By Topic

Microelectromechanical Systems, Journal of

Early Access Articles

Early Access articles are new content made available in advance of the final electronic or print versions and result from IEEE's Preprint or Rapid Post processes. Preprint articles are peer-reviewed but not fully edited. Rapid Post articles are peer-reviewed and edited but not paginated. Both these types of Early Access articles are fully citable from the moment they appear in IEEE Xplore.

Filter Results

Displaying Results 1 - 25 of 95
  • Parylene-Based Electrochemical-MEMS Force Sensor for Studies of Intracortical Probe Insertion Mechanics

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1925 KB)  

    To investigate the mechanical interactions between the implanted cortical multielectrode probes and brain tissue, a Parylene C-based electrochemical-microelectromechanical systems force sensor array was developed. The array consists of seven linearly distributed sensor units arranged along the length of a flexible Parylene C microchannel. The seven sensor units are formed by eight fluidically coupled and adjacent platinum electrode pairs enclosed within the microchannel. Deformation of the top surface of the mechanically compliant microchannel changes the volumetric conduction path between the pairs of sensing electrodes, and therefore, the measured electrochemical impedance, which is proportional to the magnitude of the contacting force. Each sensor unit demonstrated a linear response from 0 to 60 mN with a sensitivity of 0.13 ± 0.01 percentage change in impedance/μN (%/μN; mean ± SE, n = 6). The sensor arrays were mounted onto a ceramic intracortical probe and inserted into the tissue phantoms to verify in situ functionality and assess interfacial probe mechanics. Probe surface force distribution was measured under various insertion speeds and the results indicated that interfacial forces are distributed nonuniformly along the probe shaft length, concentrating within the first 1 mm of the advancing probe tip. Faster insertion speeds were also found to decrease the magnitude of the interfacial forces, suggesting that the tissue strain during cortical implantation may be minimized through appropriate selection of the insertion speed. [2014-0320] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Development of Silicon Probe With Acute Study on In Vivo Neural Recording and Implantation Behavior Monitored by Integrated Si-Nanowire Strain Sensors

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2798 KB)  

    The silicon probe with highly P-doped Si electrodes was realized on 8-in Silicon on insulator wafer through standard Complementary metal-oxide semiconductor process. By leveraging the same thin Si device layer (~100 nm), the built-in piezoresistive Si-nanowires (SiNWs) configured in full-bridge structure were also equipped along the probe shank for strain sensing. After additional coatings of nanocomposite (Carbon nanotubes + Au nanoparticles) on silicon electrodes, the functionality of neural recording was validated with a low noise level (<20 μV) during in vivo neural recording on rat brain (CA1 region). The additional capability of monitoring probe mechanical behavior was first verified through the probe buckling experiments and further examined with implantations on rat brain (S1 region). Besides the large buckling mechanics, the physiological brain micromotion (e.g., caused by respiration) was successfully picked up by integrated SiNWs strain sensors, which would provide the research platform to practically understand the correlation between the electrical neural signal and the brain micromotion. [2014-0370] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Flexible Capacitive Tactile Sensor Array With Truncated Pyramids as Dielectric Layer for Three-Axis Force Measurement

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3564 KB)  

    This paper presents a flexible capacitive tactile sensor array embedded with a truncated polydimethylsiloxane pyramid array as a dielectric layer. The proposed sensor array has been fabricated with 4 x 4 sensor units. The measurement ranges of forces in the x-axis, y-axis, and z-axis are 0-0.5, 0-0.5, and 0-4 N, respectively. In the range of 0-0.5 N, the sensitivities of the sensor unit are 58.3%/N, 57.4%/N, and 67.2%/N in the x-axis, y-axis, and z-axis, respectively. In the range of 0.5-4 N, the sensitivity in the z-axis is 7.7%/N. Three-axis force measurement has been conducted for all the sensor units. The average errors between the applied and calculated forces are 11.8% ± 6.4%. The sensor array has been mounted on a prosthetic hand. A paper cup and a cube are grasped by the prosthetic hand and the three-axis contact force is measured in real time by the sensor array. Results show that the sensor can capture the three-axis contact force image both in light and tight grasping. The proposed capacitive tactile sensor array can be utilized in robotics and prosthetic hand applications. [2014-0350] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dynamic Modeling of Scratch Drive Actuators

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2968 KB)  

    There has been much research in developing scratch drive actuators (SDAs), but because of their dynamic complexity, these microelectromechanical system-based actuators have not been dynamically analyzed up to now. In this paper, a comprehensive model is presented to describe the dynamic behavior of SDA and its components during stepwise motion. In this model, Hamilton's principle and Newton's method are used to extract dynamic equations of the SDA plate and dynamic equation for the linear motion of SDA. This model presents a good insight into the operating principles of SDA by predicting the variation of different variables, such as bushing angle, contact length, horizontal position, and friction forces, during the application of different voltage profiles. Comparison between the modeling results and the available experimental data shows that this model is very effective in predicting some design objectives, such as step size and output force, for these type of actuators. [2013-0357] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Significance of Adhesion-Reduced Bouncing in Dynamic Contacts of Ohmic RF MEMS Switches

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1700 KB)  

    This paper presents a mathematical Euler-Bernoulli beam-based model that simulates the dynamic behavior of typical cantilever-type radio frequency microelectromechanical systems (RF MEMS) switches, including nonlinearly adhesive contact theory and cycle-dependent bouncing patterns. In particular, the adhesion-induced energy dissipation per cycle is modeled as an effective damping parameter and included in the dynamic model of the device. This new modeling approach eliminates the time-consuming calculation related to the complexity of the tip-drain switch contact. This model also accurately captures previously reported switch bouncing patterns and their time evolution. Comparing the modeling and experimental data enables us to estimate the time-dependent adhesion force throughout the switch lifetime. Furthermore, a nondimensionalized model is presented to analyze the characteristics of a general RF MEMS switch without a priori knowledge of its dimensions. [2014-0266] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Multiarray Micromachined Probe for Turbulence Measurements Assembled of Suspended Hot-Film Sensors

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1235 KB)  

    To meet the need to access experimentally the full tensor of velocity derivatives at smallest scales of turbulent flows, we developed, fabricated, and tested an out-of-plane micromachined hot-film sensor that has a suspended 100-nm thick sensing element. We present a unique multiarray hot-film probe as an assembly of five arrays of four sensors each. Experimental results demonstrate the improved resolution of the sensor compared with a conventional hot-wire and to a nonsuspended version of such a sensor. A simple and clear method for sensor spatial resolution evaluation is also discussed. [2015-0044] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Paper-Based ZnO Nanogenerator Using Contact Electrification and Piezoelectric Effects

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (546 KB)  

    In this letter, we present a ZnO nanogenerator built on a paper substrate producing electricity using both contact electrification and piezoelectric effects. Paper is an environmentally friendly material and can help to improve the performance of the ZnO nanogenerator due to its natural roughness. The nanogenerator produced a maximum peak voltage of 38.4 V and a maximum peak current density of 3.2 μA/cm² from both the inherent piezoelectric property of ZnO and contact electrification between poly(methyl methacrylate) and ZnO nanostructures. [2014-0388] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Highly Reliable Two-Axis MEMS Relay Demonstrating a Novel Contact Refresh Method

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2891 KB)  

    This paper reports on a two-axis actuated microelectromechanical systems (MEMS) relay to realize a unique contact-refresh concept. In comparison with all other conventional MEMS relays utilizing only several designated contact spots during their whole lifetime, the proposed concept can change the real contact spots (asperities) by altering the lateral position of contact asperities, thus providing highly reliable contact endurance. In addition, it can enhance lifetime of the switches that fail by contact resistance increase, and potentially even for switches that fail by contact stiction if the contact position is changed before a critical number of switching cycles is reached; however, the device inevitably has a relatively large device area and additional control circuitry in this stage of development. The fabricated relays showed vertical actuation voltages under 40 V, a switching delay of 190 μs, and a maximum lateral displacement of 10 μm. Owing to the suggested contact-refresh scheme, the total contact endurance in one switching device was dramatically increased, and the sum of dozens of lifetimes measured at the selected lateral positions reached 6 x 10⁰ cycles at 100 mA in hot switching conditions (Au-to-Au contact), which is nearly 50 times higher than the average value of the measured lifetimes in a designated contact spot. [2014-0225] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Scalable Throughput and Stable Scanning Probe Nanolithography Based on Local Anodic Oxidation by Arrayed Wear-Insensitive Sidewall Microprobes

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3502 KB)  

    In this paper, scalable throughput and stable scanning probe nanolithography is demonstrated using arrayed wear-insensitive sidewall probes (WISPs). Tips of the proposed arrayed probes have a uniform cuboid shape. Each probe tip consists of a microscale mechanical contact and two separated nanoscale electrical contacts (sidewall electrodes) formed on the sidewall of the mechanical contact, and an eave formed at the end. The microscale mechanical contacts reduce the tip wear by dispersing the force applied to the tip, and the nanoscale electrical contacts enable the drawing of nanoscale features. The eaves at the end of the cantilevers play an essential role in preventing metal from being deposited on the mechanical contact, which simplifies the fabrication process. Even when the probe is mechanically worn, the width of the sidewall electrodes does not change; this ensures the wear-insensitive performance of the probe over long drawing distance. A microelectromechanical systems technique is used to fabricate the arrayed probes. Eight linearly arrayed WISPs with an 80-μm-wide mechanical contact and two 30-nm-thick electrical contacts are fabricated. Using the fabricated probes, eight sets of patterns with a line width of ~100 nm and a total drawing distance of 1600 μm (200 μm x 8 cycles) are drawn in parallel within the 50 s in contact and vector scan modes. Furthermore, eight sets of multiscale pattern with a line width from 100 nm to several micrometers and a drawing area of 100 μm x 50 μm, corresponding to a total distance of 400 mm (50 mm x 8 cycles), are stably drawn within 30 min in contact- and raster-scan modes. Better resolution is achieved by increasing the scan rate, as well as by reducing the bias voltage and the environmental humidity. Thus, line patterns with a width of ~50 nm are drawn. [2014-0245] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Piezoresistive Readout Mechanically Coupled Lamé Mode SOI Resonator With Q of a Million

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3944 KB)  

    This paper describes the use of the coupling beam in a pair of mechanically coupled Lamé mode resonators to enhance electromechanical transduction by piezoresistive sensing, while at the same time maintaining a high quality factor of a million. This corresponds to an fQ product of 1.3 x 10¹³, which approaches the Akhiezer limit of silicon. With a 15 mA bias current, electrical characterization of the array using the piezoresistive readout via the coupling-beam provides a 25 dB enhancement over a single Lamé mode resonator using capacitive readout. In this paper, we have modeled the piezoresistive electromechanical frequency response function of the device both analytically and by finite elements. The models mutually agree and are experimentally verified by measured results of fabricated resonators. The model indicates that the transduction factor is independent of the lateral dimensions and thickness of the resonator. [2015-0009] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • JMEMS Letters Electrostatic Energy Harvester Using Magnetically Actuated Liquid Dielectric Layers

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (862 KB)  

    We propose a fully liquid-based energy harvester that uses ferrofluid droplets as a movable dielectric material. The proposed device consists of top and bottom plates with conducting electrodes coated with a thin solid dielectric layer, a conducting liquid, and oil-based ferrofluid droplets as movable dielectric layers. The rotational motion of the ferrofluid droplets is actuated by a magnetic field that causes a capacitance variation that is used to generate electric power. An average output power of 19.3 μW is generated when eight ferrofluid droplets are used at a rotational speed of 180 r/min. [2014-0387] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Laser Micromachining and Characterization of Metal-on-Glass High Density Pitch Adapters

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3073 KB)  

    Pitch adapters (PAs) are passive electronic components widely used to adapt different pitches between silicon strip detectors and readout electronics. This paper presents an optimized process to fabricate high-density PAs using laser ablation of metal-on-glass layers. Minimum pitch sizes of 40 μm for the pads and 25 μm for the conductive traces were achieved. The resolution of the method allowed the cutting of traces as narrow as 15 μm. Different prototypes and small production series have been successfully manufactured and tested for electrical parameters, bondability, and metrology. Ageing tests were also performed to ensure long-term reliability. The production yield reached 80%. Fully functional particle detectors for high-energy physics have been assembled using these PAs, characterized and tested with lasers and radioactive sources. [2014-0371] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Role of Microstructure and Doping on the Mechanical Strength and Toughness of Polysilicon Thin Films

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4089 KB)  

    The role of microstructure and doping on the mechanical strength of microscale tension specimens of columnar grain and laminated polysilicon doped with different concentrations of phosphorus was investigated. The average tensile strengths of undoped columnar and laminated polysilicon specimens were 1.3 ± 0.1 and 2.45 ± 0.3 GPa, respectively. Heavy doping reduced the strength of columnar polysilicon specimens to 0.9 ± 0.1 GPa. On grounds of Weibull statistics, the experimental results from specimens with gauge sections of 1000 μm x 100 μm x 1 μm predicted quite well the tensile strength of specimens with gauge sections of 150 μm x 3.75 μm x 1 μm, and vice versa. The large difference in the mechanical strength between columnar and laminated polysilicon specimens was due to sidewall flaws in columnar polysilicon, which were introduced during reactive ion etching (RIE) and were further exacerbated by phosphorus doping. Removal of the large defect regions at the sidewalls of columnar polysilicon specimens via ion milling increased their tensile strength by 70%-100%, approaching the strength of laminated polysilicon, which implies that the two types of polysilicon films have comparable tensile strength. Measurements of the effective mode I critical stress intensity factor, KIC,eff, also showed that all types of polysilicon films had comparable resistance to fracture. Therefore, additional processing steps to eliminate the edge flaws in RIE patterned devices could result in significantly stronger microelectromechanical system components fabricated by conventional columnar polysilicon films. [2014-0269] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Methods for Atomistic Simulations of Linear and Nonlinear Damping in Nanomechanical Resonators

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1677 KB)  

    Atomistic simulations can be used to compute damping from first principles and gain unprecedented insights into the mechanisms of dissipation. However, the technique is still in its infancy and many foundational aspects remain unexplored. As a step toward addressing these issues, we present here a comparative study of five different methods for estimating damping under isothermal conditions. Classical molecular dynamics was used to simulate the fundamental longitudinal-mode oscillations of nanowires and nanofilms of silicon and nickel at room temperature (300 K) in the canonical ensemble using the Nosé-Hoover thermostat. In the subresonant regime, damping was quantified using the loss tangent and loss factor during steady-state harmonic vibration. The quality factor was obtained by analyzing the spectrum of thermomechanical noise and also from the Duffing-like nonlinearity in the frequency response under harmonic excitation. In addition, the nonlinear logarithmic decrement was obtained from the Hilbert transform of freely decaying oscillations. We discuss the factors that must be considered while selecting simulation parameters, establish criteria for convergence and linearity, and highlight the relative merits and limitations of each method. [2014-0255] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ka-Band Tunable Filter Using Metamaterials and RF MEMS Varactors

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2481 KB)  

    The design of a metamaterial-based tunable band elimination filter is described on silicon coplanar wave-guide (CPW) using complementary split ring resonators (CSRRs) and radio frequency microelectromechanical systems (MEMS) varactors to ensure compatibility with integrated circuit fabrication technology. CSRRs are patterned on both the active signal line and ground on both sides. A cantilever bridge is suspended on the signal line to realize variable capacitance. The rejection band of the filter is tuned by moving the MEMS bridge up or down using electrostatic actuation. A stopband around the center frequency of 35.32 GHz with a rejection ratio of ~20.19 dB is obtained when the bridge is pulled down. Another stopband around the center frequency 38.80 GHz is observed with a rejection ratio of ~18.29 dB when the bridge is allowed to remain in its up state without electrostatic actuation. Simulation for RF behavior is performed using ANSOFT High Frequency Structural Simulator v13. Numerical extraction of the filter parameters has been done using Agilent ADS (2009) and COVENTORWARE (2010) for mechanical and electromechanical characterization. This is the first reported tunable CPW filter having CSRR on the signal line and ground plane on silicon substrate using MEMS technology. [2014-0365] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Advantages of Electrostatic Spring Hardening in Biomimetic Hair Flow Sensors

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6745 KB)  

    We report on a fully adaptable flow sensor with adjustable detection limit, responsivity, range, and bandwidth by addition of electrostatic spring hardening (ESH) to our previously developed microelectromechanical systems hair flow sensors. The sensor's mechanical transfer shows large voltage-controlled electromechanically affected responsivity for frequencies below the sensor's resonance. Using capacitive readout, a bias voltage-controlled sensory threshold is obtained, giving a threefold tunable ac-airflow detection threshold (down to 0.3 mms⁻¹). The mechanism of spring control also extends to dc-flows, as shown for the first time; electrostatic spring hardening allows to increase the dc-flow measurement range by almost a factor 2, up to about 5 ms⁻¹. Furthermore, the application of ESH is demonstrated both theoretically and experimentally for nonresonant parametric amplification (NRPA) by achieving suppression of residual frequency components at the cost of overall gain. In addition, we show that ESH allows to extend selective gain and tunable filtering by NRPA to a larger range of flow frequencies. [2014-0256] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Advanced MEMS Process for Wafer Level Hermetic Encapsulation of MEMS Devices Using SOI Cap Wafers With Vertical Feedthroughs

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2972 KB)  

    This paper reports a novel and inherently simple fabrication process, so-called advanced MEMS (aMEMS) process, that is developed for high-yield and reliable manufacturing of wafer-level hermetic encapsulated MEMS devices. The process enables lead transfer using vertical feedthroughs formed on an Silicon-On-Insulator (SOI) wafer without requiring any complex via-refill or trench-refill processes. It requires only seven masks to fabricate the hermetically capped sensors with an experimentally verified process yield of above 80%. Hermetic encapsulation is achieved by Au-Si eutectic bonding at 400 °C, and the pressure inside the encapsulated cavity has been characterized to be as low as 1 mTorr with successfully activated thin-film getters. The pressure inside the encapsulated cavity can also be adjusted in the range of 1 mTorr-5 Torr by various combinations of outgassing and gettering options in order to satisfy the requirements of different applications. The package pressure is being monitored for the selected chips and is observed to be stable below 10 mTorr since their fabrication about 10 months ago. The shear strengths of several packages are measured to be as high as 30 MPa with average shear strength of 22 MPa, indicating a mechanically strong bonding. The robustness of the packages is tested by thermal cycling between 100 °C and 25 °C, and absolutely no degradation is observed in the hermeticity and the package pressure. The package pressure is also verified to remain unchanged after storing the packages at a high storage temperature of 150 °C for 24 h. Furthermore, the packaged chips are observed to withstand a high temperature shock test performed at 300 °C for 5 min, at the end of which the characteristics of the encapsulated sensor indicates that the package still remains hermetic (no detectable leaks) and also the package pressure remains constant at ~20 mTorr. [2014-0338] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Development of a Miniature Shear Sensor for Direct Comparison of Skin-Friction Drags

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2036 KB)  

    This paper presents the design, fabrication, and characterization of a silicon-micromachined mechanical sensor that directly compares the wall shears of two different surfaces in a liquid flow. The 27 mm x 27 mm sensor contains two 10 mm x 20 mm x 0.2 mm plates suspended to displace in proportion to the shear force on each surface. The monolithic sensor designed to compare skin-friction drag on two different surfaces consists of two floating plates, each suspended from a frame by identical flexure beams etched out of a 0.2-mm-thick silicon wafer. Design of the sensor is assisted by finite-element analysis to ensure adequate structural characteristics in the intended flows and validated by experimental characterization. The fabrication process is presented in detail, including how to form millimeter-long beams with a uniform cross section in micrometers and release the centimeter-scale plates suspended by the delicate beams. This paper provides a guidance to develop a miniature shear comparator using silicon microfabrication technologies. [2014-0258] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Integrated Flexible Harvester Coupled Triboelectric and Piezoelectric Mechanisms Using PDMS/MWCNT and PVDF

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (923 KB)  

    This paper describes the design, fabrication, and characterization of an integrated flexible energy harvester with triboelectric and piezoelectric hybrid mechanisms. The double-side tribological layers are polydimethylsiloxane (PDMS) and PDMS/multiwall carbon nanotube (MWCNT) carbon nanotube, respectively, which works at triboelectric mechanism. The Polyvinylidene Fluoride (PVDF) film with double-side Al electrodes is bonded with PDMS layer to form the functional layer of piezoelectric harvester. The dimension of the fabricated prototype is 15 mm x 10 mm x 5 mm. The experiments at the varied frequencies from 1 to 5 Hz are conducted to characterize the performance of the harvester under the tapping force of 5 N. The output voltages from triboelectric and piezoelectric harvester are 30 and 6.5 V at 5 Hz, respectively. The maximum output power from triboelectric one is ~3.4 μW under the matched resistance of 15 MΩ. While the maximum power from piezoelectric one was ~0.12 μW at 1 MΩ. [2015-0003] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fabrication of 3-D Silicon Microneedles Using a Single-Step DRIE Process

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (991 KB)  

    Fabrication of 3-D microstructures is one of the most challenging aspects of silicon micromachining. In this paper, we present a novel microfabrication method using one single-step deep reactive ion etching process with gray-scale e-beam lithography mask that offers deeply etched (>350-μm deep) dual-angle 3-D microneedles with control over the height and shape of the structures. Moreover, we found that the shape of the e-beam lithography patterns can determine the general configuration and features of the final etched microneedles, and that the etching process parameters have the most impact on the microneedles' shape, such as size and vertical base angle. Large arrays of 20 x 20 microneedles with height uniformity of better than 3% are fabricated. [2014-0209] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Flexible Conformal Micromachined Absolute Pressure Sensors

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2942 KB)  

    The fabrication and characterization of micromachined piezoresistive absolute pressure sensors in a flexible substrate is presented. A suspended aluminum oxide diaphragm containing nichrome (Ni-80%/Cr-20%) piezoresistive sensors backed by a vacuum cavity was utilized to form the sensor. The piezoresistors were placed in a half-Wheatstone bridge geometry to provide a linear response and thermal stability. The average value of the gauge factor of nichrome was measured to be 1.95. The average normalized Hooge coefficient K1/f was found to be 4.64 x 10⁻¹¹ for the nichrome piezoresistors. The pressure sensors displayed an average sensitivity of 1.25 nV/Pa and average value of noise equivalent pressure (NEPr) of 7.44 kPa in the bandwidth of 1-10 Hz in the 1/f-noise limited regime. In the Johnson noise-limited regime, the NEPr was found to be 10 Pa in a 1-Hz bandwidth. [2014-0028] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Triboelectric Energy Harvester Using Low-Cost, Flexible, and Biocompatible Ethylene Vinyl Acetate (EVA)

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2131 KB)  

    In this paper, we propose a triboelectric energy harvester (EH) using ethylene vinyl acetate (EVA) polymer for the first time. EVA acts as a polymer with positive electrification properties against metals such as gold and aluminum. The EVA sheet provides us with a low-cost EH as the usage of already roll-to-roll-patterned sheet enables us to avoid the common expensive patterning methods for introducing the required roughness to the EH device. Moreover, the biocompatibility and flexibility of EVA makes it a suitable candidate for future implantation of this EH inside body. The transparency of EVA helps us to design the EVA-based EHs in different configurations for the characterization with two types of setups. The proposed new mass-tapping and detachment setups for the EVA EHs bring us more effective methods to quantitatively investigate important properties of EH while resembling the daily motions of a living being rather than using motorized characterization methods. [2014-0305] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A 3-D Overbridge-Shaped Micromixer for Fast Mixing Over a Wide Range of Reynolds Numbers

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3736 KB)  

    This paper reports the development of a 3-D passive micromixer named the overbridge-shaped micromixer (OBM), which can achieve fast mixing by taking advantage of the splitting, recombination, and chaotic advection mechanisms simultaneously. A scheme with the splitting channels of unequal widths is proposed for tremendously enhancing the mixing uniformity in the regions closing to the side walls. The channel depth-to-width ratio is the key factor to mixing performance. A four-unit OBM has been successfully fabricated via a multilayer polydimethylsiloxane process, and the total length of the OBM is <2 mm. Up to a 90% efficiency has been achieved within a Reynolds number (Re) range from 0.01 to 200 by numerical analysis, and the same mixing efficiency was also proven experimentally within a Re range from 0.01 to 50. A high efficiency of 90% was also obtained when mixing two fluids with different flow rates at the two inlets ranging from a ratio of 1:9 to 9:1. [2014-0186] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High-Aspect-Ratio Metal Microfabrication by Nickel Electroplating of Patterned Carbon Nanotube Forests

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2481 KB)  

    High-aspect-ratio metallic microstructures have a variety of potential applications in sensing and actuation. However, fabrication remains a challenge. We have fabricated nickel microstructures with over 20:1 aspect ratios by electroplating patterned carbon-coated carbon-nanotube forests using a nickel chloride bath. Pulse plating allows nickel ions to diffuse into the interior of the forest during off portions of the cycle. Done properly, this solves the problem of the formation of an external crust, which otherwise blocks nickel deposition in the interior of the structures. Thus, densities of 86 ± 3% of bulk Ni for the composite structures are achieved. Cantilever structures do not yield under load, but break. Measurements of the material properties of this composite material indicate an elastic modulus of ~42 GPa and a strength of 400 MPa. We demonstrate the utility of this method with an external field magnetic actuator consisting of a proof mass and two flexures. We achieved 1-mN actuation forces. [2014-0274] View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A MEMS Implementation of a Classic Parametric Resonator

    Publication Year: 2015 , Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1488 KB)  

    We present a microelectromechanical systems realization of a classic parametric resonator. This parametric resonator is ideal in the sense that the electrostatic stiffness, which may be time modulated, is not affected by motion. We also present a simple, efficient, and intuitive model of parametric excitation. This model predicts the minimal modulation amplitude required to obtain an unbounded response in a parametric system with linear damping. We show experimental results in which the system is operated as a Meissner resonator. [2014-0381] 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