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 flat diaphragms, with different thicknesses are investigated and their sensitivity and non-linearity are compared together. Finally for increasing the sensitivity and linearity, a new capacitive pressure sensor with a stepped diaphragm is introduced. A numerical solution for determination of the accurate 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. Manuscript profile

In this paper a new model of Pull-in Voltage for MEMS capacitor with fully clamped diaphragm is presented. This model not only makes it possible to calculate the exact value of pull-in voltage in a capacitor but also provides the ability to detect the accurate deflection of a fully clamped diaphragm. By introducing this model, the precise value of pull-in voltage at the border, between stable and un-stable state, can be calculated.  As an advantage of this new achievement, it is exhibited that the all theoretical equations are fully compatible with simulation results using finite element analysis (FEA). Manuscript profile

Separation of charged particles is a major problem in biological and chemical researches. There are several techniques for separate charged particles, one of them is electrophoresis. electrophoresis separates electrically charged particles by applying external uniform electric field. In recent  years,conventionalcross-form of geometry has been used for microchip electrophoresis. this paper represents  new cross-form geometry of microchip capillary electrophoresis with low separation time and high resolution and efficiency and are respectively equal to 100s,3.1,1166.5 while these values for conventional geometries are respectively equal to 120s,2.85,1004.8. these geometries are simulated by comsol. Manuscript profile

The structure of pure and Al doped ZnO (AZO) nanorods (NRs) has been studied. A post annealing procedure in oxygen ambience at 400ﹾC were used in order to improve crystallinity of both group of samples. The XRD patterns illustrate that the Al doped ZnO NRs were successfully synthesized using our method. Then, the field emission properties of the as grown NRs before and after annealing process were evaluated by our home-made setup. Experimental results show that Al density in ZnO NRs directly affects FE properties of these samples. The oxygen post annealing process leads to a significant improvement in the field emission performances of pristine and doped ZnO NRs including considerably lower turn on voltage, and higher emission current. Manuscript profile

Study on effects of changing the oxide thickness, can give us a view of the aspects of MOSFET, in field of design of the transistor elements. Changing the oxide thickness affects on both Cox and Vt. At first, in this paper, the relation between the threshold voltage and oxide thickness will be discussed. Then, the relation between the drain current and oxide thickness will be modeling. The result is a nonlinear and parabolic relationship between the drain current and oxide thickness. To ensure the authenticity of the obtained model, a MOSFET parameters, based on 5 µm CMOS technology was designed. This MOSFET was simulated with COMSOL software and obtained mathematical model analyzed with MATLAB. Finally, the data were compared, which confirmed the authenticity of the mathematical model. Manuscript profile

In this paper a novel RF MEMS cantilever type switch with low actuation voltage is presented. The cantilever beam of switch is supported by two L-shaped springs to reduce the spring constant. The switch is simulated using Intellisuite software. The actuation voltage of switch is achieved about 2 volt and the size of the switch is 110×60µ2m, that in compared with other electrostatic cantilever beam switch, it has a small size, low spring constant and as a result low actuation voltage. Its fabrication is simple due to its simple design. The S-parameters of switch have been simulated with HFSS 9.1 that the results show the insertion loss of 0.07 dB, return loss 0f 25 dB and 17 dB isolation for V, Ka frequencies band. The results show proper performance of switch in this frequencies band and it had less insertion loss compare pervious work and with these properties of switch, return loss and isolation did not changed much. Manuscript profile

In this paper a novel planar micro-transformer with high quality factor is presented. Non-uniform current density distribution, especially in inner turn, increases the effective metal resistance due to skin and proximity effect .In order to overcome this problem, a novel crossover connection between turns to equal the distance current path across the turns and uniform the current distribution, has been used. With diminished current crowding effects, the effective resistance is minimized, thereby increasing the performance-parameter values. Simulation has been taken by using ADS Momentum and HFSS software. The quality factor, self-inductance, mutual inductance and coupling factor at 3.5 GHz frequency are achieved about 42.6, 4.9 nH, 3.3 nH, 0.747 respectively, and occupied structure space is 860 um×860 um. Because of the structure is symmetric, the primary and secondary characteristic is same .compare to conventional micro-transformer 17% in quality factor,5% in coupling coefficient and more than 20% in self and mutual inductance, improvement are achieved.    Manuscript profile

This paper presents a new dual beam RF MEMS capacitive shunt switch with low voltage, low loss and high isolation for K-band applications. In this design, we have proposed the step structure to reduce the air gap between the bridge and the signal line, thus the actuation voltage is reduced to 2.9V. Furthermore, to reach more isolation, we used Aluminum Nitride (AlN) as a dielectric layer instead of conventional dielectric materials such as  and which has more  led to increase the down-state capacitance and increase the isolation of switch. The results show that the switch in up position involve  less than -10 dB from 1 to 40 GHZ and  more than -0.72 dB from 1 to 22 GHZ. In down state, switch has an excellent isolation at the frequency range of K-band. The maximum isolation of -58 dB is obtained at resonance frequency of 27 GHZ. Furthermore, we used the -match circuit to improve the reflection and isolation of switch. In this case, the double-bridge switch has the return loss of around -12 dB at the range of 1-31 GHZ. The insertion loss of switch is less than -0.8 dB at the range of 1-27 GHZ. The isolation around -40 dB is obtained at the range of 15-40 GHZ. The proposed dual beam switch is the wideband and low-loss switch that appropriate for applications of K-band frequencies. Manuscript profile