In this paper, a highly sensitive piezoresistive differential pressure microsensor is proposed. This microsensor is consisted of a silicon microcantilever (Length=145 μ m; Width=100 μ m; Thickness=0. 29 μ m) and two piezoresistors were mounted (via proper connections) on the microsensor for measuring the created pressure difference. Applying pressure to the microcantilever induces longitudinal and transverse stresses in the piezoresistors, changing their electric resistance and, consequently, the output voltage in the reading circuit of the microsensor. Longitudinal and transverse stresses, different relative sensor resistances resulting from different pressures, voltage variations along the piezoresistors, and microcantilever deflection resulting from different pressures were investigated. To improve the sensor sensitivity, effect of doping concentration, piezoresistors width, and the width of the structure placed under the piezoresistors were studied. In addition, we studied how increasing the width and length of the beam influenced the sensitivity of the sensor. Based on analysis results, the sensor sensitivity was increased from 0. 26  /Pa to 15. 78  /Pa ( 60 times). To evaluate the behavior and performance of the proposed microsensor, the following characteristics were analyzed: maximum microcantilever displacement, von Mises stress distribution along the beam and microsensor resistance variations.

Networks of closed conduits containing pressurized fluid flow occur in many different instances throughout the natural and manmade world. The dynamics of such networks are dependent not only on the complex interactions between the fluid body and the conduit material within each fluid line, but also on the coupling between different lines as they influence each other through their common junctions. The forward modeling (time-domain simulation), and inverse modeling (system parameter identification) of such systems is of great interest to many different research fields. An alternative approach to time-domain descriptions of fluid line networks is the Laplace-domain representation of these systems. In this paper we will consider a pressured fluid line, and we will find an optimized upper bound to the pressure by using Laplace transforms to solve the related differential system.

In this research, in order to investigate the effect of the piezoelectric patch which is used as a sensor or actuator in rotating flexible structures such as a helicopter blade, the free vibrations of the rotating rectangular sheet with and without the piezoelectric patch have been presented. First-order shear deformation theory is considered for plate displacement and piezoelectric field. Considering the effect of Coriolis acceleration, centrifugal acceleration and centrifugal in-plane forces, the equations of motion are derived from Hamilton's principle and the electromechanical couple equation is obtained from Maxwell's equation. For piezoelectric, two electrical conditions, open circuit and closed circuit, which are used in sensors and actuators, respectively, have been considered. The equations are discretized with the help of the numerical method of generalized differential squares and the matrices of inertia mass, eccentricity, Coriolis and stiffness matrix are obtained. Natural frequency values for beam and rotating plate have been compared in Abaqus software. Also, the values obtained from the numerical solution in MATLAB have been verified with articles and ABAQUS, which have high accuracy. The effect of parameters such as hub radius, rotation speed, sheet thickness, aspect ratio, piezoelectric patch thickness and applied voltage on the natural frequency of the system has also been investigated.

Background: The current study is to evaluate cardiovascular effects of anesthetic medications and volatile anesthetics on cardiac stress using cardiac stress index (CSI) and rate pressure product (RPP) and to determine which of them in useful in evaluating cardiac stress after comparing results obtained from each method.Materials and methods: 40 patients, 60-80 years old, who were all performed trans abdominal prostatectomy were studied. Patients were divided into two groups, half of patients were placed in group A and the other half in group B. The study was carried out as a blinded study. CSI was measured and evaluated in group A and RPP changes were studied in group B.Results: The mean CSI were 60.25±5.57, 63.05±5.54, 55.75±4.78 and 67.65±4.88 before anesthesia induction, after induction, before surgical incision and in recovery respectively. There was no meaningful difference.RPP mean in four above mentioned stages was 10.15±0.44, 9.9±0.69, 6.8±0.36 and 9.2±0.61 respectively. There was a meaningful difference between RPP in stages before anesthesia induction and before surgical incision (P<0.0001).Conclusion: Considering the obtained results from this study, it can be seen that even in noncardiac surgery, the stress level is high in patients in the stage before surgery. This figure was not clear in RPP index case and was not in accordance with CSI, which means CSI has been able to illustrate existing stress level better and efficiently.