Search Results (94)

The quality factor is a key metric for evaluating the performance of micro-electro-mechanical and nano-electro-mechanical system resonators. Although reducing device dimensions enhances resonator sensitivity, it also intensifies energy dissipation, thereby degrading the quality factor. Among the dominant dissipation mechanisms in micro-/nano-resonators, support loss is strongly influenced by surface effects at small scales, particularly the surface elastic modulus and initial surface stress. In this study, support loss in a double-clamped micro-/nano-beam resonator with surface effects incorporated is investigated. A dynamic model incorporating the surface elastic modulus and initial surface stress is developed based on Euler–Bernoulli beam theory and Gurtin–Murdoch surface elasticity theory. A quality-factor calculation method is then established by combining elastic wave radiation in the supports with an energy-based formulation. The theoretical predictions are validated using a three-dimensional finite element model comprising the resonator with a surface layer, supports, and a perfectly matched layer. Further, the effects of the surface elastic modulus, initial surface stress, characteristic size, and dimensionless geometric parameters on support loss are examined. The results show that the surface elastic modulus and initial surface stress increase support loss and reduce the quality factor, with the initial surface stress exhibiting the stronger influence. The influence of these parameters becomes more pronounced as the characteristic size decreases, and variations in the length-to-thickness and width-to-thickness ratios further modify their contribution to support loss. Mechanistically, surface effects alter the effective bending stiffness and axial force, thereby changing the dynamic loads transmitted to the supports and resulting elastic-wave radiation. These findings provide theoretical insights for the design of high-quality-factor micro-/nano-devices. Full article

Reliable calibration that converts transduced signals into physical displacement is essential for quantitative studies and applications of nanoelectromechanical resonators, including nonlinear dynamics, precision sensing, and optomechanical and electromechanical coupling. Existing harmonic calibration based on nonlinear optical transduction is generally restricted to systems with optically thin suspended layers and highly reflective substrates. Their weak higher-order harmonic signals are also susceptible to noise, drift, and inconsistencies between separately acquired frequency sweeps. Here, we generalize this approach to hexagonal boron nitride/graphene (h-BN/Gra) heterostructure resonators without local metallic reflectors. Multilayer thin-film interference calculations show that a branch-local phase correction enables the effective two-beam inversion to recover vibration amplitude and local static gap within acceptable error bounds. Experimentally, we use multi-demodulator lock-in detection to acquire the ω, 2ω, and 3ω optical responses simultaneously at each frequency point. Ratios among these harmonics then yield frequency-resolved vibration amplitude and local static gap. Repeated frequency sweeps at a constant gate bias simultaneously track the resonance characteristics and local static gap, revealing a time-dependent relaxation of approximately 24 nm in the local device configuration. This work provides a practical in situ route for simultaneously resolving resonance characteristics and configurational evolution across a broader range of nanomechanical resonator architectures. Full article

This research investigates the systematic nanomechanical behavior of tetragraphene-based nanotubes (TGCNTs) using classical molecular dynamics (CMD) simulations performed via the LAMMPS package with the reactive AIREBO-Morse potential. Tetragraphene is a novel carbon allotrope characterized by a unique mixture of $s{p}^2$ and $s{p}^3$ hybridization. We analyzed the nanomechanical properties of zigzag-like TGCNTs under uniaxial tensile loading, systematically examining the effects of chirality, diameter, length, and temperature ranging from 300 K to 2100 K, while maintaining a constant nanotube length. Our results reveal a distinct nanostructural degradation at high temperatures, where the nanotubes completely lose their structural stability above 1500 K. Under mechanical strain, the stress–strain curves highlight a strong dependence on chirality. The $(0,n)$ TGCNTs exhibit brittle behavior, characterized by a short, nearly linear curve that terminates abruptly at a rapid fracture point without significant plastic deformation. In contrast, the $(n,0)$ TGCNTs demonstrate remarkable ductility and irreversible plastic deformation flow. This is evidenced by a distinct plateau effect with constant stress up to 20% strain, followed by ultimate fracture at a strain over $40\%$, indicating a stress-induced structural phase transition. To map their transverse elasticity, Poisson’s ratio ($\nu$) was evaluated within the elastic regime, revealing an ultra-low value of $\nu =0.07$ for the TGCNT $(0,10)$ in close agreement with density functional theory (DFT) benchmarks, contrasting with an anomalously high value of $\nu =1.19$ for the TGCNT $(14,0)$ due to severe chiral anisotropy. The calculated Young modulus values range from 2379.90 to 3499.20 GPa.Å for $(n,0)$ TGCNTs and 1886.70 to 2374.40 GPa.Å for $(0,n)$ TGCNTs. These insights into the nanostructure–property relationships of TGCNTs provide essential design guidelines for their application in flexible electronics, nanocomposites, and advanced nanoelectromechanical systems (NEMSs). Full article

Resonant mass sensors based on micro/nanoelectromechanical systems (MEMS/NEMS) offer a promising approach for label-free gravimetric detection. However, practical applications often require not only high sensitivity but also improved loading repeatability and reduced dependence on mass loading position. In this work, a suspended resonant mass sensor based on a 10 nm-thick Hf_0.5Zr_0.5O₂ (HZO) piezoelectric film is proposed. A central silicon loading platform is introduced to provide a mechanically robust and spatially uniform sensing region. A Kirchhoff plate model incorporating residual stress is established to analyze the effects of residual stress and platform geometry on the resonant characteristics. The device is fabricated by combining SOI micromachining with wet transfer of the ultrathin HZO film. Laser Doppler vibrometry measurements show a first-order resonant frequency of 1.303 MHz and a quality factor of 342, corresponding to an extracted residual stress of approximately 1.319 GPa. Finite element simulations calibrated by experimental parameters indicate a uniform first-mode displacement distribution and a linear frequency response to added mass from 0 to 1 ng. The obtained mass sensitivities are 150.7 Hz/pg and 166.8 Hz/pg from finite element and analytical models, respectively. The proposed structure provides a feasible route toward repeatable pg-level resonant mass sensing based on ultrathin piezoelectric films. Full article

In recent years, microelectromechanical systems (MEMS) filters exploiting structural nonlinearity and coupled resonance have enabled programmable passband shaping beyond traditional single-peak designs, yet they still face low operating frequencies and limited electrical tuning range. Here, leveraging 1:1 internal resonance, we propose a gate-programmable tuning strategy for two-dimensional (2D) material-based nanoelectromechanical systems (NEMS), enabling high-frequency operation and wide-range reconfigurability. Benefiting from the high resonant frequency and wide electrostatic tunability of 2D materials such as MoS₂, our theoretical analysis indicates wide-range programmability up to $f/f_0\approx 200\%$. Sweeping $V_{g1}=V_{g2}$ from 9 to 16 V while maintaining $\approx 1:1$ frequency matching shifts the passband upward quasi-linearly at $4.4~\mathrm{MHz}/\mathrm{V}$. In contrast, with the coupling strength nearly unchanged, mV-level bias mismatch perturbs the frequency ratio by ${10}^{-5}$, enabling highly sensitive bandwidth trimming from 3.18 to 5.20 kHz, supporting a two-step strategy of coarse center-frequency tuning followed by fine bandwidth control. To broaden the bandwidth, we further analyze a three-drum case: with $V_{g1}=V_{g2}=V_{g3}=16 \mathrm{V}$, the bandwidth reaches 21.79 kHz with a 5056.05 dB/MHz transition slope and 0.95 dB ripple, which is nearly 4 times wider than the two drum case with the same gate voltage. This study shows that 1:1 internal resonance can be used to tune the bandpass response of NEMS resonators. All results are obtained from theoretical modeling and numerical simulations. Full article

Fullerene-based polymer nanocomposites are promising candidates for micro- and nano-electromechanical systems (MEMSs/NEMSs) due to their tunable mechanical performance and high surface-to-volume ratios. At the nanoscale, interfacial stresses strongly influence the effective elastic response, yet quantitative interface parameters are rarely available for continuum modeling. In the current investigation, a molecular dynamics (MD)-based calibrated micromechanics framework is developed to predict the bulk modulus of fullerene-poly(methyl methacrylate) (PMMA) nanocomposites that incorporate interface stress effects. Atomistic representative volume elements (RVEs) containing individual fullerene nanoparticles embedded in a polymer matrix are generated using controlled molecular packing and systematically equilibrated. The bulk moduli of both isolated fullerenes and fullerene-PMMA RVEs are extracted from energy-volume relationships using a Birch-Murnaghan equation of state. These MD results are used to calibrate a size-dependent micromechanics model and to extract the surface Lamé modulus of the polymer-fullerene interface directly. The extracted surface Lamé modulus remains nearly constant (approximately 19 N/m) across all investigated fullerene sizes. In contrast, the interfacial contribution to the effective bulk modulus increases significantly for smaller nanoparticles due to their higher surface to volume ratios. The calibrated model accurately reproduces MD predictions and provides a physically grounded multiscale link between atomistic interfacial behavior and continuum elastic properties. The proposed framework offers a predictive tool for the rational design of surface-dominated nanocomposites in MEMS/NEMS applications. Full article

The presence of dominant interatomic dispersion forces on the nanoscale holds the promise for breakthrough applications in key areas of quantum sensing, such as accelerometry, as well as nano-manipulation and energy storage. In order to do work, nano-machines enabled by dispersion forces must exchange energy with the surrounding environment. Such processes can be described in terms of thermodynamical engine cycles involving individual atoms or material boundaries, separated by possibly empty gaps and interacting via time-dependent dispersion forces. The fundamental strategy indispensable to achieve dispersion force time-modulation, demonstrated experimentally by independent groups on different scales, is based on the illumination of interacting, semiconducting elements by appropriate radiation beams. Here we analyze the operation of ideal nano-engines in the quasi-static regime by means of the Lifshitz theory of dispersion forces involving semiconducting boundary or atom irradiation. Firstly, we verify that the First Law of Thermodynamics is satisfied so that the total energy of the system is rigorously conserved. Secondly, we show that, within this first approximate treatment, the Second Law of Thermodynamics may be violated for extremely small interboundary gap widths. We identify important limitations to be addressed to determine whether this is a reliable conclusion. The technological and historic backdrops are presented, and important topics for future research are identified. Full article

This study introduces a novel numerical approach to analyze the axisymmetric bending behavior of functionally graded (FG) graphene platelet (GPL)-reinforced annular sandwich nanoplates featuring a porous core. The nanostructures are exposed to coupled magnetic and hygrothermal environments. The porosity distribution and GPL weight fraction are modeled as nonlinear functions through the thickness, capturing realistic gradation effects. The governing equations are derived using the virtual displacement principle, taking into account the Lorentz force and the interaction with an elastic foundation. To address the size-dependent behavior and thickness-stretching effects, the model employs the nonlocal strain gradient theory (NSGT) integrated with a modified version of Shimpi’s quasi-3D higher-order shear deformation theory (Q3HSDT). The differential quadrature method (DQM) is applied to obtain numerical solutions for the displacement and stress fields. A detailed parametric study is conducted to investigate the influence of various physical and geometric parameters, including the nonlocal parameter, strain gradient length scale, magnetic field strength, thermal effects, foundation stiffness, core thickness, and radius-to-thickness ratio. The findings support the development of smart, lightweight, and thermally adaptive nano-electromechanical systems (NEMS) and provide valuable insights into the mechanical performance of FG-GPL sandwich nanoplates. These findings have potential applications in transducers, nanosensors, and stealth technologies designed for ultrasound and radar detection. Full article

We present a detailed mathematical description, both an analytical model and a numerical simulation, of a physical system based on a superconducting nanoelectromechanical setup that generates nanomechanical cat-states entangled with charge qubit states. The system consists of a superconducting grain in a regime of the Cooper pair box (the charge qubit) that performs mechanical vibrations between two bulk superconductors. Operation of the device is based on the AC Josephson effect, i.e., the phase difference between superconducting electrodes is controlled by a DC bias voltage following the operational switch on/off protocol. We compare an analytical idealised solution with numerical simulation using experimentally feasible parameters, different decoherence processes, as well as imperfections of experimental procedures such as time-control of the bias voltage, to get insight into how they influence the time-evolution of the realistic system, deteriorate the quantum coherence, and affect the formation of the cat-states. Full article

Designing and manufacturing devices at the micro- and nanoscales offers significant advantages, including high precision, quick response times, high energy density ratios, and low production costs. These benefits have driven extensive research in micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS), resulting in various classifications of materials and manufacturing techniques, which are ultimately used to produce different classifications of MEMS devices. The current work aims to systematically organize the literature on MEMS in biomedical devices, encompassing past achievements, present developments, and future prospects. This paper reviews the current research trends, highlighting significant material advancements and emerging technologies in biomedical MEMS in order to meet the current challenges facing the field, such as ensuring biocompatibility, achieving miniaturization, and maintaining precise control in biological environments. It also explores projected applications, including use in advanced diagnostic tools, targeted drug delivery systems, and innovative therapeutic devices. By mapping out these trends and prospects, this review will help identify current research gaps in the biomedical MEMS field. By pinpointing these gaps, researchers can focus on addressing unmet needs and advancing state-of-the-art biomedical MEMS technology. Ultimately, this can lead to the development of more effective and innovative biomedical devices, improving patient care and outcomes. Full article

Oscillator networks display intricate synchronization patterns. Determining their stability typically requires incorporating the symmetries of the network coupling. Going beyond analyses that appeal only to a network’s automorphism group, we explore synchronization patterns that emerge from the phase-shift invariance of the dynamical equations and symmetries in the nodes. We show that these nonstructural symmetries simplify stability calculations. We analyze a ring-network of phase–amplitude oscillators that exhibits a “decoupled” state in which physically-coupled nodes appear to act independently due to emergent cancellations in the equations of dynamical evolution. We establish that this state can be linearly stable for a ring of phase–amplitude oscillators, but not for a ring of phase-only oscillators that otherwise require explicit long-range, nonpairwise, or nonphase coupling. In short, amplitude–phase interactions are key to stable synchronization at a distance. Full article

Motivated by the potential of surface texturing to enhance the tribological performance of micro- and nano-electromechanical systems (MEMS/NEMS), this study proposes a novel non-linear optimization approach for designing textured surfaces. This model minimizes the contact area between interacting surfaces and deformation during sliding under dry conditions by controlling key design parameters, such as the size and shape of the designed surface. We test the performance of the proposed model using the lotus leaf surface with dimensions of 248 × 136 micrometers. Due to the large size of the model, we propose a solution approach which consists of a data aggregation step, an optimization step, and a data disaggregation step. The optimization step decomposes the model into smaller models that are easier to solve. Via the sensitivity analysis, we highlight the trade-offs between data aggregation and model decomposition and their effect on the quality of the solutions found. In conclusion, our approach bridges the gap between fabrication capabilities and design requirements, paving the way for significant advances in tribological performance and surface engineering. Full article

Using gradient-corrected density functional theory we investigate the mechanical properties of ultrathin boron (B) and phosphorus (P) doped silicon nanowires (SiNWs) along the [001] and [111] orientations within the PBE approximation. Both pristine and doped SiNWs under study have diameters ranging from 5 to 8 Å. Our results show that doping significantly enhances the bulk modulus ($B_0$), shear modulus ($G_V$), Young’s modulus (Y), and other mechanical parameters. The significant anisotropy observed in the mechanical properties of Si[111] NWs, with varying moduli along different axes, further illustrates the complex interplay between mechanical behavior and electronic structure at the nanoscale. The mechanical flexibility of SiNWs, combined with their tunable electronic properties due to quantum confinement, makes them promising candidates for advanced nanoelectronic devices, nanoelectromechanical systems (NEMS), and advanced technologies. Full article