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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]

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]

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]

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 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]

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]

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]

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]

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]

We present an experimental technique to construct the response of nonlinear resonators under harmonic excitation as a control parameter is swept. Our technique can resolve nonlinear features in the resonator response, such as bifurcations and hysteresis. To validate it, we construct the frequency response of a MEMS resonator while the excitation frequency is swept. The response is measured optically and recorded in the time domain. The root-mean-square of the response is calculated over a variable-size time-window. The sweep time, window size, and frequency step size were found to be limited by the quality factor of the resonator under test. We examine and describe those limitations in terms of the slew rate and sampling frequency. Although we used optical measurements to validate the technique, the methods described herein are applicable to any measured response signal. [ABSTRACT FROM AUTHOR]

Here, we present a one-degree-of-freedom model of a nonlinear parametrically driven resonator in the presence of a small added ac signal that has spectral responses similar to a frequency comb. The proposed nonlinear resonator has a spread spectrum response with a series of narrow peaks that are equally spaced in frequency. The system displays this behavior most strongly after a symmetry-breaking bifurcation at the onset of parametric instability. We further show that the added ac signal can suppress the transition to parametric instability in the nonlinear oscillator. We also show that the averaging method is able to capture the essential dynamics involved. [ABSTRACT FROM AUTHOR]

A piezoelectrically actuated high quality factor (Q) mechanically coupled Lamé mode resonator based on a thin-film piezoelectric-on-silicon (TPoS) platform is demonstrated. The reported coupled resonator consists of two identical square plates of single-crystal silicon (SCS) coupled with a SCS beam having thin-film piezoelectric stacked layers on top. The coupled resonator is piezoelectrically driven into resonance, and the two square plates are excited into vibrations in a coupled Lamé mode through mechanical coupling. An impressive passive Q-enhancement is obtained by such a scheme based on mechanical coupling of two SCS square plates with a piezoelectrically transduced beam. A fabricated mechanically coupled Lamé mode resonator exhibits an ultra-high Q of 309 894 while still maintaining a moderate impedance (Rm) of 6652 Ω at its resonant frequency of 18.2838 MHz, corresponding to the record highest f-Q product of 5.67 × 1012 for TPoS resonators. The reported high Q microelectromechanical system (MEMS) resonator overcomes the inherent low-Q nature of piezoelectric MEMS resonators, indicating an application for providing a high-performance timing solution in a MEMS timing field. [ABSTRACT FROM AUTHOR]

A reconfigurable ultra-wideband reflective polarization conversion metasurface (RUR-PCM) is proposed. The unit cell of the RUR-PCM consists of an anisotropic metal patch incorporated with a voltage controlled PIN diode, a dielectric layer, and a metal ground. When the PIN diode is switched on, the RUR-PCM can convert an incident linearly polarized electromagnetic (EM) wave to its orthogonal counterpart; when the PIN diode is switched off, the RUR-PCM can convert a linearly polarized EM wave to a circularly polarized one. The performance of the RUR-PCM is further improved by adding the superstrate and the "double L" metal patch to the unit cell of the RUR-PCM. Simulated and experimental results show that the RUR-PCM is able to achieve linear-to-linear (LTL) polarization conversion in the frequency range of 6.5–19.9 GHz with the polarization conversion ratio higher than 90%, and linear-to-circular (LTC) polarization conversion in the frequency range of 7.6–23.6 GHz, with the axial ratio better than 3 dB. Therefore, the LTL and the LTC polarization conversion methods are integrated into one metasurface in an ultra-wideband range, and each unit uses only one PIN diode, which makes the RUR-PCM have a broad application prospect in secure communication and polarization compatibility. [ABSTRACT FROM AUTHOR]

This paper presents a hardware emulator of microelectromechanical systems (MEMS) vibratory gyroscopes that can be used for characterization and verification of control/interface electronics by means of hardware-in-the-loop testing, thus speeding up design cycles by decoupling these tasks from the often longer MEMS design and fabrication cycles. The easily re-configurable hardware emulator is completely synthesized on a field-programmable gate array board. The emulator is shown to successfully model the Coriolis effect along with the prominent error sources present in typical MEMS gyroscopes, namely, quadrature error, spring nonlinearity, and thermo-mechanical, electronic, and environmental noise. Preliminary experimental results characterizing the noise and nonlinearity models based on a prototype with user-controllable device parameters synthesized on the Xilinx Zynq®-7020 SoC (Digilent ZYBO Z7 board) are presented. [ABSTRACT FROM AUTHOR]

Electromechanical computing based on micro/nano resonators has recently attracted significant attention. However, full implementation of this technology has been hindered by the difficulty in realizing complex logic circuits. We report here an alternative approach to realize complex logic circuits based on multiple MEMS resonators. As case studies, we report the construction of a single-bit binary comparator, a single-bit 4-to-2 encoder, and parallel XOR/XNOR and AND/NOT logic gates. Toward this, several microresonators are electrically connected and their resonance frequencies are tuned through an electrothermal modulation scheme. The microresonators operating in the linear regime do not require large excitation forces, and work at room temperature and at modest air pressure. This study demonstrates that by reconfiguring the same basic building block, tunable resonator, several essential complex logic functions can be achieved. [ABSTRACT FROM AUTHOR]

Analytical and numerical modeling techniques are presented to predict n-type-doped silicon resonators' temperature coefficient frequencies for the extensional mode of vibration by modeling of single-crystal silicon ([100] and [110]) directions. We utilized a previously reported empirical exponential expression for the uniaxial deformation potential that allows us to determine the deformation potential constant. It was observed that by using the empirical model of exponential expression for the uniaxial deformation potential, our result shows that the frequency variation with temperature is closely dependent on the direction and the variation of the different doping levels. We apply our analytical model to the [100] and [110] length extensional modes of a Microelectromechanical Systems (MEMS) resonator. We calculated the resonance frequency with temperature dependence and found that the first-order temperature coefficient frequency shows zero values at doping concentration levels of 0.5 and 1 × 1019 cm−3, which indicates the existence of frequency turnover at room temperature. We also extended our study by finite element analysis of MEMS resonators to investigate the mode shapes and resonant frequency for different aspect ratios in the extensional mode of vibration. It is observed that the mode shapes are more stressed with higher aspect ratios, and the frequency variation (ppm) of the resonance frequency between the [100] and [110] crystal directions of the MEMS resonator increases with increasing aspect ratios. [ABSTRACT FROM AUTHOR]

We report the thermal tuning of the mechanical nonlinearity in GaAs double-clamped MEMS beam resonators for sensitive thermal sensing applications. We have estimated the mechanical nonlinearity in GaAs MEMS beam resonator by measuring its resonance frequency as a function of oscillation amplitude. The MEMS resonator shows a hardening nonlinearity with a small linear oscillation range of ∼30 nm. When electrical heat is applied to the MEMS beam, we have observed a significant reduction in the mechanical nonlinearity of MEMS resonators near the buckling point of the MEMS beam. The decrease in the mechanical nonlinearity originates from the bending of the MEMS beam, which gives a softening nonlinearity term and, hence, compensates the total nonlinearity. With the thermal tuning effect, MEMS resonator can maintain a very large quasi linear oscillation amplitude of ∼300 nm, which is ∼10 times larger than the linear oscillation range without the control of nonlinearity. [ABSTRACT FROM AUTHOR]

We demonstrate dramatic enhancement in thermal responsivities of doubly clamped microelectromechanical systems (MEMS) beam resonators by introducing a prescribed amount of compressive strain to the beam. As a compressive strain in the MEMS beam is increased, the beam eventually becomes buckled. At the critical buckling point, the MEMS beam is expected to exhibit an enhanced thermal responsivity. We have realized such a critical buckling condition by carefully varying the length of the strained In0.004Ga0.996As beam grown on a GaAs substrate. At the critical buckling point, the responsivity is found to be 16 times higher than that of the unstrained beam resonators of the same length. This scheme provides a route to circumvent the trade-off between detection speeds and responsivities and achieve higher responsivities without deteriorating the detection speed. [ABSTRACT FROM AUTHOR]

As an analog of the optical frequency comb, the phononic frequency comb has been demonstrated in mechanical resonators recently. In this Letter, we generate the frequency comb in a rhombic micro-resonator with stiffness parametrically modulated by low-frequency pumping. Interestingly, this comb exhibits the asymmetry in the amplitude, i.e., the amplitudes of comb fingers on either side of the central comb finger decay with different rates. With a parametrically modulated model, we analyzed in detail the asymmetry in the frequency comb and accurately captured the reason for the asymmetry. Furthermore, the asymmetry of the frequency comb can be adjusted experimentally. These results provide a theoretical basis for manipulating the comb fingers and are expected to open the door for potential applications of the frequency comb. [ABSTRACT FROM AUTHOR]

10.1119/10.0003380.1 Modern mobile phones contain a three-axis microelectromechanical system (MEMS) gyroscope, capable of taking accurate measurements of the angular velocity along the three principal axes of the phone with a sampling rate of 100 Hz or better. If the phone is tossed in the air, then, neglecting air resistance, it is in free rotation (rotation in the absence of a torque) with respect to its centre of mass, and the phone's gyroscope can be used to record the rotational dynamics. This enables experimental investigation of free rotation. In this paper, we use a mobile phone to demonstrate the steady states for rotation of the phone about two of its principal axes, and the instability in rotation about the third corresponding to the intermediate moment of inertia. We also show the approximate conservation of angular momentum and rotational kinetic energy during motion in the air, and compare the data with numerical solution of Euler's equations for free rotation. Our results demonstrate the capability of smartphones for investigating free rotation, and should be of interest to college and university teachers developing "at home" physics labs for remote learning. [ABSTRACT FROM AUTHOR]

Thermoelastic damping effects are very important intrinsic losses in microelectromechanical system/nanoelectromechanical system based sensors and filters, which limit the maximum achievable quality factor. Thermoelasticity arises due to coupling between the temperature field and elastic field of the material and its interaction within the material structure. The impacts of axisymmetric and non-axisymmetric vibrations, plate dimensions, material parameters, boundary conditions, mode switching, and temperature on thermoelastic damping limited quality factors (QTED) and critical thickness (hc) were analyzed, and the conditions for an enhanced quality factor were optimized in this work. The analytical models of circular plate resonators have been developed in terms of material performance indices for axisymmetric and non-axisymmetric vibrations. QTED and hc were analyzed based on two boundary conditions: simply supported and clamped–clamped. In order to obtain maximum QTED, micro-circular plates with diamond as the structural material operating at a lower temperature and with non-axisymmetric vibrations are proposed in this paper. [ABSTRACT FROM AUTHOR]

In this paper, we fabricate and demonstrate a functional complementary metal-oxide-semiconductor (CMOS) compatible pyroelectric uncooled thermal detector using 12% doped Scandium Aluminum Nitride (ScAlN) as the sensing layer. The ScAlN pyroelectric material is deposited at a temperature of ∼200 °C over an 8-in. wafer area. This detector has shown, in general, improved performance compared to AlN, with specific detectivity as high as ∼ 6.08 × 10 7 cm Hz / W and noise equivalent power as low as ∼ 8.85 × 10 − 10 W / Hz . The results show the specific detectivity of ScAlN-based pyroelectric detectors in the range of 107 cm Hz / W , which is an improvement compared to AlN-based pyroelectric detectors which report specific detectivity typically in the range of 105–106 cm Hz / W . This promising result opens up the opportunities for a CMOS compatible, 8-in. wafer-level manufacturable lead-free pyroelectric detector toward low cost and high throughput, allowing microelectromechanical systems (MEMS) and CMOS integration for increased applications in CMOS–MEMS integrated devices utilizing pyroelectric detectors. [ABSTRACT FROM AUTHOR]

This article presents a pressure sensor composed of a set of three Archimedean spiral inductors. One of them is below the other two concentric spirals, where the upper coils are over a flexible membrane. When external pressure is applied over the sensor, the membrane deforms and changes the distance between the lower spirals and the upper inside coil, the capacitance, and its resonance frequency. However, once the sensor is in contact with a conductive medium, a change in the effective permittivity surrounding the sensor takes place reshaping the resonant frequencies. To improve the sensor response, we introduce a reader resonator sensor system. We present the comparative response of the system as a prototype, an analytical model, and a finite element model (FEM). The prototype system is fabricated using a photolithographic process for the elements of the sensor over a polymethylsiloxane and glass substrate, while the reader is fabricated over a FR4 substrate. COMSOL Multiphysics is used for the FEM simulation of the system to evaluate its behavior. The analytical model involves the integration of techniques to obtain the effective permittivity for each element plane and a coupled magnetic resonance to represent the interaction of the parts. We obtain a correspondence between the resonances of the different elements, with a maximum displacement frequency of 240 MHz for the proposed model, and 80 MHz in the FEM case related to the implemented prototype. The accuracy of this model allows a fast analysis to improve the design of this type of topology without high computational processing. [ABSTRACT FROM AUTHOR]

Piezoelectric materials have excellent energy conversion efficiency between mechanical and electrical domains and have been used in a variety of electromechanical devices. These technologies include new piezoelectric thin-film materials, innovative thin-film processes, and new evaluation methods with the goal of advancing the piezo-MEMS applications. Evolving around the development of piezo-MEMS are interdisciplinary and intertwined technologies, including materials science, surface and thin-film processes, measurement and device technologies, etc. This APL Special Topic "Piezoelectric thin films for MEMS" features recent advances in piezoelectric thin films and related technologies aimed for MEMS applications. [Extracted from the article]

The dynamic response of a nonlinear resonator in the presence of resonant mode coupling is studied experimentally and theoretically. For the case of a clamped-clamped beam resonator in the presence of a 1:3 internal resonance, we show that at the onset of internal resonance, steady state oscillations cannot be sustained. At higher drive levels, stable oscillations can be maintained but the resonator amplitude undergoes amplitude modulated responses. We use these dynamic responses to build a bifurcation diagram that can be described remarkably well with a simple model consisting of a Duffing resonator coupled to a linear one. [ABSTRACT FROM AUTHOR]

This paper reports a silicon micromechanical resonator with Duffing nonlinearity weakened and temperature-frequency drift suppressed by electrostatic tuning. By operating the resonator in an elastic mode via semicircular beams, we can weaken the instability of amplitude-frequency dependence to linearize the behavior of electrostatic stiffness softening. The mutual independence of linear frequency modulation by temperature and DC bias is theoretically modelled and experimentally verified. Based on this finding, an active temperature compensation model by slightly regulating DC bias voltage is established. The experimental results show that the resonator has a slight Duffing nonlinearity and a maximum frequency inaccuracy of only ±6 ppm during a temperature ramp across a testing span of 70 °C. This active technique does not need additional power consumption and is generic to a variety of electrostatic resonators. [ABSTRACT FROM AUTHOR]

In this paper, a detection model of a chaotic oscillator is applied in the weak signal detection of an electrothermal excitation MEMS resonator, and the maximum Lyapunov exponent is used to obtain the threshold value and monitor the motion transition of a detection system. The phase drift caused by the electrothermal excitation is studied theoretically and experimentally, and according to the results of above study, the phase of a reference current signal is set to eliminate the phase when the resonator is in a resonant state. Then a new detection algorithm is proposed to detect the resonant signal. The simulation experiment on a weak signal under different magnifications and different levels of noises is conducted, after the impact of the quality factor Q of a resonator on detection results is analyzed. Finally, experiments on the output signal of a detected sensor sample are carried out by a proposed algorithm. Simulation and experiment results show that the detection model can effectively detect the weak signal and accurately obtain the resonant frequency, and it is immune to the noises. [ABSTRACT FROM AUTHOR]

We demonstrate systematic control of mechanical nonlinearities in micro-electromechanical (MEMS) resonators using shape optimization methods. This approach generates beams with nonuniform profiles, which have nonlinearities and frequencies that differ from uniform beams. A set of bridge-type microbeams with selected variable profiles that directly affect the nonlinear characteristics of in-plane vibrations was designed and characterized. Experimental results have demonstrated that these shape changes result in more than a three-fold increase and a two-fold reduction in the Duffing nonlinearity due to resonator mid-line stretching. The manipulation of this nonlinearity has significant interest in many applications, including precise mass sensing, accurate measurement of angular rates, and timekeeping. [ABSTRACT FROM AUTHOR]

The effect of coupling between the extensional bulk mode and the flexural mode of a cantilever beam resonator has been experimentally studied by exciting the two modes simultaneously. The modal frequency shift of linear extensional bulk mode shows a quadratic relationship with the square of flexural mode's amplitude displacement, and a frequency shift up to 1492 Hz is observed when the flexural mode is driven by a AC signal Vac of 3 V and a DC bias of 30 V. The flexural mode shows a Duffing-like behavior with a softening nonlinearity and its frequency shift is influenced not only by its own nonlinear amplitude-frequency effect but also the extensional mode's amplitude as predicted. The nonlinear coupling coefficient is found to be about two orders of magnitude larger than the softening nonlinearity. [ABSTRACT FROM AUTHOR]

We experimentally demonstrate an efficient approach to excite primary and parametric (up to the 4th) resonance of Microelectromechanical system MEMS arch resonators with large vibrational amplitudes. A single crystal silicon in-plane arch microbeam is fabricated such that it can be excited axially from one of its ends by a parallel-plate electrode. Its micro/nano scale vibrations are transduced using a high speed camera. Through the parallel-plate electrode, a time varying electrostatic force is applied, which is converted into a time varying axial force that modulates dynamically the stiffness of the arch resonator. Due to the initial curvature of the structure, not only parametric excitation is induced, but also primary resonance. Experimental investigation is conducted comparing the response of the arch near primary resonance using the axial excitation to that of a classical parallelplate actuation where the arch itself forms an electrode. The results show that the axial excitation can be more efficient and requires less power for primary resonance excitation. Moreover, unlike the classical method where the structure is vulnerable to the dynamic pull-in instability, the axial excitation technique can provide large amplitude motion while protecting the structure from pull-in. In addition to primary resonance, parametrical resonances are demonstrated at twice, one-half, and two-thirds the primary resonance frequency. The ability to actuate primary and/or parametric resonances can serve various applications, such as for resonator based logic and memory devices. [ABSTRACT FROM AUTHOR]

Phononic crystals (PnCs) and n-type doped silicon technique have been widely employed in silicon-based MEMS resonators to obtain high quality factor (Q) as well as temperature-induced frequency stability. For the PnCs, their band gaps play an important role in the acoustic wave propagation. Also, the temperature and dopant doped into silicon can cause the change in its material properties such as elastic constants, Young's modulus. Therefore, in order to design the simultaneous high Q and frequency stability silicon-based MEMS resonators by two these techniques, a careful design should study effects of temperature and dopant on the band gap characteristics to examine the acoustic wave propagation in the PnC. Based on these, this paper presents (1) a proposed silicon-based PnC strip structure for support tether applications in low frequency silicon-based MEMS resonators, (2) influences of temperature and dopant on band gap characteristics of the PnC strips. The simulation results show that the largest band gap can achieve up to 33.56 at 57.59 MHz and increase 1280.13 % (also increase 131.89 % for ratio of the widest gaps) compared with the counterpart without hole. The band gap properties of the PnC strips is insignificantly effected by temperature and electron doping concentration. Also, the quality factor of two designed length extensional mode MEMS resonators with proposed PnC strip based support tethers is up to 1084.59% and 43846.36% over the same resonators with PnC strip without hole and circled corners, respectively. This theoretical study uses the finite element analysis in COMSOL Multiphysics and MATLAB softwares as simulation tools. This findings provides a background in combination of PnC and dopant techniques for high performance silicon-based MEMS resonators as well as PnC-based MEMS devices. [ABSTRACT FROM AUTHOR]

Hydrodynamic loading greatly affects resonant characteristic of microfabricated structures immersed in a viscous fluid. In this letter, we demonstrate a technique to measure hydrodynamic loading on a MEMS resonator in a broad range of actuation frequency. The extracted hydrodynamic loading is in a good agreement with an analytical solution of an oscillating sphere, and a highly accurate model is developed for the hydrodynamic loading of the resonator. The developed technique can directly characterize the hydrodynamic loading of a microstructure with an arbitrary geometry and will facilitate the optimization of MEMS devices and AFM probes operating in a viscous fluid. [ABSTRACT FROM AUTHOR]

Strong parametric mode coupling in mechanical resonators is demonstrated at room temperature by using the photothermal effect in thin membrane structures. Thanks to the large stress modulation by laser irradiation, the coupling rate of the mechanical modes, defined as half of the mode splitting, reaches 2.94 kHz, which is an order of magnitude larger than electrically induced mode coupling. This large coupling rate exceeds the damping rates of the mechanical resonators and results in the strong coupling regime, which is a signature of coherent mode interaction. Roomtemperature coherent mode coupling will enable us to manipulate mechanical motion at practical operation temperatures and provides a wide variety of applications of integrated mechanical systems. [ABSTRACT FROM AUTHOR]

The authors report the resonance frequency and the energy dissipation of single crystal diamond cantilevers with different dimensions, which were fabricated by ion implantation assisted technique. The resonance frequency well followed the inverse power law relationship with the length of the cantilevers and exhibited a high reproducibility with varying the dimensions. The energy dissipation decreased with increasing the cantilever length and saturated or reduced at a certain value. For the shorter cantilevers, clamping loss governed the energy dissipation. As the cantilever length increased to a certain value, defects relaxation or surface effect became dominant. The possible origins for these energy dissipations were discussed. [ABSTRACT FROM AUTHOR]

This paper presents a method for designing and fabricating a Love wave resonator utilizing the phononic crystal (PC) as the reflectors. The PCs were formed by depositing 2D, periodically etched silica film on a quartz substrate. We analyzed the PC structure, and within its partial bandgap we designed a one-port resonator that contained a set of inter-digital transducer (IDT) inside the resonant cavity bonded by two PC arrays. With sub-micrometer structures, the resonator was designed to operate at 1.25 GHz. The device was fabricated by employing the microelectromechanical system (MEMS) fabrication technology and the resonant performance was evaluated. [ABSTRACT FROM AUTHOR]