101,791 research outputs found
Gas Damping Coefficient Research for MEMS Comb Linear Vibration Gyroscope
Silicon-MEMS gyroscope is an important part of MEMS (Micro Electrical
Mechanical System). There are some disturb ignored in traditional gyroscope
that must be evaluated newly because of its smaller size (reach the level of
micron). In these disturb, the air pressure largely influences the performance
of MEMS gyroscope. Different air pressure causes different gas damping
coefficient for the MEMS comb linear vibration gyroscope and different gas
damping coefficient influences the quality factor of the gyroscope directive.
The quality factor influences the dynamic working bandwidth of the MEMS comb
linear vibration gyroscope, so it is influences the output characteristic of
the MEMS comb linear vibration gyroscope. The paper shows the relationship
between the air pressure and the output amplified and phase of the detecting
axis through analyzing the air pressure influence on the MEMS comb linear
vibration gyroscope. It discusses the influence on the frequency distribute and
quality factor of the MEMS comb linear vibration gyroscope for different air
pressure.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
Evaluation of MEMS Structures with Directional Characteristics Based on FRAT and Lifting Wavelet
Steps and grooves, which have typical directional characteristic, are two main functional structures of MEMS (Micro-Electro-Mechanical Systems). This paper proposes a method for analysis and evaluation of MEMS steps and grooves based on finite radon transform (FRAT) and lifting wavelet. The method consists of three steps. Firstly, FRAT is adopted to detect the directional characteristic of a MEMS structure. Secondly, on the basis of the directional characteristic obtained, the profiles of the MEMS structure are analyzed by lifting wavelet. Finally, Histogram-fitting is employed for areal evaluation of a MEMS structure. Simulated and experimental results show that MEMS structures with directional characteristic can be extracted and evaluated by the method effectively
Tunable MEMS VCSEL on Silicon substrate
We present design, fabrication and characterization of a MEMS VCSEL which
utilizes a silicon-on-insulator wafer for the microelectromechanical system and
encapsulates the MEMS by direct InP wafer bonding, which improves the
protection and control of the tuning element. This procedure enables a more
robust fabrication, a larger free spectral range and facilitates bidirectional
tuning of the MEMS element. The MEMS VCSEL device uses a high contrast grating
mirror on a MEMS stage as the bottom mirror, a wafer bonded InP with quantum
wells for amplification and a deposited dielectric DBR as the top mirror. A 40
nm tuning range and a mechanical resonance frequency in excess of 2 MHz are
demonstrated
Experiments and simulations of MEMS thermal sensors for wall shear-stress measurements in aerodynamic control applications
MEMS thermal shear-stress sensors exploit heat-transfer effects to measure the shear stress exerted by an air flow on its solid boundary, and have promising applications in aerodynamic control. Classical theory for conventional, macroscale thermal shear-stress sensors states that the rate of heat removed by the flow from the sensor is proportional to the 1/3-power of the shear stress. However, we have observed that this theory is inconsistent with experimental data from MEMS sensors. This paper seeks to develop an understanding of MEMS thermal shear-stress sensors through a study including both experimental and theoretical investigations. We first obtain experimental data that confirm the inadequacy of the classical theory by wind-tunnel testing of prototype MEMS shear-stress sensors with different dimensions and materials. A theoretical analysis is performed to identify that this inadequacy is due to the lack of a thin thermal boundary layer in the fluid flow at the sensor surface, and then a two-dimensional MEMS shear-stress sensor theory is presented. This theory incorporates important heat-transfer effects that are ignored by the classical theory, and consistently explains the experimental data obtained from prototype MEMS sensors. Moreover, the prototype MEMS sensors are studied with three-dimensional simulations, yielding results that quantitatively agree with experimental data. This work demonstrates that classical assumptions made for conventional thermal devices should be carefully examined for miniature MEMS devices
Novel Bonding technologies for wafer-level transparent packaging of MOEMS
Depending on the type of Micro-Electro-Mechanical System (MEMS), packaging
costs are contributing up to 80% of the total device cost. Each MEMS device
category, its function and operational environment will individually dictate
the packaging requirement. Due to the lack of standardized testing procedures,
the reliability of those MEMS packages sometimes can only be proven by taking
into consideration its functionality over lifetime. Innovation with regards to
cost reduction and standardization in the field of packaging is therefore of
utmost importance to the speed of commercialisation of MEMS devices. Nowadays
heavily driven by consumer applications the MEMS device market is forecasted to
enjoy a compound annual growth rate (CAGR) above 13%, which is when compared to
the IC device market, an outstanding growth rate. Nevertheless this forecasted
value can drift upwards or downwards depending on the rate of innovation in the
field of packaging. MEMS devices typically require a specific fabrication
process where the device wafer is bonded to a second wafer which effectively
encapsulates the MEMS structure. This method leaves the device free to move
within a vacuum or an inert gas atmosphere.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
Dynamic metasurface lens based on MEMS Technology
In the recent years, metasurfaces, being flat and lightweight, have been
designed to replace bulky optical components with various functions. We
demonstrate a monolithic Micro-Electro-Mechanical System (MEMS) integrated with
a metasurface-based flat lens that focuses light in the mid-infrared spectrum.
A two-dimensional scanning MEMS platform controls the angle of the lens along
the two orthogonal axes (tip-tilt) by +-9 degrees, thus enabling dynamic beam
steering. The device can compensate for off-axis incident light and thus
correct for aberrations such as coma. We show that for low angular
displacements, the integrated lens-on-MEMS system does not affect the
mechanical performance of the MEMS actuators and preserves the focused beam
profile as well as the measured full width at half maximum. We envision a new
class of flat optical devices with active control provided by the combination
of metasurfaces and MEMS for a wide range of applications, such as miniaturized
MEMS-based microscope systems, LIDAR scanners, and projection systems
MEMS practice, from the lab to the telescope
Micro-electro-mechanical systems (MEMS) technology can provide for deformable
mirrors (DMs) with excellent performance within a favorable economy of scale.
Large MEMS-based astronomical adaptive optics (AO) systems such as the Gemini
Planet Imager are coming on-line soon. As MEMS DM end-users, we discuss our
decade of practice with the micromirrors, from inspecting and characterizing
devices to evaluating their performance in the lab. We also show MEMS wavefront
correction on-sky with the "Villages" AO system on a 1-m telescope, including
open-loop control and visible-light imaging. Our work demonstrates the maturity
of MEMS technology for astronomical adaptive optics.Comment: 14 pages, 15 figures, Invited Paper, SPIE Photonics West 201
Design principles for six degrees-of-freedom MEMS-based precision manipulators
In the future, the precision manipulation of small objects will become more and more important for appliances such as data storage, micro assembly, sample manipulation in microscopes, cell manipulation, and manipulation of beam paths by micro mirrors. At the same time, there is a drive towards miniaturized systems.\ud
Therefore, Micro ElectroMechanical Systems (MEMS), a fabrication technique enabling micron sized features, has been researched for precision manipulation. MEMS devices comprise micro sensors, actuators, mechanisms, optics and fluidic systems. They have the ability to integrate several functions in a small package. MEMS can be commercially attractive by providing cost reduction or enabling new functionality with respect to macro systems. Combining design principles, a mature design philosophy for creating precision machines, and MEMS fabrication, a\ud
technology for miniaturization, could lead to micro systems with deterministic behavior and accurate positioning capability. However, in MEMS design trade-offs\ud
need to be made between fabrication complexity and design principle requirements.\ud
Therefore, the goal of this research has been twofold:\ud
1. Design and manufacture a 6 Degrees-of-Freedom (DOFs) MEMS-based manipulator with nanometer resolution positioning.\ud
2. Derive principle solutions for the synthesis of exact kinematic constraint design and MEMS fabrication technology for multi DOFs precision manipulation in the\ud
micro domain
Modelling methodology of MEMS structures based on Cosserat theory
Modelling MEMS involves a variety of software tools that deal with the
analysis of complex geometrical structures and the assessment of various
interactions among different energy domains and components. Moreover, the MEMS
market is growing very fast, but surprisingly, there is a paucity of modelling
and simulation methodology for precise performance verification of MEMS
products in the nonlinear regime. For that reason, an efficient and rapid
modelling approach is proposed that meets the linear and nonlinear dynamic
behaviour of MEMS systems.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/handle/2042/16838
Workload-Based Configuration of MEMS-Based Storage Devices for Mobile Systems
Because of its small form factor, high capacity, and expected low cost, MEMS-based storage is a suitable storage technology for mobile systems. However, flash memory may outperform MEMS-based storage in terms of performance, and energy-efficiency. The problem is that MEMS-based storage devices have a large number (i.e., thousands) of heads, and to deliver peak performance, all heads must be deployed simultaneously to access each single sector. Since these devices are mechanical and thus some housekeeping information is needed for each head, this results in a huge capacity loss and increases the energy consumption of MEMS-based storage with respect to flash.
We solve this problem by proposing new techniques to lay out data in MEMS-based storage devices. Data layouts represent optimizations in a design space spanned by three parameters: the number of active heads, sector parallelism, and sector size. We explore this design space and show that by exploiting knowledge of the expected workload, MEMS-based devices can employ all heads, thus delivering peak performance, while decreasing the energy consumption and compromising only a little on the capacity. Our exploration shows that MEMS-based storage is competitive with flash in most cases, and outperforms flash in a few cases
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