A New Macro-Model of Gas Flow and Parameter Extraction for a CMOS-MEMS Vacuum Sensor

Shu-Jung Chen; Yung-Chuan Wu

doi:10.3390/sym12101604

A New Macro-Model of Gas Flow and Parameter Extraction for a CMOS-MEMS Vacuum Sensor

Symmetry ◽

10.3390/sym12101604 ◽

2020 ◽

Vol 12 (10) ◽

pp. 1604

Author(s):

Shu-Jung Chen ◽

Yung-Chuan Wu

Keyword(s):

Gas Flow ◽

Characteristic Length ◽

Parameter Extraction ◽

Average Error ◽

Transition Flow ◽

Characteristic Parameters ◽

Macro Model ◽

Transition Pressure ◽

Vacuum Sensor ◽

Cmos Mems

When using a MEMS sensor to measure the vacuum of a medium, the transition flow between the viscous flow and molar flow is usually used to describe the gas convection due to the physical principle, which is difficult to study through analysis and simulation. In this study, the description of gas flow under different pressures in a CMOS-MEMS vacuum sensors has been incorporated into a new behavioral ANSYS model. The proposed model was built and the characteristic parameters in the model were obtained based on a CMOS-MEMS thermopile patterned with circular symmetry and an embedded heater as a heat source. It contains a characteristic length to describe the effective distance of heat dissipation to the silicon substrate, and the corresponding transition pressure to describe the symmetrical phenomenon of gas heat conduction. The macro-model is based on the description of the physical characteristics of heat transfer and the characteristic parameters of the CMOS-MEMS vacuum sensor. The characteristic length of 49 μm and the corresponding transition pressure of 2396 mTorr for the thermoelectric-type vacuum sensor were extracted and verified successfully. The results show that the average error for the prediction of vacuum sensing by the macro-model we proposed is about 1.11%. This approach provides more applications for vacuum analysis. It can reduce the complexity of simulation and analysis and provide better simulation effects, including gas conduction mechanisms.

Download Full-text

Influence of the Variation of Plasma Torch Parameters on Particle Melting and Solidification

Thermal Spray 1997: Proceedings from the United Thermal Spray Conference ◽

10.31399/asm.cp.itsc1997p0535 ◽

1997 ◽

Author(s):

M. Vardelle ◽

P. Fauchais ◽

A. Vardelle ◽

A.C. Léger

Keyword(s):

Flow Rate ◽

High Speed ◽

Gas Flow ◽

Operating Conditions ◽

Characteristic Parameters ◽

Powder Mass ◽

Arc Current ◽

Plasma Sprayed ◽

Carrier Gas Flow ◽

Melting And Solidification

Abstract A study of the flattening and cooling of particles plasma-sprayed on a substrate is presented. The characteristic parameters of the splats are linked to the parameters of the impacting particles by using an experimental device consisting of a phase Doppler particle analyzer and a high-speed pyrometer. However, during the long experiments required to get reliable correlations, it was observed that variations in plasma spray operating conditions may alter the particles behavior in the plasma jet. Therefore, a simple and easy-to-use system was developed to control in real time the spray jet. In this paper, the effect of carrier gas flow rate, arc current and powder mass flow rate is investigated. The results on zirconia and alumina powders show the capability of the technique to sense the particle spray position and width.

Download Full-text

Lattice Boltzmann Simulation of Rarefied Gas Flow Along Moving Rigid Objects in Micro-Cavities

ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2015-48030 ◽

2015 ◽

Cited By ~ 1

Author(s):

Weilin Yang ◽

Hongxia Li ◽

TieJun Zhang ◽

Ibrahim M. Elfadel

Keyword(s):

Free Path ◽

Lattice Boltzmann ◽

Path Length ◽

Gas Flow ◽

Rarefied Gas ◽

Free Path Length ◽

Mean Free Path ◽

Fluid Simulation ◽

Transition Flow ◽

Rarefied Gas Flow

Rarefied gas flow plays an important role in the design and performance analysis of micro-electro-mechanical systems (MEMS) under high-vacuum conditions. The rarefaction can be evaluated by the Knudsen number (Kn), which is the ratio of the molecular mean free path length and the characteristic length. In micro systems, the rarefied gas flow usually stays in the slip- and transition-flow regions (10−3 < Kn < 10), and may even go into the free molecular flow region (Kn > 10). As a result, conventional design tools based on continuum Navier-Stokes equation solvers are not applicable to analyzing rarefaction phenomena in MEMS under vacuum conditions. In this paper, we investigate the rarefied gas flow by using the lattice Boltzmann method (LBM), which is suitable for mesoscopic fluid simulation. The gas pressure determines the mean free path length and Kn, which further influences the relaxation time in the collision procedure of LBM. Here, we focus on the problem of squeezed film damping caused by an oscillating rigid object in a cavity. We propose an improved LBM with an immersed boundary approach, where an adjustable force term is used to quantify the interaction between the moving object and adjacent fluid, and further determines the slip velocity. With the proposed approach, the rarefied gas flow in MEMS with squeezed film damping is characterized. Different factors that affect the damping coefficient, such as pressure of gas and frequency of oscillation, are investigated in our simulation studies.

Download Full-text

Research on a New Metal-N-Poly Thermoelectric Material Sensor for Vacuum Sensing with Self Heating

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.773.152 ◽

2018 ◽

Vol 773 ◽

pp. 152-156

Author(s):

Chih Hsiung Shen ◽

Shu Jung Chen ◽

Shih Hao Lin

Keyword(s):

Temperature Drop ◽

Second Phase ◽

Vacuum Measurement ◽

Self Heating ◽

Custom Design ◽

Wide Range ◽

Vacuum Sensor ◽

Cmos Mems ◽

Thermoelectric Sensor ◽

Mems Process

This paper proposes a new vacuum sensor with CMOS Metal-N-Poly thermoelectric materials which works for both thermoelectric sensing and resistive heating. A new method of vacuum measurement with self-heating is proposed based on the dual phases of heating and sensing for the same element which is realized with CMOS thermoelectric sensor. Using the TSMC 0.35 μm CMOS-MEMS process, the proposed thermoelectric sensor is designed and fabricated with standard CMOS materials of the 4th metal and N-polysilicon to form 64 pairs of central-symmetrical thermocouples. There is an air convection-sensing area at the center of membrane and is filled with array of micro-through-holes to enhance the effect of heat convection. When the air molecules move through the array of hole, the heat exchange will take away the heat to cause a temperature drop of sensing area which gives a weak voltage between the cold and hot end of the thermocouples. The heating of thermopile itself is designed at the first phase and sensing the output voltage at the second phase subsequently. According to a careful investigation of the measurement with a wide range of 10m~10k torr, our proposed sensing scheme based on a thermoelectric type sensor is proved for practical vacuum detection and most of all it is proved as a new approach to use a commercial thermopile without heater, which is easier to include than a special custom design.

Download Full-text

Active Thermoelectric Vacuum Sensor Based on Frequency Modulation

Micromachines ◽

10.3390/mi11010015 ◽

2019 ◽

Vol 11 (1) ◽

pp. 15 ◽

Cited By ~ 3

Author(s):

Shu-Jung Chen ◽

Yung-Chuan Wu

Keyword(s):

Frequency Modulation ◽

Signal To Noise Ratio ◽

Complementary Metal Oxide Semiconductor ◽

Harmonic Signal ◽

Phase Lock Loop ◽

Oxide Semiconductor ◽

Alternative Approach ◽

Vacuum Sensor ◽

Cmos Mems ◽

Mems Process

This paper introduces a thermoelectric-type sensor with a built-in heater as an alternative approach to the measurement of vacuum pressure based on frequency modulation. The proposed sensor is fabricated using the TSMC (Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan) 0.35 μm complementary metal-oxide-semiconductor-microelectro-mechanical systems (CMOS–MEMS) process with thermocouples positioned central-symmetrically. The proposed frequency modulation technique involves locking the sensor output signal at a given frequency using a phase-lock-loop (PLL) amplifier to increase the signal-to-noise ratio (SNR) and thereby enhance the sensitivity of vacuum measurements. An improved first harmonic signal detection based on asymmetrical applied heating gives a precise measurement. Following calibration, the output voltage is in good agreement with the calibration values, resulting in an error of 0.25% under pressures between 0.1–10 Torr.

Download Full-text

Gas flow regimes judgement in nanoporous media by digital core analysis

Open Physics ◽

10.1515/phys-2018-0062 ◽

2018 ◽

Vol 16 (1) ◽

pp. 448-462

Author(s):

Wenhui Song ◽

Hua Liu ◽

Weihong Wang ◽

Jianlin Zhao ◽

Hai Sun ◽

...

Keyword(s):

Gas Flow ◽

Characteristic Length ◽

Three Dimensional ◽

Flow Regimes ◽

Core Analysis ◽

Mcmc Algorithm ◽

Sem Images ◽

Digital Core ◽

Shale Formation ◽

Organic Pores

Abstract A method to judge shale gas flow regimes based on digital core analysis is proposed in this work. Firstly, three-dimensional shale digital cores in an anonymous shale formation in the Sichuan Basin are reconstructed by a Markov Chain Monte Carlo (MCMC) algorithm based on two-dimensional Scanning Electron Microscope (SEM) images. Then a voxel-based method is proposed to calculate the characteristic length of the three-dimensional shale digital core. The Knudsen number for three-dimensional shale digital cores is calculated by the ratio of the molecular mean free path to the characteristic length and is used to judge the flow regimes under different reservoir conditions. The results indicate that shale gas flow regimes are mainly located at the slip flow and transition flow region. Furthermore, adsorption has no obvious influence on the free gas flow regimes. Because adsorption only exists in organic pores, three-dimensional inorganic pores and organic pores in the Haynesville shale formation are reconstructed by a MCMC algorithm based on two-dimensional SEM images. The characteristic lengths of the three-dimensional inorganic pores and three-dimensional organic pores are both calculated and gas flow regimes in organic pores and inorganic pores are judged.

Download Full-text

DSMC Simulation of Supersonic Gas Flow in Microchannel

ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, Volume 1 ◽

10.1115/icnmm2011-58111 ◽

2011 ◽

Author(s):

Mohamad M. Joneidipour ◽

Reza Kamali

Keyword(s):

Gas Flow ◽

Characteristic Length ◽

Flow Characteristics ◽

Mean Free Path ◽

Incoming Flow ◽

Characteristic Length Scale ◽

Flow Pressure ◽

Supersonic Gas Flow ◽

The Mean ◽

Gas Molecules

The present study is concerned with the flow characteristics of a microchannel supersonic gas flow. The direct simulation Monte Carlo (DSMC) method is employed for predicting the density, velocity and temperature distributions. For gas flows in micro systems, the continuum hypothesis, which underpins the Navier-Stokes equations, may be inappropriate. This is because the mean free path of the gas molecules may be comparable to the characteristic length scale of the device. The Knudsen number, Kn, which is the ratio of the mean free path of the gas molecules to the characteristic length scale of the device, is a convenient measure of the degree of rarefaction of the flow. In this paper, the effect of Knudsen number on supersonic microchannel flow characteristics is studied by varying the incoming flow pressure or the microchannel height. In addition, the microchannel height and the incoming flow pressure are varied simultaneously to investigate their effects on the flow characteristics. Meanwhile, the results show that until the diffuse reflection model is used throughout the microchannel, the temperature and the Mach number in the microchannel entrance may not be equal to free-stream values and therefore a discontinuity appear in the flow field.

Download Full-text

Extraction Algorithm of Lip Characteristic Parameters Based on Interpolation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.536-537.235 ◽

2014 ◽

Vol 536-537 ◽

pp. 235-240

Author(s):

Ying Jie Meng ◽

Li Xin Bai ◽

Wen Jun Liu ◽

Ming Wen Liu

Keyword(s):

High Efficiency ◽

Parameter Extraction ◽

Characteristic Parameters ◽

Motion Feature ◽

Identity Recognition ◽

Features Fusion ◽

Parameters Extraction ◽

Key Points ◽

Extraction Algorithm ◽

Motion Features

In the research of identity recognition based on lip motion features, there are limitations for the existing algorithms of lip characteristic parameters extraction. This paper uses the strategy of lip static/dynamic geometric features fusion, designs the lip feature parameter extraction program based on interpolation, and implements the major aspects of processing algorithm of the program. The solution is based on the speaker's key six primitives spelling lip sequence image, firstly generates the lip key point coordinates in the image, then based on Lagrange interpolation obtains function curve coefficient of upper and lower lips' key points , lastly the two curve coefficients are combined to form lip motion feature information of human speaker's some specific sounds; Simulation results show that the extraction of characteristic parameters of the program not only have a high efficiency and availability, but also have the advantages of good storage.

Download Full-text

Laboratory measurement and interpretation of nonlinear gas flow in shale

International Journal of Modern Physics C ◽

10.1142/s0129183115500631 ◽

2015 ◽

Vol 26 (06) ◽

pp. 1550063 ◽

Cited By ~ 11

Author(s):

Yili Kang ◽

Mingjun Chen ◽

Xiangchen Li ◽

Lijun You ◽

Bin Yang

Keyword(s):

Pore Pressure ◽

Gas Flow ◽

Gas Adsorption ◽

Slip Flow ◽

Transition Flow ◽

Confining Stress ◽

Slippage Effect ◽

Longmaxi Shale ◽

Close Relationship ◽

Flow Mechanisms

Gas flow mechanisms in shale are urgent to clarify due to the complicated pore structure and low permeability. Core flow experiments were conducted under reservoir net confining stress with samples from the Longmaxi Shale to investigate the characteristics of nonlinear gas flow. Meanwhile, microstructure analyses and gas adsorption experiments are implemented. Experimental results indicate that non-Darcy flow in shale is remarkable and it has a close relationship with pore pressure. It is found that type of gas has a significant influence on permeability measurement and methane is chosen in this work to study the shale gas flow. Gas slippage effect and minimum threshold pressure gradient weaken with the increasing backpressure. It is demonstrated that gas flow regime would be either slip flow or transition flow with certain pore pressure and permeability. Experimental data computations and microstructure analyses confirm that hydraulic radius of flow tubes in shale are mostly less than 100 nm, indicating that there is no micron scale pore or throat which mainly contributes to flow. The results are significant for the study of gas flow in shale, and are beneficial for laboratory investigation of shale permeability.

Download Full-text

Nonlinear Seepage Model of Gas Transport in Multiscale Shale Gas Reservoirs and Productivity Analysis of Fractured Well

Journal of Chemistry ◽

10.1155/2015/349507 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10 ◽

Cited By ~ 3

Author(s):

Ting Huang ◽

Xiao Guo ◽

Kun Wang

Keyword(s):

Gas Flow ◽

Slip Flow ◽

Gas Production ◽

Productivity Analysis ◽

Transition Flow ◽

Gas Reservoirs ◽

Slippage Effect ◽

Wellbore Pressure ◽

Fractured Well ◽

And Diffusion

Shale is abundant in nanoscale pores, so gas flow in shales cannot be simply represented by Darcy formula anymore. It is crucial to figure out the influence of gas flow in nano/micro pores on actual productivity, which can provide basic theories for optimizing parameters and improving the gas production from engineering perspective. This paper considers the effects of slippage and diffusion in nanoscale based on Beskok-Karniadakis (BK) equation, which can be applicable for different flow regimes including continuum flow, slip flow, transition flow, and free-molecule flow. A new non-Darcy equation was developed based on the analysis of effects of high order terms of BK equation on permeability correction factor. By using the conformal transformation principle and pressure coupling method, we established the productivity formula of fractured well (infinite and limited conductivity) satisfying mass variable seepage flowing in fractures. The simulation results have been compared with field data and influencing parameters are analyzed thoroughly. It is concluded that slippage effect affects gas production of fractured well when wellbore pressure is less than 15 MPa, and the effects of slippage and diffusion have greater influence on gas production of fractured well for reservoir with smaller permeability, especially when permeability is at nano-Darcy scale.

Download Full-text