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The performance of a microgyroscope consisting of a rotating microbeam made of nanocrystalline silicon connected to a proof mass and subjected to electric actuation is investigated. The microgyroscope is assumed to operate in frequency-based mode; that is, the measurement of the rotation rate is extracted from the shift in the frequency response along the drive and sense directions. Closed-form expressions of the natural frequencies and mode shapes of the coupled dynamical system are derived. The onset of the base rotation is observed to split the common natural frequency of the two bending modes into a pair of closely-spaced natural frequencies. This frequency shift used as the output parameter detecting the rotation rate. A sensitivity analysis of this parameter to the rotation rate when varying the material properties of the microbeam and electric actuation is then performed. When applying the same DC voltage for the drive and sense modes, the differential frequency is found to vary linearly with the base rotation. Incorporating the fringing field in the electrostatic forcing and varying the grain size of the nanocrystalline silicon have insignificant impact on the calibration curve for this case. Breaking the symmetry of the microgyroscope in terms of the applied DC voltage along the drive and sense directions is observed to reduce significantly the sensitivity of the differential frequency to the base rotation rate. The larger the DC voltage bias is, the lower the sensor sensitivity is. Furthermore, under these operating conditions, the results show that the variations of the differential frequency with the rotation rate undergo nonlinear trends. Considering higher order modes is found to reduce the impact of the DC voltage bias on the calibration curve of the microgyroscope. [ABSTRACT FROM AUTHOR]

In this paper, the dynamics of microbeams under the effects of electrostatic force, mechanical shock, Squeeze Film Damping (SQFD), and fringing field are modeled. A Galerkin-based reduced-order model is used to convert the Partial Differential Equation of motion (PDE) to an Ordinary Differential Equation (ODE). Furthermore, the system dynamics are studied using the developed nonlinear finite element code. Two different simpler models are validated by the results in the literature, which are in good compatibility with them. It is shown that the effect of squeeze film damping can dominate mechanical shock significantly. The response of microbeam to electrostatic actuation is also delayed when damping is included. The simultaneous and sole effects of electrostatic actuation, mechanical shock, squeeze film damping, and fringing field are investigated in this study for the first time. [ABSTRACT FROM AUTHOR]

Micro- and nanolectromechanical systems (MEMS/NEMS) incorporating two-dimensional structural elements such as plates and shells attracted significant interest in recent years. These structures demonstrate rich electromechanical behavior and could be advantageous in applications. In this work, we explore implementation of two models describing axisymmetric behavior of initially curved circular micro plates, subjected to a distributed nonlinear electrostatic force. While both models are based on the Kirchoff hypothesis and on the nonlinear Föppl von Kármán (FvK) strain-displacements relations, the second model employs the Berger approximation, which significantly simplifies the formulation and describes the plate by a single governing equation. In both cases, the solution is based on the Galerkin decomposition with buckling modes of an initially flat plate used as the base functions. To track the unstable branches of the equilibrium curve, continuation methods in conjunction with the Riks algorithm are implemented. The validation of the models is conducted for two loading cases, namely “mechanical” deflection-independent load, and electrostatic displacement-dependent load. Results of a finite elements (FE) analysis, as well as of a finite differences (FD) solution of the differential equations, were used as a reference. We estimate the accuracy of the RO models and provide recommendations concerning the number of degrees of freedom (DOF) required to reach a desired accuracy. We show that a simple RO model based on Berger plate theory, can be conveniently used for analysis of electrostatically actuated plates with low initial curvature and small thickness to electrostatic gap ratio. [ABSTRACT FROM AUTHOR]

In this study, the nonlinear vibration response and instability behavior of double-walled carbon nanotubes (DWCNTs) subjected to electrostatic actuation are investigated. Both deterministic and stochastic modeling are considered. In deterministic modeling, two Euler-Bernoulli beams are adopted to model the inner and outer layers of the DWCNTs. The governing equations of motion are solved by Galerkin and multiple scales methods for primary and secondary resonances. The frequency response of the system is obtained as a function of some of the system parameters. The stability analysis of the response is performed and bifurcation points are obtained. In stochastic modeling, the finite element formulation and the perturbation technique are adopted to investigate the vibration response and instability behavior of the DWCNTs under electrostatic actuation. Note that both layers of the DWCNTs vibrate with the same frequency under the primary and secondary resonance conditions. The nonlinear vibration behaviors in both deterministic and stochastic cases are very similar to each other, except in the stochastic case, some statistical quantities such as the mean values and standard deviations of the displacements of DWCNTs must be considered and dealt with in the whole process. [ABSTRACT FROM AUTHOR]

This paper presents a new approach based on Extended Kantorovich Method to simulate the static response of micro-plates to electrostatic actuation. The presented model accounts for the electric force nonlinearity of the excitation as well as the applied in-plane loads. Using a one term Galerkin approximation and following the extended Kantorovich procedure, the nonlinear partial differential equation governing the micro-plate deflection reduces to two un-coupled nonlinear ordinary differential equations with constant coefficients which can be solved iteratively with rapid convergence to yield the desired solution. A parametric study has also been performed to characterize the effect of various design parameters such as applied in-plane loads and micro-plate aspect ratio to pull-in limits of micro-plates. Results in some specific cases have been validated, comparing them with other theoretical and experimental findings reported in the literature as well as the results of the finite element simulation of the problem. It is shown that rapid convergence, high precision and independency of initial guess function make extended Kantorovich method an effective and accurate design tool for design optimization of micro-plates under electrostatic actuation. [ABSTRACT FROM AUTHOR]

An analytical method is proposed to accurately estimate the pull-in parameters of a micro- or nanocantilever beam elastically constrained by a rotational spring at one end. The system is actuated by electrostatic force and subject to Casimir or van der Waals forces according to the beam size. The deflection of the beam is described by a fourth-order nonlinear boundary value problem, or equivalently in terms of a nonlinear integral equation. New a priori analytical estimates on the solution from both sides are first derived and then lower and upper bounds for the pull-in parameters are obtained, with no need of solving the nonlinear boundary value problem. The lower and upper bounds turn out to be very close each other and in excellent agreement with the numerical results provided by the shooting method. The approach also provides accurate predictions for the pull-in parameters of a freestanding nanoactuator. [ABSTRACT FROM AUTHOR]

By integrating a triboelectric nanogenerator (TENG) and an electrostatic actuation system (EAS), two kinds of self-powered EAS are designed for manipulating the movement of both microfluid and tiny solid objects. The mechanical triggering of the TENG can generate an extremely high electrostatic field inside EAS and thus the tiny object (liquid or solid) in the EAS can be actuated by the Coulomb force. Accordingly, the tribomotion of TENG can be used as both the driving power and control signal for the EAS. The TENG device with a contact surface of 70 cm2 can drive a water droplet to move across a gap of 2 cm. Meanwhile, the confluence of two droplets with the same charge polarity and different components can also be induced and controlled by this self-powered EAS. In addition, based on the same working principle, this EAS also demonstrates its capability for manipulating solid object (e.g., a tiny steel pellet). By sliding the Kapton film along a segmented annular electrode, the tiny pellet can well follow the rotated motion of the Kapton film. The demonstrated concept of this self-powered EAS has excellent applicability for various micro/miniature actuation devices, electromechanical systems, human-machine interaction, etc. [ABSTRACT FROM AUTHOR]

An eight-stage reconfigurable charge pump for microelectromechanical system (MEMS) electrostatic actuation was designed and fabricated in a standard 0.13- \mu \textm CMOS technology. The purpose of the circuit is to generate sufficient on-chip voltages that are continually reconfigurable for MEMS actuation. Small 1-pF pumping capacitors are used to reduce the circuit area. Digitally programmable voltage levels can be outputted by varying the number of stages and the clock drive levels dynamically. Reduced power consumption is achieved using a variable frequency clock. The circuit attains a measured maximum output voltage of 10.1 V from a 1.2 V supply. Its nominal clock is set to 50 MHz. The circuit has a compact area of 215 \mu \text m \times 300~\mu \textm and consumes 864 \mu \textW at a 50-MHz clock and 252 \mu \textW at an 8-MHz clock. [ABSTRACT FROM PUBLISHER]

The atomic force microscope (AFM) is an invaluable scientific tool; however, its conventional implementation as a relatively costly macroscale system is a barrier to its more widespread use. A microelectromechanical systems (MEMS) approach to AFM design has the potential to significantly reduce the cost and complexity of the AFM, expanding its utility beyond current applications. This paper presents an on-chip AFM based on a silicon-on-insulator MEMS fabrication process. The device features integrated xy electrostatic actuators and electrothermal sensors as well as an AlN piezoelectric layer for out-of-plane actuation and integrated deflection sensing of a microcantilever. The three-degree-of-freedom design allows the probe scanner to obtain topographic tapping-mode AFM images with an imaging range of up to 8\mu \mathrm m\times 8\mu \mathrm m in closed loop. [2016-0211] [ABSTRACT FROM PUBLISHER]

The electrical response of vibrating, electrostatically driven microelectromechanical and nanoelectromechanical system (MEMS and NEMS) devices was measured electrically using impedance spectroscopy. A physical model of this structure was elaborated, allowing us to predict the electrical response based on the dimensions and mechanical properties of the structure as well as the measurement conditions. This result was correlated with the results of the electrical equivalent circuit model. The physical model predicted that the magnitude of the electrical response is inversely proportional to the distance between the electrodes to the power of 4. Such a strong dependence was verified experimentally using a vibrating electrostatically driven MEMS operating in vacuum. The verified physical model is suitable for optimization of MEMS structures designed for electrical detection of vibrations. • Specialized doubly-clamped cantilevers were produced with low parasitic capacitance. • Physical and electrical models of electrostatically driven MEMS were calculated. • Electrostatically driven MEMS vibrations can be measured with impedance analyzer. • Impedance response depends extremely strongly on the electrodes spacing. [ABSTRACT FROM AUTHOR]

The paper presents the effects of fluid flow on the static and dynamic properties of carbon nanotubes that convey a viscous fluid. The mathematical model is based on the modified couple stress theory. The effects of various fluid parameters and boundary conditions on the pull-in voltages are investigated in detail. The applicability of the proposed system as nanovalves or nanosensors in nanoscale fluidic systems is elaborated. The results confirm that the nanoscale system studied in this paper can be properly applied for these purposes.

In this work, we use the micro-masonry technique to fabricate nanoplate resonators with integrated electrostatic actuation and capacitive detection in a few steps. Our approach is an alternative solution to the current fabrication methods used to create membranes and plates that usually rely on the selective etching of a sacrificial layer. Highly doped silicon plates were transfer-printed using microtip elastomeric stamps onto insulated bases displaying cavities in order to form suspended structures with airtight gaps. By post-processing adequate interconnections, the fabricated resonators were actuated and their resonant frequency measured in a fully integrated manner. The tested nanoplate devices behave as predicted by theory and offer quality factors of more than 30 in air. Because the cavities used for electrostatic actuation/sensing of the devices are tight sealed, nanoplates fabricated via micro-masonry are suitable for liquid environment operation and are thus a promising solution for biosensing applications.

Microelectromechanical systems (MEMS) resonators require fast, accurate, and cost-effective testing for mass production. Among the different test methods, frequency domain analysis is one of the easiest and fastest. This paper presents the measurement uncertainties in electrostatically actuated MEMS resonators, using frequency domain analysis. The influence of the applied driving force was studied to evaluate the measurement variations in resonant characteristics, such as the natural frequency and the quality factor of the resonator. To quantify the measurement results, measurement system analysis (MSA) was performed using the analysis of variance (ANOVA) method. The results demonstrate that the resonant frequency ( f r ) is mostly affected by systematic error. However, the quality (Q) factor strongly depends on the applied driving force. To reduce the measurement variations in Q factor, experiments were carried out to study the influence of DC and/or AC driving voltages on the resonator. The results reveal that measurement uncertainties in the quality factor were high for a small electrostatic force.

This study proposes a novel shape optimization methodology based on evolutionary algorithms to maximize the harvesting energy from piezoelectric energy harvester stimulated by the β -emitted radioisotope. The parametric width function is used to model the piezoelectric layer non-prismatically. All the geometrical dimensions as well as parameters related to the parametric width function are optimized using the metaheuristic algorithms The piezoelectric layer partially covers the beam to obtain the optimal location of the piezoelectric layer. The pull-in instability causes the discharge in the system, and the piezoelectric layer converts the vibration of the released microcantilever into electricity. The nonlinear effects of electrostatic force and geometry are taken into account, and the differential equations governing the system are discretized utilizing the exact mode shapes of the system considering the geometrical effects of non-uniform microcantilever and the piezoelectric layer. The robust chaotic Harris Hawk optimization (RCHHO) algorithm is proposed for finding the optimal shape of the system. The performance of the proposed algorithm is compared with various metaheuristic algorithms in the literature. After optimizing the shape of the piezoelectric layer, the maximum voltage produced with the optimal model using the presented method was 8.105 times that of the classic model with rectangular piezoelectric layer used in previous works. Moreover, the maximum energy and average energy harvested in the optimal model were 61 and 7.22 times, respectively, of the non-optimal model. • Shape optimization of PEH under electrostatic actuation is investigated. • An optimization-based approach for enhancing the energy in PEH is developed. • The optimal non-prismatic shape for the piezoelectric layer is obtained. • The proposed method performs better than other algorithms in the literature. • The efficiency of the proposed method is demonstrated statistically. [ABSTRACT FROM AUTHOR]

In this article, the pull-in instability and dynamic characteristics of electrostatically actuated suspended microchannel resonators are studied. A theoretical model is presented to describe the pull-in effect of suspended microchannel resonators by considering the electrostatic field and the internal fluid. The results indicate that the system is subjected to both the pull-in instability and the flutter. The former is induced by the applied voltage which exceeds the pull-in value while the latter occurs as the velocity of steady flow get closer to the critical velocity. The statically and dynamically stable regions are presented by thoroughly studying the two forms of instability. It is demonstrated that the steady flow can remarkably extend the dynamic stable range of pull-in while the applied voltage slightly decreases the critical velocity. It is also shown that the dc voltage and the steady flow can adjust the resonant frequency while the ac voltage can modulate the vibrational amplitude of the resonator. [ABSTRACT FROM AUTHOR]

In this research, based on nonlocal elasticity theory, static and dynamic analysis of an elastic homogeneous nanotube conveying fluid with clamped - clamped boundary conditions is investigated. The nanotube is under electrostatic actuation and magnetic field with considering the surface effects, mechanical and thermal force. Transverse displacement of the nanotube consists of two parts static and dynamic displacement. In this study, the static displacement is calculated by using the weighted residual method and instability and vibration frequency is analyzed by applying the generalized differential quadrature method. By applying a voltage greater than the critical value (called Pull - in voltage) the nanotube may undergo instability. In this investigation, the effect of various parameters such as velocity of fluid, length scale parameter, magnetic field, electrostatically voltage, effects of surface layer and thermal loading on the static displacements, natural frequency and Pull - in voltage of the nanotubes conveying fluid has been studied. Finally, the validity of the results by comparing them with the results of the numerical methods in previous research is investigated, in which there is very good agreement between the results of the present work and previous studies. The results show that the length scale parameter is significant parameter in the system's Pull - in voltage and its increasing lead to decreasing the Pull - in voltage. Also, it is shown that the dimensionless frequency and the static displacements, respectively, is decreased and increased with increases in the applied voltage. [ABSTRACT FROM AUTHOR]

We propose a multiphysics model to investigate the nonlinear dynamics of two coupled nanocantilevers under electrostatic actuation and 1:1 internal resonance (IR). We demonstrate that the region below the first pull-in instability is governed by the veering phenomenon between the modes. IR conditions are analyzed in the veering region and the modulation equations are derived and numerically solved. Remarkably, the first NEMS imposes its bifurcation topology to the second one and the energy transfer between the two oscillators can be controlled by the actuation voltages. [ABSTRACT FROM AUTHOR]

The paper focuses on a MEMS mass detection sensor using mode localization and electrostatic actuation to counterbalance the manufacturing defects. The sensor is composed of two cantilevers with different lengths, connected together with a weak mechanical spring. A DC voltage is applied on the shortest beam so that the system is balanced when no mass is added, allowing the manufacturing defects to be compensated. Harmonic simulations were carried out using COMSOL Multiphysics®. It shows for example that for 100 μm/90 μm long, 20 μm width and 2 μm thick cantilevers, a DC voltage of 60.4 V is necessary to balance the system. In these conditions and with a quality factor of 1500, a 17.5pg added mass will create a relative change of 22% in the modal amplitude of the first mode of the longest cantilever while the relative shift in the resonant frequency is only 0.24%. [ABSTRACT FROM AUTHOR]

We present analytic and computational studies of the dynamical behavior of an undamped electrostatic MEMS actuator with one-degree of freedom subject to a Casimir force. In such a situation, the well-known mathematical difficulty associated with an inverse quadratic term due to a Coulomb force is supplemented with an inverse quartic term due to the joint application of a Casimir force. We show that the small Coulomb and Casimir force situations, described by sufficiently low values of two positive parameters, λ and μ, respectively, are characterized by one-stagnation-point periodic motions and there exists a unique critical pull-in curve in the [ABSTRACT FROM AUTHOR]

We present an experimental and theoretical investigation of the static and dynamic behavior of electrostatically coupled laterally actuated silicon microbeams. The coupled beam resonators are composed of two almost identical flexible cantilever beams forming the two sides of a capacitor. The experimental and theoretical analysis of the coupled system is carried out and compared against the results of beams actuated with fixed electrodes individually. The pull-in characteristics of the electrostatically coupled beams are studied, including the pull-in time. The dynamics of the coupled dual beams are explored via frequency sweeps around the neighborhood of the natural frequencies of the system for different input voltages. Good agreement is reported among the simulation results and the experimental data. The results show considerable drop in the pull-in values as compared to single microbeam resonators. The dynamics of the coupled beam resonators are demonstrated as a way to increase the bandwidth of the resonator near primary resonance as well as a way to introduce increased frequency shift, which can be promising for resonant sensing applications. Moreover the dynamic pull-in characteristics are also studied and proposed as a way to sense the shift in resonance frequency. [ABSTRACT FROM AUTHOR]

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] [ABSTRACT FROM AUTHOR]

This paper demonstrates experimentally, theoretically, and numerically for the first time, a wide-range tunability of an in-plane clamped–clamped microbeam, bridge, and resonator actuated electrothermally and electrostatically. Using both actuation methods, we demonstrate that a single resonator can be operated at a wide range of frequencies. The microbeam is actuated electrothermally by passing a dc current through it, and electrostatically by applying a dc polarization voltage between the microbeam and the stationary electrode. We show that when increasing the electrothermal voltage, the compressive stress inside the microbeam increases, which leads eventually to its buckling. Before buckling, the fundamental frequency decreases until it drops to very low values, almost to zero. After buckling, the fundamental frequency increases, which is shown to be as high as twice the original resonance frequency. Adding a dc bias changes the qualitative nature of the tunability both before and after buckling, which adds another independent way of tuning. This reduces the dip before buckling, and can eliminate it if desired, and further increases the fundamental frequency after buckling. Analytical results based on the Galerkin discretization of the Euler Bernoulli beam theory are generated and compared with the experimental data and simulation results of a multi-physics finite-element model. A good agreement is found among all the results. [2015-0341] [ABSTRACT FROM PUBLISHER]

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.

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.

More than 55% of electronic failures are caused by damage from localized overheating. Up to now, there is still no efficient method for targeted temperature control against localized overheating. Although some existing thermal management devices handle this issue by full coverage cooling, it generates a lot of useless energy consumption. Here, a highly efficient pixel-matrix electrocaloric (EC) cooling device is reported, which can realize a targeted and differential thermal management. The modified poly(vinylidene fluoride-tertrifluoroethylene-chlorofluoroethylene) reaches a large adiabatic temperature change of 7.8 K and is more suitable for thermal transfer and electrostatic actuation at high frequencies. All active pixels in the EC cooling device exhibit a stable temperature span of 4.6 K and a heat flux of 62 mW cm -2 , which is more than twice that of the one-layer EC device. Each refrigeration pixel can be independently controlled and effectively cooled down the localized overheating site(s) in situ. The surface temperature of the simulated central processing unit decreases by 33.2 K at 120 s after applying this EC device. Such a compact, embeddable, low cost, and active solid-state pixel-matrix cooling device has great potential for localized overheating protection in microelectronics., (© 2023 Wiley-VCH GmbH.)

A photonic wire antenna embedding individual quantum dots (QDs) constitutes a promising platform for both quantum photonics and hybrid nanomechanics. We demonstrate here an integrated device in which on-chip electrodes can apply a static or oscillating bending force to the upper part of the wire. In the static regime, we achieve control over the bending direction and apply at will tensile or compressive mechanical stress on any QD. This results in a blue shift or red shift of their emission, with direct application to the realization of broadly tunable sources of quantum light. As a first illustration of operation in the dynamic regime, we excite the wire fundamental flexural mode and use the QD emission to detect the mechanical vibration. With an estimated operation bandwidth in the GHz range, electrostatic actuation opens appealing perspectives for the exploration of QD-nanowire hybrid mechanics with high-frequency vibrational modes.

Diaphragm micropumps are the most common type among indirectly driven micropumps. The elastic diaphragm is deflected using a bias voltage and then driven to vibrate around its deflected position by a harmonic AC load to produce a flow rate. This paper investigates the nonlinear resonant behavior of a circular elastic diaphragm interacting with incompressible and inviscid liquids inside a cylindrical chamber containing a central discharge opening. The governing equations of the system are derived by taking into account the nonlinear electrostatic force and fluid pressure exerted upon the diaphragm which is formulated using the linear form of Bernoulli's equation. In the modeling stage, the kinematic and compatibility conditions are incorporated into the elastic vibration of the diaphragm. The method of multiple scales is used to obtain an approximate analytical solution to the nonlinear resonant curves of the transverse oscillation amplitudes. It is shown that, as the DC voltage increases, the system exhibits softening behavior. The results also show that decreasing the discharge diameter further bends the frequency response cure to left side, which is an indication of increase in the system nonlinearity. The effects of micropump chamber height on the frequency curves were also studied and showed that softening behavior increases with decreasing chamber height. In addition, it was found that the electrical and inertial properties of the operating fluid can change the resonant curves significantly. [ABSTRACT FROM AUTHOR]

The paper analyzes the nonlinear electromechanical behavior of nanobeams under electrostatic actuation based on the recently developed consistent couple stress theory. The effects of interatomic forces including the Casimir force and van der Waals interaction are analyzed. The static and dynamic pull-in instabilities are investigated for the nanobeams with cantilever and doubly clamped boundary conditions. According to the results, the applied theory leads to models with higher stiffness and consequently, higher frequencies and pull-in voltages. The results prove that, for large gaps, the cantilever nanobeams show softening behavior and the doubly clamped ones presents hardening characteristics. In the nonlinear dynamic part of the research, bifurcation and chaos appear in the latter. Moreover, the formulation and physical concepts applied in some literature are scrutinized and the sources of errors are studied. [ABSTRACT FROM AUTHOR]

We present an experimental and theoretical investigation of a micromachined mirror under a mixed-frequency signal composed of two harmonic ac sources. The micromirror is made of polyimide as the main structural layer. The experimental and theoretical dynamics are explored via frequency sweeps in the desired neighborhoods. One frequency is fixed while the other frequency is swept through a wide range to study the dynamic responses. To simulate the behavior of the micromirror, it is modeled as a single degree of freedom system, where the parameters of the model are extracted experimentally. A good agreement is reported among the simulation results and the experimental data. These responses are studied under different frequencies and input voltages. The results show interesting dynamics, where the system exhibits primary resonance and combination resonances of additive and subtractive type. The mixed excitation is demonstrated as a way to increase the bandwidth of the resonator near primary resonance, which can be promising for resonant sensing applications in the effort to increase the signal-noise ratio over extended frequency range. [2014-0286] [ABSTRACT FROM PUBLISHER]

We present an electrostatic transducer in which voltage remains constant while charge is stored or extracted from the device. We achieve this by designing a nonlinear mechanical spring, which exactly counteracts the nonlinearity associated with electrostatic attraction forces. In essence, the new device responds like a rechargeable battery, only that here we store electric energy in elastic deformation, whereas in common batteries, electric energy is stored as chemical potential. The capacitance of the presented test devices is currently too small to be practical, and we are not, by any means, suggesting that this transducer can replace chemical rechargeable batteries. Nevertheless, some necessary steps toward constructing a more viable device with larger energy density are discussed. [2014-0093] [ABSTRACT FROM PUBLISHER]

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 Si 3 N 4 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 Si 3 N 4 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. [ABSTRACT FROM AUTHOR]

In this paper, a comprehensive model of a piezoelectric laminated micro-switch subjected to electrostatic excitation, which accounts for the nonlinearities due to inertia, curvature, and electrostatic forces, is presented. Dynamic equations of this model is derived by the Lagrange method and solved by the Galerkin method using five modes. The laminated micro-switch is assumed as an elastic Euler–Bernoulli beam, and the piezoelectric material is bonded onto a portion of it. The electrostatic actuation results are compared with other existing experimental results. Whereas the major drawback of electrostatically actuated micro-switches is the high driving voltage, using the piezoelectric materials in these systems can provide less driving voltage. The effect of variation in the length, thickness, and applying voltage of the piezoelectric materials on mechanical characterizations is discussed. The aim of this work is design and control of a micro-switch using three different methods: the softening effect due to electrostatic actuation, the hardening effect due to piezoelectric materials, and varying the length and thickness of the piezoelectric materials. Also, this model can be used to design an actuator-sensor smart micro device. [ABSTRACT FROM AUTHOR]

Motivated by specific applications, electrostatically actuated bistable arch shaped micro-nano resonators have attracted growing attention in the research community in recent years. Nevertheless, some issues relating to their nonlinear dynamics, including the possibility of chaos, are still not well known. In this paper, we investigate the chaotic vibrations of a bistable resonator comprised of a double clamped initially curved microbeam under combined harmonic AC and static DC distributed electrostatic actuation. A reduced order equation obtained by the application of the Galerkin method to the nonlinear partial differential equation of motion, given in the framework of Euler-Bernoulli beam theory, is used for the investigation in this paper. We numerically integrate the obtained equation to study the chaotic vibrations of the proposed system. Moreover, we investigate the effects of various parameters including the arch curvature, the actuation parameters and the quality factor of the resonator, which are effective in the formation of both static and dynamic behaviors of the system. Using appropriate numerical tools, including Poincaré maps, bifurcation diagrams, Fourier spectrum and Lyapunov exponents we scrutinize the effects of various parameters on the formation of chaotic regions in the parametric space of the resonator. Results of this work provide better insight into the problem of nonlinear dynamics of the investigated family of bistable micro/nano resonators, and facilitate the design of arch resonators for applications such as filters. [ABSTRACT FROM AUTHOR]

Fast settling, accurate positioning, and a large tilt angle range are important for MEMS mirrors. Here, residual vibration and the pull-in phenomenon--both major problems affecting the performance of an electrostatically actuated mirror--are investigated. Based on the analysis of a nonlinear proportional-derivative (PD) control with parametric uncertainties, a closed-loop feedback control strategy with a combined control scheme is proposed. This method, combining nonlinear PD control and sliding mode control (SMC), not only inherits the virtue of a good dynamic performance from the nonlinear PD control, but also further improves the robustness with SMC for such MEMS mirrors. Furthermore, this method can be convenient when tuning design gains of the controller to obtain a faster error convergence rate. Numerical simulation results show that with this combined control scheme not only the transient response of the MEMS mirror is improved but the influence of parametric uncertainties and external disturbance is also reduced. [ABSTRACT FROM AUTHOR]

The tactile sensation is the human interact with machines in the form of felt sensations in the hand or other parts of body skin. This paper presents a film type actuator for haptic feedback devices, based on electrostatic actuation of plasticized cellulose acetate stacked membranes actuator, which is fabricated and evaluated for suitability of haptic feedback devices. The stacked membranes actuator shows many promising properties such as high transparency, lightweight, wide range of actuation frequency and high vibration acceleration for instance. The actuator structure shows intense vibration acceleration due to several layers of stacked membranes associated with the intensified electrostatic attraction force between chargeable cellulose acetate membranes. Experiment for measuring vibrational acceleration was conducted over a wide frequency range and actuation voltage to prove actuator's great potential application as tactile actuator of haptic feedback devices. In addition, the operating principle, fabrication method and performance measurements are explained in details. [ABSTRACT FROM AUTHOR]

This paper presents the deflection and pull-in instability of the double-walled carbon nanotubes with different dimensions and boundary conditions. Molecular dynamic technique is applied to model the desired behaviors of the nano systems. The effects of cross-linking between the carbon walls are investigated on the pull-in charge. In addition, the influences of axial stretching on the pull-in charge and vibrational frequencies of the carbon nanotubes are scrutinized. The effects of electrostatic charge distribution on the vibration amplitude are also reported. [ABSTRACT FROM AUTHOR]

We present a frequency-domain method to measure angular speeds using electrostatic micro-electro-mechanical system actuators. Towards this end, we study a single-axis gyroscope made of a micro-cantilever and a proof-mass coupled to two fixed electrodes. The gyroscope possesses two orthogonal axes of symmetry and identical flexural mode shapes along these axes. We develop the equations of motion describing the coupled bending modes in the presence of electrostatic and Coriolis forces. Furthermore, we derive a consistent closed-form higher-order expression for the natural frequencies of the coupled flexural modes. The closed-form expression is verified by comparing its results to those obtained from numerical integration of the equations of motion. We find that rotations around the beam axis couple each pair of identical bending modes to produce a pair of global modes. They also split their common natural frequency into a pair of closely spaced natural frequencies. We propose the use of the difference between this pair of frequencies, which is linearly proportional to the speed of rotation around the beam axis, as a detector for the angular speed. [ABSTRACT FROM PUBLISHER]

Bi-axial or two-dimensional (2D) MEMS micro-scanning mirrors (or micro-scanners) are considered the key component for laser scanning projectors. Many studies have shown the mechanical characterization of fabricated devices driven by various mechanisms. This work presents an electrostatically driven bi-axial micro-scanner with capacitive position sensing for Lissajous scanning projection. With the added sensing capability, a PLL (phase-locked loop)-based oscillator loop is developed to sustain mechanical resonance and to provide mirror position information, which are equally important for practical applications. The micro-scanner and the required circuits are implemented using bulk micromachining SOI (silicon on insulator) and 0.35-μm CMOS (complementary metal oxide semiconductor) technologies, respectively. The measured resonant frequencies of the bi-axial micro-scanner for the slow and fast-axis scans are 1.4 and 21.9 kHz, and the associated optical scan angles are 22.5° and 40°, respectively, under pulse modulation of 48 and 115 V pp . The fabricated micro-scanner is adopted in a laser beam scanning projection system to achieve WVGA (852 × 480) display resolution. [ABSTRACT FROM AUTHOR]