Cascaded "Triple-Bent-Beam" MEMS Sensor for Contactless Temperature Measurements in Nonaccessible Environments

International audienceA microelectromechanical systems (MEMS) temperature sensor based on a cascade three-stage "bent-beam" structure is described in this paper. A suspended structure mechanically deforms in response to the change in ambient temperature, and then, a displacement is obtained; the structure is composed of three cascaded systems in order to enhance sensor sensitivity. The final conversion is made to an electrical signal that is obtained by using an interdigitated capacitor having one electrode fixed to the substrate and one electrode embedded into the moving tip of the MEMS sensor. The device has been conceived to operate passively in harsh environments where high temperatures could harm active electronic devices. The readout of the unknown temperature is therefore remotely performed by coupling the variable MEMS capacitor to a fixed inductor to compose a resonant LC circuit, which ismagnetically coupled to a reader circuit placed outside the environment where the measurement takes place. The temperature to be measured is therefore first converted into a displacement that, in turn, induces a change in a capacitor value; a variation in the resonant frequency of an LC circuit is finally observed through the remote readout circuit. This paper focuses on the analytical and numerical modeling of both the temperature-todisplacement and displacement-to-capacitance conversions, on the design and fabrication of an experimental prototype, on the experimental validation where results are extensively presented and commented, and, finally, on the design of the integrated resonant device for contactless measurements

A BE-SOI MEMS for Inertial Measurement in Geophysical Applications

International audienceAbstract--In this paper, an inertial transducer developed in bulk and etch silicon-on-insulator microelectromechanical-system technology is presented. The device is suitable for low-frequency observation and could represent an interesting solution to implement low-cost monitoring systems for applications requiring a large number of monitoring sites and disposable devices. In particular, the sensor design and the technology adopted are presented here along with models describing the device operation. In addition, an experimental sensor prototype is proposed, and experimental results confirming the suitability of the proposed architecture and its consistence with the predicted behavior are discussed

Numerical and Experimental Investigation on Contactless Resonant Sensors

International audienceThis paper reports numerical and experimental investigation on a (bulk and etch silicon on insulator) BESOI MEMS device. The implemented contactless actuation principle, exploits Lorentz forces exerted on a conductive-non magnetic surface of the sensor. These forces derive from the interaction between the eddy-currents and the radial magnetic field, both generated by a sinusoidally driven external inductor. Both excitation and readout strategies are performed remotely via a magnetic strategy. The sensor proposed here has been first analytically and numerically studied by using CoventorWareTM 2008, then the device prototype has been fabricated and a preliminary experimental campaign has been performed to characterize the system in terms of variation of its resonance frequency against changes in the sensor mass

Neither amateurs nor professionals: The status of Greek Athletes

The aim of this chapter is to question whether it is reasonable to apply the labels "amateurs" or "professionals" to Ancient Olympics, whether they fit the specific features of ancient athletics, and whether they are useful tools or mere obstacles for an understanding of the ancient phenomena. This article argues that neither of the two terms helps in understanding the social reality of ancient athletes