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Microelectromechanical Systems, Journal of

Issue 4 • Date Aug. 2007

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Displaying Results 1 - 25 of 26
  • Table of contents

    Publication Year: 2007 , Page(s): C1 - C4
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    Freely Available from IEEE
  • Journal of Microelectromechanical Systems publication information

    Publication Year: 2007 , Page(s): C2
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  • Microchannel Pressure Measurements Using Molecular Sensors

    Publication Year: 2007 , Page(s): 777 - 785
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1722 KB) |  | HTML iconHTML  

    Fluid mechanics on the microscale is an important subject for researchers who are interested in studying microdevices since physical phenomena change from macroscale to microscale. Channel flow is a fundamental topic for fluid mechanics. By using a molecular sensor known as pressure-sensitive paint (PSP), detailed pressure data can be obtained inside the microchannel and at the channel entrance. The achievable spatial resolution of the acquired pressure map can be as high as 5 mum. PSP measurements are obtained for various pressure ratios from 1.76 to 20, with Knudsen number (K n) varying from 0.003 to 0.4. Compressibility and rarefaction effects can be seen in the pressure data inside the microchannel and at the channel entrance. View full abstract»

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  • Discrete Chemical Release From a Microfluidic Chip

    Publication Year: 2007 , Page(s): 786 - 794
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (787 KB) |  | HTML iconHTML  

    We demonstrate a discrete chemical release method, capable of delivering picoliter volumes of chemical solutions with 100 mum of spatial resolution and 20 mus of response time. The releasing mechanism is based on the transfer of pulsed liquid plugs through a hydrophobic air chamber. A microfluidic chip consisting of such a releasing array (2 times 10) is designed and fabricated. Numerical simulation and experimental testing are performed to verify the working principle. Advantages of this release-on-demand technology include leakage-free, fast response and versatile control of release profile. This new method could be a key enabling technology for precisely controlled release of biochemicals for modern pharmacological and biological research. View full abstract»

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  • Wafer-Level Process for Single-Use Buckling-Film Microliter-Range Pumps

    Publication Year: 2007 , Page(s): 795 - 801
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (724 KB) |  | HTML iconHTML  

    In this paper, we present the development of disposable single-use microfluidic pumps entirely based on a straightforward wafer-level fabrication scheme, which allows for precise integrated active dosing in the microliter range. To accomplish stroke-lengths needed for microliter-range applications, we utilize a new method of bending of a unimorph-composite-actuator film. The unimorph composite actuator consists of a temperature-sensitive silicone elastomer composite, i.e., polydimethylsiloxane, with incorporated expandable microspheres. The fabricated micropumps successfully demonstrated precise liquid-volume control, both at low and high flow rates, and show a standard deviation of 6.7% for consecutive pump experiments. Moreover, the method of fluorescent thermometry was used to measure the thermal load on liquid volumes dispensed with the micropumps. The liquid temperature reaches a maximum of 50degC during the operation. The presented fully integrated single-use micropumps are electrically controllable, do not require external means for liquid actuation, are made of low-cost materials only, and might potentially be used in drug-delivery applications. View full abstract»

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  • Nanomechanical Protein Concentration Detector Using a Nanogap Squeezing Actuator With Compensated Displacement Monitoring Electrodes

    Publication Year: 2007 , Page(s): 802 - 808
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1216 KB) |  | HTML iconHTML  

    We present a new class of the protein concentration detector based on the mechanical stiffness measurement of protein-receptor layers in a squeezed nanogap. Compared to the previous protein size detector, the present device reduces the distortion and uncertainty in the displacement measurement by adding an actuated nanogap and reference electrodes. Compared to the conventional protein detectors based on electrochemical, optical, optomechanical, and mechanical principles, the present device also offers simple, inexpensive, and high-precision protein detection. We design and fabricate the protein concentration detector using an electrothermal actuator and two nanogaps with reference electrodes. In an experimental study, we verify that the present protein detector measures the size of the proteins streptavidin and m-antibiotin as 12.1 plusmn 2.3 and 13.2 plusmn 3.3 nm at the measurement uncertainty of plusmn1.9 nm, respectively, while showing the concentration detection sensitivity of 2.88 N/m/nM in the m-antibiotin concentration range of 5-10 nM. View full abstract»

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  • Miniaturization of Electrostatic Fluid Accelerators

    Publication Year: 2007 , Page(s): 809 - 815
    Cited by:  Papers (14)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (768 KB) |  | HTML iconHTML  

    Existing thermal-management methods for electronics do not meet the technology needs and remain a major bottleneck in the evolution of computing, sensing, and information technology. The decreasing size of microelectronic components and the resulting increasing thermal output density require novel cooling solutions. Electrostatic fluid accelerators (EFAs), also known as electrohydrodynamic ionic wind pumps, have the potential of becoming a critical element of electronic thermal-management solutions. In order to take full advantage of EFA-based thermal management, it is essential to miniaturize EFA technology. This paper demonstrates the successful operation of a mesoscale microfabricated silicon EFA. Several cantilever structures fabricated in bulk silicon with radii of tip curvature ranging from 0.5 to 25 mum are used as the corona electrode. The device was fabricated using the combination of deep reactive ion etching (DRIE) and reactive ion etch (RIE) microfabrication processes. Forced convection cooling is demonstrated using infrared imaging, showing a 25degC surface temperature reduction over an actively heated substrate. The fabrication and test results of a mesoscale microfabricated EFA are presented in this paper. View full abstract»

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  • A Programmable Biochip for the Applications of Trapping and Adaptive Multisorting Using Dielectrophoresis Array

    Publication Year: 2007 , Page(s): 816 - 825
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1031 KB) |  | HTML iconHTML  

    The adaptive biochip integrating dielectrophoresis (DEP) traps and a programmable multisorting DEP array for the multisorting applications of biomolecules such as proteins and DNA is proposed and demonstrated in this paper. In this research, movable beads are used as the mobile probes to capture the target protein molecules. These beads are chemically modified and immobilized with p50 proteins in our demonstration. An array of micropyramid DEP traps with a good levitation control on the height of the beads is located at the upstream to enhance the hybridization function of the mobile probes. The sample solution mixed with Cy3-I-kappa-B-alpha complex is used in the demonstration. A programmable multisorting DEP array that is located at the downstream sorts out the hybridized beads, which are fluorescently labeled based on the fluorescent detection signals. The magnitude and direction of the DEP force that is applied to the beads with/without labeling fluorescence in the multisorting DEP array are controlled via the distribution of time-variant nonuniform electric fields. The voltage on the individual electrode of the multisorting DEP array is preprogrammed and controlled by a LabVIEW controller with fluorescence detection feedback signals. In contrast to the research of Manaresi et al. [IEEE J. Solid-State Circuits, vol. 38, no. 12, p. 2297, 2003], which was proposed for trapping and sorting beads and cells via Dent traps, to our knowledge, the design of this biochip with the hybridization enhancement via micropyramid DEP traps and the adaptive multisorting DEP array for the mobile probes has never been proposed and implemented to date. View full abstract»

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  • Design of a Self-Flapping Microfluidic Oscillator and Diagnosis With Fluorescence Methods

    Publication Year: 2007 , Page(s): 826 - 835
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (987 KB) |  | HTML iconHTML  

    To measure a microflow rate and to accelerate the reaction between proteins by an unbalanced impingement of feedback flow, we have proposed and verified the design of a self- flapping microfluidic oscillator. Three specific features - the large aspect ratio of the micronozzle, the structure of the sudden- expansion inlet, and the asymmetric feedback channels - are developed to induce stable oscillation. The large aspect ratio of the micronozzle diminishes the influence of viscous force, and the inlet structure triggers flow instability. The conjunction of both factors promotes the occurrence of the Coanda effect, and initiates oscillation. The asymmetric feedback channels produce an unbalanced impingement of the inlet flow, thus reinforcing the initial oscillation to become stably periodic. Beyond the function of a microflowmeter, the oscillatory characteristics are applicable to accelerate the biochemical reaction between two fluorescent proteins, B-phycoerythrin and an allophycocyanin alpha subunit. With fluorescence induced with a laser, we detected the proteins at a specific wavelength to define the region of interaction caused by the oscillatory motions, which clearly enhances the rate of reaction of these fluids. To focus on the reaction phenomenon of twin fluids, we demonstrated biotin-streptavidin binding that was detected via a fluorescence-resonance-energy-transfer (FRET) pair of fluorescent proteins. The FRET signal demonstrated conclusively that the biochemical reaction was promoted through the oscillatory function. View full abstract»

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  • Ionic-Liquid Lubrication of Sliding MEMS Contacts: Comparison of AFM Liquid Cell and Device-Level Tests

    Publication Year: 2007 , Page(s): 836 - 843
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (822 KB)  

    Lubrication of microelectromechanical systems (MEMS) became very critical as the devices became complex and its reliability began to deteriorate. In this paper, ionic liquids (ILs) with low volatility and high environmental stability were investigated as lubricants for sliding MEMS devices. A method that is based on atomic force microscopy (AFM) with a liquid cell was developed to study friction and wear properties of surfaces lubricated with ILs, having a systematic variation in molecular geometry and chemistry. Six-member pyridinium and five-member imidazolium rings are compared as cations in ethyl methyl pyridinium and ethyl methyl imidazolium ethyl sulfate; influence of short and long alkyl chain lengths on lubrication is studied with butyl methyl pyrrolidinium and hexyl methyl pyrrolidinium bis(trifluro methyl sulfonyl) imide. Formation of a surface-screening cation layer was discovered and linked to low friction and wear of IL-lubricated hydrogenated-silicon (H-Si) substrates. Several promising IL lubricants were identified from the AFM study and were tested in real MEMS motor devices. The friction and wear data obtained for these tests showed good correlation with the failure life span of lubricated MEMS motors. This supports a conclusion that the AFM-liquid-cell technique can be used in screening IL lubricants for MEMS devices. View full abstract»

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  • Fabrication of High-Aspect-Ratio Electrode Arrays for Three-Dimensional Microbatteries

    Publication Year: 2007 , Page(s): 844 - 852
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1107 KB) |  | HTML iconHTML  

    Silicon-micromachining techniques have been combined with conventional material-synthesis methods to develop microelectrodes for 3-D microbatteries. The resulting electrodes feature an organized array of high-aspect-ratio microscale posts fabricated on the current collector to increase their surface area and volume for a given footprint area of the device. The diameter of the posts ranges from a few micrometers to a few hundred micrometers, with aspect ratios as high as 50. The fabrication approach is based on micromolding of the electrode materials and subsequent etching of the mold to release the electrode structures. Deep reactive-ion-etching or photo-assisted anodic etching has been used to form an array of deep holes in the silicon mold. Electroplating or colloidal-processing method has been used to fill the mold with battery-electrode materials. Measurements on electrochemical half-cells indicated that the 3-D electrode arrays, which are composed of vanadium oxide nanorolls or carbon, exhibited much greater energy densities (per-footprint area) than that of the traditional 2-D electrode geometries. The use of electroplating enabled us to fabricate 3-D interdigitated arrays of nickel and zinc; and battery operation was demonstrated. [2006-0293]. View full abstract»

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  • Low-Mass PECVD Oxynitride Gas Chromatographic Columns

    Publication Year: 2007 , Page(s): 853 - 860
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (740 KB) |  | HTML iconHTML  

    This paper describes the realization of low-power micro gas chromatography columns for portable gas analysis systems. The columns are fabricated using complimentary metal-oxide-semiconductor-compatible buried-channel plasma- enhanced chemical vapor deposition oxynitride films that have nearly zero stress at room temperature, high deposition rate (~1 mum/min), high etch rate selectivity (~1:80), low thermal conductivity (< 5 W/mdegC), and low thermal stress (< 140 kPa/degC). The buried channel process utilizes these films to form 25-cm-long 65-mum-ID semicircular columns on a 6-mm-square chip. With more than 5000 theoretical plates, these columns separate multicomponent gas mixtures with performance comparable to that of commercial fused silica capillary columns. The columns are capable of multisecond analyses when integrated with low-dead-volume injectors and dissipate less than 10 mW at 150degC in vacuum. View full abstract»

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  • Nanoscale Calorimetry Using a Suspended Bridge Configuration

    Publication Year: 2007 , Page(s): 861 - 871
    Cited by:  Papers (7)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (908 KB) |  | HTML iconHTML  

    Abstract A new setup for small-scale differential scanning calorimetry (DSC) studies based on a suspended bridge configuration is presented. The new setup has three major advantages over previously reported DSC setups: 1) superior temperature uniformity in the bridge cross section; 2) less heat loss to the surroundings by at least two orders of magnitude; and 3) a faster transient response by three orders of magnitude. This paper includes a thermal analysis to support these improvements. A major contribution of the new thermal analysis over previous reports is the inclusion of the thermal mass of the substrate in calculations, which makes thermal design more detailed, dramatically affecting accuracy and sensitivity in measurements. Furthermore, the new thermal analysis more accurately accounts for heat loss to the substrate and the surroundings in efforts to resolve suspected inconsistencies in previously reported data. Experimental validation of the new setup is presented by measuring the specific heat of thin layers of Si02 and CoFe. The specific heat of Si02 was found to be 2.2 times 106 Jm -3 K-1 which is nearly 10% different from the literature values of bulk specimens. For CoFe, the specific heat value of 3.16 x 106 Jm -3 K-1 is obtained using differential Cu/Si02 and Cu/Si02/CoFe structures compared to the value of 3.5 times 106 Jm -3 K-1 obtained using single CoFe suspended structure. View full abstract»

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  • Integrated Lithographic Molding for Microneedle-Based Devices

    Publication Year: 2007 , Page(s): 872 - 884
    Cited by:  Papers (13)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1192 KB) |  | HTML iconHTML  

    This paper presents a new fabrication method consisting of lithographically defining multiple layers of high aspect-ratio photoresist onto preprocessed silicon substrates and release of the polymer by the lost mold or sacrificial layer technique, coined by us as lithographic molding. The process methodology was demonstrated fabricating out-of-plane polymeric hollow microneedles. First, the fabrication of needle tips was demonstrated for polymeric microneedles with an outer diameter of 250 mum, through-hole capillaries of 75-mum diameter and a needle shaft length of 430 mum by lithographic processing of SU-8 onto simple v-grooves. Second, the technique was extended to gain more freedom in tip shape design, needle shaft length and use of filling materials. A novel combination of silicon dry and wet etching is introduced that allows highly accurate and repetitive lithographic molding of a complex shape. Both techniques consent to the lithographic integration of microfluidic back plates forming a patch-type device. These microneedle-integrated patches offer a feasible solution for medical applications that demand an easy to use point-of-care sample collector, for example, in blood diagnostics for lithium therapy. Although microchip capillary electrophoresis glass devices were addressed earlier, here, we show for the first time the complete diagnostic method based on microneedles made from SU-8. View full abstract»

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  • Contactless Electrochemical Actuator for Microfluidic Dosing

    Publication Year: 2007 , Page(s): 885 - 892
    Cited by:  Papers (3)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (457 KB) |  | HTML iconHTML  

    A contactless microfluidic dosing system based on actuation by an electrochemical reaction has been designed and tested. The device is composed of two chambers separated by a polydimethylsiloxane (PDMS) plate. One chamber is loaded with the liquid sample to be dosed while the electrochemical reaction occurs in the second chamber. Due to the strict separation between the reaction responsible of the actuation and the sample, the latter is preserved from contamination and/or electrochemical modification. Silicon master microstructures were fabricated using clean-room technologies and subsequently replicated into the PDMS. A full microsystem has been fabricated and tested. Microliter sample solutions can be easily and reproducibly dispensed in a time frame of a few tens of seconds. View full abstract»

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  • Influence of Boundary Conditions on the Dynamic Characteristics of Squeeze Films in MEMS Devices

    Publication Year: 2007 , Page(s): 893 - 903
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (850 KB) |  | HTML iconHTML  

    Micromechanical structures that have squeeze-film damping as the dominant energy dissipation mechanism are of interest in this paper. For such structures with narrow air gap, the Reynolds equation is used for calculating squeeze-film damping, which is generally solved with trivial pressure boundary conditions on the side walls. This procedure, however, fails to give satisfactory results for structures under two important conditions: 1) for an air gap thickness comparable to the lateral dimensions of the microstructure and 2) for nontrivial pressure boundary conditions such as fully open boundaries on an extended substrate or partially blocked boundaries that provide side clearance to the fluid flow. Several formulas exist to account for simple boundary conditions. In practice, however, there are many micromechanical structures such as torsional microelectromechanical system (MEMS) structures that have nontrivial boundary conditions arising from partially blocked boundaries. Such boundaries usually have clearance parameters that can vary due to fabrication. These parameters, however, can also be used as design parameters if we understand their role on the dynamics of the structure. We take a MEMS torsion mirror as an example device that has large air gap and partially blocked boundaries due to static frames. We actuate the device and experimentally determine the quality factor Q from the response measurements. Next, we model the same structure in ANSYS and carry out computational fluid dynamics analysis to evaluate the stiffness constant K, the damping constant D, and the quality factor Q due to the squeeze film. We compare the computational results with experimental results and show that without taking care of the partially blocked boundaries properly in the computational model, we get unacceptably large errors. View full abstract»

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  • A Fracture Mechanics Description of Stress-Wave Repair in Stiction-Failed Microcantilevers: Theory and Experiments

    Publication Year: 2007 , Page(s): 904 - 911
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (759 KB) |  | HTML iconHTML  

    Microcantilever beams are frequently utilized as sensor platforms in microelectromechanical system devices. These highly compliant surface-micromachined structures generally fail by adhering to the underlying substrate during processing or subsequent operation. Such failures, which are commonly known as ldquostictionrdquo failures, can be prevented or repaired in a number of ways, including low adhesion coatings, rinsing with low surface energy agents, and active approaches such as laser irradiation. Gupta [ J. Microelectromech. Syst. vol. 13, pp. 696-700, 2004] recently demonstrated that stress waves could be used to repair stiction-failed structures. This paper extends the work of Gupta by developing a fracture mechanics theory of the repair process and compares that theory with corresponding experiments. We show that: 1) incremental crack growth is associated with each laser pulse, the extent of which is directly related to the laser fluence; 2) repeated pulsing fully repairs all of the microcantilevers; and 3) a fracture mechanics model accurately predicts the observed experimental results. [1664]. View full abstract»

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  • Deep Vertical Etching of Silicon Wafers Using a Hydrogenation-Assisted Reactive Ion Etching

    Publication Year: 2007 , Page(s): 912 - 918
    Cited by:  Papers (17)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (784 KB) |  | HTML iconHTML  

    A novel hydrogenation-assisted deep reactive ion etching of silicon is reported. The process uses sequential hydrogen-assisted passivation and plasma etching at low-density plasma powers to stimulate the vertical removal of the exposed Si substrate. The main feature of this technique is the sequential alternation of the electrodes while switching between different gases. Three-dimensional structures with aspect ratios in excess of 40:1 and features as small as 0.7 mum have been realized. The net etch rate is about 0.25 mum/min, although higher rates are expected to be achievable. View full abstract»

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  • Nanoenergetic Materials for MEMS: A Review

    Publication Year: 2007 , Page(s): 919 - 931
    Cited by:  Papers (70)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (973 KB) |  | HTML iconHTML  

    New energetic materials (EMs) are the key to great advances in microscale energy-demanding systems as actuation part, igniter, propulsion unit, and power. Nanoscale EMs (nEMs) particularly offer the promise of much higher energy densities, faster rate of energy release, greater stability, and more security (sensitivity to unwanted initiation). nEMs could therefore give response to microenergetics challenges. This paper provides a comprehensive review of current research activities in nEMs for microenergetics application. While thermodynamic calculations of flame temperature and reaction enthalpies are tools to choose desirable EMs, they are not sufficient for the choice of good material for microscale application where thermal losses are very penalizing. A strategy to select nEM is therefore proposed based on an analysis of the material diffusivity and heat of reaction. Finally, after a description of the different nEMs synthesis approaches, some guidelines for future investigations are provided. View full abstract»

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  • Dynamics of Nanostructured Origami

    Publication Year: 2007 , Page(s): 932 - 949
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1028 KB) |  | HTML iconHTML  

    The nanostructured origami approach to 3-D nano manufacturing is a novel way to gain functionality from the third dimension in nanotechnology applications. After first patterning devices onto a structural membrane using traditional 2-D tools, the segments can be folded along predefined creases in order to realize a final shape in 3-D. In order to manufacture increasingly complex devices, knowledge of the origami's dynamics is imperative. This paper describes a method to model the dynamics of two types of origamis using methods that were originally developed for use in robotic manipulation tasks. The stability of the devices in the folded state is also discussed. View full abstract»

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  • Development of a Dual-Axis Convective Gyroscope With Low Thermal-Induced Stress Sensing Element

    Publication Year: 2007 , Page(s): 950 - 958
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (887 KB) |  | HTML iconHTML  

    This paper describes the design, simulation, and fabrication of a dual-axis gyroscope, whose working principle is based on the thermal convective and thermoresistive effects in lightly doped p-type silicon. The sensor configuration consists of a piezoelectric pump and a microthermal sensing element that is packaged in an aluminum case with a diameter of 14 mm and a length of 25 mm. The novel structure of the sensing element reduces the thermal-induced stress up to 89% as compared with the previous design. The sensor has been fabricated by micro- electromechanical systems technology, and completely packaged and characterized. The measured sensitivities of the gyroscope for the X-axis and Y-axis were 0.082 and 0.078 mV/deg/s, respectively. The cross sensitivities between the two input axes were less than 0.26%, and the nonlinearity was smaller than 0.5% full scale in the range of plusmn200deg/s. The resolution was 0.2deg/s at a measurement frequency of 1 Hz. The noise equivalent rate was 0.18deg/s/radicHz, which is equivalent to an angle random walk of 10.8deg/radich in a 65-Hz bandwidth. The offset drift was 360deg/h in 12-h measurement. View full abstract»

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  • Polyimide Spacers for Flip-Chip Optical MEMS

    Publication Year: 2007 , Page(s): 959 - 968
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (791 KB) |  | HTML iconHTML  

    Multichip integration provides an attractive means to overcome space limitations for large-port-count optical microelectromechanical systems (MEMS) routing systems by allowing actuation and control wiring to be fabricated separately on one chip and then attached beneath a second chip that is populated with a densely packed mirror array. In such systems, vertical as well as horizontal chip alignment is critical when a large but very uniform separation must be maintained across the extent of the array. A technique for creating a structure that simultaneously provides accurate large-gap spacing and acts as a chip-bonding agent is presented here. Specialized processing of an 80- mum thick photoimaged polyimide structure for bonding mirror and electrode chips for a 1296-mirror array is described, along with measurements of height uniformity within 1% and structure characterization demonstrating suitability for production and long-term stability. The process parameters and simplicity of the technique make it suitable for a wide range of applications where MEMS must be integrated with electronic control circuitry. [2006-0042]. View full abstract»

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  • Two-Dimensional MEMS Scanner for Dual-Axes Confocal Microscopy

    Publication Year: 2007 , Page(s): 969 - 976
    Cited by:  Papers (38)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (861 KB) |  | HTML iconHTML  

    In this paper, we present a novel 2-D microelectromechanical systems (MEMS) scanner that enables dual-axes confocal microscopy. Dual-axes confocal microscopy provides high resolution and long working distance, while also being well suited for miniaturization and integration into endoscopes for in vivo imaging. The gimbaled MEMS scanner is fabricated on a double silicon-on-insulator (SOI) wafer (a silicon wafer bonded on a SOI wafer) and is actuated by self-aligned vertical electrostatic combdrives. Maximum optical deflections of plusmn4.8deg and plusmn5.5deg are achieved in static mode for the outer and inner axes, respectively. Torsional resonant frequencies are at 500 Hz and 2.9 kHz for the outer and inner axes, respectively. The imaging capability of the MEMS scanner is successfully demonstrated in a breadboard setup. Reflectance images with a field of view of are achieved at 8 frames/s. The transverse resolutions are 3.94 mum and 6.68 mum for the horizontal and vertical dimensions, respectively. View full abstract»

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  • A Microassembled Low-Profile Three-Dimensional Microelectrode Array for Neural Prosthesis Applications

    Publication Year: 2007 , Page(s): 977 - 988
    Cited by:  Papers (29)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1041 KB) |  | HTML iconHTML  

    This paper describes the design and micro- assembly process of a low-profile 3-D microelectrode array for mapping the functional organization of targeted areas of the central nervous system and for possible application in neural prostheses. The array consists of multiple planar complimentary metal-oxide-semiconductor stimulating probes and 3-D assembly components. Parylene-encapsulated gold beams supported by etch-stopped silicon braces allow the backends of the probes to be folded over to reduce the height of the array above the cortical surface. A process permitting parylene to be used at wafer level with bulk-silicon wet release has been reported. Spacers are used to fix the microassembled probes in position and are equipped with interlocking structures to facilitate the assembly process and increase yield. Four-probe 256-site 3-D arrays operate from plusmn5 V with an average per-channel power dissipation of 97 muW at full range stimulation with pulse widths of 100 mus at 500-Hz frequency. Thirty-two sites can be stimulated simultaneously with maximum currents of plusmn127 muA and a current resolution of plusmn1 muA. The microassembly techniques allow a variety of 3-D microstructures to be created from planar components. View full abstract»

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  • Electromagnetic Two-Dimensional Scanner Using Radial Magnetic Field

    Publication Year: 2007 , Page(s): 989 - 996
    Cited by:  Papers (16)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4419 KB) |  | HTML iconHTML  

    In this paper, we present the design, fabrication, and measurement results of a two-dimensional electromagnetic scanning micromirror actuated by radial magnetic field. The scanner is realized by combining a gimbaled single-crystal-silicon micromirror with a single turn electroplated metal coil, with a concentric permanent magnet assembly composed of two concentric permanent magnets and an iron yoke. The proposed scanner utilizes the radial magnetic field rather than using a lateral magnetic field oriented 45deg to the horizontal and vertical scan axes to achieve a biaxial magnetic actuation. The single turn coil fabricated with electroplated copper achieves a nominal resistance of 1.2 Omega. A two-dimensional scanner with mirror size of 1.5 mm in diameter was fabricated. Maximum optical scan angle of 8.8deg in horizontal direction and 8.3deg in vertical direction were achieved. Forced actuation of the gimbal at 60 Hz and resonant actuation of the micromirror at 19.1-19.7 kHz provide slow vertical scan and fast horizontal scan, respectively. The proposed scanner can be used in raster scanning laser display systems and other scanner applications. View full abstract»

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Aims & Scope

The topics of interest include, but are not limited to: devices ranging in size from microns to millimeters, IC-compatible fabrication techniques, other fabrication techniques, measurement of micro phenomena, theoretical results, new materials and designs, micro actuators, micro robots, micro batteries, bearings, wear, reliability, electrical interconnections, micro telemanipulation, and standards appropriate to MEMS. Application examples and application oriented devices in fluidics, optics, bio-medical engineering, etc., are also of central interest.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Christofer Hierold
ETH Zürich, Micro and Nanosystems