scholarly journals Curvature-Modulated Si Spherical Cap-Like Structure Fabricated by Multistep Ring Edge Etching

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 764
Author(s):  
Tieying Ma ◽  
Jiachen Wang ◽  
Dabo Li
Keyword(s):  
Quartz Crystal ◽  
Microelectromechanical Systems ◽  
Wet Etching ◽  
Surface Structures ◽  
Etching Time ◽  
Spherical Cap ◽  
Inclination Angles ◽  
Spherical Structures ◽  
Quartz Crystal Resonators ◽  
Spherical Curvature

To create approximately spherical structures with curved sidewalls, this paper presents a method for building a series of decreasing slopes along the sidewall of a circular truncated cone. The multistep ring-edge etching technology of first reducing the concentric mask and then cutting the top off to create a mesa shape can be used to form the slopes. This wet-etching method avoids the constraints of crystallographic properties with surfactant-added Tetramethylammonium hydroxide (TMAH), enabling the manufacture of successive given inclination angles, the precise modulation of the spherical curvature by reduction design of concentric masks, and the setting of etching time. The newly approximated spherical Si microstructure patterns can be used for microlenses, quartz crystal resonators, micropulleys, and other applications. The present research is an approach to fabricate advanced microelectromechanical systems (MEMS) curved-surface structures, extending the range of 3D structures fabricated by silicon wet etching.

Laser-Assisted Wet Etching of Quartz Crystal Resonators

2018 ◽  
Vol 27 (1) ◽  
pp. 22-24 ◽  
Author(s):  
William Clower ◽  
Ville Kaajakari ◽  
Chester G. Wilson
Keyword(s):  
Quartz Crystal ◽  
Wet Etching ◽  
Quartz Crystal Resonators

The Effect of Catalyst on Carbon Nanotubes (CNTs) Synthesized by Catalytic Chemical Vapor Deposition (CVD) Technique

2011 ◽  
Vol 364 ◽  
pp. 232-237 ◽  
Author(s):  
S.Y. Lim ◽  
M.M. Norani
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Dry Etching ◽  
Wet Etching ◽  
Etching Time ◽  
Catalytic Chemical Vapor Deposition ◽  
Catalyst Pretreatment ◽  
Diameter Range

Catalyst plays a crucial role in determining the characteristics of carbon nanotubes (CNTs) produced by using thermal catalytic chemical vapor deposition (CVD). It is essential to investigate how the catalyst preparation affects the characteristics of CNTs because certain application demands specific size for optimum performance. This study reports the effect of the types of catalyst and the duration of the catalyst pre-treatment (wet etching time, dry etching time and ball milling) on the diameter of CNTs. The synthesized CNTs samples were characterized by scanning and transmission electron microscopy and Raman spectroscopy. Wet etching (2M hydrofluoric acid) time was varied from 1 to 2.5 hrs and the diameter range was found to be in the range of 23 to 52 nm. The diameter range for CNTs produced for 3 hrs and 5 hrs of dry etching treatment (with ammonia gas) are 38 to 51 nm and 23 to 48 nm, respectively. The diameter size of CNTs produced using Ni (14 to 25 nm) was found to be smaller than Fe (38 to 51 nm). There is a significant decrease in the diameter of CNTs by prolonging the wet etching period. Shorter and curly shaped CNTs can also be obtained by using Ni as the catalyst. Keywords: chemical vapor deposition, carbon nanotubes, catalyst pretreatment

Electrical behaviour of AT-cut quartz crystal resonators as a function of overtone number

2010 ◽  
Vol 159 (2) ◽  
pp. 174-183 ◽  
Author(s):  
M. Cassiède ◽  
J.H. Paillol ◽  
J. Pauly ◽  
J.-L. Daridon
Keyword(s):  
Quartz Crystal ◽  
Electrical Behaviour ◽  
Quartz Crystal Resonators

scholarly journals Characterizing Vibrating Cantilevers for Liquid Viscosity and Density Sensing

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
Christian Riesch ◽  
Erwin K. Reichel ◽  
Franz Keplinger ◽  
Bernhard Jakoby
Keyword(s):  
Cross Sections ◽  
Quartz Crystal ◽  
Model Parameters ◽  
Additional Mass ◽  
Liquid Loading ◽  
Fitting Procedure ◽  
Saw Devices ◽  
Quartz Crystal Resonators ◽  
Macroscopic Parameters ◽  
Online Process

Miniaturized liquid sensors are essential devices in online process or condition monitoring. In case of viscosity and density sensing, microacoustic sensors such as quartz crystal resonators or SAW devices have proved particularly useful. However, these devices basically measure a thin-film viscosity, which is often not comparable to the macroscopic parameters probed by conventional viscometers. Miniaturized cantilever-based devices are interesting alternatives for such applications, but here the interaction between the liquid and the oscillating beam is more involved. In our contribution, we describe a measurement setup, which allows the investigation of this interaction for different beam cross-sections. We present an analytical model based on an approximation of the immersed cantilever as an oscillating sphere comprising the effective mass and the intrinsic damping of the cantilever and additional mass and damping due to the liquid loading. The model parameters are obtained from measurements with well-known sample liquids by a curve fitting procedure. Finally, we present the measurement of viscosity and density of an unknown sample liquid, demonstrating the feasibility of the model.

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