Multi-Frequency Resonance Behaviour of a Si Fractal NEMS Resonator

Abstract

Novel Si-based nanosize mechanical resonator has been top-down fabricated. The shape of the resonating body has been numerically derived and consists of seven star-polygons that form a fractal structure. The actual resonator is defined by focused ion-beam implantation on a SOI wafer where its 18 vertices are clamped to nanopillars. The structure is suspended over a 10 μm trench and has width of 12 μm. Its thickness of 0.040 μm is defined by the fabrication process and prescribes Young’s modulus of 76 GPa which is significantly lower than the value of the bulk material. The resonator is excited by the bottom Si-layer and the interferometric characterisation confirms broadband frequency response with quality factors of over 800 for several peaks between 2 MHz and 16 MHz. COMSOL FEM software has been used to vary material properties and residual stress in order to fit the eigenfrequencies of the model with the resonance peaks detected experimentally. Further use of the model shows how the symmetry of the device affects the frequency spectrum. Also, by using the FEM model, the possibility for an electrical read out of the device was tested. The experimental measurements and simulations proved that the device can resonate at many different excitation frequencies allowing multiple operational bands. The size, and the power needed for actuation are comparable with the ones of single beam resonator while the fractal structure allows much larger area for functionalisation.

Si-based MEMS Resonant Sensor: A Review from Microfabrication Perspective

“…25. Vassil et al [182] fabricated the resonator on SOI wafer with 2 µm having device layer. The resonator structure contains seven-star polygons arrange in a fractal structure.…”

“…Figure 26: Images of the fractal nanostructure taken with a scanning electron microscope (SEM): (a) SEM micrograph of the suspended fractal resonator tilted 45 degrees. (b)Top-view SEM micrograph of the suspended structure[182]. (Reprinted with permission from[182]).…”

Vibrational and stochastic resonances in driven nonlinear systems: part 2

“…It may include multiple frequencies, the simplest form being a bi-harmonic/dual-frequency driving force, and is often engineered to act as a control input with the aim of achieving, e.g. the general improvement of system performance [3], amplification and detection of weak signal inputs [4][5][6], enhancement of operating conditions and efficiency [7,8], control of the ion mean flux and ion energy in plasmas due to electrical asymmetry effect (EAE) [9][10][11], control of aerodynamic instabilities [12], particle excitation in magnetic particle imaging (MPI) [13,14], design of logic gates [15] as well as the control and annihilation of chaos and coexisting attractors [16]. It has been established that these applications are connected to a plethora of dynamical phenomena induced by driving forces, yielding insights into a diversity of microscopic and macroscopic processes as enumerated in a very recent review by Vincent & Kolebaje [2].…”

Temperature Effects on Dynamic Properties of Suspended Cables Subjected to Dual Harmonic Excitations

“…On the other hand, considering different types of excitations, for example, direct/indirect excitation and auto-/ parametric excitation, the loads applied on structures are very complicated and always contain multifrequency harmonic forces. e rich and complex dynamics of nonlinear oscillations attracted the attention of the research community, leading to exploring the possibility of understanding dynamical behaviors in nonlinear systems subjected to multifrequency excitations [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39].…”

“…Jabar et al [36] analytically and experimentally investigated the nonlinear oscillations of a clamped-clamped microbeam under multifrequency excitations. Tzanov et al [37] studied the nonlinear resonant behaviors of a Si fractal NEMS resonator subjected to multifrequency excitations. Considering a piezoelectric nanoplate resting on a viscoelastic foundation, Ebrahimi and Hosseini [38] investigated its nonlinear vibration behaviors subjected to dual harmonic external excitation and thermoelectromechanical loads.…”