Nano-plate Resonator Research Articles

Curvature and Stress Effects on the Performance of Contour-Mode Resonant ΔE Effect Magnetometers.

Miniaturized piezoelectric/magnetostrictive contour-mode resonators have been shown to be effective magnetometers by exploiting the ΔE effect. With dimensions of ~100-200 μm across and <1 μm thick, they offer high spatial resolution, portability, low power consumption, and low cost. However, a thorough understanding of the magnetic material behavior in these devices has been lacking, hindering performance optimization. This manuscript reports on the strong, nonlinear correlation observed between the frequency response of these sensors and the stress-induced curvature of the resonator plate. The resonance frequency shift caused by DC magnetic fields drops off rapidly with increasing curvature: about two orders of magnitude separate the highest and lowest frequency shift in otherwise identical devices. Similarly, an inverse correlation with the quality factor was found, suggesting a magnetic loss mechanism. The mechanical and magnetic properties are theoretically analyzed using magnetoelastic finite-element and magnetic domain-phase models. The resulting model fits the measurements well and is generally consistent with additional results from magneto-optical domain imaging. Thus, the origin of the observed behavior is identified and broader implications for the design of nano-magnetoelastic devices are derived. By fabricating a magnetoelectric nano-plate resonator with low curvature, a record-high DC magnetic field sensitivity of 5 Hz/nT is achieved.

Thermoelastic damping in orthotropic and isotropic NEMS resonators accounting for double nonlocal thermoelastic effects

Thermoelastic damping is a prominent internal dissipation mechanism in small-scale mechanical resonators. It has been given a lot of attention recently due to the endeavors to design high-quality nanoelectromechanical systems. In the article, this phenomenon is analyzed for in-plane vibration of orthotropic and isotropic nanoplate resonators using coupled nonlocal heat conduction and nonlocal elasticity theories. The obtained thermal-displacement equations are solved using the Galerkin residual technique and the output results are illustrated and compared for isotropic and orthotropic materials, using the classical theory, the nonlocal elasticity theory, the nonlocal heat conduction theory, and coupled nonlocal thermoelasticity. The results show significant impacts of both the nanosystem geometrical and physical parameters on the quality factor.

High figure-of-merit NEMS thermal detectors based on 50-nm thick AlN nano-plate resonators

This paper reports on the demonstration of ultrafast (thermal time constant, τ ∼ 166 μs) and high resolution (noise equivalent power, NEP ∼ 549 pW/Hz1/2) thermal detectors based on high quality factor 50-nm thick aluminum nitride (AlN) piezoelectric resonant nanoplates. Here we show that by employing nanoscale (30 nm) aluminum anchors, both high thermal resistance (Rth ∼ 1.1 × 106 K/W) and high quality factor (Q ∼ 1000) can be achieved in greatly scaled AlN nanoplate resonators. Furthermore, the absorptance of such ultrathin AlN resonators was characterized, in mid-wavelength infrared region showing an average absorptance of ∼36% from 2.75 μm to 6.25 μm. These unique features were exploited for the experimental demonstration of AlN NEMS resonant thermal detectors with greatly reduced thermal capacitance and over doubled figure of merit [FoM = 1/(NEP × τ)] compared to what was previously achieved by the same technology.

Mass loading effects in the acoustic vibrations of gold nanoplates.

The breathing modes of single suspended gold nanoplates have been examined by transient absorption microscopy. These vibrational modes show very high quality factors which means that their frequencies can be accurately measured. Measurements performed before and after removing the organic layer that coats the as synthesized nanoplates show significant increases in frequency, which are consistent with removal of a few nm of organic material from the nanoplate surface. Experiments were also performed after depositing polymer beads on the sample. These measurements show a decrease in frequency in the region of the beads. This implies that adding a localized mass to the nanoplate hybridizes the vibrational normal modes, creating a new breathing mode which has a maximum amplitude at the bead. The nanoplate resonators have a mass sensing detection limit of ca. 10 attograms, which is comparable to the best results that have been achieved with plasmonic nanoparticles.

A Simple Fabrication Process Based on Micro-masonry for the Realization of Nanoplate Resonators with Integrated Actuation and Detection Schemes

In this work, we use the micro-masonry technique to fabricate nanoplate resonators with integrated electrostatic actuation and capacitive detection in a few steps. Our approach is an alternative solution to the current fabrication methods used to create membranes and plates that usually rely on the selective etching of a sacrificial layer. Highly doped silicon plates were transfer-printed using microtip elastomeric stamps onto insulated bases displaying cavities in order to form suspended structures with airtight gaps. By post-processing adequate interconnections, the fabricated resonators were actuated and their resonant frequency measured in a fully integrated manner. The tested nanoplate devices behave as predicted by theory and offer quality factors of more than 30 in air. Because the cavities used for electrostatic actuation/sensing of the devices are tight sealed, nanoplates fabricated via micro-masonry are suitable for liquid environment operation and are thus a promising solution for biosensing applications.

Fabrication of nanoplate resonating structures via micro-masonry

Advantages of using nanoscale membrane and plate resonators over more common cantilever shapes include higher quality factor (Q factor) for an equivalent mass and better suitability to mass sensing applications in fluid. Unfortunately, the current fabrication methods used to obtain such membranes and plates are limited in terms of materials and thickness range, and can potentially cause stiction. This study presents a new method to fabricate nanoplate resonating structures based on micro-masonry, which is the advanced form of the transfer printing technique. Nanoplate resonators were fabricated by transfer printing 0.34 µm thick square-shaped silicon plates by means of polydimethylsiloxane microtip stamps on top of silicon oxide base structures displaying 20 µm diameter cavities, followed by a thermal annealing step to create a rigid bond. Typical resulting suspended structures display vibration characteristics, i.e. a resonance frequency of a few MHz and Q factors above 10 in air at atmospheric pressure, which are in accordance with theory. Moreover, the presented fabrication method enables the realization of multiple suspended structures in a single step and on the same single base, without mechanical crosstalk between the resonators. This work thus demonstrates the suitability and the advantages of the micro-masonry technique for the fabrication of plate resonators for mass sensing purpose.