By Topic

Microelectromechanical Systems, Journal of

Issue 5 • Date Oct. 2010

Filter Results

Displaying Results 1 - 25 of 33
  • Table of contents

    Publication Year: 2010 , Page(s): C1 - C4
    Save to Project icon | Request Permissions | PDF file iconPDF (43 KB)  
    Freely Available from IEEE
  • Journal of Microelectromechanical Systems publication information

    Publication Year: 2010 , Page(s): C2
    Save to Project icon | Request Permissions | PDF file iconPDF (57 KB)  
    Freely Available from IEEE
  • Fabrication and Characterization of Micromachined Active Probes With Polymer Membranes for Biomolecular Force Spectroscopy

    Publication Year: 2010 , Page(s): 1021 - 1028
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (698 KB) |  | HTML iconHTML  

    A micromachined polymer membrane-based active probe has been developed for biomolecular force spectroscopy. The probe has integrated but significantly decoupled electrostatic actuation and optical interferometric force sensing capabilities. Devices have been fabricated on silicon substrates using Parylene as the membrane material. The electrostatic actuator integrated into the probe could provide > 1-μm displacement with a flat response of up to 30 kHz in fluid, a feature particularly useful in fast-pulling force spectroscopy experiments involving biomolecules. The probes were successfully employed to measure the unbinding forces between biotin and streptavidin, wherein the force noise level was <;10 pN with a 1-kHz bandwidth for an 8-N/m membrane with a 25-kHz resonance frequency in fluid. This is in agreement with the thermal noise data generated by a finite-element model that predicts further improvements with simple design changes. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • EIT-Inspired Microfluidic Cytometer for Single-Cell Dielectric Spectroscopy

    Publication Year: 2010 , Page(s): 1029 - 1040
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1977 KB) |  | HTML iconHTML  

    A new microfluidic cytometer for single-cell dielectric spectroscopy is proposed in this paper and analyzed in silico by means of a finite-element model. The device, inspired by electrical impedance tomography, includes two circumferential arrays of electrodes instead of just two pairs of coplanar or parallel-facing electrodes, thus allowing a great versatility in stimulation and measurement patterns. In particular, using stimulation patterns with different spatial orientation provides information on cell morphology, besides quantitative cell-volume estimation. Moreover, the performance limitation at low frequency due to electrode polarization is overcome, owing to a peculiar recording scheme: Current is injected between an electrode pair, and the resulting voltages are measured at remaining electrodes using high-input impedance differential amplifiers. These features significantly enhance the cytometer discrimination capabilities. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dual-Column Miniseparator to Separate Alpha-Fetoprotein From Fibrinogen and Immunoglobulin

    Publication Year: 2010 , Page(s): 1041 - 1049
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (921 KB) |  | HTML iconHTML  

    This paper reports a dual-column miniseparator that depletes and separates target analytes from a mixed sample. The prototype was designed to address the need for a sample preparation stage in portable point-of-care testing devices, and its efficacy was tested with Immunoglobulin G (IgG), α-fetoProtein (AFP), and fibrinogen. The miniseparator connects two minicolumns in series: The first column is an affinity minicolumn containing Protein A/G agarose beads, and the second column is a size exclusion chromatography (SEC) minicolumn that separates mixed analytes by size. When a mixture of IgG, fibrinogen, and AFP flows through the dual-column miniseparator, IgG is depleted in the first column, and AFP is separated from fibrinogen in the second column. Each protein was conjugated with fluorescent dyes, and IgG depletion and SEC separation results were confirmed by evaluating the eluents' fluorescent intensity. Red (IgG), green (AFP), and blue (fibrinogen) intensities showed that, in 10 min, the first column (affinity minicolumn) depleted over 99.5% of IgG, and the second column (SEC minicolumn) separated AFP (1 μg/mL ) from a fibrinogen-rich solution (10 μg/mL) with 1.76 resolution and 0.093-mm plate height. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A High-Yield Process for 3-D Large-Scale Integrated Microfluidic Networks in PDMS

    Publication Year: 2010 , Page(s): 1050 - 1057
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1127 KB) |  | HTML iconHTML  

    This paper presents an uncomplicated high-yield fabrication process for creating large-scale integrated (LSI) 3-D microfluidic networks in poly(dimethylsiloxane) (PDMS). The key innovation lays in the robust definition of miniaturized out-of-plane fluidic interconnecting channels (=vias) between stacked layers of microfluidic channels in standard PDMS. Unblocked vias are essential for creating 3-D microfluidic networks. Previous methods either suffered from limited yield in achieving unblocked vias due to residual membranes obstructing the vias after polymerization, or required complicated and/or manual procedures to remove the blocking membranes. In contrast, our method prevents the formation of residual membranes by inhibiting the PDMS polymerization on top of the mold features that define the vias. In addition to providing unblocked vias, the inhibition process also leaves a partially cured, sticky flat-top surface that adheres well to other surfaces and that allows self-sealing stacking of several PDMS layers. We demonstrate the new method by manufacturing a densely perforated PDMS membrane and an LSI 3-D PDMS microfluidic channel network. We also characterize the inhibition mechanism and study the critical process parameters. We demonstrate that the method is suitable for structuring PDMS layers with a thickness down to 10 m. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Embedded Microstructure Fabrication Using Developer-Permeability of Semi-Cross-Linked Negative Resist

    Publication Year: 2010 , Page(s): 1058 - 1069
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1251 KB) |  | HTML iconHTML  

    This paper reports on a novel and simple 3-D fabrication technique of microstructures embedded in a single-layer negative resist. The proposed technique allows one the fabrication of an embedded microstructure with a single exposure and the subsequent development process. The unique feature of the proposed fabrication technique is the development method which enables the rapid fabrication of polymer-based microfluidic systems with relatively large areas but with micrometer-sized features. For example, features of microchannels, on the order of 100 m in width and 50 mm in length, sufficient for microfluidic systems, were successfully fabricated with a relatively short (<; 20 min) development time. These features are realized by the interesting physical response of the top-membrane to the developer; the developer permeates through the top-membrane region made of semi-cross-linked photoresist, and the permeated developer dissolves the uncross-linked photoresist at the same time. As a step toward the practical use of the proposed development method, process parameter sets (exposure dose, postexposure bake (PEB) time, and temperature) related to the cross-linking reaction of the top-membrane region were investigated by employing the cross-linking reaction model describing the chemical reaction during the UV exposure and the PEB. Through a series of experiments, 1) a criterion of process parameter sets for the fabrication of centimeter-long embedded microchannels was obtained, and 2) the applicability to polymer-based microfluidic systems was successfully demonstrated. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Novel Structure for a Pneumatically Controlled Flow Regulator With Positive Gain

    Publication Year: 2010 , Page(s): 1070 - 1078
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (824 KB) |  | HTML iconHTML  

    In this paper, a novel structure for a continuous flow regulator using pneumatic actuation is designed and integrated “in-channel.” Unlike other pneumatically actuated devices, the present one provides a positive gain, so that when the control pressure is increased, the working flow rate is also increased, owing to the decrease in resistance to flow in the working channel. This novel structure allows normally closed flow regulators to be opened using only a positive pressure source and makes it possible to control all pneumatic devices in a chip without having to employ vacuum sources. The flow regulator has been fabricated using SU-8, and its behavior is studied using the theory of thin plates and by numerical simulation. The behavior is also experimentally characterized, and its characteristic curves are provided, validating the proposed structure. The device fabricated using this structure has a maximum positive gain of 6.8 mL/(min bar) for a control pressure of gas up to 1600 mbar and a working pressure of liquid up to 300 mbar in order to control flow rates in the range of milliliters per minute. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Flow Control Using a Thermally Actuated Microfluidic Relay Valve

    Publication Year: 2010 , Page(s): 1079 - 1087
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (866 KB) |  | HTML iconHTML  

    This paper demonstrates a new two-stage valving concept for microfluidic systems that uses the reversible gelation of a thermally responsive polymer solution in a control channel to deflect a membrane into the main flow channel for flow control. This method can control flow through a system of microchannels using integrated electric heating elements and only one control pressure source, compared to the off-chip pressure manifold needed in existing systems. This valve technology therefore enables portable microfluidics-based diagnostic tools for biomedical applications and environmental monitoring allowing on-site analysis. Valves with zero leakage rates and a response time of about 3 s have been achieved. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Integration of a Fabrication Process for an Aluminum Single-Electron Transistor and a Scanning Force Probe for Tuning-Fork-Based Probe Microscopy

    Publication Year: 2010 , Page(s): 1088 - 1097
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (927 KB) |  | HTML iconHTML  

    In this paper, we report on the integration technique and fabrication of a scanning probe interrogating the location of charges and their tracks inside quantum devices. Our unique approach is to pattern the charged sensor into a high topography micromechanical structure. A single-electron transistor (SET) is directly integrated onto the microfabricated cantilever that extends out from the body of a scanning force microscope (SFM) probe of standard dimensions. In a novel tactic and by reversing their traditional roles, a tuning fork (TF) completes the probe to provide the self-actuating and self-sensing qualities necessary for an oscillatory force sensor. We show sharp edges on the Coulomb diamonds, indication that the SET fabrication step yields devices of high quality. We demonstrate topographical scans with this probe. All stages of the fabrication process are executed on batches of probes which is an essential step away from the time-consuming and individual preparation of other implementations. It opens the door to a more reproducible and large volume production. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Numerical Modeling of a Circularly Interdigitated Piezoelectric Microactuator

    Publication Year: 2010 , Page(s): 1098 - 1104
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1233 KB) |  | HTML iconHTML  

    Accurate modeling and simulation techniques are vital for actuated membranes. Using multiphysical modeling techniques, coupled with variation in design parameters, accurate performance predictions can be realized. A 2-D axis-symmetric model of a circularly interdigitated piezoelectrically membrane is presented. The model includes the piezoelectric material and properties, as well as the membrane materials and properties, and incorporates various design considerations. This model also includes the electromechanical coupling for piezoelectric actuation and highlights a novel approach to take advantage of the higher d33 piezoelectric coupling coefficient. Changes in parameters, including electrode pitch, electrode width, and piezoelectric material thickness, are evaluated. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • CMOS-MEMS Variable Capacitors Using Electrothermal Actuation

    Publication Year: 2010 , Page(s): 1105 - 1115
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (833 KB) |  | HTML iconHTML  

    Microelectromechanical-systems variable capacitors which are monolithically integrated with CMOS using a post-CMOS fabrication process are presented. The variable capacitors use electrothermal actuation for lateral gap tuning. A mechanical latch is included to maintain the capacitance at different values without expending power. Measured tuning ratios up to 6.9 : 1 are reported with a Q of 95 at 1 GHz corresponding to the maximum capacitance and an electrical self-resonant frequency of 11 GHz. The capacitors can be reconfigured in 30 ms using no more than 3 V and 15 mW for actuation. The latched capacitance values are repeatable to within 1% of their nominal value and remain stable for ambient temperatures up to 65 ^C. Reliability testing shows that the capacitor is capable of millions of cycles and that the latched capacitance values remain stable after applying accelerations up to 40 g. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design and Fabrication of a Planar Three-DOFs MEMS-Based Manipulator

    Publication Year: 2010 , Page(s): 1116 - 1130
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1401 KB) |  | HTML iconHTML  

    Abstract-This paper presents the design, modeling, and fabrication of a planar three-degrees-of-freedom parallel kinematic manipulator, fabricated with a simple two-mask process in conventional highly doped single-crystalline silicon (SCS) wafers (100). The manipulator's purpose is to provide accurate and stable positioning of a small sample (10 × 20 × 0.2 μm3), e.g., within a transmission electron microscope. The manipulator design is based on the principles of exact constraint design, resulting in a high actuation-compliance combined with a relatively high suspension stiffness. A modal analysis shows that the fourth vibration mode frequency is at least a factor 11 higher than the first three actuation-related mode frequencies. The comb-drive actuators are modeled in combination with the shuttle suspensions gaining insight into the side and rotational pull-in stability conditions. The two-mask fabrication process enables high-aspect-ratio structures, combined with electrical trench insulation. Trench insulation allows structures in conventional wafers to be mechanically connected while being electrically insulated from each other. Device characterization shows high linearity of displacement wrt voltage squared over ±10 μm stroke in the xand y-directions and ±2° rotation at a maximum of 50 V driving voltage. Out-of-plane displacement crosstalk due to in-plane actuation in resonance is measured to be less than 20 pm. The hysteresis in SCS, measured using white light interferometry, is shown to be extremely small. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Magnetostatic MEMS Switch Designed for Portable Applications

    Publication Year: 2010 , Page(s): 1131 - 1139
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1142 KB) |  | HTML iconHTML  

    A passive magnetostatic microelectromechanical systems (MEMS) switch using only one electroplated soft magnetic layer of nickel-iron (Ni80Fe20) alloy was designed, fabricated, and characterized. The switch is composed of an electroplated Ni80Fe20 plate supported by a pair of torsion bars from two sides. The Ni80Fe20 plate is patterned into long and narrow strips to improve the sensitivity. The switch is actuated by bringing an external magnet closer to the switch. Therefore, no internal electrical power is consumed by the device for actuation. The magnetic field required to turn on the switch is 4.8 mT, and the initial contact resistance is 0.5 Ω with gold contacts. The switch has been tested to pass more than 34 million hot-switching cycles at 2-mA current at room temperature when packaged at the wafer level with SU-8 sealing. The die size is 2.1 × 1.94 × 1.1 mm3. The magnetic switch of this paper has the potential to replace the conventional reed switch in portable electronics such as laptops, cellular phones, personal data assistants, pacemakers, and hearing aids. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Resonant Microaccelerometer With High Sensitivity Operating in an Oscillating Circuit

    Publication Year: 2010 , Page(s): 1140 - 1152
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1853 KB) |  | HTML iconHTML  

    A new micromachined uniaxial silicon resonant accelerometer characterized by a high sensitivity and very small dimensions is presented. The device's working principle is based on the frequency variations of two resonating beams coupled to a proof mass. Under an external acceleration, the movement of the proof mass causes an axial load on the beams, generating opposite stiffness variations, which, in turn, result in a differential separation of their resonance frequencies. A high level of sensitivity is obtained, owing to an innovative and optimized geometrical design of the device that guarantees a great amplification of the axial loads. The acceleration measure is obtained, owing to a properly designed oscillating circuit. In agreement with the theoretical prediction, the experimental results show a sensitivity of 455 Hz/ ( g being the gravity acceleration) with a resonant frequency of about 58 kHz and a good linearity in the range of interest. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Accurate Separation Estimation Algorithm for the Casimir Oscillator

    Publication Year: 2010 , Page(s): 1153 - 1161
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (729 KB) |  | HTML iconHTML  

    A novel algorithm is proposed for estimating the separation gap in the Casimir oscillator. The Casimir oscillator is a nanoelectromechanical system actuated by the Casimir force that exists between two conductive metals. The Casimir oscillator has a great potential for use as a separation sensor at the nanometer scale. However, the complex nonlinear behavior of the Casimir oscillator makes it difficult to achieve an accurate separation estimation. The novel estimation algorithm proposed here is able to give an accurate separation estimate even when the nonlinearity is severe. Theoretical analysis and extensive simulations have been conducted to prove its effectiveness and robustness. In addition, this algorithm is also applicable to other estimation problems like the gap separation estimation in electrostatically actuated microelectromechanical systems (MEMS). View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Hybrid RF-MEMS Switches Realized in SOI Wafers by Bulk Micromachining

    Publication Year: 2010 , Page(s): 1162 - 1174
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1402 KB) |  | HTML iconHTML  

    This paper presents an RF microelectromechanical systems (MEMS) switch based on hybrid technology. Electromechanical, microwave, and fabrication design considerations are presented. The methodology is illustrated using shunt contact MEMS switches. The fabrication of the MEMS devices was performed using bulk micromachining processing of a silicon-on-insulator wafer, followed by vertical (3-D) integration with a microwave coplanar transmission line on a GaAs and silicon substrates. The electromechanical and RF performance of the switch were characterized. An isolation of 34 dB at 35 GHz and an insertion loss of 0.1 dB at 35 GHz for a shunt switch were achieved. The concept of a packaged RF switch described in this paper enables a modular implementation of a flexible switch design, independent of the RF circuit substrate material or technology being used. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Integrity of Micro-Hotplates During High-Temperature Operation Monitored by Digital Holographic Microscopy

    Publication Year: 2010 , Page(s): 1175 - 1179
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (605 KB) |  | HTML iconHTML  

    An investigation on the integrity of micro-hotplates using in situ digital holographic microscopy is reported. The surface topography and surface evolution of the devices during high-temperature operation (heating/cooling cycles) is measured with nanometer-scale resolution. A localized permanent out-of-plane surface deformation of 40% of the membrane thickness caused by the top measurement electrodes occurring after the first cycle is observed. The integrity-related issues caused by such a permanent deformation are discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Strategy to Efficiently Extend the Change Rate of Period for Comb-Drive Micromechanical Pitch-Tunable Gratings

    Publication Year: 2010 , Page(s): 1180 - 1185
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (633 KB) |  | HTML iconHTML  

    In this paper, we present a new design strategy with two major considerations to efficiently extend the change rate of period for comb-drive micromechanical pitch-tunable gratings. The proposed strategy is mainly based on the critical state when “side instability” happens. All the ideas were originated from our previous study to develop a silicon-on-glass (SOG)-based pitch-tunable grating with a large change rate of period, from which we found that once the comb structure was connected with the grating beams, the maximum displacement of movable fingers would be sharply decreased according to the experiments. Detailed discussions and analysis are thus performed to explain the finding. Finally, another grating sample based on the silicon-on-insulator (SOI) technology is developed to prove the new design strategy, and a change rate of period of 10.34% is ultimately achieved. The so-developed pitch-tunable grating will greatly expand the device's application domains. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Double-Layered Vibratory Grating Scanners for High-Speed High-Resolution Laser Scanning

    Publication Year: 2010 , Page(s): 1186 - 1196
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2358 KB) |  | HTML iconHTML  

    A novel micromachined electrostatic double-layered vibratory grating scanner has been successfully developed for high-speed high-resolution laser scanning applications. This paper presents its design, modeling, fabrication, and measurement results. A comprehensive dynamic model considering the geometric nonlinearity of the platform suspension flexures is also proposed to predict the dynamic performance of the device at large scanning amplitudes. Compared with previously reported single-layered vibratory grating scanners, double-layered scanners - in which the diffraction grating and its driving actuator are located in different layers - have the potential to scan at large amplitudes and at high scanning speeds with large aperture sizes. We have demonstrated a prototype with a 2-mm-diameter diffraction grating which is capable of scanning at 23.391 kHz with an optical scan angle of around 33° and a resulting θopticalD product (product of the optical scan angle and diameter of the diffraction grating) of 66 deg mm. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Mechanical Reliability of a Digital Micromirror With Interdigitated Cantilevers

    Publication Year: 2010 , Page(s): 1197 - 1206
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1110 KB) |  | HTML iconHTML  

    This paper is the first to report on analytical studies and experimental results pertaining to the mechanical reliability of a micromirror with a new spring structure called as interdigitated cantilevers. The bending actuation of the interdigitated cantilevers means that it is capable of a symmetrical bidirectional rotation. Through analytical calculations, finite element method (FEM) simulations, and experiments, we show that the mechanical reliability of the micromirror can simply be improved by changing the spring structure from a conventional twisting hinge type to the new bending interdigitated cantilever type. To quantitatively demonstrate the improvement, we compare the maximum Von Mises stress exerted in two types of micromirrors. The analytical calculations and FEM simulations confirm that the maximum Von Mises stress for cyclic rotations with regard to the micromirror with interdigitated cantilevers is only half that of a conventional micromirror with a hinge when the two micromirrors have the same performance and the same rotation angle. Also, we experimentally evaluate the mechanical reliability of the micromirror with interdigitated cantilevers. The micromirror that is made of pure aluminum was successfully operated without any failures after more than 500 h of operation and 2 × 1010 cycles under a laboratory air condition (23°C and 50 %). View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Multichannel Nanoparticle Scintillation Microdevice With Integrated Waveguides for Alpha, Beta, Gamma, X-Ray, and Neutron Detection

    Publication Year: 2010 , Page(s): 1207 - 1214
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (738 KB) |  | HTML iconHTML  

    This paper reports on a glass microdevice with a new patterned nanoparticle composite resin that detects and discriminates all species of radiation emitted from fissionable bombmaking materials. Tailored charge conversion nanoparticles doped into a fast-electron scintillating resin produce different optical pulses specific to the radiation species. These pulses exit since the nanoparticles are appreciably smaller than the wavelength of light. The resins are integrated into a glass substrate where deep cavities are made using microsandblasting, forming independent optical paths leading to fiber-optic attachments. Separate off-the-shelf photomultiplier tubes measure the light pulses. The beta detector was tested with a 90Sr source which produced 1470 cpm with the doped scintillator, while the same source produced 1500 cpm with an off-the-shelf Geiger counter. An Am/Be neutron source was used to test Gd-loaded detectors which exhibited an increase in count rates with an increase in Gd loading. The different nanoparticles used convert differing radiation species into electrons through independent physical mechanisms, including charge conversion (alpha), secondary electron (beta), photoelectron (gamma/X-rays), and an on-chip thermonuclear fusion reaction (neutron) to evaluate the specific isotope radiation signature. The four different detectors use four different methods to convert four different types of radiation into electrons; as a consequence, the measured pulses are characteristic to the radiation, allowing pulse height spectroscopy to be used. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modeling and Characterization of Piezoelectric d_{33} -Mode MEMS Energy Harvester

    Publication Year: 2010 , Page(s): 1215 - 1222
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1245 KB) |  | HTML iconHTML  

    This paper presents the modeling, fabrication, and characterization of a piezoelectric microelectromechanical systems (MEMS) energy harvester using a d33 piezoelectric mode. A theoretical analysis and an analytical modeling for the d33-mode device were first performed to estimate the output power as a function of the material parameters and device geometry. A PbTiO3 seed layer was newly applied as an interlayer between the ZrO2 and Pb(Zr0.52Ti0.48)O3 (PZT) thin films to improve the piezoelectric property of the sol-gel spin-coated PZT thin film. The fabricated cantilever PZT film with an interdigital shaped electrode exhibited a remnant polarization of 18.5 C/cm2, a coercive field of less than 60 kV/cm, a relative dielectric constant of 1125.1, and a d33 piezoelectric constant of 50 pC/N. The fabricated energy-harvesting device generated an electrical power of 1.1 W for a load of 2.2 M with 4.4 Vpeak-to-peak from a vibration with an acceleration of 0.39 g at its resonant frequency of 528 Hz. The corresponding power density was 7.3 mW cm-3 · g-2. The experimental results were compared with those numerically calculated using the equations derived from the dynamic and analytical modeling. The fabricated device was also compared with other piezoelectric MEMS energy-harvesting devices. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Monolithically Integrated Two-Axis Microtensile Tester for the Mechanical Characterization of Microscopic Samples

    Publication Year: 2010 , Page(s): 1223 - 1233
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1288 KB) |  | HTML iconHTML  

    This paper describes the first monolithically integrated two-axis microtensile tester and its application to the automated stiffness measurement of single epidermal plant cells. The tensile tester consists of a two-axis electrostatic actuator with integrated capacitive position sensors and a two-axis capacitive microforce sensor. It is fabricated using a bulk silicon microfabrication process. The actuation range is +/-16 m along both axes with a position resolution of 20 nm. The force sensor is capable of measuring forces up to +/-60 N with a resolution down to 60 nN. The position-feedback sensors as well as the force sensor are calibrated by direct comparison with reference standards. A complete uncertainty analysis through the entire calibration chain based on the Monte Carlo method is presented. The functionality of the tensile tester is demonstrated by the automated stiffness measurement of the elongated cells in plant hairs (trichomes) as a function of their size. This enables a quantitative understanding and a model-based simulation of plant growth based on actual measurement data. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Piezoresistive Microcantilevers From Ultrananocrystalline Diamond

    Publication Year: 2010 , Page(s): 1234 - 1242
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (907 KB) |  | HTML iconHTML  

    This paper reports on the temperature-dependent electrical resistivity and piezoresistive characteristics of boron-doped ultrananocyrstalline diamond (UNCD) and the fabrication of piezoresistive microcantilevers using boron-doped and undoped UNCD. The devices consist of 1-μm-thick doped UNCD on either 1- or 2-μm-thick undoped UNCD. The electrical resistivity of doped UNCD is 0.1 Ω · cm at room temperature, which is five orders of magnitude smaller than the electrical resistivity of undoped UNCD. Over the temperature range of 25°C-200vC, the doped UNCD has a temperature coefficient of electrical resistance of (-1.4 × 10-3) per °C. The doped UNCD exhibits a significant piezoresistive effect with a gauge factor of 7.53 ± 0.32 and a piezoresistive coefficient of 8.12 × 10-12 Pa-1 at room temperature. The piezoresistive properties of UNCD are constant over the temperature range of 25°C-200°C. Microcantilevers having a length of 300 μm have a deflection sensitivity of 0.186 mΩ/Ω per micrometer of cantilever end deflection. These measurements of electrical and piezoresistive properties of doped UNCD could aid the design of future diamond microsystems. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

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