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We present a method to fabricate planar metal layers to be used as micromachined mirrors. Released mirrors of pure metal involve severe stress and reveal specific challenges to obtain planar mirror structures. Introducing sub-structures generating corrugated patterns, the metal mirror layers can be mechanically stabilized and undesired mirror bending can be reduced. For our investigations we used different arrangements of line structures on our metal mirrors, such as a group of straight or curved lines oriented differently. Comparing all the implemented different designs, planar micromirrors were achieved via sub-structures with a combination of straight lines arranged orthogonally to a single line. These planar micromirrors allow steering of the incident light by reflection and adjustment of the window transmittance. The presented low-cost method is suitable for large area fabrication of micromirror arrays, but also can be customized for other applications, where planar free-standing metal layers are required.

In this paper, we report a novel laterally actuated Radio Frequency (RF) Microelectromechanical Systems (MEMS) switch, which is based on a combination of electrothermal actuation and electrostatic latching hold. The switch takes the advantages of both actuation mechanisms: large actuation force, low actuation voltage, and high reliability of the thermal actuation for initial movement, and low power consumption of the electrostatic actuation for holding the switch in position in ON state. The switch with an initial switch gap of 7 µm has an electrothermal actuation voltage of 7 V and an electrostatic holding voltage of 21 V. The switch achieves superior RF performances: the measured insertion loss is −0.73 dB at 6 GHz, whereas the isolation is −46 dB at 6 GHz. In addition, the switch shows high reliability and power handling capability: the switch can operate up to 10 million cycles without failure with 1 W power applied to its signal line.

We present HapTable; a multi-modal interactive tabletop that allows users to interact with digital images and objects through natural touch gestures, and receive visual and haptic feedback accordingly. In our system, hand pose is registered by an infrared camera and hand gestures are classified using a Support Vector Machine (SVM) classifier. To display a rich set of haptic effects for both static and dynamic gestures, we integrated electromechanical and electrostatic actuation techniques effectively on tabletop surface of HapTable, which is a surface capacitive touch screen. We attached four piezo patches to the edges of tabletop to display vibrotactile feedback for static gestures. For this purpose, the vibration response of the tabletop, in the form of frequency response functions (FRFs), was obtained by a laser Doppler vibrometer for 84 grid points on its surface. Using these FRFs, it is possible to display localized vibrotactile feedback on the surface for static gestures. For dynamic gestures, we utilize the electrostatic actuation technique to modulate the frictional forces between finger skin and tabletop surface by applying voltage to its conductive layer. To our knowledge, this hybrid haptic technology is one of a kind and has not been implemented or tested on a tabletop. It opens up new avenues for gesture-based haptic interaction not only on tabletop surfaces but also on touch surfaces used in mobile devices with potential applications in data visualization, user interfaces, games, entertainment, and education. Here, we present two examples of such applications, one for static and one for dynamic gestures, along with detailed user studies. In the first one, user detects the direction of a virtual flow, such as that of wind or water, by putting their hand on the tabletop surface and feeling a vibrotactile stimulus traveling underneath it. In the second example, user rotates a virtual knob on the tabletop surface to select an item from a menu while feeling the knob's detents and resistance to rotation in the form of frictional haptic feedback., Scientific and Technological Research Council of Turkey (TÜBİTAK)

Nowadays, the concept of programmable matter paves the way for promising applications such as reshaping an object to test different configurations, modeling or rapid prototyping. Based on elementary modules, such matter can be arranged and disassembled easily according to the needs of the designers. Several solutions have been proposed to implement this concept. Most of them are based on modular self-reconfigurable robotics (SMR) that can work together and move relatively to one another in order to change their configuration. Achieving such behavior requires to solve some technological challenges in particular module&rsquo, s geometry and actuation. In this paper, we build and develop a proof of concept for a catom based on electrostatic actuation. The modeling and analysis of the actuator functioning as catom is given after a comparison of various possible actuation. Simulations as well as experiments validations are afterwards carried out to confirm and demonstrate the efficiency of electrostatic actuation to achieve latching capabilities of the proposed catom.

This paper presents a method to enhance the stroke level of a MEMS micromirror that, unlike conventional micromirrors, is actuated using a repulsive electrostatic force. The designed and proposed micromirror is held by L-shaped arms suspended over a set of bottom electrodes. In this configuration, three bottom electrodes are centered below each arm and are separated with a designed gap from each other to optimize the generated repulsive force. Using this approach, the micromirror surface is forced to deflect upward compared with the conventional downward deflection. The designed micromirror is proposed to utilize the PolyMUMPs fabrication technique from MEMSCAP Inc. In this work and in an unconventional approach, an air cavity of 2.75 &micro, m can be achieved by combining the two available oxide layers through an additional removal of a polysilicon structural layer. It is shown that this design can significantly enhance the stroke level of the proposed micromirror to 5 &micro, m at 150 V DC.

In this paper, we present the fabrication of on-chip piezoelectric acoustic actuation for 2D materials. Acoustic actuation is achieved at device level through patterning of aluminum nitride (AlN) thin film at wafer scale. Two piezoelectric stacks consisting of a 100 nm-thick AlN layer sandwiched between 25 nm-thick platinum (Pt) and molybdenum (Mo) electrodes are fabricated close to the suspended 2D material such as graphene. The graphene nanoelectromechanical resonator is first actuated electrostatically using highly doped silicon (Si) back gate. Due to the effect of damping on amplitude, the frequency response curves do not lie on top of each other. Nonetheless, when actuated through the on-chip piezoelectric stack, the various frequency response curves lie on top of each other, indicating a linearly damped system. We also find that the acoustic actuation technique to be less dissipative than the electrostatic one.

This paper presents a microelectromechanical system (MEMS)-based oscillator based on a Lam&eacute, mode capacitive micromachined resonator and a fully differential high-gain transimpedance amplifier (TIA). The proposed TIA is designed using TSMC 65 nm CMOS technology and consumes only 0.9 mA from a 1-V supply. The measured mid-band transimpedance gain is 98 dB &Omega, and the TIA features an adjustable bandwidth with a maximum bandwidth of 142 MHz for a parasitic capacitance C P of 4 pF. The measured input-referred current noise of the TIA at mid-band is below 15 pA/ Hz . The TIA is connected to a Lam&eacute, mode resonator, and the oscillator performance in terms of phase noise and frequency stability is presented. The measured phase noise under vacuum is &minus, 120 dBc/Hz at a 1-kHz offset, while the phase noise floor reaches &minus, 127 dBc/Hz. The measured short-term stability of the MEMS-based oscillator is &plusmn, 0.25 ppm.

In this paper we present a detailed evaluation of a micro-opto-electromechanical system (MOEMS) for active focusing which is realized using an electrostatically deformed thin silicon membrane. The evaluation is done using finite element methods and experimental characterization of the device behavior. The devices are realized in silicon on insulator technology. The influence of internal stress especially resulting from the high compressive buried oxide (BOX) layer is evaluated. Additionally, the effect of stress gradients in the crystalline device layer and of high reflective coatings such as aluminum is discussed. The influence of variations of some important process steps on the device performance is quantified. Finally, practical properties such as focal length control, long-term stability, hysteresis and dynamical response are presented and evaluated. The evaluation proves that the proposed membrane focusing device is suitable for high performance imaging (wavefront errors between λ/5–λ/10) with a large aperture (5 mm).

Adaptive optical (AO) components play an important role in numerous optical applications, from astronomical telescopes to microscope imaging systems. For most of these AO components, the induced wavefront correction, respectively added optical power, is based on a rotationally symmetric or segmented design of the AO component. In this work, we report on the design, fabrication, and characterization of a micro-electronic-mechanical system (MEMS) adaptive membrane mirror in the shape of a parabolic cylinder. In order to interpret the experimental characterization results correctly and provide a tool for future application development, this is accompanied by the setup of an optical simulation model. The characterization results showed a parabolically deformable membrane mirror with an aperture of 8 × 2 mm2 and an adaptive range for the optical power from 0.3 to 6.1 m−1 (dpt). The optical simulation model, using the Gaussian beamlet propagation method, was successfully validated by laser beam profile measurements taken in the optical characterization setup. This MEMS-based adaptive astigmatic membrane mirror, together with the accompanying simulation model, could be a key component for the rapid development of new optical systems, e.g., adaptive laser line generators.

We present a design for an on-chip MEMS-actuated Variable Optical Attenuator (VOA) based on Silicon Photonic MEMS technology. The VOA consists of 30 individual mechanically movable MEMS cantilevers, suspended over an integrated, 1 mu m wide bus waveguide, each terminating with two optical attenuation bars. By exploiting the pull-in instability, electrostatic actuation allows to move the individual cantilevers into proximity of the waveguide, leading to scattering of the evanescent field and thus attenuation of the remaining optical power in the waveguide. Electrodes are placed below the cantilevers for electrostatic actuation. Mechanical stoppers are used to avoid contact between the cantilevers and the electrodes and to keep the bars at a precisely defined distance of 60 nm away from the bus waveguide. The attenuator provides nearly zero insertion loss in OFF state, while in ON state, the attenuation range is defined by the number of actuated digital attenuation cantilevers and can be adjusted in discrete increments of only 1.2 dB. Owing to the small size, fast microsecond scale response time can be achieved, and electrostatic MEMS actuation allows for broadband and low-power operation. Our design exhibits a compact footprint of 30 mu m x 45 mu m, attenuation from 0 dB to 36 dB, while keeping return loss below 27 dB. To the best of our knowledge, this is the first presentation of a design of a VOA in Silicon Photonic MEMS technology.

The electrostatic actuation behaviour of the gold bridge in capacitive radio frequency microelectromechanical system switches, fabricated on GaAs substrate, is investigated. An unconventional imaging technique, based on the out-of-focus reflection, was used to evaluate the topographic profile of the suspended bridge and its lowering as a function of the voltage. Important parameters for the switch actuation, such as the pull-down voltage and the air gap between the bridge and the actuator, are estimated. Capacitance-voltage curves allow to evaluate the capacitance associated to the bridge in the up and down states as well as the dielectric constant of the Si3N4 layer, which covers the actuator. The experimental values of the pull-down voltage and the dielectric constant are used to extract from the theoretical equations the residual stress of the fabricated gold membrane. Finally, the current through the dielectric Si3N4 layer was measured as a function of the voltage applied to the actuator, finding that the Poole-Frenkel effect is the dominant conduction mechanism when the switch is actuated.

We report on the realization of a biomimetic MEMS speaker inspired by field crickets. This speaker is at least five times thinner and four times more efficient than the current dynamic speakers used in portable electronics. We present results of the acoustic characterization of a single MEMS speaker. Computational extrapolation of the results suggests that an array of such thin speakers will be highly efficient compared to the existing speakers of equal area.

Curved micromechanical beams are a versatile platform for exploring multistable behavior, with potential applications in mechanical based logic elements and electrical and optical switches. Here we demonstrate bidirectional electrostatic actuation of a bistable, latched, micromechanical beam by the same electrode, which was used for the snap-through switching of the device. The release of the mechanically-latched beam is achieved by pre-loading the structure using a rising voltage applied to the electrode, followed by a sudden decrease of the voltage. This abrupt removal of the loading results in a transient response and dynamic snap-back of the beam.

International audience; Considering a cantilever motion subject to electrostatic actuation and tunnelingcurrent sensing, a multi-mode model is first analyzed, with an emphasis on the effect ofactuator/sensor location. In particular, it is underlined how specific locations can result ina model of reduced order, making in turn a related control design more simple. This is thenillustrated by a robust control scheme aiming at positioning the cantilever. This control inparticular handles the effect of proximity forces, and the results are illustrated in simulation

The nanoscaled electrostatically actuated electromechanical ohmic switch is an emerging device with advanced performance in terms of ION/IOFF ratio. It is imperative that compact models accompany such novel devices in order to fully evaluate their potential at the circuit-level. A minimal, yet, adequate compact model is developed and analyzed in this work. Further, the model is used as a compass for switch design space exploration and, simultaneously, a corresponding parameter extraction methodology is compiled. The application on data from numerical simulations and on measurements of fabricated devices, verifies the potential of the model, while circuit-level simulations validate its robustness within an industrial IC design environment.

Nowadays, electronics face a challenge regarding the power consumption of integrated circuits (ICs). There is a need for new devices that can provide improved switching capabilities. The downscaled electrostatically actuated ohmic switch, as a (re)emerging device, is a promising candidate to meet this need. To bring such a device seamlessly into IC design, it must be accompanied by an accurate, fast and robust analytical compact model. The development and the main characteristics of such a model are described within this paper. Extensive numerical simulations and measurements have been used to validate the model.

Micro deformable porous mirrors are designed and investigated in this work. Finite element methods are used to analyze mirror deflection induced by electrostatic force. The porous micro mirror is designed by bulk micromachining and bonds with aluminum plate which is ground electrode with photo resist for its good adhesion ability. This design has advantages of avoiding warpage, using less masks, and easily fabricated. It is found mirror boundary types and holes shapes and arrangement in mirror would affect deflection under applying voltage. Spring like boundary will induce larger deflection than traditional clamped boundary condition. However, the effect is more obvious for mirror with round holes in radical direction. Although porous mirror has smaller electrode area and electrostatic force than mirror without holes, yet it has larger displacement. The effect of holes overcomes disadvantage of smaller driving force due to avoiding air resisting force as mirror having airtight bounding. In this study, spring-like boundary has advantages of better performance and easier alignment in mirror fabrication. Therefore, it is useful for mirror design and fabrication in practice.

SUMMARY An equivalent circuit model for a semiparallel plate electrostatic torsion mirror has been developed based on an electrical circuit simulator. An analytical model for the electrostatic torque has been translated into a nonlinear dependent current source as a function of the input voltages that interpret the drive voltages and the mirror angle. Use of the suspension width as a fitting parameter explained well the experimental results on frequency response and the mirror's static deflection. © 2013 Wiley Periodicals, Inc. Electron Comm Jpn, 97(1): 37–47, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11486

This paper deals with the influence of the shape of the driving waveform on the frequency responses of microelectromechanical systems (MEMS) resonators under nonlinear actuation. Our models show that, at large oscillation amplitudes, these responses are strongly dependent on the shape of the actuation waveform so that the nonlinear frequency response is not the system signature, but the system signature under a specific driving waveform. The case of a MEMS resonator electrostatically driven with a sine-, pulsed-, or square-wave voltage is specifically addressed. Our models and simulations, supported by experimental evidence, predict counterintuitive phenomena resulting from the distortion of the actuation waveform by the displacement-dependent electrostatic nonlinearity. This paper emphasizes that this issue should not be overlooked in order to perform quantitative MEMS characterization in the nonlinear regime. [2015-0283]

We developed an innovative type of varifocal liquid lens actuated by electrostatic parallel plates. The 3mm diameter lens is made of a polymer membrane that encapsulates a high permittivity liquid in a cavity on top of a glass wafer. Annular electrodes situated below the membrane and on the glass wafer form the electrostatic parallel plates actuator. Applying a voltage between the electrodes reduces the gap and pushes the liquid towards the center of the lens changing the curvature of the membrane. Compared to previous liquid lenses, significant outline improvement (

cited By 1; Conference of 10th IEEE Nanotechnology Materials and Devices Conference, NMDC 2015 ; Conference Date: 12 September 2015 Through 16 September 2015; Conference Code:121065; International audience; New dielectric-engineering concept is developed intending a net improvement of the performance of dielectric layers under electrical stress. Instead of synthesis of new dielectric materials a new class of dielectric layers that gain their performance from design rather than from composition is established. Two kinds of nanostructured dielectric layers are presented here: (i) silicon oxynitride layers (SiOxNy:H) with gradual variation of their properties (discrete or continuous), and (ii) SiO2 layers with tailored interfaces; a single layer of silver nanoparticles (AgNPs) is embedded in the vicinity of the dielectric free surface. The nanostructured layers exhibit much shorter charge retention times and appear promising candidates for general applications where surface charging of dielectrics must be avoided, in particular for implementation in RF MEMS capacitive switches with electrostatic actuation.

We present the design, fabrication and characterization of an electrostatically actuated AFM probe. The probe consists of two cantilevers, a relatively long, stiff cantilever on which end a smaller and softer cantilever with a sharp tip is incorporated. The deflection of the small cantilever is controlled by an electrostatic gap-closing actuator, which is monolithically integrated on the cantilevers. A combination of a small and fast cantilever with an integrated electrostatic actuator allows for a high frequency operation and high speed AFM imaging. We have designed and fabricated a probe with the large cantilever having a stiffness of over 400 N/m and small cantilevers with a stiffness of up to 3.2 N/m and a resonance frequency up to 643 kHz. We have confirmed a proper operation of the probe using high-speed imaging (8 scan lines per second) in electrostatically driven tapping mode.

International audience; This paper introduces the tunneling current as a sensor to detect and control displacements of Micro and Nano Electromechanical Systems (MNEMS). Due to its extremely small magnitude, the tunneling current can not be used without an appropriate control strategy. A control methodology involving two feedback loops is proposed to control displacements with an accuracy of 40pm while also compensating the sensor drift. With this strategy, controlling displacements with an amplitude larger than one nanometer is possible, extending the predicted capabilities of tunneling current by the literature. The overall approach is a solution for control of macro to nano systems and may be embedded in positioning applications requiring a very high degree of accuracy.

A high fill-factor, dual-axis micromirror array with novel spring and actuator design is developed for high thermal load applications. Each pixel can attain an omnidirectional mechanical DC rotation angle of +/- 4 degrees.

This thesis describes the design, fabrication, and characterization of compact optical devices for sensing and switching applications. Our focus has been to realize the devices using CMOS-compatible fabrication processes. Particularly the silicon photonics fabrication platform, ePIXfab, has been used for this purpose.

This work is focused on the design, fabrication, and characterization of silicon laterally resonant microcantilevers for measuring absolute pressure. The authors have demonstrated the integration of resonance electrostatic actuation and capacitive readout with a microstructure based on a couple of electrodes and an external amplifier. The microcantilevers have been fabricated with a standard silicon on insulator micromachining process. The characterization method is based on measuring the current at the third harmonic of the excitation frequency flowing through the time-varying cantilever-based capacitor. The variation in resonance response of microcantilevers has been investigated as a function of pressure (10−2−105 Pa), both in terms of resonance frequency and quality factor. Theoretical models and experimental data show very good agreement. The microstructure behavior demonstrates the feasibility of an absolute pressure sensor working over a six-decade range with integrated electrical actuation and rea...

International audience; A closed-loop control approach for the dynamic shaping of a microbeam by electrostatic actuation is described. Starting from a desired displacements reference vector of N small segments of the beam (representing the approximation of the continuous case), n controllers (n is the number of considered modes) output the stresses that must be distributed throughout the beam, on the N actuators. Because this reference may vary with time, the controllers are designed so that they accomplish good response dynamics, as well as performance and robustness specifications. The innovation in this method is that we control the dynamic coefficients associated to the modes of the microbeam and not directly the physical displacements in each small segment, which reduces the number of correctors from N to the number of n modes to control.

The general study is dedicated to Wireless Sensor Networks. The idea is to associate micro-mechanical and microwave communication functions to exchange information between a remote sensor and a base station [1]. A specific part of this project concerns the conception, realisation, and characterisation of a passive microwave frequency shifter used for back-modulation around 2 GHz. The interesting point was to develop this function with an integrated silicon micro-mechanical rotating structure. The paper describes the prototype of the RF MEMS already developed in ESIEE laboratory. And we insist on the microwave measurements performed and the associated equivalent models.

Gap-closing electrostatic actuators are inherently nonlinear and their dynamic range is often limited by the pull-in instability. To overcome this, we propose a nonlinear spring that counteracts the nonlinear effects of electrostatic attraction. The nonlinear spring is designed to extend the stable range of the actuator and to enforce a linear electromechanical response. We present a method for designing elastic springs with monotonically increasing stiffness. The mechanism we propose is effective shortening of a straight clamed-guided beam flexure, by wrapping it over a cam. We consider two specific cases. The first case assumes the wrapped section of the beam flexure fully conforms to the cam shape. The second case assumes that there is a single contact point between the beam flexure and the cam. To validate the concept we have designed and measured the response of a nonlinear spring with a prescribed force–displacement law. Experimental measurements of a macro-scale spring are in good agreement with the model predictions.

We present a novel approach for hydrogen gas detection, based on palladium-coated micromechanical resonators. A sequence of thin film technniques allows the large-scale parallel fabrication of free-standing beams separated from a counter-electrode by a mesoscopic air gap. The readout principle has been confirmed. The device manifests a resonance frequency drop from 6.5 to 3 MHz as it is exposed to 4 % of H2 during 15s. The sensor responds within a few seconds to hydrogen gas and has a power consumption of about 10 pW. Preliminary results suggest that this technique can detect very minute concentrations.