توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Fabrication of a Novel MEMS Capacitive Microphone using Lateral Slotted Diaphragm
نویسنده(ها): ،
اطلاعات انتشار: International Journal of Engineering، بيست و سوم،شماره۳-۴، December ۲۰۱۰، سال
تعداد صفحات: ۱۰
In this paper, we have fabricated a new microphone with lateral slotted diaphragmpositioned over the back plate electrode using 8 anchors. It consists of a 3μm thick aluminum (Al) as a diaphragm, a 0.5μm as a back plate electrode and 1.3 μm thick resist (AZ1500) as a sacrificial layer on 4 inches silicon wafer. The novelty of this method relies on diaphragm which includes some lateral slots to reduce the effect of residual stress and stiffness of diaphragm for increasing the microphone sensitivity and also air damping in the gap has been reduced laterally. By this way, it is not needed to make acousticholes in back plate, thus the effective surface of diaphragm has been increased and it causes to increase the microphone capacitance. Compared with previous works, the chip size of this microphone is reduced, the complex and expensive fabrication process can be avoided and the sensitivity can be increased. The measured zero bias capacitance of microphone is 17.5 pF, and its pull–in voltage is 25 V. The capacitance of the microphone was measured as a function of the applied bias voltage using C–V analyzer. The capacitance increased with increasing bias voltage due to the decrease in the air gap thickness as the Al membrane is electrostatically pulled towards the back plate. The microphone has been tested with external amplifier and speaker, the external amplifier was able to detect the sound waves from microphone on speaker and oscilloscope. The maximum amplitude of output speech signal of amplifier is 45 mV, and the maximum output of MEMS microphone is 1.125 μV.

۲Accurate Determination of the Pull–in Voltage for MEMS Capacitive Microphone with Clamped Square Diaphragm
نویسنده(ها): ،
اطلاعات انتشار: International Journal of Engineering، بيست و پنجم،شماره۳، August ۲۰۱۲، سال
تعداد صفحات: ۶
Accurate determination of the pull–in, or the collapse voltage is critical in the design process. In this paper an analytical method is presented that provides a more accurate determination of the pull–in voltage for MEMS capacitive devices with clamped square diaphragm. The method incorporates both the linearized modle of the electrostatic force and the nonlinear deflection model of a clamped square diaphragm. The capacitor structure has been designed using a low stress doped poly silicon diaphragm with a proposed thickness of 0.8 μm and an area of 2.4 mm2, an air gap of 3.0 μm, and a 1.0 μm thick back plate. The value of pull–in voltage calculated using equation is about 6.85V and the finite element analysis (FEA) results show that the pull–in occurs at 6.75V. The resulting pull–in voltage and deflection profile of the diaphragm are in close agreement with finite element analysis results.

۳Design of Novel High Sensitive MEMS Capacitive Fingerprint Sensor
نویسنده(ها): ،
اطلاعات انتشار: International Journal of Engineering، بيست و پنجم،شماره۳، August ۲۰۱۲، سال
تعداد صفحات: ۸
In this paper a new design of MEMS capacitive fingerprint sensors is presented. The capacitive sensor is made of two parallel plates with air gap. In these sensors, the capacitance changes is very important factor. It is caused by deformation of the upper electrode of sensor. In this study with making slots in upper electrode, using T–shaped protrusion on diaphragm in order to concentrate the force from finger ridges, making holes in lower electrode to reduce the air damping and using low stress material for diaphragm, we have been succeeded to design a novel MEMS fingerprint sensor with high sensitivity compared with the previous one. In the present research, simulations were carried out using FEA method.

۴The Effect of Corrugations on Mechanical Sensitivity of Diaphragm for MEMS Capacitive Microphone
نویسنده(ها): ،
اطلاعات انتشار: International Journal of Engineering، بيست و ششم،شماره۱۱، November ۲۰۱۳، سال
تعداد صفحات: ۸
In this paper the effect of corrugations on mechanical sensitivity of diaphragm for MEMS capacitive microphone is investigated. Analytical analyses have been carried out to derive mathematic expression for mechanical sensitivity and displacement of corrugated diaphragm with residual stress. It is shown that the mechanical sensitivity and displacement of diaphragm can be modeled using thin plate theory. The mechanical stress of corrugated diaphragm is calculated using mathematical model and its relationship with residual stress is expressed. The analytical results show that the mechanical sensitivity of diaphragm can be increased using corrugations, because of reducing the effect of residual stress in corrugated diaphragm

۵Modeling of Capacitance and Sensitivity of a MEMS Pressure Sensor
نویسنده(ها): ،
اطلاعات انتشار: International Journal of Engineering، بيست و ششم،شماره۱۱، November ۲۰۱۳، سال
تعداد صفحات: ۶
In this paper, for the first time, the modeling of capacitance and sensitivity for MEMS capacitive pressure sensor with clamped square diaphragm is presented. In capacitive sensor the sensitivity is proportional to deflection and capacitance changes with pressure. Therefore, first the diaphragm displacement, capacitance and sensitivity of sensor with square diaphragm have been modeled and then simulated using finite element method (FEM). It can be seen that the analytical results agree with simulation. The results also show that the high sensitivity can be achieved by decreasing the diaphragm thickness and increasing its size.

۶A New Design of Dual Band Phase Shifter using MEMS Technology
نویسنده(ها): ،
اطلاعات انتشار: International Journal of Engineering، بيست و ششم،شماره۱۱، November ۲۰۱۳، سال
تعداد صفحات: ۱۰
This paper presents a new design of microwave microelectromechanical systems (MEMS) phase shifter for dual band wireless local area network (WLAN) applications. A bit is designed which produce a constant phase shift of 11.25° by switching between two lines that consist of 12 and 6 unitcells in each frequency band. A unitcell is constructed by gold membrane suspended over the coplanar waveguide (CPW) that can be moved vertically by electrostatic actuation. It can also ultimately be used for changing the operating frequency band. Two states of unitcell are used to switch between two frequency bands of 2.4 GHz and 5.2 GHz (IEEE 802.11 standard employed in dual band WLAN systems). First, a closed form equation of simplified model of the structure is obtained. Then, using this equation and advanced design system (ADS) simulator, the dual band phase shifter is designed. The validation of modeling and equations are demonstrated using the High Frequency Structure Simulator (HFSS). At the frequency of 2.4 GHz, maximum return and insertion losses are – 16.96 and –0.12 dB, respectively that exhibit a phase shift efficiency of 93.75 °\dB (60.22 °\cm). At the frequency of 5.2 GHz, maximum return and insertion loss are –16.86 and –0.15 dB, respectively exhibiting a phase shift efficiency of 75 °\dB (60.22 °\cm). The new proposed design is only to achieve a dual band phase shifter using MEMS technology which has low loss and weight with high linearity respect to the other technologies

۷Design of High Sensitivity and Linearity Microelectromechanical Systems Capacitive Tire Pressure Sensor using Stepped Membrane Article in Press
نویسنده(ها): ،
اطلاعات انتشار: International Journal of Engineering، بيست و نهم،شماره۳، Mar ۲۰۱۶، سال
تعداد صفحات: ۷
This paper is focused on a novel design of stepped diaphragm for MEMS capacitive pressure sensor used in tire pressure monitoring system. The structure of sensor diaphragm plays a key role for determining the sensitivity of the sensor and the non–linearity of the output.First the structures of two capacitive pressure sensors with clamped square flatdiaphragms, with different thicknesses are investigatedand their sensitivity and non–linearityare compared together.Finally for increasing the sensitivity and linearity,anew capacitive pressure sensor with a stepped diaphragm is introduced. A numerical solution for determination of theaccurate sensitivity of the sensor is presented.The results show that the sensitivity of the sensor is increased from 0.063 fF\KPa with flat diaphragm to 0.107 fF\KPa with stepped diaphragm and also the non–linearity is decreased from 2.37% to 1.857%. In this design, the sensor sensitivity and output linearity are increased simultaneously.
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