Tunable Micro- and Nanomechanical Resonators

Abstract

Advances in micro- and nanofabrication technologies have enabled the development of novel micro- and nanomechanical resonators which have attracted significant attention due to their fascinating physical properties and growing potential applications. In this review, we have presented a brief overview of the resonance behavior and frequency tuning principles by varying either the mass or the stiffness of resonators. The progress in micro- and nanomechanical resonators using the tuning electrode, tuning fork, and suspended channel structures and made of graphene have been reviewed. We have also highlighted some major influencing factors such as large-amplitude effect, surface effect and fluid effect on the performances of resonators. More specifically, we have addressed the effects of axial stress/strain, residual surface stress and adsorption-induced surface stress on the sensing and detection applications and discussed the current challenges. We have significantly focused on the active and passive frequency tuning methods and techniques for micro- and nanomechanical resonator applications. On one hand, we have comprehensively evaluated the advantages and disadvantages of each strategy, including active methods such as electrothermal, electrostatic, piezoelectrical, dielectric, magnetomotive, photothermal, mode-coupling as well as tension-based tuning mechanisms, and passive techniques such as post-fabrication and post-packaging tuning processes. On the other hand, the tuning capability and challenges to integrate reliable and customizable frequency tuning methods have been addressed. We have additionally concluded with a discussion of important future directions for further tunable micro- and nanomechanical resonators.

3D Tunable, Multiscale, and Multistable Vibrational Micro‐Platforms Assembled by Compressive Buckling

“…In addition, ambient vibrations are essentially three-dimensional, and hence conventional 2D MEMS devices for kinetic energy harvesting applications have disadvantages. Recent advances in MEMS technologies include the development of devices with resonant frequencies that can be tuned to compensate for frequency shifts associated with changes in the operating environment [20, 30–32] and that can be continuously adapted for time-varying ambient vibrations, both of which improve the efficiency for energy harvesting. Common methods for tuning the frequency include changing the associated mass and/or tuning the effective stiffness of the resonator by applying stresses through piezoelectric effects, thermal expansion or electrostatic forces.…”

“…Common methods for tuning the frequency include changing the associated mass and/or tuning the effective stiffness of the resonator by applying stresses through piezoelectric effects, thermal expansion or electrostatic forces. [20, 30–32] These approaches require, however, integration of additional components and materials, and, therefore, significantly complicate the fabrication process. 3D structures formed via origami, [33, 34] buckling, [35–38] and 3D printing [39] have attracted significant attentions due to their wide range of applications such as microphysiological systems, [39] cell studies, [40, 41] bio-mimic actuators, [42, 43] and the control of wave propagation.…”

Optomechanical cooling beyond the quantum backaction limit with frequency modulation

“…In this paper, we propose a proposal to improve micromechanical resonator cooling in OMS via modulating frequencies of both the optical and mechanical components. The FM of optical component is easy to implement and the modulation of micromechanical resonators has also been reported [38][39][40][41][42][43][44]. Here we provide a complete and simple understanding of the physical processes about improving mechanical cooling, which allows us to illustrate the deep reasons of the lower mechanical cooling.…”

Mechanism of geometric nonlinearity in a nonprismatic and heterogeneous microbeam resonator

“…In this design, we intentionally implement a drastic change in the stiffness between the Si cantilever and polymer attachment by varying the geometrical dimensions (i.e., length and cross-sectional area) and material (i.e., Young's modulus) of the beam structure. As a result, the ratio of effective bending stiffness between the Si cantilever (1) and polymer attachment (2) is k bending,1 : k bending,2 = 0.18 : 1 and the ratio of effective axial stiffness between these two components is k axial,1 : k axial,2 = 40 : 1. Note that this non-prismatic, non-homogeneous structural design not only results in a large discrepancy in the effective stiffness between the Si cantilever and polymer attachment but also gives an opposite trend in the magnitude ratio of the bending and axial terms.…”

“…The high structural quality of those materials combined with the reduced effective mass allows such beams to operate at very high resonance frequencies with extremely high Q factors (i.e., low damping). These beneficial attributes provide the basis for exceptional performance of MEMS applications such as extremely sensitive sensors [1][2][3][4], mechanical energy harvesters [5][6][7], nano/micro-relays [8,9], logic memory and computation [10][11][12], field effect transistors [13], and a high frequency reference in oscillators [14][15][16]. The MEMS devices implemented in these applications were mostly designed to operate in their linear resonant modes with the above-mentioned benefits.…”