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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.

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Displaying Results 1 - 25 of 105
  • Analytical Modeling of a Novel High-$Q$ Disk Resonator for Liquid-Phase Applications

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    To overcome the detrimental effects of liquid environments on microelectromechanical systems resonator performance, the in-fluid vibration of a novel disk resonator supported by two electrothermally driven legs is investigated through analytical modeling and the effects of the system's geometric/material parameters on the dynamic response are explored. The all-shear interaction device (ASID) is based on engaging the surrounding fluid primarily through shearing action. The theory comprises a continuous-system, multimodal model, and a single-degree-of-freedom model, the latter yielding simple formulas for the fundamental-mode resonant characteristics that often furnish excellent estimates to the results based on the more general model. Comparisons between theoretical predictions and previously published liquid-phase quality factor (Q) data (silicon devices in heptane) show that the theoretical results capture the observed trends and also give very good quantitative estimates, particularly for the highest Q devices. Moreover, the highest Q value measured in the earlier study (304) corresponded to a specimen whose disk radius-to-thickness ratio was 2.5, a value that compares well with the optimal value of 2.3 predicted by the present model. The insight furnished by the proposed theory is expected to lead to further improvements in ASID design to achieve unprecedented levels of performance for a wide variety of liquid-phase resonator applications. [2014-0253] View full abstract»

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  • JMEMS Letters Sidewall Nanotexturing for High Rupture Strength of Silicon Solar Cells

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    Photovoltaic, microelectromechanical systems, and integrated circuit industries are demanding a technology to enable the high rupture resistant silicon wafer production to improve the manufacturing yield. The presented silicon nanotexture patterning on the edges and sidewalls by wet chemical etching process can protect single-crystalline and multicrystalline silicon samples from rupture. Bending tests indicate a mechanical strength enhancement of ~72%-75% for sc-silicon and ~71%-73% for mc-silicon samples. In addition, the front and back surfaces of the samples remain intact and appropriate for any further semiconductor processes. This technology was implemented in solar cells that exhibited a strength improvement of nearly 73% without affecting their photovoltaic performances, anticipating an effective solution for the solar cell manufacturing industry. [2014-0234] View full abstract»

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  • Anchor Losses in AlN Contour Mode Resonators

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    In this paper, we analyze possible sources of dissipation in aluminium nitride (AlN) contour mode resonators for three different resonance frequency devices (fr) (220 MHz, 370 MHz, and 1.05 GHz). For this purpose, anchors of different widths (Wa) and lengths (La) proportional to the acoustic wavelength (λ) are designed as supports for resonators in which the dimensions of the vibrating body are kept fixed. The Q extracted experimentally confirms that anchor losses are the dominant source of damping for most anchor designs when fr is equal to 220 and 370 MHz. For specific anchor dimensions (Wa/λ is in the range of 1/4–1/2) that mitigate energy leakage through the supports, a temperature-dependent dissipation mechanism dominates as seen in higher fr resonators operating close to 1.05 GHz. To describe the Q due to anchor losses, we use a finite-element method with absorbing boundary conditions. We also propose a simple analytical formulation for describing the dependence of the temperature-dependent damping mechanism on frequency. In this way, we are able to quantitatively predict Q due to anchor losses and qualitatively describe the trends observed experimentally. [2014-0232] View full abstract»

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  • Demonstration of 1 Million Q-Factor on Microglassblown Wineglass Resonators With Out-of-Plane Electrostatic Transduction

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    In this paper, we report Q-factor over 1 million on both n = 2 wineglass modes, and high-frequency symmetry (Δf/f) of 132 ppm on wafer-level microglassblown 3-D fused silica wineglass resonators at a compact size of 7-mm diameter and center frequency of 105 kHz. In addition, we demonstrate for the first time, out-of-plane capacitive transduction on microelectromechanical systems wineglass resonators. High Q-factor is enabled by a high aspect ratio, self-aligned glassblown stem structure, careful surface treatment of the perimeter area, and low internal loss fused silica material. Electrostatic transduction is enabled by detecting the spatial deformation of the 3-D wineglass structure using a new out-of-plane electrode architecture. Out-of-plane electrode architecture enables the use of sacrificial layers to define the capacitive gaps and 10 μm capacitive gaps have been demonstrated on a 7-mm shell, resulting in over 9 pF of active capacitance within the device. Microglassblowing may enable batch-fabrication of high-performance fused silica wineglass gyroscopes at a significantly lower cost than their precision-machined macroscale counterparts. [2014-0251] View full abstract»

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  • Parallel Averaging for Thermal Noise Mitigation in MEMS Electrothermal Displacement Sensors

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    The sensitivity of an electrothermal displacement sensor increases with its temperature, whereas a higher temperature range leads to higher thermal noise level, which imposes a tradeoff on the sensor’s achievable resolution. We have developed a multiple sensor displacement measurement technique on a 1-degree-of-freedom silicon-on-insulator microelectromechanical systems nanopositioner that mitigates the mentioned tradeoff. To obtain maximum improvement, it is necessary to supply equal power to all of the sensors to ensure equal sensitivity. By combining three identical sensors, we have successfully achieved a 4-dB improvement in signal-to-noise ratio, which is in a good agreement with the averaging theory. Experiments show that the displacement resolution is improved from 0.3 to 0.15 nm/ (sqrt (rm Hz)) in the prototype nanopositioner. Furthermore, improvement is possible by increasing the number of sensors around the stage. [2014-0120] View full abstract»

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  • JMEMS Letters Batch Mode Microultrasonic Machining ((boldsymbol mu )USM) Using Workpiece Vibration

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    This letter reports on the evaluation of an unconventional approach to microultrasonic machining in which the workpiece is vibrated while the tool remains static. The vibration of the workpiece, and not the tool, alleviates the accumulation and the agglomeration of the slurry particles and debris between the machined features. This approach is appealing for batch mode pattern transfer of closely packed features into ceramics and glass. However, the question of how the workpiece vibration will cause selective machining of features on the opposing tool surface has not been addressed. In this effort, fluidic modeling is performed to study slurry flow due to workpiece vibration. The modeling reveals a higher slurry velocity (2.20–2.46 m/s) in the target machining regions confined by the proximity of the tool tips and a lower velocity (0.16–0.50 m/s) elsewhere. To demonstrate and characterize the resulting machining ability, arrayed tools made from stainless steel #304 with feature sizes ranging from 5–(50~mu )m were used on flat workpieces of fused silica. At 20-kHz vibration frequency and 12-(mu )m tool-to-workpiece separation, the average machining rates ranged from 6–90 nm/s for workpiece vibration amplitudes ranging from 1–(5~mu )m. The average surface roughness, (S _{{{a}}}), was 40–65 nm. The tool wear, i.e., the ratio of the tool height worn to the machined depth, was (<4)%. [2014-0216] View full abstract»

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  • Osmotically Actuated Micropumps and Control Valves for Point-of-Care Applications

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    We present novel micropumps and valves actuated by osmotic flow for point-of-care (POC) applications. Although there has been significant progress in the development of microfluidic flowcontrol components, such as fluidic switches, diodes, and resonators, the flow needs to be ultimately supplied by bulky off-chip active components. These off-chip components cannot be easily miniaturized integrated micropumps that utilize electrostatic, piezoelectric, or electroosmotic actuation require high operational voltages, limiting their applications. Other novel approaches, such as magnetic actuation and liquid metal pumping, are also limited by their nonstandard processes and biocompatibility. In this paper, we report two active components, control valves and fluid pumps, actuated by osmotic mechanism, allowing completely stand-alone integrated microfluidic systems. To the best of our knowledge, this is the first attempt to realize control valves by osmosis. The valve can maintain robust sealing up to 125 kPa of back pressure. The fabricated osmotic pump is capable of pumping at (>30) (mu )L/min, which is higher than that of previous works by an order of magnitude. To demonstrate the feasibility of manipulating biofluids, white blood cells suspended in serum were driven and filtered by osmotic actuation. The experimental results verified the potential use of osmotic actuation for POC disposable microfluidics. [2014–0219] View full abstract»

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  • Metallic Glass Hemispherical Shell Resonators

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    By utilizing bulk metallic glasses’ (BMGs) unique combination of amorphous structure, material properties, and fabrication opportunities, ultrasmooth and symmetric 3-D metallic glass resonators that are complimentary metal oxide semiconductor (CMOS) post-processing compatible are fabricated. Surface roughness to size ratio fabrication precision in the order of 100 parts per billion is demonstrated with a 3-mm diameter Pt(_{mathrm {{57.5}}})Cu(_{mathrm {{14.7}}})Ni(_{mathrm {{5.3}}})P(_{mathrm {{22.5}}}) BMG hemispherical shell with a thickness variation (<100) nm and a surface roughness of (<1) nm R(_{mathrm {{a}}}). The resonator exhibits a resonant frequency of (13.9440~{rm kHz},pm ,0.1) Hz with 0.035% frequency mismatch between degenerate ({{N}} = 2) wineglass modes with a quality factor of 6200. This performance was obtained in the as-molded state without any device tuning or trimming. Another resonator with ({{N}} = 2) resonant modes at 9.393 and 9.401 kHz, and quality factors of 7800 and 6500 was mounted into an integrated electrode system. Electrical readout by capacitive sensing in both time and frequency domains showed a resonance shift to 9.461 and 9.483 kHz, respectively. The quality factor was reduced to 5400 and 5300, respectively. This investigation demonstrates that BMG resonators may serve as a basis for robust microelectromechanical systems resonator devices with increased performance and low-cost fabrication techniques that exploits the atomic structure, unique softening behavior, strength, formability, and toughness of metallic glasses. [2014-0187] View full abstract»

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  • Complex Permittivity Measurements in 1–30 GHz Using a MEMS Probe

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    An open-ended coplanar waveguide (CPW) structured probe was implemented for the measurement of dielectric properties of liquids using microelectromechanical systems (MEMS) technology. The MEMS probe, fabricated on sapphire substrate, consists of an open-ended CPW, where the conducting layers were made using Cr/Al. A dielectric layer using SU-8 was added to protect the metal layer. An aperture at the end of the probe was added where the CPW contacts with the material under test. The size of the probe is (180~mu textrm {m}~textrm {(width)}times 660.2~mu textrm {m}~textrm {(thickness)} times 6000~mu )m (length), aperture size is (100~mu textrm {m} times 100~mu )m, and thickness of SU-8 is 10 (mu )m. The permittivities of ethanol-water mixtures measured using the MEMS probe in the 1–30 GHz agreed well with the values presented in the literature. The low cost, small, lightweight, and portable probe described in this paper can be used to measure dielectric properties of very small volume of samples. [2014-0050] View full abstract»

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  • Polymer-Based Pull-In Free Electrostatic Microactuators Fabricated on Wafer-Level

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    To further decrease feature sizes, the semiconductor industry heavily improved the photolithography. Photoresist layers are exposed through photomasks and structured accordingly. The underlying substrate is then selectively altered by adding or subtracting material. The unrivaled precision, resolution, and accuracy allow an unmatched level of miniaturization, and several thousand electrical components can be processed simultaneously. This technology was expanded to the fabrication of sensors and actuators, creating microelectromechanical systems. With silicon, the possibilities of further expanding this technology to new dimensions and applications are limited. Reasons are the stiffness, 2.5-D fabrication, and lack of optical transparency. To enable new applications, we present the successful translation of wafer-level fabrication to millimeter-scale actuators. This was achieved by changing the material to ultraviolet (UV)-curable polymers. Based on the electrostatic zipper actuator, avoiding the common pull-in-effect is essential for the successful realization of an acceptable microactuator. Therefore, the bottom electrodes are split and shaped to adjust the generated electrostatic forces, balancing the mechanical restoring forces. Besides the theoretical design, the fabrication technology based on classic photolithography is explained. Experimental results include voltage-dependent deflection measurements, achieving 110-(mu )m deflection with 70 V driving voltage. The dynamic response measurements show resonance frequencies of 1.89 kHz. [2014-0181] View full abstract»

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  • Application of GMR Sensors to Liquid Flow Sensing

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    This paper presents a feasibility study of the application of giant magneto resistive (GMR) sensors in detecting motion of slow moving fluids. A motivating application for the proposed effort is the development of a smart catheter capable of monitoring the amount of body fluid drained from the ventricles of the brain. Microfabricated ferromagnetic flaps are used to detect motion of the surrounding fluid. The deflection of the flaps is detected by an ultrasensitive GMR sensor placed outside of the lumen of the catheter. Numerical and experimental results are provided demonstrating a resolution of 1.4 mL/h. Numerical analysis of the fluid past the sensing element show an optimal hinge length of the flexible flaps, as well as a significant increase in sensitivity with reduction of the by-pass gap to (sim 50) (mu )m. The effect of electro-magnetic interference and other sources of low-frequency noise (drift) has also been investigated. The results from the study are used to derive a set of design rules that may lead to the successful development of a smart catheter. [2014-0148] View full abstract»

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  • Single-Crystal Silicon Photonic-Crystal Fiber-Tip Pressure Sensors

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    The combination of high-mechanical flexibility and high-optical reflectivity makes planar photonic crystal diaphragms excellent mirrors for optical resonators used in fiber-optic pressure sensing. We have developed a standard silicon process to construct a monolithic photonic crystal-based crystalline silicon membrane. We report on three photonic crystal pressure sensors with different compliances, and discuss the following figures of merit: 1) spectral shift sensitivity; 2) optical sensitivity; 3) pressure sensitivity; 4) resolution; and 5) dynamic range. When compared with a sensor made with an oxide diaphragm, each of our sensors is at least an order of magnitude more sensitive, with a spectral shift sensitivity magnitude of up to 8.6 nm/kPa. We show that the fabrication can be tailored to optimize figures of merit depending on the needs of the application. [2014-0151] View full abstract»

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  • Varying-Length Polymer Microneedle Arrays Fabricated by Droplet Backside Exposure

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    This paper presents a single-step backside ultraviolet lithography method, namely droplet backside exposure (DBE), for making slanted microneedle structures monolithically on a flexible polymer substrate. To demonstrate the feasibility of the DBE approach, SU-8 microneedle arrays were fabricated on polydimethylsiloxane substrates. The length of the microneedles was controlled by tuning the volume of the SU-8 droplet, utilizing the wetting barrier phenomenon at a liquid-vapor-hydrophilic surface-hydrophobic surface interface. The experimental results show excellent repeatability and controllability of the DBE method for microneedle fabrication. Analytical models and the finite element method were studied to predict the dimensions of the microneedles, which agreed with the experimental data. To verify the versatility of the proposed DBE method, different microneedle structures were implemented, including a slanted hollow microneedle array and a slanted microscale waveguide ((mu )-waveguide) array. Furthermore, an as-fabricated (mu )-waveguide array was coupled with a microlight-emitting diode array, which can potentially be utilized as an optical neural interface for applications in optogenetics-based neural stimulation. [2014-0099] View full abstract»

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  • Optimization of Hot-Wire Airflow Sensors on an Out-of-Plane Glass Bubble for 2-D Detection

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    This paper presents design, analysis, fabrication, and measurement of airflow sensors with three hot-wire resistors on an out-of-plane glass bubble. The fabrication process is based on etching cavities in silicon wafer, followed by anodic bonding of a thin Pyrex glass wafer to the etched silicon wafer. The bonded wafers are then heated inside a furnace at a temperature above the softening point of the glass, and because of the expansion of the trapped gas in the silicon cavities, the glass is blown into three-dimensional (3-D) spherical glass bubbles. Resistors patterned on the glass wafer above the cavities are elevated above the base during the glass bubble blowing process. An optimization analysis on the structure and geometry of the sensor, fabrication process, and properties of multilayer thin-film resistors on glass has been conducted in an attempt to improve the sensitivity. [2014-0177] View full abstract»

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  • Integration of Boron-Doped Diamond Microelectrode on CMOS-Based Amperometric Sensor Array by Film Transfer Technology

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    This paper reports on the fabrication of a complementary metal oxide semiconductor (CMOS)-based (20times ) 20 amperometric sensor array integrated with boron-doped diamond (BDD) microelectrodes. The BDD electrodes were formed on a Si wafer at 800 (^{circ })C, and then transferred to a 0.18 (mu )m CMOS large-scale integration (LSI) wafer with a benzocyclobutene bonding interlayer. As a result, the BDD microelectrodes were arrayed without significant damage to CMOS circuit or BDD electrodes. The integrated BDD electrodes on the CMOS LSI exhibited excellent performance for electrochemical analysis. The wider potential window and smaller background current compared with Au microelectrodes were experimentally verified. The electron transfer rate to ferrocenemethanol as a standard reagent was large. The fully implemented device successfully detected 100-nm histamine, and was used for the 2-D real-time imaging of histamine diffused in a solution. [2014-0188] View full abstract»

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  • Development of Electroplated Magnesium Microstructures for Biodegradable Devices and Energy Sources

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    This paper presents fabrication approaches for magnesium (Mg) microstructures embedded in biodegradable polymers using through-mold Mg electrodeposition and metal-transfer-molding. Biodegradable implantable electronics have garnered increasing interest from the medical community for the monitoring and treatment of transient diseases. Magnesium is a biodegradable metal with desirable properties, and the ability to micropattern Mg thick films (i.e., about (>1) (mu )m) with direct microelectromechanical systems (MEMS) integration would support the development of more sophisticated and clinically relevant biodegradable devices and microsystems. Magnesium microstructures were electroplated through micropatterned water-soluble molds in a nonaqueous electrolyte and transfer molded into a biodegradable polymer. Electroplated Mg compared favorably with commercial Mg foil based on elemental composition, crystal orientation, electrical resistivity, and corrosion behavior. Magnesium electroplated to a thickness of up to 50 (mu )m showed a grain size of (sim 10) (mu )m, and minimum feature dimensions of 100 (mu )m in width and spacing. Completely biodegradable Mg and poly-L-lactic acid constructs were demonstrated. The application of Mg thick films toward biodegradable energy sources was explored through the fabrication and testing of biodegradable Mg/Fe batteries. The batteries exhibited a capacity and power of up to 2.85 mAh and 39 (mu )W, respectively. Results confirmed the advantages of electrodeposited Mg microstructures for biodegradable MEMS applications. [2014-0103] View full abstract»

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  • Multicamera Laparoscopic Imaging With Tunable Focusing Capability

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    This paper presents a solution to overcome many of the fundamental challenges faced by current laparoscopic imaging systems. Our system is developed upon the key idea that widely spread multiple tunable microcameras can cover a large range of vantage points and field of view (FoV) for intraabdominal visualization. Our design features multiple tunable-focus microcameras integrated with a surgical port to provide panoramic intraabdominal visualization with enhanced depth perception. Our system can be optically tuned to focus on objects within a range of 5 mm to (infty ), with a FoV adjustable between 36(^{circ }) and 130(^{circ }). Our unique approach also eliminates the requirement of an exclusive imaging port and need for navigation of cameras between ports during surgery. [2014-0176] View full abstract»

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  • High-Resolution MEMS Inclinometer Based on Pull-In Voltage

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    High-resolution pull-in-based microelectromechanical system (MEMS) inclinometers are presented in this paper. Pull-in is characterized by the sudden loss of stability in electrostatically actuated parallel-plate structures, and since pull-in voltage is stable and easy to measure, it enables an effective transduction mechanism that does not require complex and stable capacitive readout electronics. The MEMS devices used to test the novel architecture have differential actuation electrodes resulting in two pull-in voltages that change differentially with applied acceleration. Dedicated MEMS microstructures with extra proof mass show high sensitivity; 269 mV/(^{circ }) with a nonlinearity (<0.5)% FS (Full Scale of (pm 23)(^{circ })). The measured noise is limited by the actuation mechanism, setting the sensor’s resolution at 75 (mu {^{circ }}); high above state-of-the-art MEMS devices.[2014-0156] View full abstract»

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  • High-Speed Ultrasmooth Etching of Fused Silica Substrates in SF (_{mathrm {6}}) , NF (_{mathrm {3}}) , and H (_{mathrm {2}}) O-Based Inductively Coupled Plasma Process

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    This paper presents a new paradigm for high aspect ratio etching of fused silica substrates using a modified inductively coupled plasma (ICP) etch chamber. In particular, we have incorporated a stainless steel gas diffuser ring on the mechanical substrate clamping plate of the etcher to introduce NF(_{{{3}}}) and H(_{{{2}}})O gases right above the wafer, whereas SF(_{{{6}}}) is introduced through the ICP source. This configuration of plasma etching allows for incomplete breakdown of NF(_{{{3}}}+textrm {H}_{{{2}}})O gas mixture, thereby creating a high local density of F, NF(_{{{x}}}), and HF (Hydrogen Fluoride) while achieving large flux of ({textrm {SF}_{{{x}}}}^{{{+}}}) ion bombardment. Using this configuration, source power of 2500 W, substrate power of 400 W, and SF(_{{{6}}})/NF(_{{{3}}})/H(_{{{2}}})O flow rates of 60/100/50 sccm, we were able to achieve a surface roughness of (sim 5)Å at an etch rate of (sim 1) (mu )m/min. In situ residual gas analysis of the plasma conditions show high concentrations of F, HF, and SF(_{{{x}}}), along with a large concentration of NF(_{{{x}}}) species. The highest etch rate was also found to be a function of the ion flux. The anisotropy of the etch was enhanced by the formation of an inert nickel fluoride/oxide skin layer on the sidewalls of the etched features.[2014-0214] View full abstract»

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  • An LC -Type Passive Wireless Humidity Sensor System With Portable Telemetry Unit

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    This paper presents a high-sensitivity passive wireless humidity sensor system with a portable telemetry unit for applications in sealed environments. A complementary metal oxide semiconductor (CMOS) interdigital capacitive humidity sensor die was attached to an organic substrate (FR-4) on which a fixed planar spiral copper inductor was fabricated. The variable capacitor and the fixed inductor were wire bonded to form an inductor–capacitor (LC) tank circuit. The resonant frequency of the sensor tank is dependent on the sensor capacitance, which changes in response to the humidity. The sensitivity of the capacitive sensor was improved significantly using graphene oxide as a sensing material. The package-level integration was achieved by employing the embedded inductor on an organic packaging substrate. The LC-type sensor is interrogated wirelessly using our homemade portable telemetry unit, which is based on a standing wave ratio bridge to measure the real part of the readout coil impedance. Measurements show a sensitivity of (-18.75) kHz/%RH over a range of 15%–95% RH. The implemented telemetry unit addresses the need for a low-cost, portable, and universal reader of the LC-type passive wireless sensors.[2013-0188] View full abstract»

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  • A High Fill-Factor Annular Array of High Frequency Piezoelectric Micromachined Ultrasonic Transducers

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    This paper presents a 1.2-mm diameter high fill-factor array of 1261 piezoelectric micromachined ultrasonic transducers (PMUTs) operating at 18.6 MHz in fluid for intravascular ultrasound imaging. At 1061 transducers/mm(^{2}), the PMUT array has a 10–20 times higher density than previous PMUT arrays realized to date. Aluminum nitride (AlN)-based PMUTs described in this paper are fabricated using a process compatible with the fabrication of inertial sensors, radio frequency (RF) resonators, and CMOS integrated circuits. The PMUTs are released using a front-side sacrificial etch through etching holes that are subsequently sealed by a thin layer of parylene. Finite element method and analytical results, including resonant frequency, pressure sensitivity, output acoustic pressure, and directivity are given to guide the PMUT design effectively, and are shown to match well with measurement results. Due to the PMUTs thin membrane (750-nm AlN/800-nm SiO(_{2})) and small diameter, a single 25-(mu )m PMUT has approximately omnidirectional directivity and no near-field zone with irregular pressure pattern. PMUTs are characterized in both the frequency and time domains. Measurement results show a large displacement response of 2.5 nm/V at resonance and good frequency matching in air, high center frequency of 18.6 MHz and wide bandwidth of 4.9 MHz, when immersed in fluid. Phased array simulations based on measured PMUT parameters show a tightly focused high-output pressure acoustic beam.[2014-0114] View full abstract»

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  • Large Vertical Displacement Electrostatic Zipper Microstage Actuators

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    An out-of-plane electrostatic microactuator delivering exceptionally high vertical displacements is described. The devices, based on an electrostatic zipper actuator design, employ composite Si/SiO(_{mathrm {{2}}}) beams with engineered stress gradients that result in large and controllable beam curvatures. The microactuators are fabricated in a silicon-on-insulator/deep reactive-ion etching process, with an additional oxidized silicon wafer serving as a bonded ground electrode. Simple cantilever Si/SiO(_{mathrm {{2}}}) zipper actuators are investigated and extended to a meander configuration with regions of variable curvature able to produce large tip deflections in a small on-chip footprint. An analytic model is presented and used to optimize deflection of the meander-shaped zipper actuators, followed by the implementation of a full microstage actuator employing parallel meanders connected to a moving silicon stage. Using this configuration, purely vertical actuation is realized. The static deflections of various actuator designs are characterized and shown to be in a good agreement with analytical predictions. Fabricated microstage actuators achieving deflections up to 60% of their in-plane dimensions are described, and reliable actuation over nearly (10^{mathrm {{6}}}) Hz is demonstrated.[2013-0397] View full abstract»

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  • Lateral-Mode Vibration of Microcantilever-Based Sensors in Viscous Fluids Using Timoshenko Beam Theory

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    To more accurately model microcantilever resonant behavior in liquids and to improve lateral-mode sensor performance, a new model is developed to incorporate viscous fluid effects and Timoshenko beam effects (shear deformation, rotatory inertia). The model is motivated by studies showing that the most promising geometries for lateral-mode sensing are those for which Timoshenko effects are most pronounced. Analytical solutions for beam response due to harmonic tip force and electrothermal loadings are expressed in terms of total and bending displacements, which correspond to laser and piezoresistive readouts, respectively. The influence of shear deformation, rotatory inertia, fluid properties, and actuation/detection schemes on resonant frequencies ((f_{rm res})) and quality factors ((Q)) are examined, showing that Timoshenko beam effects may reduce (f_{rm res}) and (Q) by up to 40% and 23%, respectively, but are negligible for width-to-length ratios of 1/10 and lower. Comparisons with measurements (in water) indicate that the model predicts the qualitative data trends, but underestimates the softening that occurs in stiffer specimens, indicating that support deformation becomes a factor. For thinner specimens, the model estimates (Q) quite well, but exceeds the observed values for thicker specimens, showing that the Stokes resistance model employed should be extended to include pressure effects for these geometries.[2014-0157] View full abstract»

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  • An Efficient Earth Magnetic Field MEMS Sensor: Modeling, Experimental Results, and Optimization

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    A new (z)-axis Lorentz force microelectromechanical systems magnetometer was designed, fabricated, and tested. The proposed device is characterized by simple design, reduced dimensions, and high efficiency. Furthermore, possible parasitic acceleration sensitivity is mechanically canceled in the proposed device. The initial design was subsequently studied through an ad hoc formulated multiphysics model used to compute the sensor dynamics; optimality of the design configuration was then obtained by means of a structural optimization approach. A wide scenario of design configurations, obtained with the proposed optimization approach, is finally discussed.[2014-0131] View full abstract»

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  • Cantilever Fabrication by a Printing and Bonding Process

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    Cantilevers are a widely used structure in electronics, covering many applications from switches to different kinds of sensors. The majority of them have been manufactured with complimentary metal–oxide–semiconductor (CMOS) technologies, but the increasing demand on printed electronics also motivates its development with printing techniques. Here, we present a cantilever beam fabricated by printing techniques with a novel manufacturing process that simplifies the fabrication procedure in terms of cost and time. The sacrificial layer is a poly(methyl methacrylate) film, which is not placed between the substrate and the beam, but, as a peculiarity of this process, on top of the beam; that is to say, the sacrificial layer is used as a sacrificial substrate. Another challenge faced in this paper is the use of a plastic foil as the substrate of this structure. In addition, we show experimental results of the physical and electrical characterization of these devices, which are in a reasonable good agreement with simulations by a finite element modeling tool. We tested the deflection of these cantilevers at different values of acceleration and frequency to show the efficiency of the innovative process.[2014-0073] 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.

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