More Like this

1. Strong internal resonance in a nonlinear, asymmetric microbeam resonator

   https://doi.org/10.1038/s41378-020-00230-1  

   Asadi, Keivan; Yeom, Junghoon; Cho, Hanna (December 2021, Microsystems & Nanoengineering)

   null (Ed.)

   Abstract Exploiting nonlinear characteristics in micro/nanosystems has been a subject of increasing interest in the last decade. Among others, vigorous intermodal coupling through internal resonance (IR) has drawn much attention because it can suggest new strategies to steer energy within a micro/nanomechanical resonator. However, a challenge in utilizing IR in practical applications is imposing the required frequency commensurability between vibrational modes of a nonlinear micro/nanoresonator. Here, we experimentally and analytically investigate the 1:2 and 2:1 IR in a clamped–clamped beam resonator to provide insights into the detailed mechanism of IR. It is demonstrated that the intermodal coupling between the second and third flexural modes in an asymmetric structure (e.g., nonprismatic beam) provides an optimal condition to easily implement a strong IR with high energy transfer to the internally resonated mode. In this case, the quadratic coupling between these flexural modes, originating from the stretching effect, is the dominant nonlinear mechanism over other types of geometric nonlinearity. The design strategies proposed in this paper can be integrated into a typical micro/nanoelectromechanical system (M/NEMS) via a simple modification of the geometric parameters of resonators, and thus, we expect this study to stimulate further research and boost paradigm-shifting applications exploring the various benefits of IR in micro/nanosystems. 

   more » « less
2. Temperature Compensated Graphene Nanomechanical Resonators

   https://doi.org/10.1002/adfm.202415708  

   Lee, Jaesung; Chiu, Hsin‐Ying; Zhao, Liang; Shan, Jie; Feng, Philip X‐L (June 2025, Advanced Functional Materials)

   We report the experimental demonstration of temperature compensated bilayer graphene two‐dimensional (2D) nanomechanical resonators operating in temperature range of 300 to 480 K. By using both microspectroscopy and scanning spectromicroscopy techniques, spatially visualized undriven thermomechanical motion is conveniently used to monitor both the resonance frequency and temperature of the device via noise thermometry while the device is photothermally agitated. Thanks to engineerable naturally integrated temperature compensation of the graphene and gold clamps that minimize variations of built‐in tension in a wide temperature range, very small linear TCfs of ≈−39 and −84 ppm K^−1 are achieved in the graphene nanomechanical resonators. The measured TCfs are orders of magnitude smaller than those in other 2D resonant nanoelectromechanical systems (NEMS). The intricately coupled thermal tuning and strain effects are further examined, elucidating that TCf can be further improved by optimizing device dimensions, which can be exploited for engineering highly stable NEMS resonators and oscillators for signal transduction and sensing applications. 

   more » « less
3. Two-dimensional FePS3 nanoelectromechanical resonators with local-gate electrostatic tuning at room temperature

   https://doi.org/10.1063/5.0243387  

   Wang, Yunong; Yousuf, S_M_Enamul Hoque; Zhang, Xiao-Xiao; Feng, Philip X-L (December 2024, Journal of Applied Physics)

   Nanoelectromechanical systems (NEMS) enabled by two-dimensional (2D) magnetic materials are promising candidates for exploring ultrasensitive detection and magnetostrictive phenomena, thanks to their high mechanical stiffness, high strength, and ultralow mass. The resonance modes of such vibrating membrane NEMS can be probed optically and also manipulated mechanically via electrostatically induced strain. Electrostatic frequency tuning of 2D magnetic NEMS resonators is, thus, an important means of investigating magneto-mechanical coupling mechanisms. Toward realizing magneto-mechanical coupled devices, we build circular drumhead iron phosphorus trisulfide (FePS3) NEMS resonators with different diameters (3–7 μm). Here, we report on experimental demonstration of tunable antiferromagnet FePS3 drumhead resonators with the highest fractional frequency tuning range up to Δf/f0 = 32%. Combining experimental results and analytical modeling of the resonance frequency scaling, we attain quantitative understanding of the elastic behavior of FePS3, including the transition from “membrane” to “plate” regime, with built-in tension (γ) ranging from 0.1 to 2 N/m. This study not only offers methods for investigating mechanical properties of ultrathin membranes of magnetic 2D materials but also provides important guidelines for designing future high-performance magnetic NEMS resonators. 

   more » « less
4. Mode-dependent scaling of nonlinearity and linear dynamic range in a NEMS resonator

   https://doi.org/10.1063/5.0215566  

   Ma, M; Welles, N; Svitelskiy, O; Yanik, C; Kaya, I I; Hanay, M S; Paul, M R; Ekinci, K L (August 2024, Applied Physics Letters)

   Even a relatively weak drive force is enough to push a typical nanomechanical resonator into the nonlinear regime. Consequently, nonlinearities are widespread in nanomechanics and determine the critical characteristics of nanoelectromechanical systems' (NEMSs) resonators. A thorough understanding of the nonlinear dynamics of higher eigenmodes of NEMS resonators would be beneficial for progress, given their use in applications and fundamental studies. Here, we characterize the nonlinearity and the linear dynamic range (LDR) of each eigenmode of two nanomechanical beam resonators with different intrinsic tension values up to eigenmode n = 11. We find that the modal Duffing constant increases as n4, while the critical amplitude for the onset of nonlinearity decreases as 1/n. The LDR, determined from the ratio of the critical amplitude to the thermal noise amplitude, increases weakly with n. Our findings are consistent with our theory treating the beam as a string, with the nonlinearity emerging from stretching at high amplitudes. These scaling laws, observed in experiments and validated theoretically, can be leveraged for pushing the limits of NEMS-based sensing even further. 

   more » « less
5. Partially embedded metabarrier to suppress surface waves in granular media

   https://doi.org/10.1121/10.0028536  

   Pillarisetti, Lalith_Sai Srinivas; Lissenden, Cliff J; Shokouhi, Parisa (September 2024, The Journal of the Acoustical Society of America)

   The gravity-induced depth-dependent elastic properties of a granular half-space result in multiple dispersive surface modes and demand the consideration of material heterogeneity in metabarrier designs to suppress surface waves. Numerous locally resonant metabarrier configurations have been proposed in the literature to suppress Rayleigh surface waves in homogeneous media, with little focus on extending the designs to a heterogeneous half-space. In this work, a metabarrier comprising partially embedded rod-like resonators to suppress the fundamental dispersive surface wave modes in heterogeneous granular media known as first order PSV (PSV1; where P is the longitudinal mode and SV is the shear-vertical mode) and second order PSV (PSV2) is proposed. The unit-cell dispersion analysis, together with an extensive frequency-domain finite element analysis, reveals preferential hybridization of the PSV1 and PSV2 modes with the longitudinal and flexural resonances of the resonators, respectively. The presence of the cutoff frequency for the longitudinal-resonance hybridized mode facilitates straightforward suppression of the PSV1 mode, while PSV2 mode suppression is possible by tailoring the hybridized flexural resonance modes. These PSV1 and PSV2 bandgaps are realized experimentally in a granular testbed comprising glass beads by embedding 3D-printed resonator rods. Also explored are novel graded metabarriers capable of suppressing both PSV1 and PSV2 modes over a broad frequency range for potential applications in vibration control and seismic isolation. 

   more » « less