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This article provides an updated review of advances in the field of mirror-based laser beam deflectors, including laser scanners. We propose a taxonomy of these techniques based mainly on the principle of operation, and we direct the reader to the literature related to the individual subgroups of deflectors and to some of the most representative examples. This review is limited to the continuous or quasi-continuous mode of operation. The following techniques for steering mirror deflection are distinguished: electromagnetic, piezo, electrothermal, electrostatic and pressure actuators. Electromagnetic voice coils and piezo deflectors form one subgroup of fast steering mirror techniques. The main technical parameters and the useable properties of each group of techniques are specified. This review forms the first part of a general overview of laser beam deflectors, which will continue with a review of refractive and diffraction deflectors. [Display omitted] • The first part of a general overview of laser beam deflectors, which will next cover refractive and diffraction deflectors. • Actualised overview of advances in specular reflection by light laser beam deflectors, including laser scanners. • New approach and taxonomy of the presented techniques. • References to the earlier reviews of subgroups. • Main steering mirror techniques distinguished: electromagnetic, piezo, electrothermal, electrostatic and pressure actuators. [ABSTRACT FROM AUTHOR]

MEMS electrostatic actuators can suffer from a high control voltage and a limited displacement range, which are made more prevalent by the pull-in effect. This study explores a tri-electrode topology to enable a reduction in the control voltage and explores the effect of various solid materials forming the space between the two underlying stationary electrodes. Employing solid dielectric material simplifies fabrication and can reduce the bottom primary electrode's fixed voltage. Through numerical analysis, different materials were examined to assess their impact. The results indicate that the primary electrode's fixed voltage can be reduced with an increase in the dielectric constant, however, with the consequence of reduced benefit to control voltage reduction. Additionally, charge analysis was conducted to compare the actuator's performance using air as the gap-spacing material versus solid materials, from the perspective of energy conservation. It was found that solid materials result in a higher accumulated charge, reducing the need for a high fixed voltage. [ABSTRACT FROM AUTHOR]

Muscles in animals and actuation systems in advanced robots consist not of the actuation component alone; the motive, dissipative, and proprioceptive components exist in a complete set to achieve versatile and precise manipulation tasks. We present such a system as a linear electrostatic actuator package incorporated with sensing and braking components. Our modular actuator design is composed of these actuator films and a dielectric fluid, and we examine the performance of the proposed system both theoretically and experimentally. In addition, we introduce a mechanism of optical proprioceptive sensing utilizing the Moiré pattern innately generated on the actuator surface, which allows high-resolution reading of the position of the actuator without noise. The optical sensor is also capable of measuring the force exerted by the actuator. Lastly, we add an electroadhesive brake in the package in parallel with the actuator, introducing a method of mode switching that utilizes all three components and presenting control demonstrations with a robot arm. Our actuation system is compact and flexible and can be easily integrated with various robotic applications. [ABSTRACT FROM AUTHOR]

Electrostatic micro electro mechanical system (MEMS) as an actuator is one of the most widely used actuators in micro dimension systems. Due to the high nonlinear characteristics in the micro actuator's model, nanopositioning has been a challenging problem for researchers. In addition, the system is subject to uncertainties associated with the system's unknown parameters and un‐modelled dynamics. Thus, to overcome these problems and achieve precise positioning a robust non‐linear control method is required. In this research, an optimal voltage control algorithm is initially designed utilizing the nonlinear predictive control approach. The Taylor expansion sequence is used to estimate the final position of the parallel plate actuator. To approximate unknown disturbances, a radial basis function neural network (RBFNN) has been designed. The estimations made were used in updating the control input in the previous step, and the obtained results showed an increase in the robustness of the designed controller. The stability of the closed‐loop system is also analyzed. Finally, a comparison is accomplished between the potential of the proposed controller and that of the feedback linearization and sliding mode controllers. The obtained results indicate better performance and robustness of the suggested controller. [ABSTRACT FROM AUTHOR]

Guiding mechanisms are among the most elementary components of MEMS. Usually, a spring is required to be compliant in only one direction and stiff in all other directions. We introduce triangular springs with a preset tilting angle. The tilting angle lowers the reaction force and implements a constant reaction force. We show the influence of the tilting angle on the reaction force, on the spring stiffness and spring selectivity. Furthermore, we investigate the influence of the different spring geometry parameters on the spring reaction force. We experimentally show tilted triangular springs exhibiting constant force reactions in a large deflection range and a comb-drive actuator guided by tilted triangular springs. [ABSTRACT FROM AUTHOR]

Micromachined electric field mills have received much interest for the measurement of DC fields; however, conventional designs with lateral moving shutters could have shutter lifting in the presence of strong fields, which affects their performance. This paper presents a MEMS electric field mill utilizing a vertical movement shutter to address this issue. The sensor is designed and fabricated based on a flexible PCB substrate and is released using a laser-cutting process. The movement of the shutter is driven by an electrostatic actuator. When the driving signal is a sine wave, the shutter moves in the same direction during both the positive and negative half-periods. This facilitates the application of a lock-in amplifier to synchronize with the signal at twice the frequency of the driving signal. In experimental testing, when the vertical shutter is driven at a resonance of 840 Hz, the highest sensitivity of the sensor is achieved and is measured to be 5.1 V/kVm−1. The sensor also demonstrates a good linearity of 1.1% for measuring DC electric fields in the range of 1.25 kV/m to 25 kV/m. [ABSTRACT FROM AUTHOR]

Developing small‐scale, lightweight, and flexible devices with integrated microactuators is one of the critical challenges in wearable haptic devices, soft robotics, and microrobotics. In this study, a novel fabrication process that leverages the benefits of 3D printing with two‐photon polymerization and flexible printed circuit boards (FPCBs) is presented. This method enables flexible microsystems with 3D‐printed electrostatic microactuators, which are demonstrated in a flexible integrated micromirror array and a legged microrobot with a mass of 4 mg. 3D electrostatic actuators on FPCBs are robust enough to actuate the micromirrors while the device is deformed, and they are easily integrated with off‐the‐shelf electronics. The crawling robot is one of the lightest legged microrobots actuated without external fields, and the legs actuated with 3D electrostatic actuators enable a locomotion speed of 0.27 body length per second. The proposed fabrication framework opens up a pathway toward a variety of highly integrated flexible microsystems. [ABSTRACT FROM AUTHOR]

The article focuses on the introduction of a novel pneumatic artificial muscle design known as X-crossing pneumatic artificial muscles (X-PAMs). Topics include a significant advancement in artificial muscle design, it employ an X-crossing mechanism that directly converts linear motion along the actuator axis, and the robustness of X-PAMs in extreme conditions, such as high temperatures and underwater environments.

The ability to mechanically stimulate touch receptors over the entire body is a key feature for fully immersive and highly realistic virtual reality experience. Haptic stickers, flexible arrays of HAXELs (hydraulically amplified TAXels), that enable cutaneous haptics over nearly all parts of the body, are reported. HAXELs are zipping electrostatic actuators that combine stretchable elastomers and high permittivity flexible films to generate both high strains and high forces, from DC to 200 Hz. A fabrication process that enables scaling HAXELs from 2 to 15 mm in diameter is presented, allowing to tailor the actuators to different body parts and to wearables such as wrist‐watches. The different sizes of HAXELs generate blocked forces from 100 to 800 mN, with DC displacements from 100 to 850 µm, well above sensation thresholds. Haptics tests of Haptic Stickers, 5 × 5 arrays of 10 mm diameter devices, on palms, back of the hand, neck, arm, and back of a dozen volunteers, are done with users reporting high pattern recognition success on many body locations. The Haptic Stickers uniquely offer a thin and lightweight form‐factor, which does not limit the freedom of motion of the user, compatible with untethered scenarios. [ABSTRACT FROM AUTHOR]

In this paper, we present a new structure of a micromachined tunable capacitor using a combination of piezoelectric and electrostatic parallel-plate actuators. Electrostatic parallel-plate capacitors have a low capacitive tuning ratio due to the "pull-in" instability. Therefore, to increase the capacitive tuning ratio, an electrostatic parallel-plate actuator, as well as a piezoelectric two-directional actuator, was used in this work. To verify the theoretical results, they were compared to the simulation results achieved by COMSOL and HFSS software. According to the analytical and simulation results, the proposed structure has a maximum capacitive tuning range of 2180% by applying 5.6 V for the electrostatic parallel-plate actuator and ± 8 V for the piezoelectric actuator. [ABSTRACT FROM AUTHOR]

This study discusses the problem of reducing the influence of external destabilizing factors on microelectromechanical angular velocity transducers. It reveals that for measurements of small angular velocities of the order of a few to tens of microradians per second, micro optoelectromechanical transducers that contain optical readout units are preferable to use. The effect of linear acceleration on the characteristics of a frame micro optoelectromechanical angular velocity transducer with two optical readout channels is analyzed. We consider two methods of angular velocity measurement error compensation when the frame micro optoelectromechanical transducer is under the influence of linear acceleration. The two compensation methods implement amplification factor control and force feedback, respectively. The readout unit, based on the optical tunnel effect and used for precision measurement of the amplitude of oscillations of the sensing element, is experimentally investigated; a function of converting the amplitude of oscillations of the sensing element into voltage is obtained. The possibility of forming transducer output signals, which are proportional to angular velocity and linear acceleration, is presented. The dependences of changes in the amplification factor on the zero off set voltage, proportional to the acting linear acceleration, are presented for different ranges of angular velocities. A system, consisting of a low-pass filter (LPF), a proportionalintegral regulator, and an additional pair of comb-type electrostatic actuators, is proposed for compensating the force effect of a destabilizing linear acceleration. Additional actuators are arranged perpendicular to the actuators that excite the primary oscillations. The measurement error of angular velocity when using the two methods of compensation, respectively, has been estimated. The proposed technical solutions enable to increase the accuracy of angular velocity measurements by micro optoelectromechanical transducers used in navigation and orientation systems of unmanned aircrafts of various types. [ABSTRACT FROM AUTHOR]

Test masses of future laser interferometric gravitational-wave detectors will be made of high-purity silicon and cooled, in particular, to 123 K in the LIGO Voyager project. Electrostatic actuators are supposed to be used to tune the test mass position. Capacitive coupling of the actuator electrodes with the silicon test mass results in the mechanical loss caused by electric currents flowing in silicon having a finite resistivity. This loss is a cause of additional thermal noise. In this study, we present the results of temperature dependence of the electric field induced loss in the bending vibration mode of commercial disk-shaped undoped silicon wafers in the temperature range of 100–295 K. [ABSTRACT FROM AUTHOR]

The properties of a mechanical resonator provide a valuable ability to measure liquid density and viscosity. The viscosity of liquids is of interest to researchers in both industry and medicine. In this paper, a viscosity sensor for liquids is proposed, which is designed based on an electromechanical resonator. In the proposed sensor, a capacitor is used as an electrostatic actuator. The capacitor is also used to monitor the frequency changes of the proposed resonator. The range of displacement of the resonator and capacitor in response to different fluids under test varies according to their viscosity. The design of the proposed sensor and its electrostatic and mechanical simulations are reported in this paper. Also, the effect of viscosity of several different liquids on its performance has been analyzed and presented experimentally using a prototype. [ABSTRACT FROM AUTHOR]

The article discusses a study on biodegradable electrohydraulic soft actuators that are sustainable options for soft robotics, published in the journal "Science Advances". The study presents the development of fully biodegradable high-performance soft actuators based on various biodegradable materials and demonstrates their reliability and compatibility with commercial robot arms, encouraging wider use of biodegradable materials in soft robotics.

In this paper, the electrostatic actuator-based active vibration control of a single-wall carbon nanotube conveying fluid is studied. A double electrostatic actuator scheme is developed and its decoupling method also is proposed. Then, a novel adaptive sliding-mode control (SMC) scheme is developed. The newly proposed scheme future improves existing results from two aspects: (1) the newly proposed adaptive SMC can work well under high uncertain case in which all parameters are uncertain and the uncertainties cannot be separated from control force and (2) a double electrostatic actuators scheme which can suppress the vibration of carbon nanotube in multiple directions is designed, and a novel decoupling scheme for the two actuators is developed. The stability of the closed-loop system is analyzed by using Lyapunov stability theory. Finally, the simulation results illustrate the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

This work analyzes a built-in slider detection method for a charge-induction type electrostatic film actuator with a high surface-resistance slider. In the detection method, one stator electrode is detached from the parallel driving electrodes and is dedicated to sensing. When a slider with induced charges moves over the sensing electrode, electrostatic induction occurs in the sensing electrode, which causes an electric current. The current is converted to a voltage through a detection resistance, which will be an output of the sensing circuit. This paper provides a framework to analyze the output signal waveform and shows that the waveform consists of two components. One component is caused by driving voltage and appears regardless of the existence of a slider. The other component corresponds to the movement of a slider, which appears only when a slider is moving over the sensing electrode. Therefore, the slider can be detected by monitoring the latter component. The two components generally overlap, which makes the detection of the latter component difficult in some cases. This paper proposes a method to decouple the two components by switching the detection resistance at an appropriate time. These methods are verified using a prototype actuator that has an electrode pitch of 0.6 mm. The actuator was driven with a set of pulse voltages with an amplitude of 1000 V. The experimental results show similar waveforms to the analytical results, verifying the proposed analytical framework. The performance of the sensing method as a proximity sensor was verified in the experiments, and it was confirmed that the slider can be detected when it approaches the sensing electrode within about 3 mm. [ABSTRACT FROM AUTHOR]

Soft robotic grippers achieve increased versatility and reduced complexity through intelligence embodied in their flexible and conformal structures. The most widely used soft grippers are pneumatically driven; they are simple and effective but require bulky air compressors that limit their application space and external sensors or computationally expensive vision systems for pick verification. In this study, a multi‐material architecture for self‐sensing electrohydraulic bending actuators is presented that enables a new class of highly versatile and reconfigurable soft grippers that are electrically driven and feature capacitive pick verification and object size detection. These electrohydraulic grippers are fast (step input results in finger closure in 50 ms), draw low power (6.5 mW per finger to hold grasp), and can pick a wide variety of objects with simple binary electrical control. Integrated high‐voltage driving electronics are presented that greatly increase the application space of the grippers and make them readily compatible with commercially available robotic arms. [ABSTRACT FROM AUTHOR]

Soft robotic grippers achieve increased versatility and reduced complexity through intelligence embodied in their flexible and conformal structures. The most widely used soft grippers are pneumatically driven; they are simple and effective but require bulky air compressors that limit their application space and external sensors or computationally expensive vision systems for pick verification. In this study, a multi‐material architecture for self‐sensing electrohydraulic bending actuators is presented that enables a new class of highly versatile and reconfigurable soft grippers that are electrically driven and feature capacitive pick verification and object size detection. These electrohydraulic grippers are fast (step input results in finger closure in 50 ms), draw low power (6.5 mW per finger to hold grasp), and can pick a wide variety of objects with simple binary electrical control. Integrated high‐voltage driving electronics are presented that greatly increase the application space of the grippers and make them readily compatible with commercially available robotic arms. [ABSTRACT FROM AUTHOR]

In this study, a linear electrostatic MEMS actuator is introduced. The system consists of a MEMS cantilever beam with combined parallel-plate and electrostatic levitation forces. By using these two forcing methods simultaneously, the static response and natural frequency can be made to vary linearly with the voltage. The static response shows a linear increase of 90 nm/V and is maintained for more than 12 μ m of the tip displacement. The natural frequency shows a linear increase of 16 Hz/V and is maintained throughout a 2.9 kHz shift in the natural frequency. This wide range of linear displacement and frequency tunability is extremely useful for MEMS sensors and actuators, which suffer from the inherent nonlinearity of electrostatic forces. A theoretical model of the system is derived and validated with experimental data. Static response, natural frequency, and frequency response calculations are performed. Merging these two mechanisms enables high oscillation branches for a wide range of frequencies with potential applications in MEMS filters, oscillators, and sensors. [ABSTRACT FROM AUTHOR]

This work describes a novel micromechanical structure capable of producing out-of-plane motion from in-plane forces generated by electrostatic microelectromechanical system (MEMS) actuators. The MEMS actuator is fabricated in a commercial silicon-on-insulator (SOI) MEMS process and is anchored at two distinct locations through a pair of beams with a relatively low stiffness in the vertical direction. A comb-drive, whose fixed and moveable fingers are implemented in the same layer with a uniform thickness, is employed to create an attractive electrostatic force. This in-plane electrostatic force rotates the actuator along an axis defined by the anchors, which results in the vertical motion of a suspended platform. Due to the simple structure of the actuator, it can be readily manufactured with standard bulk micromachining processes. Experimental results demonstrate that the actuator can provide $1.02~\mu \text{m}$ of vertical displacement at a resonant frequency of 395 Hz when it is excited in air by a 10 V AC signal, while the displacement can be considerably increased in vacuum. It is further shown that the functionality of the actuator is not dependent on the type of excitation voltage; therefore, it can produce a $3.09~\mu \text{m}$ static out-of-plane motion when excited by a 40 V DC voltage. A comprehensive comparison to the published works in the literature indicates that the proposed actuator is the only SOI electrostatic MEMS actuator with a relatively thick structural layer, i.e., $10~\mu \text{m}$ , that can provide out-of-plane motion at low actuation voltage reported to date. [2022-0069] [ABSTRACT FROM AUTHOR]

We provide sufficient conditions for the existence of periodic solutions for an idealized electrostatic actuator modeled by the Liénard-type equation x ¨ + F D x , x ̇ + x = β V 2 t / 1 − x 2 , x ∈ − ∞ , 1 with β ∈ ℝ + , V ∈ C ℝ / T ℤ , and F D x , x ̇ = κ x ̇ / 1 − x 3 , κ ∈ ℝ + (called squeeze film damping force), or F D x , x ̇ = c x ̇ , c ∈ ℝ + (called linear damping force). If F D is of squeeze film type, we have proven that there exists at least two positive periodic solutions, one of them locally asymptotically stable. Meanwhile, if F D is a linear damping force, we have proven that there are only two positive periodic solutions. One is unstable, and the other is locally exponentially asymptotically stable with rate of decay of c / 2. Our technique can be applied to a class of Liénard equations that model several microelectromechanical system devices, including the comb-drive finger model and torsional actuators. [ABSTRACT FROM AUTHOR]

Electrostaticmicroelectromechanicalsystems (MEMS) actuators suffer from an instability called pull-in, wherein the movable electrode snaps onto the fixed electrode beyond a certain applied voltage. Thus, the entire allowed range is not utilized for stable operation. We propose pull-in free, low-voltage operation by using a cubic nonlinear spring with a ferroelectric negative-capacitance hybrid MEMS actuator. We use a physics-based framework based on the energy landscape to illustrate stability improvement. This framework uses energy–displacement and voltage–displacement plots for analysis. We predict that the actuator can operate in three distinct modes: 1) monostable; 2) bistable; and 3) always-stable, based on the value of the cubic spring constant. We also estimate the threshold values of the cubic spring constant that demarcate the three modes of operation. By proper choice of the cubic spring constant, we predict pull-in free, low-voltage operation of the hybrid actuator, when compared to the standalone MEMS actuator. The results obtained are in agreement with the numerical simulations. This work will aid in the design of electrostatic MEMS actuators for low-voltage applications without pull-in instability. [ABSTRACT FROM AUTHOR]

As soft electrostatic actuators find applications in bio‐inspired robotics, compact and lightweight high voltage electronics that independently address many actuators are required. Here, a pocket‐sized, battery‐powered, 10‐channel high voltage power supply (HVPS) is presented, which independently addresses each channel up to 10 kV. The HVPS uses one HV amplifier to create a HV rail and each output connects to the rail via custom optocouplers that are pulse‐width modulated to vary their conductance. These optocouplers distribute charges to and from electrostatic devices at each output, creating a charge‐controlled driving scheme that can generate independent and nearly arbitrary actuation waveforms for each channel. The HVPS weighs 250 g and measures 8.4 cm × 13.3 cm × 2 cm, about the size of a smartphone. The HVPS is characterized when driving hydraulically amplified self‐healing electrostatic (HASEL) actuators. While powering a 5 nF actuator, the output of the HVPS reaches 8 kV in 100 ms and drives a 1.5 nF actuator at 100 Hz (0 to 5.4 kV). The HVPS powers an active surface consisting of an array of HASELs and generates undulatory locomotion of a soft robotic inchworm, highlighting the potential for compact HV electronics that power multi‐degree‐of‐freedom robotic systems based on electrostatic devices. [ABSTRACT FROM AUTHOR]

A new structure for low‐loss and high‐isolation radio‐frequency microelectromechanical systems (RF MEMS) switches is presented. The high contact force of the switch leads to very small ranges for contact resistance which is the main constrain of DC‐contact RF MEMS switches. The contact resistance of the switch is 27 mΩ leading to negligible thermal noise which is one of the most important parameters for devices operating at RF front‐ends immediately after the antenna where there is not any active stage. The switch is composed of two actuators: an electrothermal actuator for actuation of the switch from OFF to ON state and an electrostatic actuator to hold the switch at ON state. The insertion loss, return loss, and isolation of the switch for frequencies below 70 GHz are −0.35, −20, and −10 dB, respectively. The contact force and contact resistance of the switch are 0.93 mN and 0.027 Ω, respectively. Electrothermal and electrostatic actuators require 0.91 and 50 actuation voltages, respectively. During the ON‐state, the power consumption of the switch is near zero. The low contact resistance and high‐isolation characteristics of the switch make it very suitable for mobile front‐ends. [ABSTRACT FROM AUTHOR]

The basic purpose of MEMS actuation is to miniaturize the actuators and sensors for applications in nanoelectronics. The transistor switching current and power supply noises due to voltage drops across the metal lines can impair circuit timing and performance, posing a continuing problem for high-performance chip designers. This work presents an empirical concept of a reconfigurable charge pump based on FPGA for electrostatic actuation of the Microelectromechanical System (MEMS). The goal of the design is to produce enough on-chip voltages for actuating the MEMS that are continuously adaptive and reconfigurable. In this proposed method, pumping capacitors lying in the range of 1-pF have been deployed to decrease the area of design concerned. The various voltages are programmable digitally and created by dynamically altering the number of phases as well as the clock drive levels. The dynamic model is designed by adjusting the number of stages to produce on-chip voltages including clock drive speeds, assuming a purely capacitive load. The proposed model's power consumption can be lowered in the steady state by lowering its clock frequency and electrostatic MEMS actuators with capacitive load. An average of 0.62 W is dissipated by the circuit when the eight stages are triggered. Consequently, with adiabatic and without adiabatic architecture, 0.0186 mW of minimum power difference is obtained. [ABSTRACT FROM AUTHOR]

In recent years, untethered soft robots, free of the lines that restrict their mobility, have been studied extensively. Our research team has been focusing on the electrohydrodynamic phenomena (EHD) as a driving mechanism for untethered robots. EHD is a phenomenon in which a flow is generated by applying a high voltage to a dielectric liquid. We propose a method to drive a robot in an untethered manner using EHD by vertically stacking two types of liquids: conductive and dielectric. This method is simpler, more energy-efficient, and quieter than conventional systems. Although a lower voltage would prevent the enlargement of the system by limiting the electronic components, the generation of EHD requires a high voltage. Therefore, in this study, to realize the low voltage drive of untethered robots dominated by the electrostatic actuator, we tackled the reduction of the driving voltage by investigating the phenomenon. As a result, we achieved low voltage driving at 15 V and successfully drove with off-the-shelf batteries (18 V). We also investigated the output current flowing through the system to reduce power consumption. Therefore, in addition to improving the energy efficiency of the system, we confirmed that the difference of the generated current depended on the thickness of the dielectric liquid and the concentration of the conductive liquid. [ABSTRACT FROM AUTHOR]

The aim of this work is to improve theoretical and experimental tools for modelling and characterising the global behaviour of measurement microphones in a large range of environmental conditions. In most of measurement microphones, the sensitive part is a vibrating membrane stretched and clamped on the body of the microphone. If the sensor is operated at ambient temperatures that significantly differ from atmospheric one, thermal expansion of the microphone membrane and body causes strain and stress variations in the membrane, which lead to altered vibrational behaviour when it is submitted to an acoustic wave. An analytical approach is developed here to express the thermal stress related to the fact that thermal expansions of the microphone membrane and body are different. These effects are then taken into account in a classical modelling procedure for describing the vibration of a microphone membrane in vacuo. An experiment, that relies on the electrostatic actuator technique, has been performed in a fine vacuum to characterise the first resonance mode of a commercial microphone membrane in low temperatures range, from atmospheric to cryogenic. The experimental results highlight the significant effects of the thermal stress induced by the differences between thermal expansion properties of the materials constituting the microphone. These results are consistent with the membrane vibration predicted by the analytical modelling proposed. Thus, even small differences between the thermal expansion properties of the microphone membrane and body have to be taken into account in a modelling procedure to get reliable predictions of the membrane vibration at various ambient temperatures. • Environmental conditions impact the global behaviour of measurement microphones. • Vibration of microphone membrane is affected by ambient temperature. • Thermal stress in the membrane is analytically modelled as a function of temperature. • Experimental results highlight its effect from cryogenic to atmospheric temperature. [ABSTRACT FROM AUTHOR]

This paper presents an in-depth study of electrostatic actuators based on flexible side-electrodes focusing on the available electrostatic force and the derived useful force. A design tool is proposed considering technological aspects as aspect ratio, insulating layer material and voltage level. A space discretized mechanical approach based on Euler-Bernoulli beam theory is developed to model the bending deflection of the flexible movable electrode and "zipping" contact. Analytical developments and simplifications are achieved, rapidly and efficiently implemented in a proposed algorithm. ANSYS® simulations validate the procedure for updating the contact zone through the updating of the electrostatic pressure distribution. Optimum movable electrode width and appropriate "opposable" stiffness for guiding system are discussed. A "residual air thickness" parameter is introduced to address imperfect contact between the electrodes. characterization studies various prototypes with different structural parameters as thickness (50 µm and 200 µm), gaps (5 µm and 15 µm) and material for insulating layers (silicon oxide and parylene C). The metrology campaign highlights the impact of aspect ratio and oxidation/deoxidation on electrode sidewall quality and hence mechanical performance. A comparison with well-known comb-drive shows higher electrostatic force for flexible side-electrode actuators. As an example, for a 10 µm stroke, the available electrostatic force for flexible electrodes with irregular sidewalls (residual air thickness 0.6 µm) is 2.2 times greater and rises to 7.3 times greater for perfect sidewalls (no residual air). [Display omitted] • An analytical model and its algorithm are proposed for flexible side-electrodes electrostatic actuators. • Useful force is maximized according to an optimum electrode width and an appropriate "opposable" guiding stiffness. • Experimental characterization is conducted on set-ups including different aspect ratio and insulating layer material. • A relationship between performances and imperfection of the contact is established through a "residual air thickness". [ABSTRACT FROM AUTHOR]

We address the effects of chain connectivity on electrostatic fluctuations in polyelectrolyte solutions using a field-theoretic, renormalized Gaussian fluctuation (RGF) theory. As in simple electrolyte solutions [Z.-G.Wang, Phys. Rev. E 81, 021501 (2010)], theRGFprovides a unified theory for electrostatic fluctuations, accounting for both dielectric and charge correlation effects in terms of the self-energy. Unlike simple ions, the polyelectrolyte self energy depends intimately on the chain conformation, and our theory naturally provides a self-consistent determination of the response of intramolecular chain structure to polyelectrolyte and salt concentrations. The effects of the chain-conformation on the self-energy and thermodynamics are especially pronounced for flexible polyelectrolytes at low polymer and salt concentrations, where application of the wrong chain structure can lead to a drastic misestimation of the electrostatic correlations. By capturing the expected scaling behavior of chain size from dilute to semi-dilute regimes, our theory provides improved estimates of the self energy at lowpolymer concentrations and correctly predicts the eventual N-independence of the critical temperature and concentration of salt-free solutions of flexible polyelectrolytes.We show that the self energy can be interpreted in terms of an infinite-dilution energy μel m,0 and a finite concentration correlation correction μcorr which tends to cancel out the former with increasing concentration [ABSTRACT FROM AUTHOR]

The gas-to-crystal-shift denotes the shift of electronic excitation energies, i.e., the difference between ground and excited state energies, for a molecule transferred from the gas to the bulk phase. The contributions to the gas-to-crystal-shift comprise electrostatic as well as inductive polarization and dispersive energy shifts of the molecular excitation energies due to interaction with environmental molecules. For the example of 3,4,9,10-perylene-tetracarboxylic-diimide (PTCDI) bulk, the contributions to the gas-to-crystal shift are investigated. In the present work, electrostatic interaction is calculated via Coulomb interaction of partial charges while inductive and dispersive interactions are obtained using respective sum over states expressions. The coupling of higher transition densities for the first 4500 excited states of PTCDI was computed using transition partial charges based on an atomistic model of PTCDI bulk obtained from molecular dynamics simulations. As a result it is concluded that for the investigated model system of a PTCDI crystal, the gas to crystal shift is dominated by dispersive interaction. [ABSTRACT FROM AUTHOR]

This paper presents a novel design of a high resolution and low-cost tactile force sensor, based on the concept of mode-localization in two weakly coupled resonators (WCRs). The sensor is fabricated at mesoscale by utilizing rapid prototyping techniques. The two WCRs in the sensor are operated at resonance by using an electrostatic actuation. Change in the oscillation amplitude ratios and resonant frequency shift, corresponding to an input force is utilized as an output metric for the measurement of force. The application of an applied force on the WCRs induced electrostatic strain, which acted as a negative stiffness perturbation. The outer body of sensor is manufactured using a soft silicone elastomer and shaped using molds based on laser cutting technique. The proposed tactile force sensor is analyzed numerically through finite-element-method (FEM) based simulations. For the testing of tactile force sensor, an actuation and sensing electronics scheme is developed. The experimental results revealed that the sensor is capable of measuring input force up to 20 mN with a relative amplitude ratio (AR) and resonant frequency shift based sensitivity of 27040 ppm/mN and 3553 ppm/mN respectively. The experimentally evaluated resolution for the sensor is 7.3 µN. The sensor shows the stability in response to the thermal variations and low-frequency vibrational environments. [Display omitted] • A novel resonant tactile force sensor, using mode-localization Phenomena in two weakly coupled resonators (WCRs). • The sensing and the actuation are capacitive and electrostatic. • The drive circuitry and signal readout electronics for the sensor have been presented for the tactile force sensor. • The tactile force sensor is fabricated using the conventional machining processes. [ABSTRACT FROM AUTHOR]

For drag-free satellites, one core technology required to achieve the mission requirements is the capture control of the test mass after release. The purpose of capture control is to avoid collisions between test mass and satellite cavity. Currently, there are few studies concerning the capture control of test mass after release. This paper presented a high-precision capture control method for the test mass release, which covers attitude-orbit modeling with 12 degrees of freedom, RBF neural network adaptive sliding mode controller design, actuation waveforms selection, actuation strategy selection, performance results, and contrast analysis. [ABSTRACT FROM AUTHOR]

Several projects of the next generation gravitational-wave detectors use the high purity monocrystalline silicon test masses. The electric field of the actuator that is applied to correct the position of the silicon test mass causes additional mechanical losses and associated noise. Disk mechanical resonators are widely used to study mechanical losses in multilayer optical coatings that are deposited on the test masses of gravitational-wave detectors. We use silicon disk resonators to study losses caused by an electric field. In particular, the dependence of mechanical losses on the resistivity of silicon is investigated. The resonator is a thin commercial silicon wafer in which a low frequency nodal diameter mode is excited. A DC voltage is applied between the wafer and a nearby electrode. We use two measurement configurations. In the first configuration, the dependence of losses on the resistance in the voltage supply circuit is investigated. The dependence of losses on the resistivity of silicon is investigated in the second configuration. We propose a model that relates the electric field induced mechanical loss in disk resonators to the resistivity of the material. Measurements are carried out for low and high resistivity silicon wafers. The measurement results are compared with calculations. Based on these studies, it is possible to estimate the loss and noise of the test masses of gravitational-wave detectors associated with electrostatic actuators. [ABSTRACT FROM AUTHOR]

Electrostatic adhesion (EA) technique have been used recently for the electrostatic sorting of metal/polymer granular material mixture. The action seat on the materials is an EA actuator composed of an interposed electrodes network covered by a dielectric barrier and powered by polyphase voltages. The sorting principle consists of attaching the metal particles by EA, and of moving the polymer particles larger than 500 μm, mainly by gravity and vibration. The purpose of this paper is to optimize the EA mechanism for electrostatic sorting. The first part consists of evaluating the behavior of materials (Cu, PE, and PVC) on the EA actuator surface using a 180°-rotating system. The results showed that the metal attaches to the actuator surface while the polymer does not; they also indicate the optimal factors contributing to the adhesion process. In the second part related to sorting application, the granular materials behavior and the influencing factors are explored in an inclined vibrating system to process a Cu/PVC mixture. For an inclination of 10°, Cu recovery on the actuator exceeds 98% with a purity of about 99%. [Display omitted] • Electrostatic adhesion is applied to metal/polymer granular mixture sorting. • Actuator is fixed on 180° rotating system for electric and geometric optimization. • Metal particles attach to the actuator surface while polymer ones fall by gravity. • Optimal parameters are used in a vibrating inclined plane system for sorting. • High performance of recovery and purity is obtained by separation demonstrator. [ABSTRACT FROM AUTHOR]

It is an urgent requirement to suppress surface partial discharge (PD) activities of dielectrics for modern electrical and electronic devices. Here, we introduce a method to mitigate the surface PD in a manner of tailoring insulation surface conductivity. A surface coating with a conductivity ranging from 10−13 to 10−10 S is developed to regulate the surface charge migration in the vicinity of the triple junction and to suppress effectively the surface PD activity. The excellent performance of this coating provides an approach for surface PD suppression at DC voltage, which has great application potential in the insulation design of DC electric power equipment, DC generators, power electronic devices, printed circuit board (PCB) layout, and various integrated electrostatic sensors and actuators. [ABSTRACT FROM AUTHOR]

In this work, we propose a new concept of phase shifting by tuning the coupling distance between two parallel silicon slabs that support the propagation of an in-phase supermode. A prototype device was implemented in the 220–330-GHz band by integrating the micro-electro-mechanical system (MEMS)-actuated phase-shifting mechanism, based on two moveable parallel-coupled high-resistivity silicon slabs, inside a metallized hollow rectangular waveguide in silicon-on-insulator (SOI) micromachining technology. The prototype device has been characterized to a maximum continuous phase tunability of 550° with a maximum insertion loss of 1.87 dB achieved at 330 GHz. A maximum figure-of-merit (FOM) of 375°/dB is achieved at around 320 GHz, which presently is the highest FOM value reported for any phase shifter in the subterahertz (sub-THz) frequency range. The bandwidth covers the whole waveguide band with an average and worst case insertion loss of 1.94 and 2.5 dB, respectively, a worst case insertion-loss variation of 0.7 dB and a phase error better than 4° for all phase states. A large displacement of MEMS electrostatic comb-drive actuators that are co-fabricated in the micromachined waveguide platform is achieved by a driving voltage of 50 V. The prototype footprint is $7.3 \times 5.3$ mm2. [ABSTRACT FROM AUTHOR]

In this article, adaptive backstepping sliding mode controller and adaptive fractional backstepping sliding mode controller methods are proposed to control an electrostatic microplate with a piezoelectric layer. Based on the modified couple stress theory, a size-dependent mathematical model is proposed, in which the microplate is modeled using the Kirchhoff plate theory. To take into account the geometric nonlinearities, the von Kármán nonlinear strains are considered in the mathematical model. The Hamilton's principle is used to obtain the nonlinear equation of motion of the system, which is then converted into a nonlinear ordinary differential equation via the Galerkin technique. The validity of the results obtained from the proposed reduced-order model is checked through direct numerical simulation of the partial differential equation using the finite element method. Finally, two Lyapunov-based control approaches that are adaptive backstepping sliding mode and adaptive fractional backstepping sliding mode are applied to the system. In the adaptive fractional backstepping sliding mode controller method, the adaptive control law is used to evaluate the upper bound of uncertainties and random disturbances. The fractional-order form of sliding surface is used to reduce the amount of chattering and also to improve the tracking error. In the results section, first, numerical studies are conducted to study the effect of system parameters, such as material length scale parameter, aspect ratio, fractional order, and robustness of the controller, on the performance of the system. In addition, the performances of the two control methods are compared, and the merits and demerits of each method are discussed. [ABSTRACT FROM AUTHOR]

Millimeter-sized electrostatic film actuators, inspired by the efficient spatial arrangement of insect muscles, achieve a muscle-like power density (61 W kg−1) and enable robotic applications in which agility is needed in confined spaces. Like biological muscles, these actuators incorporate a hierarchical structure, in this case building from electrodes to arrays to laminates, and are composed primarily of flexible materials. So comprised, these actuators can be designed for a wide range of manipulation and locomotion tasks, similar to natural muscle, while being robust and compact. A typical actuator can achieve 85 mN of force with a 15 mm stroke, with a size of 28 × 5. 7 × 0. 3 mm3 and mass of 92 mg. Two millimeter-sized robots, an ultra-thin earthworm-inspired robot and an intestinal-muscle-inspired endoscopic tool for tissue resection, demonstrate the utility of these actuators. The earthworm robot undertakes inspection tasks: the navigation of a 5 mm channel and a 19 mm square tube while carrying an on-board camera. The surgical tool, which conforms to the surface of the distal end of an endoscope, similar to the thin, smooth muscle that covers the intestine, completes tissue cutting and penetrating tasks. Beyond these devices, we anticipate widespread use of these actuators in soft robots, medical robots, wearable robots, and miniature autonomous systems. [ABSTRACT FROM AUTHOR]

Here, we demonstrate an in situ electrostatic actuator that can operate underwater across a wide range of displacements and frequencies, achieving a displacement of approximately 10 μm at 500Hz and 1 μm at 5 kHz; this performance surpasses that of existing underwater physical actuators. To attain these large displacements at such high speeds, we optimized critical design parameters using a computationally efficient description of the physics of low quality (Q) factor underwater electrostatic actuators. Our theoretical model accurately predicts actuator motion profiles as well as limits of bandwidth and displacement. [ABSTRACT FROM AUTHOR]

Photonic Integrated Circuits (PICs) benefit from the technology advances in the semiconductor industry to incorporate an ever-increasing number of photonic components on a single chip to create large-scale photonic integrated circuits. We here present a broadband, compact and low-loss Silicon Photonic MEMS switch based on a Single-Pole Double-Throw (SPDT) architecture, where curved electrostatic actuators mechanically displace a movable input waveguide to redirect the optical signal on chip efficiently to either of two output waveguides. The photonic switch has been fabricated in an established silicon photonics technology platform with custom MEMS release post-processing. With a compact footprint of 65 × 62 μm2, the switch exhibits an extinction ratio exceeding 23 dB over 70 nm optical bandwidth, a low insertion loss and a fast response time below 1 μs, meeting the requirements for integration in large-scale reconfigurable Photonic Integrated Circuits. [2020-0391] [ABSTRACT FROM AUTHOR]

Compact and entirely soft optics with tunable and adaptive properties drive the development of life‐like soft robotic systems. Yet, existing approaches are either slow, require rigid components, or use high operating voltages of several kilovolts. Here, soft focus‐tunable lenses are introduced, which operate at practical voltages, cover a high range of adjustable focal lengths, and feature response times in the milliseconds range. The nature‐inspired design comprises a liquid‐filled elastomeric lens membrane, which is inflated by zipping electroactive polymers to tune the focal length. An analytic description of the tunable lens supports optimized designs and accurate prediction of the lens characteristics. Focal length changes between 22 and 550 mm (numerical aperture 0.14–0.005) within 260 ms, equal in performance to human eyes, are demonstrated for a lens with 3 mm aperture radius, while applying voltages below 500 V. The presented model, design rules, and fabrication methods address central challenges of soft electrostatic actuators and optical systems, and pave the way toward autonomous bio‐inspired robots and machines. [ABSTRACT FROM AUTHOR]

[Display omitted] • A microdevice driven by a comb actuator was fabricated using the DRIE process. • The MEMS-based microdevice was integrated onto an AFM. • The AFM was employed to quantify the friction force on the strained Si surface. • The FFM image was consistent with the strain image acquired through FEM analysis. • A 1.2% variation in atomic distance resulted in a 9% reduction in the friction force. Investigations on the influence of the interatomic distance (IAD) on friction are crucial for gaining a better understanding of friction and comprehending the essential nature of graphene friction. We obtained friction force microscopy (FFM) images of strained surfaces to examine how the IAD affects the friction force. First, using microelectromechanical system (MEMS) fabrication techniques, we fabricated a strain-generating microdevice that can generate surface strain on its Si surface by an electrostatic comb actuator. The microdevice was installed in a high vacuum atomic force microscope. Next, FFM measurements were performed on the stress concentration section of the microdevice using a Si cantilever. The driving voltage on the comb actuator was switched on/off for each scan line during a single raster scan. This procedure allowed us to obtain FFM images representing the surface strain (i.e., the IAD variation) by excluding friction/wear-induced disturbances. The FFM images agreed well with the strain distribution calculated by the elastic finite element method analysis. The relative reduction of the friction was approximately 9% against the calculated strain of 1.2%. [ABSTRACT FROM AUTHOR]

Flapping micro air vehicles (MAVs) possess advantageous characteristics such as agility, stability, and maneuverability, making them potential candidates for search and rescue operations in confined spaces. However, the development of electrostatic flapping MAVs faces a significant challenge due to the limited availability of actuators with high power density. In this study, we present optimized self-excited electrostatic actuators featuring an insulated-electrodes configuration that enables enhanced operating voltage and increased power density. To improve upon previous designs, our new actuator incorporates a pair of auxiliary electrodes, while the main electrodes and cantilever are covered with insulating polyimide films. A fabrication method is devised to ensure precise construction of the actuator while maintaining the desired conductive and insulating properties of each component. The optimized actuator demonstrates notable improvements, including a 20.9% increase in operating voltage to 2600 volts, an electrostatic force of up to 1.2 mN, and a heightened power density of 24.7 W/kg. Building upon this optimized actuator, we propose a prototype of a flapping MAV capable of generating a lift force of 117.6 μN, approximately 19% of its self-weight. These results contribute to the advancement of electrostatic flapping MAVs and offer prospects for future breakthroughs in overcoming gravitational forces through geometry optimization. [Display omitted] • An optimized configuration of the self-excited electrostatic actuators is presented. • The power density of the optimized electrostatic actuator can reach 24.7 W/kg. • The optimized electrostatic actuator can generate electrostatic force up to 1.2 mN. • A flapping MAV is designed based on the actuator and its lift force can reach 117 μN. [ABSTRACT FROM AUTHOR]

The design and simulation of a continuously tunable LC filter by integration of microelectromechanical systems (MEMS) is presented in this work. The proposed tunable LC filter consists of a tunable capacitor and four inductors. The novelties of this RF-MEMS circuit include the integration of both mechanical suspensions with electrical inductors and the electrostatic actuator with the electrical capacitor. This filter is designed based on standard MetalMUMPs fabrication process trademark of MEMSCAP. With this filter, the frequency range from 2.5 to 3 GHz is achieved in the UHF band. High-quality performance is determined based on the 3 dB-bandwidth with about 83 MHz. The insertion loss of − 2.8 dB and the return loss of − 17.58 dB up to − 21.43 dB are other bold characteristic points of this design. The power consumption is near-zero thanks to the use of the electrostatic actuator. Therefore this filter can be used in low power and high-performance RF tuning applications. The group delay of this filter is less than 2.5 ns and the quality factor is from 45 to 85. [ABSTRACT FROM AUTHOR]

With the increasing development of nanopositioning stages, the study of their deformation and instability under various actuators is very important. Accordingly, in the present paper, the nanopositioning mechanism based on flexible links with the ability to move in three directions of XYZ is introduced using an electrostatic actuator. Then, using the analytical method, static behavior and performance of this mechanism under the influence of electrostatic force are studied. For this purpose, part of this mechanism, which includes a flexible beam with the electrostatic force, is considered. Then, using the nonlinear Euler–Bernoulli beam theory and taking into account the nonlinear effects arising from the radius of curvature, for the first time, the nonlinear differential equation is extracted. Applying the step-by-step linearization method and assuming the static voltage applied to the end of the flexible beam, the effect of different parameters on static deformation is investigated. The results of this study show that considering the nonlinear effects caused by curvature radius has a significant effect on the mechanical behavior of the system, and with increasing the value of this parameter, the hardening behavior of the flexing beam increases. This reduces the static deflection of the flexible beam in comparison with the results of linear theory. Also, by increasing the voltage applied to the flexible beam, the created nonlinear strains are increased, and the nonlinear effects of the radius of curvature become significant. For example, with an increase in the dimensionless bending stiffness parameter from 0 to 10 × 10−3, the maximum deflection of the flexible beam for 10 V, 15 V, and 20 V voltages decreases by 7.7%, 35.8%, and 48.6%, respectively. [ABSTRACT FROM AUTHOR]

In this paper a sensor based on MEMS resonators is proposed for digital microfluidics applications. The sensor system consists of a disk as active area immobilized for capturing any special particles. This disk can azimuthally vibrate by means of two in phase electrostatic actuators both sides. Two capacitive sensing elements determine the vibrating amplitude. The moving droplets by digital microfluidic module will envelope the disk of active zone, so the captured particles can change the vibration frequency of resonance. Due to azimuthal vibration, the fluidic damping is low enough to achieve measurable quality factor by resonator. The total system is simulated and the result is presented. [ABSTRACT FROM AUTHOR]