scholarly journals Q-Factor Enhancement of Thin-Film Piezoelectric-on-Silicon MEMS Resonator by Phononic Crystal-Reflector Composite Structure

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1130
Author(s):  
Jiacheng Liu ◽  
Temesgen Bailie Workie ◽  
Ting Wu ◽  
Zhaohui Wu ◽  
Keyuan Gong ◽  
...  
Keyword(s):  
Thin Film ◽  
Acoustic Wave ◽  
Composite Structure ◽  
Phononic Crystal ◽  
Q Factor ◽  
Leakage Loss ◽  
One Dimensional ◽  
High Q ◽  
Mems Resonator ◽  
Mems Resonators

Thin-film piezoelectric-on-silicon (TPoS) microelectromechanical (MEMS) resonators are required to have high Q-factor to offer satisfactory results in their application areas, such as oscillator, filter, and sensors. This paper proposed a phononic crystal (PnC)-reflector composite structure to improve the Q factor of TPoS resonators. A one-dimensional phononic crystal is designed and deployed on the tether aiming to suppress the acoustic leakage loss as the acoustic wave with frequency in the range of the PnC is not able to propagate through it, and a reflector is fixed on the anchoring boundaries to reflect the acoustic wave that lefts from the effect of the PnC. Several 10 MHz TPoS resonators are fabricated and tested from which the Q-factor of the proposed 10 MHz TPoS resonator which has PnC-reflector composite structure on the tether and anchoring boundaries achieved offers a loaded Q-factor of 4682 which is about a threefold improvement compared to that of the conventional resonator which is about 1570.

Acoustic wave frequency filtering in constant total length phononic crystals of Al/Pb multilayer

2021 ◽  
Author(s):  
Chittaranjan Nayak ◽  
Mehdi Solaimani ◽  
Alireza Aghajamali ◽  
Arafa H. Aly
Keyword(s):  
Acoustic Wave ◽  
Phononic Crystal ◽  
Phononic Crystals ◽  
Geometrical Parameters ◽  
One Dimensional ◽  
Internal Geometry ◽  
Total Length ◽  
Acoustic Filters ◽  
System Length ◽  
Phononic Band Gaps

In this study, we have scrutinized the frequency gap generation by changing the geometrical parameters of a one-dimensional phononic crystal. For this purpose, we have calculated the transmission coefficient of an incident acoustic wave by using the transfer matrix method. We have retained and fixed the total length of the system and changed the system internal geometry not to increase the system length too much. Another reason was to adjust the phononic band gaps and get the desired transmission properties by finding the optimum internal geometry without increasing or decreasing the total length of phononic crystals. In addition, we also propose few structures with the opportunity of applications in acoustical devices such as sonic reflectors. Our results can also be of high interest to design acoustic filters in the case that transmission of certain frequencies is necessary.

Controlling Crystallization Structures in Thin Si Film for Improving Characteristics of MEMS Resonators

2012 ◽  
Vol 1427 ◽  
Author(s):  
Shinya Kumagai ◽  
Hiromu Murase ◽  
Takashi Tomikawa ◽  
Syohei Ogawa ◽  
Ichiro Yamashita ◽  
...  
Keyword(s):  
Tensile Stress ◽  
Domain Size ◽  
Q Factor ◽  
Random Orientation ◽  
Mems Resonator ◽  
Mems Resonators ◽  
Small Grains ◽  
Thin Polycrystalline ◽  
Lateral Crystallization ◽  
Conventional Annealing

ABSTRACTAn approach to control the tensile stress and Q factor of thin Si film beams in MEMS resonators was investigated. Metal-induced lateral crystallization (MILC) using Ni nanoparticles that were synthesized within a cage-shaped protein, apoferritin, was applied to a thin morphous Si film for making a MEMS resonator with thin film beams. The MILC produced a thin polycrystalline Si (poly-Si) film with large crystallized domain (50-60 μm) with nearly the same crystalline orientation, whereas the poly-Si film obtained by conventional annealing (without MILC) consisted of small grains (less than 1 μm) with random orientation. The MEMS resonator with a beam made of poly-Si film by MILC was fabricated. The large domain size and the improved crystallinity increased the tensile stress, and resulted in 20% increase in Q factor in the resonant characteristics.

scholarly journals Periodic Tubular Structures and Phononic Crystals towards High-Q Liquid Ultrasonic Inline Sensors for Pipes

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5982
Author(s):  
Nikolay Mukhin ◽  
Ralf Lucklum
Keyword(s):  
Mode Conversion ◽  
Phononic Crystal ◽  
Resonant Mode ◽  
Phononic Crystals ◽  
Acoustic Energy ◽  
Wave Radiation ◽  
Q Factor ◽  
Tubular Structures ◽  
High Q ◽  
Ultrasound Sensor

The article focuses on a high-resolution ultrasound sensor for real-time monitoring of liquid analytes in cylindrical pipes, tubes, or capillaries. The development of such a sensor faces the challenges of acoustic energy losses, including dissipation at liquid/solid interface and acoustic wave radiation along the pipe. Furthermore, we consider acoustic resonant mode coupling and mode conversion. We show how the concept of phononic crystals can be applied to solve these problems and achieve the maximum theoretically possible Q-factor for resonant ultrasonic sensors. We propose an approach for excitation and measurement of an isolated radial resonant mode with minimal internal losses. The acoustic energy is effectively localized in a narrow probing area due to the introduction of periodically arranged sectioned rings around the tube. We present a sensor design concept, which optimizes the coupling between the tubular resonator and external piezoelectric transducers. We introduce a 2D-phononic crystal in the probing region for this purpose. The Q-factor of the proposed structures show the high prospects for phononic crystal pipe sensors.

scholarly journals Design and Optimization of a Novel SAW Gyroscope Structure Based on Amplitude Modulation with 1-D Phononic Crystals

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1485
Author(s):  
Fei Ge ◽  
Liye Zhao ◽  
Yang Zhang
Keyword(s):  
Signal Processing ◽  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Amplitude Modulation ◽  
Phononic Crystal ◽  
Defect Mode ◽  
High Sensitivity ◽  
Phononic Crystals ◽  
Linear Range ◽  
One Dimensional

Surface acoustic wave gyroscopes (SAWGs), as a kind of all-solid-state micro-electro-mechanical system (MEMS) gyroscopes, can work normally under extremely high-impact environmental conditions. Among the current SAWGs, amplitude-modulated gyroscopes (AMGs) are all based on the same gyro effect, which was proved weak, and their sensitivity and intensity of the output are both lower than frequency-modulated gyroscopes (FMGs). However, because FMGs need to process a series of frequency signals, their signal processing and circuits are far less straightforward and simple than AMGs. In order to own both high-sensitivity and simple signal processing, a novel surface acoustic traveling wave gyroscope based on amplitude modulation is proposed, using one-dimensional phononic crystals (PCs) in this paper. In view of its specific structure, the proposed gyroscope consists of a surface acoustic wave oscillator and a surface acoustic wave delay line within a one-dimensional phononic crystal with a high-Q defect mode. In this paper, the working principle is analyzed theoretically through the partial wave method (PWM), and the gyroscopes with different numbers of PCs are also designed and studied by using the finite element method (FEM) and multiphysics simulation. The research results demonstrate that under a 1 V oscillator voltage output, the higher sensitivity of −23.1 mV·(rad/s)−1 in the linear range from −8 rad/s to 8 rad/s is reached when the gyro with three PC walls, and the wider linear range from −15 rad/s to 17.5 rad/s with the sensitivity of −6.7 mV·(rad/s)−1 with only one PC wall. Compared with the existing AMGs using metal dots to enhance the gyro effect, the sensitivity of the proposed gyro is increased by 15 to 112 times, and the linear range is increased by 4.6 to 186 times, even without the enhancement of the metal dots.

scholarly journals Optimization of the Spatial Configuration of Local Defects in Phononic Crystals for High Q Cavity

2020 ◽  
Vol 6 ◽  
Author(s):  
Delfino Reyes ◽  
David Martínez ◽  
Miguel Mayorga ◽  
Hyeonu Heo ◽  
Ezekiel Walker ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Spatial Configuration ◽  
Phononic Crystal ◽  
Periodic Lattice ◽  
Ultrasonic Frequency ◽  
Q Factor ◽  
Frequency Range ◽  
High Q ◽  
Acoustic Waveguides ◽  
Local Defects

Defects can be introduced within a 2-D periodic lattice to realize phononic cavities or phononic crystal (PnC) waveguides at the ultrasonic frequency range. The arrangement of these defects within a PnC lattice results in the modification of the Q factor of the cavity or the waveguide. In this work, cavity defects within a PnC formed using cylindrical stainless steel scatterers in water have been modified to control the propagation and Q factor of acoustic waveguides realized through defect channels. The defect channel–based waveguides within the PnC were configured horizontally, vertically, and diagonally along the direction of the propagation of the acoustic waves. Numerical simulations supported by experimental demonstration indicate that the defect-based waveguide’s Q factor is improved by over 15 times for the diagonal configuration compared to the horizontal configuration. It also increases due to an increase in the scatterers’ radius, which was varied from 0.7 to 0.95 mm.

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