Optoelectronic Methodology for Development of MEMS

2007 ◽  
Author(s):  
Ryszard J. Pryputniewicz ◽  
Ryan T. Marinis ◽  
Adam R. Klempner ◽  
Peter Hefti
Keyword(s):  
Computer Technology ◽  
Microelectromechanical Systems ◽  
Design Analysis ◽  
Operating Conditions ◽  
Functional Characteristics ◽  
Optimum Performance ◽  
Recent Advances ◽  
Challenging Tasks ◽  
Optoelectronic Method

Development of microelectromechanical systems (MEMS) constitutes one of the most challenging tasks in today’s micromechanics. In addition to design, analysis, and fabrication capabilities, this task also requires advanced test methodologies for determination of functional characteristics of MEMS to enable refinement and optimization of their designs. Until recently, this characterization was hindered by lack of a readily available methodology. However, building on recent advances in photonics, electronics, and computer technology, we have developed an optoelectronic methodology particularly suitable for development of MEMS. In this paper, we describe the optoelectronic methodology and illustrate its use with representative examples. By quantitatively characterizing performance of MEMS, under different vibration, thermal, and other operating conditions, we can make specific suggestions for their improvements. Then, using the optoelectronic method, we can verify the effects of these improvements. In this way, we can develop better understanding of functional characteristics of MEMS, which will ensure that they are operated at optimum performance, are reliable, and are durable.

Optical Methodology for Testing of Microsystems

2009 ◽  
Author(s):  
Ryszard J. Pryputniewicz ◽  
Ryan T. Marinis ◽  
Peter Hefti
Keyword(s):  
High Performance ◽  
Emerging Technologies ◽  
Reliability Assessment ◽  
Design Analysis ◽  
Functional Characteristics ◽  
Micro Scale ◽  
Combined Use ◽  
Challenging Tasks ◽  
Micro Structures

Advancing the emerging technologies of MEMS, especially relating to the applications, constitutes one of the most challenging tasks in today’s micromechanics. In addition to design, analysis, and fabrication capabilities, this task also requires advanced test methodologies for determination of functional characteristics of devices produced to enable verification of their operation as well as refinement and optimization of specific designs. The tools used can be categorized as analytical, computational, and experimental. Solutions using the tools from any one category alone do not usually provide all of the necessary information on MEMS and extensive merging, or hybridization, of the tools from different categories is used. One of the approaches employed in the development of micro-structures of contemporary interest, is based on a combined use of the analytical, computational, and experimental solutions (ACES) methodology. In this paper, applicability of the ACES methodology is illustrated by use of selected MEMS samples. The representative results presented in this paper indicate that the optical methodology is a viable tool for micro-scale measurements and, as such, it is particularly useful for development of MEMS, especially while considering MEMS reliability assessment. In fact, this methodology is being used in various manufacturing stages of MEMS for high-performance applications.

Effect of Process Parameters on TED-Based Q-Factor of MEMS

2007 ◽  
Author(s):  
Ryszard J. Pryputniewicz ◽  
Dariusz R. Pryputniewicz ◽  
Emily J. Pryputniewicz
Keyword(s):  
Internal Friction ◽  
Microelectromechanical Systems ◽  
Coefficient Of Thermal Expansion ◽  
Operating Conditions ◽  
Q Factor ◽  
Accuracy And Precision ◽  
Mems Technology ◽  
Q Factors ◽  
Application Specific

Continued advances in microelectromechanical systems (MEMS) technology have led to development of numerous applications including, but not limited to: automotive, communication, information technology, deep-space, medical, safety, national security, etc. These developments are being made possible because of creative designs and novel packaging based on use of some of the most sophisticated analytical and experimental tools available today. These tools are also employed to overcome limitations due to inherent behavior of materials fabricated into miniature shapes subjected to extremely harsh operating conditions while satisfying very challenging specifications/requirements of their applications. Thermoelastic internal friction is present in all structural materials and has been found experimentally in miniature silicon resonators (e.g., microgyroscopes, accelerometers, as well as biological, chemical, and other sensors/actuators) that rely on vibrations of either sensing elements or application-specific elastic suspensions that resonate. Regardless of their applications, sensors are always designed to provide the most sensitive responses to the signals they are developed to detect and/or monitor. One way to describe this sensitivity is to use the Quality (Q) factor. Most recent experimental evidence indicates that as the physical sizes of sensors decrease (especially because of continued advances in fabrication, e.g., by surface micromachining) the corresponding Q-factors become more and more dependent on thermoelastic damping (TED). This form of damping depends on material properties such as coefficient of thermal expansion, thermal conductivity, specific heat, density, and modulus of elasticity. It is also related to such design/operating parameters as resonator dimensions and temperature. This paper reviews a theoretical analysis of the effects that thermoelastic internal friction has on the Q-factor of microscale resonators and shows that the internal friction relating to TED is a fundamental damping mechanism in determination of quality of high-Q resonators over a range of operating conditions. Furthermore, the analysis also shows that the Q of resonators can be critical to the development of modern sensors. Microscale resonators are often used as basic sensing elements in the modern micromachined sensors. These sensors are frequency-modulated devices and exhibit a change in output frequency that is related to measurements and/or control of a physical variable. Accuracy and precision of these measurements/controls are inherently dependent on the frequency stability of the sensor/device output. This, in turn, greatly depends on damping in the resonating element itself.

Simulation and Contrast Analysis of tem Images of Cracks

1990 ◽  
Vol 48 (1) ◽  
pp. 578-579
Author(s):  
D. Goyal ◽  
A. H. King
Keyword(s):  
Displacement Vector ◽  
Crack Tip ◽  
Perfect Crystal ◽  
Operating Conditions ◽  
Displacement Fields ◽  
Fringe Contrast ◽  
Orthogonal Geometry ◽  
Moire Fringe ◽  
Moiré Fringe

TEM images of cracks have been found to give rise to a moiré fringe type of contrast. It is apparent that the moire fringe contrast is observed because of the presence of a fault in a perfect crystal, and is characteristic of the fault geometry and the diffracting conditions in the TEM. Various studies have reported that the moire fringe contrast observed due to the presence of a crack in an otherwise perfect crystal is distinctive of the mode of crack. This paper describes a technique to study the geometry and mode of the cracks by comparing the images they produce in the TEM because of the effect that their displacement fields have on the diffraction of electrons by the crystal (containing a crack) with the corresponding theoretical images. In order to formulate a means of matching experimental images with theoretical ones, displacement fields of dislocations present (if any) in the vicinity of the crack are not considered, only the effect of the displacement field of the crack is considered.The theoretical images are obtained using a computer program based on the two beam approximation of the dynamical theory of diffraction contrast for an imperfect crystal. The procedures for the determination of the various parameters involved in these computations have been well documented. There are three basic modes of crack. Preliminary studies were carried out considering the simplest form of crack geometries, i. e., mode I, II, III and the mixed modes, with orthogonal crack geometries. It was found that the contrast obtained from each mode is very distinct. The effect of variation of operating conditions such as diffracting vector (), the deviation parameter (ω), the electron beam direction () and the displacement vector were studied. It has been found that any small change in the above parameters can result in a drastic change in the contrast. The most important parameter for the matching of the theoretical and the experimental images was found to be the determination of the geometry of the crack under consideration. In order to be able to simulate the crack image shown in Figure 1, the crack geometry was modified from a orthogonal geometry to one with a crack tip inclined to the original crack front. The variation in the crack tip direction resulted in the variation of the displacement vector also. Figure 1 is a cross-sectional micrograph of a silicon wafer with a chromium film on top, showing a crack in the silicon.

Stability of Ring-Type MEMS Gyroscopes Subjected to Stochastic Angular Speed Fluctuation

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Samuel F. Asokanthan ◽  
Soroush Arghavan ◽  
Mohamed Bognash
Keyword(s):  
Angular Velocity ◽  
Degrees Of Freedom ◽  
Microelectromechanical Systems ◽  
Damping Ratio ◽  
Operating Conditions ◽  
System Stability ◽  
System Response ◽  
Ring Type ◽  
Mems Gyroscopes ◽  
The Stability

Effect of stochastic fluctuations in angular velocity on the stability of two degrees-of-freedom ring-type microelectromechanical systems (MEMS) gyroscopes is investigated. The governing stochastic differential equations (SDEs) are discretized using the higher-order Milstein scheme in order to numerically predict the system response assuming the fluctuations to be white noise. Simulations via Euler scheme as well as a measure of largest Lyapunov exponents (LLEs) are employed for validation purposes due to lack of similar analytical or experimental data. The response of the gyroscope under different noise fluctuation magnitudes has been computed to ascertain the stability behavior of the system. External noise that affect the gyroscope dynamic behavior typically results from environment factors and the nature of the system operation can be exerted on the system at any frequency range depending on the source. Hence, a parametric study is performed to assess the noise intensity stability threshold for a number of damping ratio values. The stability investigation predicts the form of threshold fluctuation intensity dependence on damping ratio. Under typical gyroscope operating conditions, nominal input angular velocity magnitude and mass mismatch appear to have minimal influence on system stability.

Device for the Experimental Determination of Control Objects' Mathematical Models

2013 ◽  
Vol 650 ◽  
pp. 493-497 ◽  
Author(s):  
Valerij I. Goncharov ◽  
Vadim A. Onufriev ◽  
Ilya O. Ilyin
Keyword(s):  
Control Systems ◽  
Computer Technology ◽  
Interpolation Method ◽  
Facilities Management ◽  
Operational Conditions ◽  
Automatic Control Systems ◽  
Interpolation Procedure ◽  
Real Interpolation Method ◽  
Inverse Problems Of Dynamics

Authors review methods of determining a plant’s mathematical model. Then, they show a numerical method of pulse automatic control systems’ (ACS) identification, focused on computer technology, the interpolation procedure and iterative methods of approximation to the desired solution. The basis of the approach is the method of inverse problems of dynamics and real interpolation method for calculating the linearized dynamical systems. An algorithm and the mobile device designed for the identification of facilities management in operational conditions are proposed. There is results’ application in the conclusion.

Prediction of the Flow and Force Characteristics of Safety Relief Valves

2006 ◽  
Author(s):  
W. Dempster ◽  
C. K. Lee ◽  
J. Deans
Keyword(s):  
Operating Conditions ◽  
Cfd Analysis ◽  
Flow Conditions ◽  
Relief Valve ◽  
Good Correspondence ◽  
Geometry Modeling ◽  
Valve Opening ◽  
Satisfactory Prediction ◽  
Force Characteristics

The design of safety relief valves depends on knowledge of the expected force-lift and flow-lift characteristics at the desired operating conditions of the valve. During valve opening the flow conditions change from seal-leakage type flows to combinations of sub-sonic and supersonic flows It is these highly compressible flow conditions that control the force and flow lift characteristics. This paper reports the use of computational fluid dynamics techniques to investigate the valve characteristics for a conventional spring operated 1/4” safety relief valve designed for gases operating between 10 and 30 bar. The force and flow magnitudes are highly dependent on the lift and geometry of the valve and these characteristics are explained with the aid of the detailed information available from the CFD analysis. Experimental determination of the force and flow lift conditions has also been carried out and a comparison indicates good correspondence between the predictions and the experiment. However, attention requires to be paid to specific aspects of the geometry modeling including corner radii and edge chamfers to ensure satisfactory prediction.

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