جستجوی مقالات مرتبط با کلیدواژه
تکرار جستجوی کلیدواژه microsensor در نشریات گروه فنی و مهندسی
microsensor
در نشریات گروه مکانیک
تکرار جستجوی کلیدواژه microsensor در مقالات مجلات علمی
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In this paper, the two-layer micro sensor is modeled as a two-layer clamped-clamped microbeam and it is optimized by using the genetic algorithm. Using the results of this research, clamped-clamped microbeams can be designed in such a way that the performance of microsensors whose structure includes these microbeams will be improved. The quality factor, the sensitivity, and the maximum stress are selected as objective functions. The sensitivity and the quality factor are the functions of the natural frequency. The natural frequency is calculated based on Rayleigh’s method. The quality factor is calculated by approximation established on the one layer’s quality factor formula. To calculate the maximum stress, the system is assumed as a mass-spring system that has a harmonic displacement and the maximum deflection is the static deflection. The thickness of each layer, the width of the microbeam, and the length of the microbeam are selected as design variables. The optimization is done based on classical and non-classical theory by the genetic algorithm. The results based on both theories are approximately equal. The length of the microbeam is the most important variable and very changes (approximately 190%). The thickness of the silicon layer has the least effect on the results and changes just lower than (approximately 20%). The results show that when the maximum stress decreases and the sensitivity increases, the quality factor decreases which is undesirable. Maximum sensitivity is obtained when the microbeam is very small.Keywords: Microsensor, Clamped-Clamped Microbeam, Optimization, Sensitivity, Quality Factor
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Multi-objective Optimization of Two-Layer Microbeam used for Sensing of Viruses by Genetic AlgorithmIranian Journal of Mechanical Engineering Transactions of ISME, Volume:24 Issue: 1, Mar 2023, PP 70 -84In this paper, new optimizations of the two-layer microbeams based on the classical and non-classical theory are presented. In the first step, the natural frequency is obtained based on the modified couple stress theories. Afterwards, three important functions of the microbeams which are used as microsensors, sensitivity, quality factor, and maximum stress are defined. In the subsequent stage, two and three objective optimizations are carried out by using the genetic algorithm. At the two-objective optimization, sensitivity and quality factor are selected as objective functions. At the three objective optimizations, the maximum stress adds to the objective functions. The geometric parameters are design variables and there are some constraints and limits for those. The results are presented based on the classical and non-classical theory and optimal points are obtained for each optimization by using MATLAB.Keywords: Multi-objective optimization, microsensor, microbeam, Sensitivity, Quality factor
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Journal of Theoretical and Applied Vibration and Acoustics, Volume:8 Issue: 1, Winter & Spring 2022, PP 1 -12Predicting the vibration behavior of microsystems is of great importance. In this study, the vibration behavior of a microsensor modeled as a two-layer microplate is investigated. The effect of size has been investigated through the modified couple stress theory. The first natural frequency is extracted using the penalty approach. Boundary conditions are modeled using linear or torsional springs. Finally, changes in the natural frequency of the microsystem are presented according to different values of the microplate parameters such as the thickness of the silicon layer and material of the second layer. The results show that the natural frequency decreases as the thickness of the second layer increases. In addition, despite the different first natural frequencies for different parameters, the natural frequency diagram shows the same behavior in terms of system parameters under various boundary conditions. Finally, the effect of the thicknesses ratio and material length scale parameters ratio on the natural frequency is investigated. Predicting the vibration behavior of microsystems is of great importance. In this study, the vibration behavior of a microsensor modeled as a two-layer microplate is investigated. The effect of size has been investigated through the modified couple stress theory. The first natural frequency is extracted using the penalty approach. Boundary conditions are modeled using linear or torsional springs. Finally, changes in the natural frequency of the microsystem are presented according to different values of the microplate parameters such as the thickness of the silicon layer and material of the second layer. The results show that the natural frequency decreases as the thickness of the second layer increases. In addition, despite the different first natural frequencies for different parameters, the natural frequency diagram shows the same behavior in terms of system parameters under various boundary conditions. Finally, the effect of the thicknesses ratio and material length scale parameters ratio on the natural frequency is investigated.Keywords: Microsensor, Two-Layered Microplate, Modified Couple Stress Theory, Vibration Analysis
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در سال های اخیر مطالعات بر روی میکرو حسگرهای اکسید فلز برای تشخیص گازها در حال توسعه می باشد. این حسگرها دارای هزینه کمتر، اندازه کوچک تر و مصرف توان کمتری نسبت به حسگرهای دیگر می باشند. هدف از این مقاله بررسی عددی تاثیر میکرو کانال همگرا بر روی دما و سرعت گاز ورودی تحت تاثیر خزش حرارتی می باشد. معادلات دیفرانسیلی غیرخطی حاکم بر مسئله بقای جرم، مومنتوم، انرژی و گونه ها می باشد که توسط کد تجاری حل شده اند. از آنجاییکه عدد نادسن بین 001/0 و 1/0 می باشد، از شرایط مرزی لغزش و معادلات ماکسول استفاده شده است. نتایج نشان می دهد هر چه به منبع حرارتی نزدیک می شویم سرعت و دما به بیشینه خود می رسد و در خروجی چون تاثیرات جریان معکوس وجود دارد مقدار سرعت و دما کاهش می یابد. همچنین با افزایش ارتفاع ورودی میکروکانال و همگرایی بیشتر آن سرعت درون میکروکانال ابتدا افزایش و سپس کاهش می یابد و دما ابتدا کاهش و سپس افزایش می یابد.کلید واژگان: خزش حرارتی، شرایط لغزش، میکرو کانال همگرا، میکروحسگرIn recent years, research on metal oxide gas micro-sensors has been rapidly developed. These sensors are small in size, low cost in fabrication and consume little power. The purpose of the current study is to numerically investigate converge micro-channel on gas inlet temperature under the influence of thermal creeping. The governing nonlinear differential equations, mass, momentum, energy, and species, are coupled and solved by a commercial code. Since the Knudsen number is between 0.01 and 0.1, the slip boundary condition, Maxwell equation, is utilized. The result shows that flow velocity and temperature increases from the micro-channel inlet to the heat source and decreases from the heat source to the micro-channel outlet. Also as the inlet height and convergence increases, at the first flow velocity increases then decreases. This trend for temperature is reverse of the trend for flow velocity.Keywords: : Thermal Creep, Slip Condition, Converge Micro-Channel, Microsensor
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Journal of Transport Phenomena in Nano and Micro Scales, Volume:8 Issue: 1, Winter-Spring 2020, PP 1 -8The vibration analysis is an important step in the design and optimization of microsensors. In most of the cases, COMSOL software is employed to consider the size-dependency on the dynamic behavior in the MEMS sensors. In this paper, the Modified Couple Stress Theory (MCST) is used to capture the size effect on dynamic behavior in a microsensor with two layers of the silicon and piezoelectric. The governing equations of the system and also associated boundary conditions are derived based on the MCST and using Hamilton’s principle by obtaining the total kinetic and potential energies of the system. Then, the obtained governing equations are solved using an analytical approach to determine the natural frequencies of the system. The first, second and third natural frequencies of the microsensor are determined using an analytical approach. Finally, the natural frequency variations of the system are presented with respect to different values of the system parameters such as dimensionless parameters of the sensor geometric, the thickness of the silicon and piezoelectric layers and also the dimensionless material length scale parameter. The obtained results show that the material length scale parameter values and also the length, width, and thickness of each layer of the sensor are extremely effective on the vibration characteristics of the piezoelectric cantilever-based Micro Electro Mechanical System (MEMS) sensors. Also, the results show that the first natural frequency of the microsensor will decrease with either increasing dimensionless material length scale parameter or decreasing the thickness of silicon and piezoelectric. This analytical approach presents an efficient method to predict the dynamic behavior of microsensors and consequent optimization in their design procedure.Keywords: Free vibration, MEMS, Microsensor, Modified couple stress theory, Piezoelectric, Size-dependency
نکته
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