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Lead zirconate titanate (PZT) thin films offer advantages in microelectromechanical systems (MEMSs) including large motion, lower drive voltage, and high energy densities. Depending on the application, different substrates are sometimes required. Self-heating occurs in the PZT MEMS due to the energy loss from domain wall motion, which can degrade the device performance and reliability. In this work, the self-heating of PZT thin films on Si and glass and a film released from a substrate were investigated to understand the effect of substrates on the device temperature rise. Nano-particle assisted Raman thermometry was employed to quantify the operational temperature rise of these PZT actuators. The results were validated using a finite element thermal model, where the volumetric heat generation was experimentally determined from the hysteresis loss. While the volumetric heat generation of the PZT films on different substrates was similar, the PZT films on the Si substrate showed a minimal temperature rise due to the effective heat dissipation through the high thermal conductivity substrate. The temperature rise on the released structure is 6.8× higher than that on the glass substrates due to the absence of vertical heat dissipation. The experimental and modeling results show that the thin layer of residual Si remaining after etching plays a crucial role in mitigating the effect of device self-heating. The outcomes of this study suggest that high thermal conductivity passive elastic layers can be used as an effective thermal management solution for PZT-based MEMS actuators. [ABSTRACT FROM AUTHOR]

Colloidal probes are often used in force microscopy when the geometry of the tip–sample interaction should be well controlled. Their calibration requires an understanding of their mechanical response, which is very sensitive to the details of the force sensor consisting of a cantilever and the attached colloid. We present some analytical models to describe the dynamics of the cantilever and its load positioned anywhere along its length. The thermal noise calibration of such probes is then studied from a practical point of view, leading to correction coefficients that can be applied in standard force microscope calibration routines. Experimental measurements of resonance frequencies and thermal noise profiles of raw and loaded cantilevers demonstrate the validity of the approach. [ABSTRACT FROM AUTHOR]

This paper presents the investigation of a metastructure, built with periodic arrays of inertial amplification (IA) cantilever-type resonators on a host beam, to improve its low-frequency flexural wave attenuation performance. The IA mechanism is composed of an additional mass and three rigid bars, which are connected by hinges and embedded on the host beam and cantilever-type resonators, respectively. The dynamical model of an IA cantilever-type resonant beam (IACRB) is established by the spectral element method, and its bandgap characteristics and vibration transmissibility are verified numerically and experimentally. The bandgaps of the lumped mass cantilever-type resonant beam are compared to those of the IACRB, showing that the latter has better low-frequency wave attenuation ability. To reveal the underlying physics, the effects of the amplification ratio, IA span, and length ratio of cantilever-type resonators on the band diagram of the IACRB are investigated. It is found that the variation of the amplification ratio results in the bandgap near-coupling phenomenon and the bandgap transposition phenomenon. The increase of IA span by changing position 1 weakens the coupling effect of local resonance and IA. However, the increase of IA span by changing position 2 creates the super-wide pseudo-bandgap as well, which is potential in engineering practices. The variation of the length ratio of cantilever-type resonators decreases its first bending modal frequency and shifts the IA bandgap to a lower frequency range slightly. The modal analysis results of the IACRB show that the proposed mechanism affects the modal distributions of the host structure. The modal frequencies existing in bandgaps are caused by the local vibration mode of the ends of the IACRB. [ABSTRACT FROM AUTHOR]

The cantilevered micro-beam is an important component in the field of Atomic Force Microscope (AFM) and its behavior is governed by chaotic dynamics. To better understand these dynamics, a theoretical model based on the Euler–Bernoulli beam model has been developed and experiments have been conducted. The model incorporates both the modified couple stress theory (MCST) and external forces to account for the size-dependent effect and electrostatic load. The reduced model in one degree of freedom is obtained by the Galerkin method. The validity of the reduced model is tested by comparing the results from simulations and published results and experiments. The Melnikov method is then used to detect the chaotic threshold the cantilevered micro-beam. The numerical results test the effects of MCST on the complex responses of the micro-cantilever. Implications of the research can extend to the design and optimization of MEMS devices. [ABSTRACT FROM AUTHOR]

We report on the piezoresistive method for detecting stability loss events in microelectromechanical sensors based on bifurcation. The method involves measuring the resistivity changes of an entire beam to detect snap-through transitions in an electrostatically actuated, bistable double-clamped crystalline silicon (Si) microbeam. The applicability of the suggested approach in two types of sensors—an ambient air temperature sensor or a mean air velocity sensor, is demonstrated. In both cases, the bistable beam, serving as the sensing element, is affected by the electrothermal Joule's heating and air cooling. The measured signal is obtained by monitoring the critical voltages of the snap-through transitions. Piezoresistive sensing is especially suitable for the response monitoring of the exposed to the environment, free-standing heated microbeam sensors, where optical, piezoelectric, or electrostatic interrogation methods are not applicable. The approach can be implemented in various bifurcation microsensors and for response monitoring of bistable actuators. [ABSTRACT FROM AUTHOR]

• Thermoelastic dissipation (TED) in microbeams with multiple coatings is studied. • Rules for utilizing the simple model for evaluating TED are explored in detail. • Low contact conductivity leads to a notable increment in the TED values. • A methodology for a mixture of multiple partial coatings to reduce TED is proposed. Thermoelastic dissipation (TED) is a mechanism for intrinsic energy dissipation that governs the upper limit on microresonators' quality factor (Q -factor). The demands for high performance and diverse functionality have led to the development of MEMS resonators with increasingly complex structural geometries and materials. This work proposes an analytical framework to evaluate TED behavior in microbeam resonators coated with multiple partial coatings. By determining the one-way thermoelastic coupled equation in the thickness direction, the temperature function is obtained for each region, and TED model is derived by capturing the energy loss of each region within the framework of thermal energy method. The effectiveness of present framework is verified by comparing it with experimental data and finite element method (FEM) results. The developed TED model has an explicit closed-form expression that converges rapidly, and retaining only leading terms yields a simple TED model. Rules for applying the simple TED model to ensure accuracy are discussed. TED behaviors considering finite thermal contact conductance are comprehensively investigated. A methodology for a mixture of multiple partial coatings to suppress TED is proposed. This work is helpful in suppressing the TED and achieving high Q -factors for the microbeam resonators. [ABSTRACT FROM AUTHOR]

The rising number of devices created using pop‐up microelectromechanical systems (MEMS) and related folding‐based assembly techniques highlights the need for robust design and manufacturing workflows to support the wide range of device variations. To push the bounds of miniaturization, design for manufacturing is key in dealing with fabrication challenges. Iterative building of intermediate device prototypes is a promising way to explore an often very large design space and can highlight mechanical limitations that may not be obvious to the designer. Manufacturing of pop‐up MEMS devices is, however, typically a lengthy process with lamination taking a significant percentage of the build time, compared to layer machining and component assembly. To expedite the design process, researchers often prototype multiple iterations at larger scales prior to committing to at‐scale designs. In this study, an at‐scale rapid prototyping workflow for pop‐up MEMS devices is introduced. This study also includes flexure design considerations for castellated hinges, to approach the behavior of an ideal pin joint. The new proposed workflow uses more accessible lower‐cost equipment and materials and reduces lamination time by over 95% (10 min lamination vs a 3.5 h lamination) compared to the previous heated press process, which is validated through a series of prototypes. [ABSTRACT FROM AUTHOR]

Phononic frequency combs (PFCs) have emerged as a pivotal technology in precision measurements and advanced signal processing, harnessing the power of discrete, evenly spaced frequency lines. Their expansion into the realm of microelectromechanical systems (MEMS) presents potential opportunities for enhanced control in various applications, from telecommunications to quantum computing. This work presents an experimental study on the generation of PFCs at the fundamental frequency and its higher harmonics in a complementary metal oxide semiconductor based electrostatic MEMS resonator measured under an open-loop configuration. The phenomenon is attributed to nonlinear mode coupling and 1:2 internal resonance between two eigenmodes and their harmonics when the resonator operates in nonlinear resonance. The experimental approach employs a combination of optical and electrical characterization techniques. This study, primarily experimental in nature, provides crucial insights into the behavior of PFCs in MEMS resonators, suggesting possible multi-harmonic internal resonance as the underlying mechanism. These findings contribute significantly to the field of MEMS research, offering potential applications in high-precision frequency control for telecommunications, sensor technology, and quantum computing. [ABSTRACT FROM AUTHOR]

The hydrodynamic force in a thin uniform beam cantilever is essential quantity for designing a resonator. We obtained the hydrodynamic drag forces in a uniform cantilever vibrating at the first four transverse modes using a semi-analytical boundary element method (BEM) and finite element method (FEM) in ANSYS. The present three-dimensional (3D) BEM inertial and damping forces are compared with FEM over a frequency range with less than 9.5% deviation until frequency parameter of 100; thereafter, it deviates numerically due to neglecting the non-linear convective forces. Considering the hydrodynamic damping force, the quality factor is estimated for the first four transverse modes of a uniform cantilever beam. As a result, the present 3D BEM model behaves well at the first bending mode compared to FEM. We also study the effect of the aspect ratio (ratio of width to length) of the beam for all four modes. However, the first mode quality factor sufficiently correlates with the numerical value for all aspect ratios. For uniform beams operating with higher modes, the influence of nonlinear and resonance frequency by the numerical model is more pronounced at smaller lengths. Hence, the 3D BEM approach can estimate the hydrodynamic forces on cantilever-based resonators, for example, atomic force microscopy and biosensors. [ABSTRACT FROM AUTHOR]

Logical gates have been used in implementation of logic sequential and combinational circuits especially in computers, DSPs and microprocessors. They are mostly fabricated based on CMOS technology that provides a few nano-seconds of delay for each digital gate. Due to limitations in more scaling CMOS transistors and cause of short channel effects, some engineers and researchers believe that there is a huge demand for new devices and fabrication technologies to produce faster logic gates. In this paper, a new architecture for NAND gate is presented which operates based on mechanical resonance of a network of weakly coupled resonators that resonate in radio frequencies. This design is achieved by employing the associative memory property of Hopfield neural networks and the theory of weakly coupled resonators. The main advantage of the proposed design is in its capability to reach out delay times of the order of 1 nano-seconds or even less. One solution to decrease the delay time can be increasing the resonance frequency of resonators which are processing elements of resonators network. In this paper just the new idea of implementation NAND gate based on weakly coupled RF MEMS resonators is presented and evaluated. Other criteria like gate power consumption, effects of temperature, fan in, fan out and noise margin are not discussed. Regarding the rapid growth in MEMS technology, resonators with super high frequency (SHF 3–30 GHz) are now available and those with Extremely High frequency (EHF 30–300 GHz) will soon be in market which enables the presented design to achieve higher speeds. In addition, mechanical resonators are more fault tolerant than CMOS circuits when utilized in harsh environments which exposed to ionic beams or electron beam radiations. In space applications, the satellite and payload are exposed to huge bombardments of space electrons and ions beams. So, the proposed NAND gate can be a good solution for enhancing reliability of devices and systems exposed to space radiations. [ABSTRACT FROM AUTHOR]

The micro-actuator is a key element of the MEMS-based initiator. In order to ensure safety and achieve the function of detonation energy isolation and transmission of the micro-pyrotechnic sequence, it is necessary to set up a safety and arming device between the micro-heater and energetic materials on the next level in the initiator. In this paper, the MEMS safety and arming device was simulated and analyzed, and the actuator chip was made based on MEMS technology and then tested. The results showed that the maximum temperature and displacement generated by the silicon-based micro-actuator increased with increasing actuation voltage. When the actuation voltage was larger than 16 V, the device could not work normally because the maximum temperature of the device was higher than the melting point of silicon. Furthermore, the influence factors on the state-recoverable property of the device were studied by changing the actuation voltage, length, width, and thickness of the V-shaped beam in a single way. The results showed that when the actuation voltage remained unchanged and the other factors were changed in a single way, the smaller structural parameters resulted in the shorter response time and recovery time, while the displacement generated was smaller. Meanwhile, the larger structural parameters resulted in larger displacements, while the response time and recovery time were larger. In addition, the state-recoverable characteristics of the device were affected by the working environmental temperature. It is of great significance to the design of the MEMS-based initiator. [ABSTRACT FROM AUTHOR]

In this article, a continuously microfluidically tunable filter using two microstrip resonators is proposed. By injecting different amount of water into the tubes, the resonant frequency as well as coupling intensity between two resonators can be controlled. As a result, the fractional bandwidth (FBW) of the proposed band can keep constant when tuning the frequency. As far as the authors know, most of the state‐of‐the‐art microfluidics tunable filters are discontinuous, and the tuning range is limited. In this article, the wide tuning capacity of the frequency is realized by placing some tubes between the microstrip resonators and the ground. By increasing or decreasing the amount of water in the pipes, the local dielectric constant and the equivalent electrical length of the transmission line are changed simultaneously. Therefore, it plays a key role in resonant frequency tuning. In the other hand, the coupling coefficient can be controlled by injecting the amount of water into the tube between the two resonators. Finally, through the analysis of computer simulation technology simulation and measurement, it can be seen that the tuning range of resonant frequency is up to 41.3%, with the central frequency varying from 1.33 to 1.88 GHz. The insertion loss is less than 3.09 dB and the return loss is higher than 15 dB, while the FBW is 3.4% ± 0.2%. The measurement matches well with the simulation results, verifying the proposed design methodology. [ABSTRACT FROM AUTHOR]

In this paper, a new structure of 2D photonic crystals for all-optical 4-bit adder based on kerr effect and ring resonators is proposed. The fundamental rods are made of silicon material with a refractive index is about 3.476 around a wavelength 1550 nm. The lattice constant of the PhC structure, and the radii of fundamental dielectric rods are about 592 nm, and 118 nm, respectively. The structure is designed using in a cascade one half adder and three full adders. The optical adder is composed of nonlinear ring resonators, input ports (Ai, Bi), and output ports (Si, Ci). The ring resonators R1 and R2 based on the optical kerr effect are created by replacing 2 × 24 dielectric rods are made of nonlinear material doped glass with a linear and nonlinear refractive index of 1.4 and 10−14 m2/W, respectively. The radii of these dielectric rods are 90 nm and 80 nm. The input and output ports are located in the best position, and the total footprint is about 2229 μm2. We used COMSOL Multiphysics Software based on the plane wave expansion and the finite element methods to simulate the photonic band gap diagram and the light propagation inside the PhC structure. The proposed 4-bit adder can be used in the next generation of optical computer systems applications and photonic integrated circuit communication. [ABSTRACT FROM AUTHOR]

Pressure sensing plays an important role in many industrial fields; conventional electronic pressure sensors struggle to survive in the harsh environment. Recently microelectromechanical systems (MEMS) fiber-optic Fabry–Perot (FP) pressure sensors have attracted great interest. Here we review the basic principles of MEMS fiber-optic FP pressure sensors and then discuss the sensors based on different materials and their industrial applications. We also introduce recent progress, such as two-photon polymerization-based 3D printing technology, and the state-of-the-art in this field, e.g., sapphire-based sensors that work up to 1200 °C. Finally, we discuss the limitations and opportunities for future development. [ABSTRACT FROM AUTHOR]

An electrostatically actuated all-metal microelectromechanical systems (MEMS) Pirani gauge with a tunable dynamic range is proposed. Contrary to the conventional fixed gap Pirani gauges, an electrostatic mechanism is employed to tune the gaseous conduction gap. Due to the electrostatic force between the heating element and heat sink, this tuning results in shifting the transition pressure to a higher pressure. As a result, the operating range of the Pirani gauge can be tuned depending on the magnitude of the actuation voltage. Theoretical estimation of the transition pressure corresponding to different gaseous conduction gaps is also presented. Depending on the available margin of gap tuning, the electromechanical and electrothermal analyses are carried out in COMSOL Multiphysics. The analytical approach is validated by experimentally characterizing the fabricated device. The experimentally tested device with the proposed actuation mechanism shows an 11.2 dB increase in dynamic range in comparison to the conventional design. In a complementary metal-oxide-semiconductor (CMOS)-compatible fabrication process flow, the proposed gauge can be used to monitor vacuum from 40 Pa to 5 × 105 Pa with the electrostatic actuation. [ABSTRACT FROM AUTHOR]

In this work, we consider MEMS devices made of mechanically coupled microbeams under electric actuation. We conduct an experimental study to identify the occurrence of veering and then investigate its dynamic response for different electric actuations. A slight change in the DC voltage bias from the veering point is observed to affect significantly the frequency response. Indeed, jump to large orbits occurred when perturbing the applied DC voltage while operating near the cyclic-fold bifurcation point. We also develop and validate a mathematical model to simulate the response of the device. The model showed similarities in the softening effect of the DC voltage bias and an added mass when matching their induced shift in the natural frequency. As such, one can discern the inherent nonlinear effects of DC voltage bias on coupled resonators and exploit them for mass sensing applications without going over the hassle of mass deposition, which requires the deployment of complex processes. We also investigate different mass detection mechanisms. We show the potential of mode localization and the significant and abrupt jumps in the deflection of the coupled microbeams due to mass perturbation to enhance the sensitivity of MEMS mass sensors. [ABSTRACT FROM AUTHOR]

Driving a micro and nanomechanical structure to resonance and observing its resonant motion in the physical world have led to numerous fundamental discoveries in physics, sciences, chemistry, biology, and engineering, as well as device commercialization. Scaling down mechanical structures from micrometric to nanometric size has enabled the utilization of resonant motions to probe material properties and various dynamical phenomena in quantum coherence and squeezing. Recent advances in material sciences and nanofabrication resulted in successful demonstration of ultra‐high frequency operation (GHz range) and ultra‐high quality factor (10 billion) micromachined mechanical resonators (MMRs). The resonant motion of these structures has been utilized as an indispensable tool to weigh biological and chemical species at resolution of atomic mass unit, sense a force as small as zepto‐newton, and to detect numerous other physical parameters. Here, a systematic view on the resonant sensing transduction is provided, underlying physics, and sensing structures realized with micro/nano‐electromechanical systems (MEMS/NEMS) technologies. It is also describe the roles of nanomaterials and structures, nano‐fabrication and rational designs on the resonance frequency and quality factor of MMRs toward high‐performance sensing. This paper discusses the most recent advances in the development of MMRs for material characterization as well as biological, chemical, and physical sensing. Finally, the paper discusses the challenges and perspectives on design, fabrication, and developments of resonant sensors with high quality factor toward quantum sensing, and ultra‐high sensitivity and resolution for classical sensing applications. [ABSTRACT FROM AUTHOR]

The present article focuses on the new meticulous model based on the postulate of memory-dependent derivatives to analyze the thermo-mechanical interactions inside the nano-beam-based machined resonators. Also, the size effect on dynamic responses of thermoelastic vibrations of homogeneous and isotropic nano-beam is considered. The fundamental expressions are formulated in the frame of non-local generalized thermoelasticity with paired relaxation times by operating the results of Euler-Bernoulli beam theory, non-local effect, and memory-dependent derivative. The proposed model is applied to study the nano-beam-based machined resonator subjected to the ramp-type heating and exponentially decaying time-dependent load. Closed-form solutions of the physical fields are examined by applying the Laplace transform mathematical mechanism. However, the coherence of the new thermal conductivity framework, a collation has been bestowed among the results obtained in the presence or absence of the memory-dependent derivative; also, the size effect is analyzed on the significant parameters of nano-beam such as deflection, temperature, displacement as well as bending moment. Moreover, the prominent influence of the distinct affecting parameters such as constituents of memory-dependent derivative (kernel function and time delay) and ramping time parameter with an applied load on the physical fields have been investigated with the help of quantitative results. [ABSTRACT FROM AUTHOR]

In this paper, we integrate deep learning techniques with the motion-induced current method to analyze the nonlinear response of electrostatic MEMS resonators consisting of vibrating beams under electrostatic actuation. The motion-induced current method relies on a transduction mechanism that converts the motion of the resonator to a current signal. The third harmonic of the induced current captures the motion characteristics of the MEMS resonator. We conduct electrical measurements on a MEMS device comprising a microcantilever beam subject to electrostatic actuation using a side electrode. The electrical measurements are verified against their optical counterparts to confirm the suitability of the motion-induced current method to analyze the motion of the MEMS resonator. Next, we develop a model by combining deep learning methods with experimental data aiming to detect the nonlinear dynamics associated with the motion of the resonator when subjected to large actuation voltages. The results demonstrate high prediction accuracy of the data-driven model in terms of capturing the peak resonance, the onset of bifurcation, the occurrence hysteresis and its bandwidth. [ABSTRACT FROM AUTHOR]

This research paper provides a simple and original approach to extend the resonant frequency tuning range for achieving high-to-low frequencies in electrostatically actuated microelectromechanical systems (MEMS) based resonators. In microstructures, low frequencies are usually achieved by increasing the effective mass or decreasing the mechanical stiffness. However, this work intends, assuming a double-sided electrodes design, to control the excited mode of the micro-system in order to achieve low frequencies through DC bias voltage variations and possibly eliminate the displacement dependency in capacitive micro-bridges-based structures. The design consists of a flexible microbeam where its equations of motion are derived within the framework of the nonlinear Euler–Bernoulli beam theory. The equations are then solved using the reduced-order modeling based on the Galerkin modal decomposition while considering the couple-stress theory. Simulation results show an improved performance of the proposed structure compared to previous studies. According to these results, a wide frequency tuning range has been achieved through a proper DC bias voltage arrangement. In addition, the outcomes of the numerical analysis were validated by comparing them with FEM results obtained by COMSOL software. [ABSTRACT FROM AUTHOR]

The mode localization phenomenon of the weakly coupled resonators (WCRs), which is revealed as a small asymmetric perturbation introduced in the symmetric weakly coupled resonant system will lead to a drastic variation in the system energy distribution and amplitude ratios of the resonators, has been widely used in the topology design of micro-electro-mechanical system (MEMS) sensors. In order to improve the noise characteristics of mode-localized sensors, this paper presents an optimized measurement and control system, including the frequency closed-loop system based on phase-locked loop (PLL) and the amplitude closed-loop system based on energy conservation. The vibration energy of a weakly coupled resonant system can be represented by the sum of the squares of the amplitude of each resonant unit, and the total energy of resonant units is stabilized at a constant value by the amplitude closed-loop system based on energy conservation. The proposed measurement and control system is optimized by Simulink simulation software and finally verified with the fabricated prototype of a mode-localized airflow sensor. Experiment results demonstrate that compared with the amplitude open-loop detection method, the closed-loop control scheme based on energy conservation has better bias stability, which indicates that our proposal can improve the long-term stability of output signals of the weakly coupled resonant system. [ABSTRACT FROM AUTHOR]

MEMS switches are of significant interest for promising radio-electronic systems, but have not yet found widespread use due to the low reliability of microcontacts. The switch develops a low contact force, which results in high and unstable contact resistance. The force is usually increased by using electrodes with complex shapes and large areas, but a simple and compact configuration is preferable. This study presents a switch based on a 50-µm-long cantilever. For the first time, a method for selecting the vertical dimensions of the product is described, increasing the contact force to values in excess of 100 μN, necessary for reliable operation of the contacts. Test samples are manufactured and tested, and the performance characteristics are compared with the calculation results. [ABSTRACT FROM AUTHOR]

In this research work, we have designed a heterostructure one-port surface acoustic wave (SAW) resonator. The multi-layer one port SAW resonator is made of a silicon (Si) substrate as base material, 128 rotated Y-cut X-propagated lithium niobate (LiNbO3) as piezoelectric substrate, and Inter Digital Transducers (IDTs) made of aluminium. This model is designed to operate on a wide frequency of 4-5 GHz with a resonance frequency of 4.74GHz. Various parameters are taken into consideration during the study and analysis such as high-quality factor, wider bandwidth, better electromechanical coupling coefficient, and a true Figure of merit (FoM). The obtained Quality factor and the electromechanical coupling coefficient (k²) of the designed model are 2700 and 0.18. By using the wide range of frequencies, the bandwidth for the designed model is 1.74MHz. The obtained results show that the device's performance of the one port multilayer SAW resonator using the Al/128οYXLiNbO3/Si multi-layered substrate exhibits a commercial application in the 5G wireless communication system. [ABSTRACT FROM AUTHOR]

Pumping a high-Q optical microresonator by an external laser is inevitably associated with thermal effects. They have a significant impact on the dynamics of nonlinear processes in such structures, including the generation of optical frequency combs and dissipative solitons. The generation process and the properties of bright solitons in such heated microresonators with anomalous group velocity dispersion (GVD) have been well studied, and a number of methods have been developed to minimize the effect of thermal processes. However, for dark solitons or platicons excited at normal GVD, these issues have been studied significantly less. In this work, the properties of platicons in heated microresonators are analyzed, and it is shown that in the case of "positive" thermal effects, when the direction of the thermal shift of the resonance frequencies of a microresonator coincides with the direction of the nonlinear shift, the widest high-energy platicons with the duration close to the round trip time in the resonator are stable. In the case of "negative" thermal effects, narrow low-energy platicons remain stable. Moreover, in microresonators with "negative" thermal effects, the interaction between cubic nonlinear and thermal processes can ensure the generation of platicons without special techniques required in other cases. [ABSTRACT FROM AUTHOR]

This work presents a MEMS resonator used as an ultra-high resolution water vapor sensor (humidity sensing) to detect human activity through finger movement as a demonstrator example. This microelectromechanical resonator is designed as a clamped-clamped beam fabricated using the top metal layer of a commercial CMOS technology (0.35 μm CMOS-AMS) and monolithically integrated with conditioning and readout circuitry. Sensing is performed through the resonance frequency change due to the addition of water onto the clamped-clamped beam coming from the moisture created by the evaporation of water in the human body. The sensitivity and high-speed response to the addition of water onto the metal bridge, as well as the quick dewetting of the surface, make it suitable for low-power human activity sensing. [ABSTRACT FROM AUTHOR]

We numerically investigate the fluid–structure interaction of thin elastic cantilever micro-structures in viscous fluids. The Kirchhoff plate equation describes the dynamics of the structure, and a boundary integral formulation represents the fluid flow. We show how the displacement spectrum of the structures changes as the geometry is altered from a narrow beam to a wide plate in a liquid. For narrow beams, the displacement spectrum exhibits only a few resonance frequencies, which correspond to the vibrational modes described by the Euler–Bernoulli equation (Euler–Bernoulli modes). The spectrum of wide plates exhibits several additional resonance frequencies associated with the plate's torsional and higher-order vibrational modes. Wide plates in Euler–Bernoulli modes exhibit higher damping coefficients, but due to an increased added-mass effect, also higher Q-factors than slender beams. An investigation into the fluid flow reveals that for the Euler–Bernoulli modes of wider plates, the fluid flow and energy dissipation near the plate's edges increase, resulting in increased damping coefficients. Concomitantly, a region of minimal viscous dissipation near the plate's center appears for wider plates, resulting in an increased added-mass effect. Higher-order modes of wider plates exhibit lower Q-factor than the Euler–Bernoulli modes due to a decreased fluid flow at the plate's edges caused by the appearance of circulation zones on both sides of the plate. This decreased flow at the edge reduces the damping and the added-mass effect, yielding lower Q-factors. We anticipate that the results presented here will play a vital role in conceiving novel MEMS resonators for operation in viscous fluids. [ABSTRACT FROM AUTHOR]

Magnetoelectric (ME)-based magnetometers have garnered much attention as they boast ultra-low-power systems with a small form factor and limit of detection in the tens of picotesla. The highly sensitive and low-power electric readout from the ME sensor makes them attractive for near DC and low-frequency AC magnetic fields as platforms for continuous magnetic signature monitoring. Among multiple configurations of the current ME magnetic sensors, most rely on exploiting the mechanically resonant characteristics of a released ME microelectromechanical system (MEMS) in a heterostructure device. Through optimizing the resonant device configuration, we design and fabricate a fixed–fixed resonant beam structure with high isolation compared to previous designs operating at ~800 nW of power comprised of piezoelectric aluminum nitride (AlN) and magnetostrictive (Co1-xFex)-based thin films that are less susceptible to vibration while providing similar characteristics to ME-MEMS cantilever devices. In this new design of double-clamped magnetoelectric MEMS resonators, we have also utilized thin films of a new iron–cobalt–hafnium alloy (Fe0.5Co0.5)0.92Hf0.08 that provides a low-stress, high magnetostrictive material with an amorphous crystalline structure and ultra-low magnetocrystalline anisotropy. Together, the improvements of this sensor design yield a magnetic field sensitivity of 125 Hz/mT when released in a compressive state. The overall detection limit of these sensors using an electric field drive and readout are presented, and noise sources are discussed. Based on these results, design parameters for future ME MEMS field sensors are discussed. [ABSTRACT FROM AUTHOR]

Functional flexible piezo-resonators are of vital interest for designing micro-electrometrical system (MEMS) based high-frequency wearable devices. The magnetoelectric (ME) heterostructure comprising highly magnetostrictive Ni–Mn–In and piezoelectric AlN films was fabricated over flexible substrates to develop the bulk acoustic wave (BAW) resonator. The BAW resonators fabricated over Ni and Kapton substrates show the fundamental resonance at ∼5.535 and 5.400 GHz, respectively. The comparative study of frequency tuning for both resonators has been executed in the presence of a dc magnetic field. A larger frequency shift ( Δ f R ) of ∼540 MHz was detected at 1200 Oe for a device fabricated over Ni with a sensitivity of ∼5.4 Hz/nT. However, it is 360 MHz in the case of Kapton, with a sensitivity of ∼3.0 Hz/nT. Moreover, the BAW resonator over the magnetostrictive Ni substrate shows a higher tunability of ∼11.4% compared to ∼8.5% for the resonator fabricated over non-magnetostrictive Kapton. The equivalent modified Butterworth–Van Dyke circuit parameters have been extracted by fitting the experimental data with and without an external magnetic field using advanced design system. The effect of an external magnetic field has been thoroughly investigated on device parameters, such as electromechanical coupling coefficient (K2), acoustic velocity, quality factor (Q), and figure of merit. The anisotropic functionality of the fabricated resonator has been studied by measuring the tunability of the resonator in parallel and perpendicular magnetic fields. The present study motivates the incorporation of flexible magnetostrictive substrates for futuristic multifunctional MEMS magnetic field sensor applications. [ABSTRACT FROM AUTHOR]

The present article proposes a novel finite-time dual-layer disturbance observer-based controller with the aim of addressing the synchronisation problem for a class of nonlinear chaotic systems experiencing unmodelled dynamics and external disturbances. The adaptive finite-time synchronisation between perturbed drive and response systems is obtained by means of higher order super-twisting terminal sliding mode control (SMC) strategy. The main innovative part of this work is the proposition of a newly designed adaptive finite-time dual-layer estimator (DLE) with two-level observation to exactly estimate the imposed perturbations on the both drive and response systems considering unknown upper bounds. The estimated signals are utilised in the proposed continuous super-twisting sliding mode controller for the purpose of addressing robust finite-time synchronisation problem for a class of chaotic systems. Numerical simulations and achieved results are illustrated to present the efficiency of the investigated approaches. [ABSTRACT FROM AUTHOR]

A model of piezoelectric phononic crystal (PC) double-layer nanobeam periodically attached by "spring-mass" resonators is proposed. As a comparison, two other simplified models are also proposed. In order to calculate the band structure, the plane wave expansion (PWE) method is improved by introducing the Euler beam and surface piezoelectricity theories. All the results and analysis demonstrate that the tunable advantage is displayed in double-layer nanobeam on account of the antisymmetric and symmetric vibrational modes controlled by adding additional springs between two different nanobeams. Moreover, the influencing rules of parameters related to additional spring and "spring-mas" resonator are also revealed. The bandgap properties can be applied to nano electro-mechanical system (NEMS) to realize active control of vibration. [ABSTRACT FROM AUTHOR]

There has been a rising interest in utilizing metamaterials to manipulate the propagation of surface waves, including Rayleigh waves. These novel materials have a diverse range of applications, from micro-scale sensors and actuators to macro-scale seismic protection systems. In the field of seismic engineering, they are commonly referred to as seismic metamaterials. While various linear seismic metamaterials have been developed, incorporating nonlinearity into the design of seismic metamaterials could reveal novel phenomena and greatly expand their potential applications. In the present study, we propose a nonlinear metamaterial to block the propagation of low-frequency Rayleigh waves. The proposed metamaterial consists of a linear elastic substrate and nonlinear resonant units periodically attached to the surface of the substrate. Each resonant unit has two Duffing oscillators connected in series. We use the first-order harmonic balance method to derive analytical solutions for the dispersion of Rayleigh waves, considering both linear and various nonlinear cases. Our findings demonstrate that by coupling the motion of an elastic substrate with the dynamics of attached masses, a linear metamaterial with serial-connected resonators can achieve two band gaps. Furthermore, introducing softening nonlinearity can facilitate the attainment of a low-frequency band gap, while introducing hardening nonlinearity may result in the closure of the original linear band gaps. Our study broadens the range of applications for elastic metamaterials and potentially contributes to the development of more effective seismic wave blockers. [ABSTRACT FROM AUTHOR]

Triangular resonators re-shaped into Sierpinski geometry and U-shaped resonators were designed, linking them with single-pole-double-through (SPDT) RF MEMS switches to provide frequency tuning for potential applications in the K-Band. Prototypes of band-stop narrowband filters working around 20 GHz and 26 GHz, interesting for RADAR and satellite communications, were studied in a coplanar waveguide (CPW) configuration, and the tuning was obtained by switching between two paths of the devices loaded with different resonators. As a result, dual-band operation or fine-tuning could be obtained depending on the choice of the resonator, acting as a building block. The studied filters belong to the more general group of devices inspired by a metamaterial design. [ABSTRACT FROM AUTHOR]

The dynamic pull-in instability of a microstructure is a vast research field and its analysis is of great significance for ensuring the effective operation and reliability of micro-electromechanical systems (MEMS). A fractal modification for the traditional MEMS system is suggested to be closer to the real state as a practical application in the air with impurities or humidity. In this paper, we establish a fractal model for a class of electrostatically driven microstructure resonant sensors and find the phenomenon of pull-in instability caused by DC bias voltage and AC excitation voltage. The variational iteration method has been extended to obtain approximate analytical solutions and the pull-in threshold value for the fractal MEMS system. The result obtained from this method shows good agreement with the numerical solution. The simple and efficient operability is demonstrated through theoretical analysis and results comparisons. [ABSTRACT FROM AUTHOR]

On-chip phononic circuits tailor the transmission of elastic waves and couple to electronics and photonics to enable new signal manipulation capabilities. Phononic circuits rely on waveguides that transmit elastic waves within desired frequency passbands, which are typically designed based on the Bloch modes of the constitutive unit cell of the waveguide, assuming periodicity. Acoustic microelectromechanical system waveguides composed of coupled drumhead resonators offer megahertz operation frequencies for applications in acoustic switching. Here, we construct a reduced-order model (ROM) to demonstrate the mechanism of transmission switching in coupled drumhead-resonator waveguides. The ROM considers the mechanics of buckling under the effect of temperature variation. Each unit cell has two degrees of freedom: translation to capture the symmetric bending modes and angular motion to capture the asymmetric bending modes of the membranes. We show that thermoelastic buckling induces a phase transition triggered by temperature variation, causing the localization of the first-passband modes, similar to Anderson localization caused by disorders. The proposed ROM is essential to understanding these phenomena since Bloch mode analysis fails for weakly disordered (<5%) finite waveguides due to the disorder amplification caused by the thermoelastic buckling. The illustrated transmission control can be extended to two-dimensional circuits in the future. [ABSTRACT FROM AUTHOR]

Numerical model of a wideband band reject filter using closed rectangular loop resonator is presented using transmission lines. The prototype design of wide band reject filter centred at 3 GHz with lower cut-off frequency of 2 GHz and upper cut-off frequency of 4 GHz is fabricate from the optimal values obtained from the numeric model on a substrate (FR4) with a dielectric constant of 4.3, loss tangent of 0.02–0.03 and substrate height of 1.6 mm. For bidirectional operations, the length-to-width ratio of filter is 2:1. The impedance of the transmission line which is connected between input and output ports is taken as double the feed line impedance while the impedance of the other half wavelength is considered as four times the feed line impedance. The design has obtained bandwidth of more than 60%. It is observed that the full wave electromagnetic results are in good agreement with the experimental and numerical results. [ABSTRACT FROM AUTHOR]

In moist air, the combined effects of temperature and relative humidity become important to discuss on the resonant frequency and quality factor of micro-electro-mechanical systems (MEMS) cantilever and bridge beam resonators. The squeeze film damping (SFD), which is the dominant energy loss of MEMS resonators, is modeled by solving the modified molecular gas lubrication (MMGL) equation, transverse vibration of micro-beam, and their appropriate boundary conditions, simultaneously by the Finite Element Modelling (FEM) in the eigen-value problem. The effective viscosity of moist air (µeff) is utilized to modify the MMGL equation taking account the combined effects of temperature and relative humidity in a wide range of gas rarefaction conditions as surface accommodation coefficients (ACs (α1 = α2)). At atmospheric pressure (p = 101,325 Pa), the SFD, which is function of temperature and relative humidity, is more dominantly than that of the other energy losses such as the thermoelastic damping (TED) and the support loss of MEMS resonators. Thus, the combined effects of temperature (T) and relative humidity (RH) are discussed on the resonant frequencies and quality factors of MEMS beam resonators in atmospheric pressure, gas rarefaction (ACs), and resonator mode. The results showed that resonant frequencies and quality factors increase as temperature and relative humidity increase at atmospheric pressure. The combined effects of temperature and relative humidity on the resonant frequency of cantilever beam are stronger than that of bridge beam. The influence of the combined effects of temperature and relative humidity on resonant frequencies and its frequency shift of MEMS resonators reduces significantly because the dominant SFD decreases as gas rarefaction increases (ACs(α1 = α2) decrease), and the resonant mode increases. [ABSTRACT FROM AUTHOR]

This paper presents a finite element method (FEM) simulation study for the frequency response analysis of a capacitive comb-drive resonator based on micro-electro-mechanical systems technology. The post-manufactured design parameters of the resonator are firstly determined after the Modified Silicon on Glass fabrication process by using the parameter extraction method. Then, these results are used to form a 3D structure of the fabricated device. Elmer FEM, an open-source finite element software for multi-physics problems, is selected within the several options for the frequency response analysis of the formed 3D structure. During the FEM analysis, an optimized mesh structure is imported to Elmer FEM for the 3D model of the resonator. Next, the frequency response analyses of the resonator are implemented with a flowchart by using Elmer FEM for a fixed AC level and various DC voltages. The parameter extraction outcomes obtained from probe test data and theoretically calculated values are crosschecked with the output of analyses obtained from the Elmer FEM. The FEM simulation results are compared with the experimental data for the frequency response analyses, the motional parameters and the motional current values as well as the rest capacitance. Furthermore, the approximation error of the simulated results of FEM analysis is calculated. Thus, the capacitive microstructures can be designed more precisely by considering expected quality factor value and fabrication-related deviations. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to design and simulate a piezoelectric micropump using microelectromechanical systems technology for drug delivery applications. Design/methodology/approach: Two piezoelectric actuators are used to actuate and bend the diaphragms in the proposed structure. In this micropump, the liquid flow is rectified by two silicon check valves. Findings: The use of two piezoelectric transducer (PZT) actuators in the parallel mod not only reduces dead volume but also increases stroke volume as well. In addition to increasing the flow rate, this phenomenon enhances the operation of the micropump to have self-priming as smoothly as possible. Originality/value: This actuating method results in a 22% increase in flow rate and compression ratio, as well as a 15% reduction in function voltage. The fluid-solid interaction is simulated using COMSOL Multiphysics 5.3a. [ABSTRACT FROM AUTHOR]

Soft robots typically exhibit limited agility due to inherent properties of soft materials. The structural design of soft robots is one of the key elements to improve their mobility. Inspired by the Archimedean spiral geometry in nature, here, a fast‐moving spiral‐shaped soft robot made of a piezoelectric composite with an amorphous piezoelectric vinylidene fluoride film and a layer of copper tape is presented. The soft robot demonstrates a forward locomotion speed of 76 body length per second under the first‐order resonance frequency and a backward locomotion speed of 11.26 body length per second at the third‐order resonance frequency. Moreover, the multitasking capabilities of the soft robot in slope climbing, step jumping, load carrying, and steering are demonstrated. The soft robot can escape from a relatively confined space without external control and human intervention. An untethered robot with a battery and a flexible circuit (a payload of 1.665 g and a total weight of 1.815 g) can move at an absolute speed of 20 mm s−1 (1 body length per second). This study opens a new generic design paradigm for next‐generation fast‐moving soft robots that are applicable for multifunctionality at small scales. [ABSTRACT FROM AUTHOR]

Here, we study the acoustic radiation generated by the vibration of miniaturized doubly clamped and cantilever beam resonators in viscous fluids. Acoustic radiation results in an increase in dissipation and consequently a decrease in the resonator's quality factor. We find that dissipation due to acoustic radiation is negligible when the acoustic wavelength in the fluid is much larger than the bending wavelength. In this regime, dissipation is primarily due to the viscous losses in the fluid and may be predicted with the two-dimensional cylinder approximation in the absence of axial flow and substrate effects. In contrast, when the bending wavelength approaches the length of the acoustic wavelength, acoustic radiation becomes prominent. In this regime, dissipation due to acoustic radiation can no longer be neglected, and the cylinder approximation inaccurately characterizes the total energy loss in the system. Experiments are performed with microcantilevers of varying lengths in Ar and N 2 to observe trends in the acoustic wavelength of the fluid and bending wavelength. Additional experimental results from doubly clamped nanoelectromechanical system beams are also presented. Experimental results illustrate an increase in dissipation, which is further analyzed with the use of three-dimensional finite element models. With the numerical simulations, we calculate the radiation efficiency of the measured devices and analyze the pressure fields generated by the vibrating resonators. This analysis allows one to estimate the effects of acoustic radiation for any resonator. [ABSTRACT FROM AUTHOR]

We have used finite-element methods to design and simulate a tunable terahertz frequency range band-stop filter based on coupled split-ring resonators integrated into planar Goubau-line waveguide. Two split-ring resonators with different geometrical lengths and gap widths were designed to resonate at the same frequency. When the two resonators were coupled, resonance splitting was observed in the transmission spectra controlled by the distance between them. The electric field distribution and surface current modes in the coupled resonators were used to identify the origin of the resonance modes. In order to dynamically tune the coupled resonance frequencies, a cantilevered microelectromechanical scheme is proposed, in which the radius of curvature of one split-ring resonator is adjusted with respect to a fixed second split-ring resonator. The coupling strength of the coupled resonators was investigated as a function of the relative separation of the resonators revealing a dispersion relation that shows anti-crossing of the coupled resonances as the cantilever bends. [ABSTRACT FROM AUTHOR]

In this paper, metamaterial and microsystem concepts have been used to study resonating structures useful for narrowband microwave signal processing. U-shaped resonators and triangular Sierpinski structures have been designed, manufactured, and tested for possible applications in the K-Band, around 20 GHz and 26 GHz, for satellite communications. Results on the metamaterial nature of both configurations and on their electrical performance are discussed. The studied structures include the possible implementation by RF MEMS of the U-resonators. The outlined novelty is in obtaining a tunable narrow-band filter using an all-passive environment with switches embedded in the resonator. The advantages and drawbacks of this solution and the proposed optimization are discussed in detail. Triangular resonators with the Sierpinski geometry are also considered for the same frequencies. In this case, the possibility to tune the frequency of operation is demanded to increase the complexity of the internal geometry of the triangle by means of empty sub-triangles in the metal path. Examples of the expected performances for coupled triangular structures are also presented. [ABSTRACT FROM AUTHOR]

Electrically integrable, high‐sensitivity, and high‐reliability magnetic sensors are not yet realized at high temperatures (500 °C). In this study, an integrated on‐chip single‐crystal diamond (SCD) micro‐electromechanical system (MEMS) magnetic transducer is demonstrated by coupling SCD with a large magnetostrictive FeGa film. The FeGa film is multifunctionalized to actuate the resonator, self‐sense the external magnetic field, and electrically readout the resonance signal. The on‐chip SCD MEMS transducer shows a high sensitivity of 3.2 Hz mT−1 from room temperature to 500 °C and a low noise level of 9.45 nT Hz−1/2 up to 300 °C. The minimum fluctuation of the resonance frequency is 1.9 × 10−6 at room temperature and 2.3 × 10−6 at 300 °C. An SCD MEMS resonator array with parallel electric readout is subsequently achieved, thus providing a basis for the development of magnetic image sensors. The present study facilitates the development of highly integrated on‐chip MEMS resonator transducers with high performance and high thermal stability. [ABSTRACT FROM AUTHOR]

In this work, we present an Opto-Electro-Mechanical Modulator (OEMM) for RF-to-optical transduction realized via an ultra-coherent nanomembrane resonator capacitively coupled to an rf injection circuit made of a microfabricated read-out able to improve the electro-optomechanical interaction. This device configuration can be embedded in a Fabry–Perot cavity for electromagnetic cooling of the LC circuit in a dilution refrigerator exploiting the opto-electro-mechanical interaction. To this aim, an optically measured steady-state frequency shift of 380 Hz was seen with a polarization voltage of 30 V and a Q-factor of the assembled device above 10 6 at room temperature. The rf-sputtered titanium nitride layer can be made superconductive to develop efficient quantum transducers. [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]