In this work, we present a novel dual-mode power sensing platform for real-time energy tracking based on a clamped-clamped microbeam resonator. The proposed device utilizes the Joule heating effect to transduce the input power to a rise in temperature in the structure, which also changes the elastic stiffness of the microbeam. This paper proposed two different readout methods for power sensing: static mode and dynamic mode. In the static mode, the beam is static without motion, the resistance of the beam was found to be linearly proportional to the input power with a responsivity of 11.12 Omega/mW. In the dynamic mode, the changes in the elasticity effects the dynamic vibration of the beam, the resonance frequency shift was found to be linearly proportional to the input power with a responsivity of 8650 Hz/mW. The increased flexibility of the dual-mode readout and the high sensitivity of the proposed approach is promising for monitoring power.

This paper presents an innovative tunable and low-power micromachined thin-film piezoelectric-on-silicon (TPoS) antisymmetric weakly-coupled gas sensor, showing high sensitivity by exploiting its nonlinearity. Adopting a special Aluminium Nitride (AlN) piezoelectric layer doped with Silicon (Si) in TPoS devices significantly improved the system's power consumption during resonance frequency tuning by 41.2 %. Two sensing theories based on linear and nonlinear behaviour are explored as operating the system near its buckling bifurcation (i.e., before and after) for increasing Helium concentrations. The results yield high linear frequency shifts of 3.60 ppm/Hz and 9.96 ppm/Hz at two operation points. Nonlinear fold bifurcation jump was exploited to enhance the sensor sensitivity, proving that such a triggered mechanism can be used as an alarming gas sensor with adjustable thresholds of 2000 ppm (i.e. 0.2 %) of Helium. The novel TPoS gas sensor shows great potential in low-power consumption, high sensitivity, and multi-functionality for environmental monitoring and hazard gas-controlling measure applications.

This work presents a novel vacuum gauge designed for ultra-high vacuum environments by exploiting the nonlinear dynamics of a micro-electromechanical systems (MEMS) double-clamped beam resonator. Traditional MEMS resonant pressure sensors face a critical limitation: their operational range is confined to pressures <= 1 Torr, primarily due to the loss of linear damping and measurable quality (Q) factors in high vacuum conditions. To address this, our design leverages the jump-behavior of a nonlinear resonator, where abrupt transitions in vibrational states occur as pressure crosses a threshold. By modulating the vibration amplitude and frequency, The designed sensor achieves a sensitivity of 34 Hz/Torr in < 1 Torr highvacuum pressure conditions. The nonlinear regime avoids electrostatic pull-in instability, enabling stable operation at large oscillation amplitudes. Experimental results validate the effectiveness of the proposed pressure switching mechanism, offering a streamlined approach to pressure monitoring in ultra-high vacuum environments.

In the present paper, a microbeam-based MEMS device is experimentally driven to experience a subcombination internal resonance (IR) of the additive type, where the second mode internally resonates with both the first and the third modes inducing a range of quasi-periodic dynamics. The main features of the experimental quasiperiodicity are analyzed, which inherently depend on the ratios established by the frequencies of the involved modes. Experimental Poincare maps are established and tracked, exhibiting a specific underlying pattern. Numerical simulations are developed and the Fast Fourier Transform frequency trend lines are examined, showing the variations of the modes frequencies values while keeping the subcombination IR relationship. We investigate the evolution of the quasi-periodic waveform as increasing the excitation frequency. Special attention is devoted to the hardening dominance of the system, which influences the modes frequencies components. The last part of the paper is focused on the impacting regime. Since the microbeam is constituted by a dielectric layer (Silicon Nitride), impacts take place as raising the oscillation amplitudes. We analyze the experimental behavior at impacts, showing the possibility of dynamics with different characteristics, including both quasi-periodic, chaotic and periodic regions, all of them holding subcombination IR signature.

This work presents a novel design based on weakly-coupled beam-based structural elements with engineered nonlinearities that hosts a piezoelectric thin film for energy harvesting. The H-shaped structure are finite elements simulated to understand their frequency response, which includes local and global mode interactions. The inherently nonlinear structures are then designed to enable the activation of the 1:1, 1:2, and 1:3 internal resonances that broadens the frequency response and increases its amplitude. The H-shaped beam-based structures are 3D printed and their dynamic behavior is experimentally investigated using LDV to get insights on how to integrate them with piezoelectric elements. The experimental power measured from individual patches of an H-shaped piezoelectric loaded structure is 5.26 µW, which is relatively less than the power of a piezoelectric loaded doubly-clamped beam (9.18 µW). This discrepancy primarily arises from differences in size between the two batches. However, by integrating the voltage outputs from both patches on the H-shaped coupled beam structure, a synergistic effect is achieved, yielding a combined power of 14.31 µW. This concentration is observed across a broader frequency spectrum, specifically ranging from 180 to 200 Hz, as compared to the single peak exhibited by the doubly-clamped beam. These findings highlight the exceptional potential of the H-shaped coupled-beam structure and emphasize their remarkable efficiency of the piezoelectric energy harvesting.

We present an electric power meter that capitalizes on the interaction of electrothermal strain and mechanical vibration in a micro-electro-mechanical systems (MEMS) beam undergoing the antisymmetric mode of vibration. This is achieved by using a resonant bridge driven with an electrothermal modulation technique. The change in electrical power is monitored through the alteration in the mechanical stiffness of the structure, which is tracked electrostatically. The observed deflection profile of the beam under the influence of electrothermal effects shows that the deflection geometry due to buckling exhibits similar trends as the first symmetric vibrational mode, in contrast to the antisymmetric mode. Therefore, we compare two distinct vibrational modes, converting the compressive thermal stress generated by the input electrical power via Joule heating into a shift in the resonance frequency. By employing antisymmetric vibrational mode, the output of our device is consistently monotonic to the input electrical power, even when the microbeam is experiencing buckling deflections. In addition, the sensing operation based on antisymmetric modes yields only a 1.5% nonlinear error in the response curve, which is ten times lower than that of symmetric modes. The observed deformation shape of the resonator agrees with the results obtained from multi-physics finite simulations. Finally, this approach has the potential to be extended to other frequency-shift-based sensors, allowing for higher linearity.

This paper reports a novel Aluminium-Nitride (AlN)-based piezoelectric micromachined gas sensor relying on thermal energy dissipation (heating or cooling) of an electrically heated weakly coupled resonator. The coupled MEMS resonator, consisting of a bridge and cantilever resonators mechanically coupled, was driven by applying AC voltage to an AlN-piezoelectric layer coated on the clamped-clamped beam. The frequency and the velocity spectra are studied with a laser Doppler vibrometer. The buckling behaviour of the devices under high electrothermal voltage was analyzed. Moreover, two modes veering phenomena were observed and discussed. Sensing performance for two operation points before and after the buckling point was explored experimentally for increasing concentrations of Helium. The results yield different directions of frequency shift with 3.123 % /kHz and 1.089 % /kHz slope respectively, showing the great potential for high-performance gas sensing.

In this work, we present the design and experimental demonstration of the first micro-resonator-based tunable hysteresis comparator. The proposed design employs an electrostatically driven clamped-clamped microbeam operated in the nonlinear regime. The design operation is assigned such that both the resonator’s drive frequency and beam bias can be utilized to tune the nonlinear dynamic behavior of the resonator. This tunable nonlinear behavior allows the device to exhibit a hysteretic voltage response with a tunable hysteresis voltage range. In the frequency tuning scheme, the hysteresis range is directly proportional to the driving frequency shift, with a maximum hysteresis portion of 51.4% achievable. In the voltage tuning scheme, the hysteresis range exhibits a linear relationship with the bias voltage variance without compromising tunability. Moreover, the voltage tuning scheme provides a simpler solution as it simplifies the complexity of the control system and provides a better stable and repeatable control capability. The proposed resonator-based comparator has many additional benefits, including stable electrical properties, a long lifetime due to the elimination of physical contact, and a wide tuning hysteresis range. Furthermore, the device has the potential for large voltage swing (~20V) interfacing in the microresonator-based electronics field. This high-voltage handling capability of our proposed resonator-based hysteresis comparator broadens its applicability, rendering it compatible with high-voltage systems. [2023-0084]

In this work, we consider a MEMS microbeam, and we investigate the experimental response of the device at the third-mode dynamics. By forward and backward sweeping, the data acquired via the laser Doppler vibrometer show the occurrence of a 2:1 internal resonance, where the coupling mode is the fifth. The experimental response is simulated via shooting technique and attractor basins. We focus on the metamorphoses of the basins of attraction scenario induced in the phase space by the activation of the internal resonance.

As natural frequencies become commensurate, internal (autoparametric) resonances involving the corresponding modes may arise. This phenomenon has been recently increasingly reported in micro- and nanosystems. Due to the intrinsic nonlinearity, internal resonances may draw complex features, which can be desirable for developing novel devices with enhanced functionality based on energy transfer among the involved modes. Here, we examine the possibility of activating internal resonance by inducing impacts. Through a specially deposited dielectric layer to prevent short-circuiting, a microelectromechanical beam is deliberately operated to have impact with the substrate, which redirects the dynamics of the system. Driven by repetitive impacts, the device widens the frequency bandwidth around the first mode and activates a non-classical type of internal resonance, at a ratio of 7:2 between the first and third vibration modes. Interestingly, this internal resonance behavior is enabled in regions of the driving parameters space, where the branch would not have existed in the absence of impacts. The dynamical phenomena featured by the impacts are affected by the characteristics of the impacting surfaces, which may controllably tune the response. This study opens up research toward utilizing impacts for favoring internal resonance activations, including in cases where they are precluded in the smooth system, as well as engineering the associated modal energy exchange.

This work reports highly selective multiple analyte detection by exploiting two different mechanisms; absorption and thermal conductivity using a single MEMS device. To illustrate the concept, we utilize a resonator composed of a clamped-guided arch beam connected to a flexural beam and a T-shaped moveable mass. A finite element model is used to study the mode shapes and mechanical behavior of the device with good agreement reported with the experimental data. The resonator displays two distinct out-of-plane modes of vibration. For humidity detection, we utilize physisorption by functionalizing the surface with graphene oxide (GO), which has strong affinity toward water vapors. The GO solution is prepared and drop-casted over the mass surface using an inkjet printer. On the other hand, cooling the heated flexural beams is used for helium (He) detection (thermal-conductivity-based sensor). The sensor characteristics are extensively studied when the modes are individually and simultaneously actuated. Results affirm the successful utilization of each mode for selective detection of relative humidity and He. This novel mode-dependent selective detection of multiple analytes can be a promising building block for the development of miniature, low-powered, and selective smart sensors for modern portable electronic devices.

Abstract This work presents the results of an experimental investigation and a low-order model development for complex resonant dynamics of a cantilever macro-plate. The plate is fabricated from a material using 3D additive manufacturing technology and the material is assumed to be ‘hyperelastic’. The geometry of the plate with cut-outs is analytically optimized assuming a linear elastic material such that the second bending mode frequency 𝜔02 is approximately twice the first twisting mode frequency 𝜔11. Based on the observed ‘near’ 2:1 resonant response under harmonic excitation near 𝜔02, a low-order 2 DOF nonlinear dynamic model is developed to simulate the plate response. A unique and novel stepwise iterative approach is developed for the modal parameter extraction. The unknown modal parameters are extracted using Harmonic Balance solutions, constructing frequency response curves, and curve-fitting techniques. The results are then validated using long-time integration for the developed model. A good agreement is observed between the analytical and experimental results for the different excitation levels considered.

There is an urgent need to develop innovative and highly selective gas sensors for environmental, residential, and industrial applications. Here, we propose a highly selective multiple gases detection system using an electro-thermally heated silicon micro-resonator and machine- learning algorithms. The device is based on the cooling/heating effect of gases on the thermal stresses of a resonating structure. As a case study, we demonstrate sensitive and selective responses toward He, Ar, and CO2. To generate the unique signature markers for each gas, multiple datasets are collected at three different concentration levels (4%, 10%, and 25%). A principal component analysis (PCA) is conducted using seven customized highly significant and unique signature markers. The markers are obtained through data processing from the response of all gases. Quadratic discriminant and medium Gaussian support vector machines (SVMs) are used for training based on the seven customized features, which yield a high classification accuracy of 100 %. The proposed gas- sensing approach can be promising for the development of intelligent and highly selective compact size sensing platforms without the need for special materials for coating and functionalization.

Microresonator-based temperature sensors offer stable and high-resolution temperature detection. However, typical temperature-sensing techniques based on resonators suffer from design complexity and low sensitivity. In this study, we present a simple high-sensitivity temperature sensor that comprises a sealed electrostatically actuated clamped–clamped silicon microbeam resonator. The sensor's high sensitivity is attributed to the thermal-strain effects due to the mismatch between the thermal expansion coefficients of the composite materials. And the sensitivity is further enhanced by operating the resonator near the buckling zone via in situ Joule heating. In addition, The sensor operates at a single drive frequency that corresponds to the resonant frequency at the maximum temperature. A change in temperature induces a thermal strain that shifts the resonant frequency, which changes the output voltage. This considerably simplifies the readout system from the typical frequency-tracking method to the proposed amplitude tracking method. The encapsulated sensor achieves a minimum detectable temperature of 0.0196 °C and an absolute temperature coefficient of frequency of 1757 ppm/°C. These results demonstrate the great potential of the proposed sensor for efficient resonant thermal sensing with high resolution, enhanced sensitivity and a simplified readout scheme.

We analyze the dynamics induced by a 2:1 internal resonance between the third (second symmetric) and the fifth (third symmetric) mode of a MEMS microbeam. An extensive experimental investigation is conducted, where forward and backward sweeps are systematically acquired up to elevated excitations. As ramping the voltage, a change along the forward sweep of the resonant branch is noted. This is analyzed via the combined use of different analytical and numerical tools, which show a phase shift between the modes involved in the 2:1 internal resonance. Constantly referring to the experimental data, simulations examine the underlying features of the system's behavior. The dynamics observed in the experimental frequency sweeps are part of a more complex scenario, where different attractors appear and coexist. The experimental behavior bifurcation chart is reported and compared with simulations, which offers a comprehensive view of the 2:1 internal resonance activation. The concurrence of numerical results and experimental data confirms on the effective actuality of these complex features in safe conditions, along wide ranges of the parameters space.

In this paper, we utilize a passive technique based on geometry optimization to control the nonlinearities and the dynamical response of MEMS resonators. To achieve this, we propose a new hybrid shape combining a straight and initially curved microbeam. The Galerkin method is employed to solve the beam equation and study the effect of the different design parameters on the ratios of the frequencies and the nonlinearities of the structure. We show by adequately selecting the parameters of the structure; we can realize systems with strong quadratic or cubic nonlinearities or even zero nonlinearity. Also, we investigate the resonator shape effect on breaking the symmetry and explore different linear coupling phenomena: crossing, veering, and mode hybridization. We demonstrate the possibility of controlling the frequencies of the different modes of vibrations to achieve commensurate ratios necessary for activating internal resonance. The ability to activate the nonlinearities and tuning the frequencies is essential for wide range of applications in signal filtering, sensing, timing, and mass and gas sensing. The proposed method is simple in principle, easy to fabricate, and offers a wide range of controllability on the sensor nonlinearities and response. In addition, the passive techniques does not need additional circuits, to control the frequencies, which help reducing the device size, cost, and power consumption.

This work investigates the dynamics of a microbeam-based MEMS device in the neighborhood of a 2:1 internal resonance between the third and fifth vibration modes. The saturation of the third mode and the concurrent activation of the fifth are observed. The main features are analyzed extensively, both experimentally and theoretically. We experimentally observe that the complexity induced by the 2:1 internal resonance covers a wide driving frequency range. Constantly comparing with the experimental data, the response is examined from a global perspective, by analyzing the attractor-basins scenario. This analysis is conducted both in the third-mode and in fifth-mode planes. We show several metamorphoses occurring as proceeding from the principal resonance to the 2:1 internal resonance, up to the final disappearance of the resonant and non-resonant attractors. The shape and wideness of all the basins are examined. Although they are progressively eroded, an appreciable region is detected where the compact cores of the attractors involved in the 2:1 internal resonance remain substantial, which allows effectively operating them under realistic conditions. The dynamical integrity of each resonant branch is discussed, especially as approaching the bifurcation points where the system becomes more vulnerable to the dynamic pull-in instability.

In this work, we demonstrate a selective gas sensor based on monitoring two different detection mechanisms; absorption and thermal conductivity. To illustrate the concept, we utilize a resonator composed of a clamped-guided arch beam connected to flexural beams and a T-shaped moveable mass. The resonator has two distinct out-of-plane modes in which the mass motion dominates the first mode while the motion of the flexural beam dominates the second mode. A highly disperse graphene oxide (GO) solution is prepared and drop-casted over the moveable mass structure using the inkjet printer for humidity sensing. On the other hand, the He is detected using the hot flexural beams. The results show no significant effect of humidity on the flexural mode (FM) nor for He on the mass mode (MM). This indicates a new technique for selectivity and identification. The device shows good sensitivity (50.1% to 50% RH @ MM and 39.2% to 50% He @ FM: (Vac = 1.5V)), linearity, and repeatability with excellent selectivity. It is demonstrated that the FM has great potential for detecting and categorizing different gases according to their thermal conductivity. The demonstrated multimode MEMS resonator can be a promising approach for the development of smart, highly selective, and sensitive gas/chemical sensors.

The present study is focused on the dynamics of a microbeam-based MEMS device and analyzes its behavior in the neighborhood of the third natural frequency. An extensive experimental investigation is conducted. The main resonant and non-resonant branches span a wide range of coexistence. The 2:1 internal resonance is activated between the third and fifth modes, in which case the device exhibits complex and intriguing dynamics. The experimental data are examined in depth using various analytical and numerical tools. Alongside with the experiments, theoretical simulations are developed, where the main features of the internal resonance are properly represented and the contribution of each mode is discussed. The main steps of the progression of the 2:1 internal resonance are highlighted and the possibility of more complex internal resonances is explored, where different higher modes are involved.

Micro/Nano-electromechanical systems, MEMS/NEMS-based resonators are presently an important part of a wide range of applications. However, many of these devices suffer from the low signal-to-noise ratio and the need for a large driving force. Different principles were proposed to enhance the sensitivity and improve their signal-to-noise ratios (SNR), such as bifurcations, jumps and higher-order excitation. However, these methods require special designs and high actuation voltages, which are not always available in the standard function generators and power supplies. Also, it increases the devices’ overall cost and power requirements. Furthermore, parametric excitation is explored as an option to amplify the signal at a lower cost and energy demand. However, this type of excitation requires specific geometrical settings, in addition to very low damping conditions. Electrothermal actuation is investigated to achieve excitation of primary resonance, which can be used for parametric excitation. This type of excitation is desirable due to its simplicity, robustness and ability to create large internal forces at low voltages. However, the time response is limited by the thermal relaxation time. In this work, we demonstrate the use of electromagnetic actuation to significantly amplify the response of electrothermally actuated clamped-clamped resonators at first mode (primary) resonance. At ambient pressure, experimental data show 18 times amplification of the response amplitude compared with electrothermal actuation only. The method is based on introducing a permanent magnetic field to induce an out-of-plane Lorentz-force. The results show the great potential of this technique being used for a variety of sensing and signal processing applications, especially, where a large signal-to-noise ratio is required while using low operational voltages.