard dipole magnet with 2.5 keV. The lateral intensity homogeneity of this beamline is very high. Tests for using the WLS mode for ultra deep X-ray lithography (UDXRL) were performed and delivered very good results. PMMA layers of up to 4 mm in thickness were patterned successfully. Similar patterning methods to fabricate high aspect ratio micro parts were reported in literature. View full abstract»

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  • Dynamics of an electrically actuated resonant microsensor

    Page(s): 188 - 196
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    We present a nonlinear model of an electrically actuated microbeam-based resonant microsensor encompassing the electrostatic force of an air gap capacitor, the restoring force of the microbeam, and the axial load applied to the microbeam. The model accounts for moderately large deflections, dynamic loads, and the coupling between the mechanical and electrical forces. It accounts for the nonlinearity in the elastic restoring forces and the electric forces. A perturbation method, the method of multiple scales, is applied to the distributed-parameter system to study the local dynamics of the sensor under primary, superharmonic, and subharmonic excitations. In each case, we obtain two first-order nonlinear ordinary-differential equations that describe the modulation of the amplitude and phase of the response and its stability, and hence the bifurcations of the response. The perturbation results are validated by comparing them to experimental results. The DC electrostatic load affects the qualitative and quantitative nature of the frequency-response curves, resulting in either a softening or a hardening behavior. The results also show that an inaccurate representation of the system nonlinearities may lead to a qualitatively and quantitatively erroneous prediction of the frequency-response curves. The results provide an analytical tool to predict a microsensor response to primary, superharmonic, and subharmonic excitations, specifically the locations of sudden jumps and regions of hysteretic behavior allowing designers to examine the impact of the design parameters on the device behavior. View full abstract»

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  • Monolayer surface coatings solve stiction and drift problems in MEMS

    Page(s): 128 - 130
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    This paper reports recent developments in monolayer surface coating process to solve stiction and drift problems in MEMS devices. The chemical strategy for the formation of high density and conformal monolayers is presented, and performance characteristics of these coatings on existing or emerging MEMS products will be discussed. Recent tests on electro-statically actuated micro-mirror devices show that a densely packed monolayer can withstand up to 100 billion cycles of contacts. View full abstract»

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  • Measurement of the conductivity exponent in random percolating networks of nanoscale bismuth clusters

    Page(s): 350 - 356
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (532 KB) |  | HTML iconHTML  

    Nanoscale bismuth clusters, produced in an inert gas aggregation source, have been deposited between lithographically defined electrical contacts. The conductivity exponent, t, of the 2D percolating network of bismuth clusters has been derived from in-situ electrical measurements. It was found to be 1.32±0.25. This value is comparable with theoretical predictions of t ·1.3 for 2D random continuum percolation networks. View full abstract»

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  • Application of adaptive multilevel substructuring technique to model CMOS micromachined thermistor gas sensor, part (I): A feasibility study

    Page(s): 279 - 284
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (386 KB) |  | HTML iconHTML  

    A study has been conducted to investigate the feasibility of using the multilevel substructuring method to perform parametric analysis for MEMS devices. The feasibility study was conducted on a CMOS micromachined thermistor gas sensor. Two multilevel substructuring methods were used, mainly the cumulative and nested superelements methods. The interface problem was found to increase rapidly with the increase in the number of superelements for the cumulative technique. On the other hand, the nested superelements technique was found to provide an almost fixed and much more reduced interface problem. The results show that, for the same number of reduced elements, the nested superelements method provides a better speedup factor (2.36-4.61) compared to the cumulative method. In the current study, two strategies were used to deal with the nonlinear thermal analysis of the microheater. In the first strategy the substructuring was only limited to the linear portions of the model. In the second strategy the substructuring was extended to include portions of the model with a reduced nonlinearity. The second strategy increased the computational savings by a percentage of 20%, compared to the first strategy with a reasonable loss of accuracy of only about 3%. View full abstract»

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  • Ultrasonic/sonic sampler and sensor platform for in-situ planetary exploration

    Page(s): 22 - 31
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (331 KB) |  | HTML iconHTML  

    The search for existing or past life in the Universe is one of the most important objectives of NASA's mission. In support of this objective, an ultrasonic/sonic mechanism is currently being developed at JPL to allow probing and sampling of rocks and to use the mechanism as a sensor platform for in-situ planetary analysis. The technology is based on the novel Ultrasonic/Sonic Driller/Corer (USDC), which requires low axial force, thereby overcoming one of the major limitations of planetary sampling using conventional drills in low gravity environments. The USDC was demonstrated to: 1) drill ice and various rocks including granite, diorite, basalt and limestone, 2) not require bit sharpening, 3) operate at low and high temperatures, and 4) operate at low average power using duty cycling.. The capabilities that are being investigated include probing the ground to select sampling sites, collecting various forms of samples, and hosting sensors for measuring various properties. A series of modifications of the USDC basic configuration were implemented including an ultrasonic abrasion tool (URAT), Ultrasonic Gopher for deep drilling, and the Lab-on-a-drill. These modifications will be described in this paper. View full abstract»

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  • Direct production of gratings on polymers using UV laser radiation

    Page(s): 172 - 176
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    Diffraction gratings with micron and submicron periods have many applications such as modifying optical waveguide characteristics, forming alignment layers for liquid crystals, and as building blocks for pattern precursor substrates used in various applications. In this paper, we describe a single step dry-etching process for the fabrication of diffraction gratings on selected commercial polymers using two coherent interfering 248 nm KrF laser beams. Grating periods from 0.2 μm to several μm were created with single and multiple laser pulses by varying the angle between the two interfering laser beams. Grating structures were characterized using laser diffraction, Scanning Electron Microscopy, and Atomic Force Microscopy. Three plastics were investigated (BCB, PAI, and PET) and it was found that the highest quality gratings formed on PET films. View full abstract»

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  • Micro and nano sensors snoop around

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    "Summary form only given". Vision and hearing, smell and taste, and the tactile senses are bridges between the external world and our brain. Micro and nano sensors are miniaturized electronic devices which pick up physical, chemical, or biomedical signals and enter them into the computer. The miniaturization of most kinds of sensors has been achieved, but the "electronic nose" able to detect a broad range of "smells" caused by complex mixtures of airborne chemical compounds is still a dream. But application specific gas sensors or "narrow band noses" are being developed, which can detect and identify gas mixtures in given application areas, such as air conditioning, dry cleaning, oil refineries, or food production. Integrated gas sensors based on CMOS IC technology with on-chip micro structures (CMOS MEMS) coated with gas absorbing polymers or metal oxides are presented. The quest of sensor selectivity is tackled by combining various polymers with different transducer principles (mass sensitive, capacitive, calorimetric). The combination of different types of transducers on a single CMOS MEMS chip with dedicated circuitry, and the assembly of several such chips, each with different chemically sensitive polymer layer, in a handheld "snooping instrument" are discussed. An outlook will address the combination of CMOS MEMS with bio materials and living cells. View full abstract»

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  • Multi-patch: a chip-based ion-channel assay system for drug screening

    Page(s): 251 - 254
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    Ion channels are cellular membrane proteins that act as specific signal transducers. They have crucial roles in physiology and pathophysiology and are important drug targets. Patch-damp is the gold-standard for assessing ion channel function but does not have the potential to be automated and parallelized. This fact underlies current efforts in developing parallel patch-on-chip platforms in order to provide higher throughput and better reproducibility. Our approach is to develop a bio-electronic sandwich interface between microstructured substrates and printed circuits. 'Multi-patch' is a patch-on-a-chip device replacing patch pipettes by micrometer-sized holes and enabling multiple simultaneous single-cell electrical measurements. We present here a comparative approach of different substrates in view of the development of a chip-based device. We emphasize on the silicon technology pointing out its advantages in terms of microstructuration and development of an integrated electronics. View full abstract»

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  • Benzocyclobutene (BCB) based intracortical neural implant

    Page(s): 418 - 422
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    A novel structure for chronically implantable cortical electrodes using new Benzocyclobutene (BCB) bio-polymer was devised, which provides both flexibility for micro-motion compliance between brain tissues and skull and stiffness for better surgical handling. BCB is very attractive polymer for stable long-term implant function, because it has flexibility, biocompatibility, low moisture uptake (<0.2 wt%), and low dielectric constant (∼2.6). For easy operation during surgical insertion, a 5∼10μm thick silicon backbone layer is attached to the desired region of the electrode to increase the stiffness. It is then followed by 1 mm of flexible part of the electrode without silicon backbone layer designed to absorb stress from any micro-motion between the brain tissue and the electrode. The fabricated implants have tri-shanks with 5 recording sites (20x20μm) and 2 vias (40x40μm) on each shank. BCB electrodes with 5μm and 10μm thick backbone silicon penetrated pia of rat brain without buckling. View full abstract»

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  • RF MEMS devices

    Page(s): 103 - 107
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    This paper addresses the use of RF MEMS devices in wireless and satellite communication systems. Novel configurations are presented for MEMS variable capacitors, MEMS tunable inductors and RF MEMS multiport switches. The tuning range of the variable capacitor was measured and found to be 280%, which far exceeds that of the traditional parallel plate MEMS variable capacitors. The MEMS tunable inductor is realized using MEMS fixed inductors, capacitors and a variable MEMS capacitor. The proposed MEMS multiport switch has demonstrated a superior RF performance up to 20 GHz. View full abstract»

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  • Electric field assisted deposition of nanowires from carbon nanotubes for nanoelectronics and sensor applications

    Page(s): 203 - 208
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    Manipulation and control of matter at the nano- and atomic level are crucial for the success of nano-scale sensors and actuators. The ability to control and synthesize multilayer structures using carbon nanotubes that will enable to build electronic devices within a nanotube is still in its infancy. In this paper, we present results on selective electric field assisted deposition of metals on carbon nanotubes realizing metallic nanowire structures. Silver and platinum nanowires has been fabricated using this approach due to its applications in chemical sensing as catalytic materials to sniff toxic agents and in the area of biomedical nanotechnology for construction of artificial muscles. The electric field assisted deposition allows the deposition of metals with high degree of selectivity on carbon nanotubes by manipulating the charges on the surface of the nanotubes. SEM and TEM investigations revealed silver and platinum nanowires between 10 nm-100 nm in diameter. The present technique is versatile and enables the fabrication of host of different types of metallic and semiconducting nanowires using carbon nanotube templates for nanoelectronics and myriad of sensor applications. Further, nanowires can also serve as model systems for studying quantum size effects at these dimensions. View full abstract»

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  • Fabrication of ultra thick, ultra high aspect ratio microcomponents by deep and ultra deep X-ray lithography

    Page(s): 10 - 14
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    Two advanced processes have been developed for fabricating ultra thick and ultra high aspect ratio (HAR) microstructures. One is the SU-8 based deep X-ray lithography (SU-8 based DXRL) process which uses the normal deep X-ray beam to expose the negative SU-8 resist. Another one is wave length shifter(WLS) based Ultra deep X-ray lithography (WLS-UDXRL) process which uses special ultra deep X-ray beam from wave length shifter to expose the positive PMMA resist. For SU-8 based DXRL process, the typical exposure time of a layer of SU-8 is about 1% of that of PMMA. Even for a few millimeters thick resists the exposure time are just a few minutes. In WLS-UDXRL process, the X-ray beam is strengthened by a wave length shifter(WLS) so the required exposure time for ultra thick PMMA is reduced greatly. In the paper, the characteristic of the these two processes are discussed and the examples of the ultra thick and ultra HAR microstructures fabricated by these processes are presented (ultra thick up to 3600 μm and HAR up to 360). View full abstract»

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  • Equilibrium and dynamic behavior of micro flows under electrically induced surface tension actuation forces

    Page(s): 197 - 202
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    It is possible to move, split, merge, and mix liquids in micro fluidic devices by applying spatially varying electric fields that effectively change the surface tension at specific spatial locations. The phenomena is brought about by a competition between surface tension effects (that cause the droplet to bead up because it has been placed on a hydrophobic surface) and electrical forces in the underlying solid dielectric (which attempt to enlarge the liquid/solid contact area so as to relieve electro static forces). In this paper we primarily present an energy minimization model for the equilibrium shape of electrically actuated droplets. By including a realistic amount of liquid resistance, this model captures the effect of contact angle saturation and predicts the experiment data we observe in the UCLA devices. At the close of the paper we also outline our results in modeling the dynamics of the moving, splitting, and merging droplets. This part includes modeling of the 2-phase low-Reynolds fluid dynamics with electrically actuated boundary conditions. View full abstract»

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  • Quantum size effect in magnetic tunnel junctions with single-crystal ultrathin electrodes

    Page(s): 316 - 320
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    Control of coherent electron transports in spintronic devices is an essential issue to realize highly functional spin-devices such as spin-dependent resonant-tunneling transistors. The spin dependent resonant tunneling via the quantum-well states in the electrode gives us many clues to understand and to control transport property in magnetic tunnel junctions (MTJs). To observe the quantum-well oscillations in TMR effect, we prepared the magnetic tunnel junctions with single-crystal ultrathin electrode or insertion layers. The MTJs with an ultrathin Fe [001] electrode shows the oscillation of TMR ratio as a function of the biasing voltage. In the case of an ultrathin Cu [001] layer inserted between a Co electrode and Al2O3 barrier layer, we found large oscillations of TMR with respect to the thickness of the Cu electrode. These results clearly show a feasibility of the coherent spintronic devices using metallic systems. View full abstract»

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