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Microelectromechanical Systems, Journal of

Issue 1 • Date Feb. 2003

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Displaying Results 1 - 14 of 14
  • 2002 Reviewers List

    Publication Year: 2003 , Page(s): 1 - 2
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    Freely Available from IEEE
  • Die-level characterization of silicon-nitride membrane/silicon structures using resonant ultrasonic spectroscopy

    Publication Year: 2003 , Page(s): 53 - 63
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1760 KB) |  | HTML iconHTML  

    Theory and experimental confirmation of a new die-level testing methodology is presented to measure physical parameters of the ubiquitous anisotropically etched silicon-nitride membrane on a silicon substrate. We have used this technique to determine the dimensions and material properties of the silicon-nitride-membrane/silicon-substrate structure (SixNy/Si die) from the measured ultrasonic resonance spectra, which is obtained within seconds by the use of resonant ultrasound spectroscopy. A linear model of the changes in resonance frequencies of the structural modes to the structural dimensions and material properties is extracted using finite element analysis. Knowing this linear relationship allows one to solve the inverse problem of finding the material's characteristics and dimensions of the structure by measuring the resonance frequencies of the structure. The success in being able to measure many variables in one measurement illustrates that the method presented in this paper is viable for a fast industrial diagnosis for presorting of viable dies, or measurement for the controlled mechanical design of silicon nitride membrane structures. View full abstract»

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  • Materials selection in micromechanical design: an application of the Ashby approach

    Publication Year: 2003 , Page(s): 3 - 10
    Cited by:  Papers (32)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (794 KB) |  | HTML iconHTML  

    The set of materials available to microsystems designers is rapidly expanding. Techniques now exist to introduce and integrate a large number of metals, alloys, ceramics, glasses, polymers, and elastomers into microsystems, motivating the need for a rational approach for materials selection in microsystems design. As a step toward such an approach, we focus on the initial stages of materials selection for micromechanical structures with minimum feature sizes greater than 1 μm. The variation of mechanical properties with length scale and processing parameters is discussed. Bounds for initial design values of several properties are suggested and the necessity for the measurement of other properties (especially residual stresses and intrinsic loss coefficients) is discussed. Adapting the methods pioneered by Ashby et al., materials indices are formulated for a number of properties and materials selection charts are presented. These concepts are applied to illustrate initial materials selection for shock-resistant microbeams, force sensors, micromechanical filters, and micromachined flexures. Issues associated with the integration of materials into microsystems are briefly discussed. View full abstract»

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  • Creating, transporting, cutting, and merging liquid droplets by electrowetting-based actuation for digital microfluidic circuits

    Publication Year: 2003 , Page(s): 70 - 80
    Cited by:  Papers (411)  |  Patents (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1323 KB) |  | HTML iconHTML  

    Reports the completion of four fundamental fluidic operations considered essential to build digital microfluidic circuits, which can be used for lab-on-a-chip or micro total analysis system (μTAS): 1) creating, 2) transporting, 3) cutting, and 4) merging liquid droplets, all by electrowetting, i.e., controlling the wetting property of the surface through electric potential. The surface used in this report is, more specifically, an electrode covered with dielectrics, hence, called electrowetting-on-dielectric (EWOD). All the fluidic movement is confined between two plates, which we call parallel-plate channel, rather than through closed channels or on open surfaces. While transporting and merging droplets are easily verified, we discover that there exists a design criterion for a given set of materials beyond which the droplet simply cannot be cut by EWOD mechanism. The condition for successful cutting is theoretically analyzed by examining the channel gap, the droplet size and the degree of contact angle change by electrowetting on dielectric (EWOD). A series of experiments is run and verifies the criterion. View full abstract»

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  • Development of an end-point detector for parylene deposition process

    Publication Year: 2003 , Page(s): 64 - 69
    Cited by:  Papers (3)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1205 KB) |  | HTML iconHTML  

    Parylene is an emerging material for MEMS. It is an organic material that is grown by using the chemical vapor deposition method at room temperature. The deposition thickness is commonly controlled by the amount of solid-phase dimer loaded in a sublimation chamber. In a conventional deposition machine, the end point of the process is designated by the moment the dimer is exhausted. However, this end-of-process criterion does not offer precise, repeatable control of film thickness. We present the results of the development of an in situ end-point detector for a Parylene chemical vapor deposition process. The detector is based on the thermal transfer principle and can be implemented on commercial parylene deposition systems with minimal system modification. Such a sensor enables a user to stop the deposition when a targeted thickness is reached. The end point detector is very simple to implement on existing parylene deposition systems. A series of such sensors with different target deposition thickness would allow extraction of the actual deposition rate within a deposition run. View full abstract»

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  • Self-balanced navigation-grade capacitive microaccelerometers using branched finger electrodes and their performance for varying sense voltage and pressure

    Publication Year: 2003 , Page(s): 11 - 20
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1396 KB) |  | HTML iconHTML  

    Presents a navigation-grade capacitive microaccelerometer, whose low-noise high-resolution detection capability is achieved by a new electrode design based on a high-amplitude anti-phase sense voltage. We reduce the mechanical noise of the microaccelerometer to the level of 5.5 μg/√Hz by increasing the proof-mass based on deep RIE process of an SOI wafer. We reduce the electrical noise as low as 0.6 μg/√Hz by using an anti-phase high-amplitude square-wave sense voltage of 19 V. The nonlinearity problem caused by the high-amplitude sense voltage is solved by a new electrode design of branched finger type. Combined use of the branched finger electrode and high-amplitude sense voltage generates self force-balancing effects, resulting in an 140% increase of the bandwidth from 726Hz to 1734 Hz. For a fixed sense voltage of 10 V, the total noise is measured as 2.6 μg/√Hz at the air pressure of 3.9torr, which is the 51% of the total noise of 5.1 μg/√Hz at the atmospheric pressure. View full abstract»

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  • A piezoelectric microvalve for compact high-frequency, high-differential pressure hydraulic micropumping systems

    Publication Year: 2003 , Page(s): 81 - 92
    Cited by:  Papers (33)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1177 KB) |  | HTML iconHTML  

    A piezoelectrically driven hydraulic amplification microvalve for use in compact high-performance hydraulic pumping systems was designed, fabricated, and experimentally characterized. High-frequency, high-force actuation capabilities were enabled through the incorporation of bulk piezoelectric material elements beneath a micromachined annular tethered-piston structure. Large valve stroke at the microscale was achieved with an hydraulic amplification mechanism that amplified (40×-50×) the limited stroke of the piezoelectric material into a significantly larger motion of a micromachined valve membrane with attached valve cap. These design features enabled the valve to meet simultaneously a set of high frequency (≥1 kHz), high pressure(≥300 kPa), and large stroke (20-30 μm) requirements not previously satisfied by other hydraulic flow regulation microvalves. This paper details the design, modeling, fabrication, assembly, and experimental characterization of this valve device. Fabrication challenges are detailed. View full abstract»

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  • Adaptive control for the conventional mode of operation of MEMS gyroscopes

    Publication Year: 2003 , Page(s): 101 - 108
    Cited by:  Papers (52)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (633 KB) |  | HTML iconHTML  

    This paper presents adaptive add-on control algorithms for the conventional mode of operation of MEMS z-axis gyroscopes. This scheme is realized by adding an outer loop to a conventional force-balancing scheme that includes a parameter estimation algorithm. The parameter adaptation algorithm estimates the angular rate, identifies and compensates the quadrature error, and may permit on-line automatic mode tuning. The convergence and resolution analysis show that the proposed adaptive add-on control scheme prevents the angular rate estimate from being contaminated by the quadrature error, while keeping ideal resolution performance of a conventional force-balancing scheme. View full abstract»

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  • Microforming of three-dimensional microstructures from thin-film metallic glass

    Publication Year: 2003 , Page(s): 42 - 52
    Cited by:  Papers (41)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1543 KB)  

    Thin-film metallic glasses (TFMGs) are characterized by an absence of size effect, high strength and high elastic limit due to their amorphous nature. As such, these materials are considered to be ideal candidates for microelectromechanical systems (MEMS). Furthermore, the TFMGs soften and show viscous flow within a certain temperature range called the supercooled liquid region (SCLR), which allows the TFMGs to be easily formed into three-dimensional (3-D) microstructures. The viscous flow in the SCLR is also useful for annealing and relaxing inner residual stresses of TFMGs. In the present paper, TFMG microcantilevers are fabricated by surface micromachining techniques. In order to heat and form the cantilevers, a local laser heating and microforming system is introduced, and the conditions of laser power and heating time that can not only form the cantilevers but also can maintain the amorphous nature of the TFMG are examined. Finally, based on the results of these investigations, microcantilevers having a 90° bend and a 90° twist, respectively, are successfully fabricated. View full abstract»

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  • Microcavity interferometry for MEMS device characterization

    Publication Year: 2003 , Page(s): 109 - 116
    Cited by:  Papers (6)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (497 KB) |  | HTML iconHTML  

    We have developed a high resolution optical technique to measure the electromechanical properties of MEMS microstructures. The technique is applied to microbridges developed for capacitive switching in coplanar radio frequency (RF) waveguides. The thin metal ground plane on the substrate and the bottom of the bridge together form a microcavity for an optical beam. The wavelength of a cavity mode is a sensitive measure of the bridge position relative to the substrate. The technique is applied to the measurement of resonances and damping times of microbridges of varying lengths. It is also used to measure dc changes in bridge height of tenths of nanometers, driven ac displacements of less than a picometer, and bridge displacement noise of hundreds of femtometers per root Hertz. This extreme sensitivity exceeds previously demonstrated optical characterization methods. View full abstract»

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  • A micromachined impact microactuator driven by electrostatic force

    Publication Year: 2003 , Page(s): 37 - 41
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (620 KB)  

    This paper presents a novel micromachined actuator which is developed to produce precise and unlimited displacement. The actuator is driven by impact force between a silicon micro-mass and a stopper. The suspended silicon micro-mass is encapsulated between two glass plates and driven by electrostatic force. When the mass hits the stopper which is fixed on glass plates, impact force is generated to drive the whole actuator in a nano size step (∼10 nm). The overall dimension of the device is 3 mm ×3 mm. The driving voltage is 100 V and average speed is 2.7 μm/s. The total thickness is 600 μm. View full abstract»

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  • Towards a palladium micro-membrane for the water gas shift reaction: microfabrication approach and hydrogen purification results

    Publication Year: 2003 , Page(s): 93 - 100
    Cited by:  Papers (35)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1089 KB) |  | HTML iconHTML  

    A novel palladium-based micromembrane is reported that can be used for hydrogen gas separation in a miniature fuel processor for micro fuel cells. The micromembrane structure is built in a silicon substrate, using standard MEMS microfabrication processes. Four layers, viz. copper, aluminum, spin-on-glass (SOG) and palladium form the composite membrane. Copper, aluminum and SOG layers provide structural support for the palladium film. Copper can act as catalyst in the water gas shift reaction that converts unwanted carbon monoxide gas into hydrogen. Palladium is used to separate hydrogen from other gases present. The micromembrane selectively separates hydrogen from a 20:80 hydrogen:argon gas mixture by weight even at room temperature. The diffusion of hydrogen through palladium is enhanced at higher temperatures and pressures, closely following the predictions from Sievert's law. Future applications of this micromembrane for simultaneous water gas shift reaction and hydrogen separation are discussed. View full abstract»

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  • A pendulous oscillating gyroscopic accelerometer fabricated using deep-reactive ion etching

    Publication Year: 2003 , Page(s): 21 - 28
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1445 KB) |  | HTML iconHTML  

    A silicon pendulous oscillating gyroscopic accelerometer (POGA) was fabricated using deep-reactive ion etching (DRIE) and silicon wafer bonding technologies. A POGA is the micromachining-compatible analog of the pendulous integrating gyroscopic accelerometer (PIGA), which is the basis of the most sensitive accelerometers demonstrated to date. Gyroscopic accelerometers rely on the principle of rebalancing an acceleration-sensing pendulous mass by means of an induced gyroscopic torque. The accelerometer is composed of three individual layers that are assembled into the final instrument. The top layer uses wafer bonding of an oxidized wafer to a handling wafer to create a silicon-on-oxide wafer pair, in which the oxide layer provides electrical isolation between the mechanical members and the handling layer. The middle layer is a two-gimbal torsionally-supported silicon structure and is in turn supported by an underlying drive/sense layer. The micromachined POGA operated according to gyroscopic accelerometer principles, having better than milligram resolution and dynamic ranges in excess of 1 g (open loop) and approximately 12 mg (closed loop). View full abstract»

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  • Design and microfabrication of a flexible oral electrotactile display

    Publication Year: 2003 , Page(s): 29 - 36
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (783 KB) |  | HTML iconHTML  

    A polyimide-based flexible oral tactile display with an array of 7×7 tactors is designed for presentation of electrotactile patterns onto the roof of the mouth. The device is microfabricated on a rigid substrate using thin-film and electroplating processes and then released by peeling it off from the substrate. Dome-shaped tactors are electroplated through round openings 300 μm in diameter in the flexible polyimide base for more uniform current distribution and better contact with the skin. The overall dimensions of the tactor array are 18.5×18.5 mm2, with a center-to-center spacing of 2.54 mm between adjacent tactors. Each tactor is 200 μm in height and 700 μm in diameter. The device robustness is improved by using a grid-pattern design for the openings to overcome the stress mismatch between the rigid tactors and the flexible base. The flexible oral tactile display has been tested in human subject experiments and found to deliver comfortable electrotactile stimulation with relatively low stimulation intensities. 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