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Abstract: A principle for contactless interrogation of passive micromechanical resonator sensors is proposed, in which an external primary coil is electromagnetically air-coupled to a secondary coil connected to a conductive path on the resonator. The interrogation periodically switches between interleaved excitation and detection phases. During the excitation phase the resonator is driven into vibrations, while in the detection phase the excitation signal is turned off and the decaying oscillations are contactless sensed. The principle advantageously avoids magnetic properties required to the resonator, thereby ensuring compatibility with standard microfabrication processes. Results are reported on the successful implementation on a MEMS SOI microcantilever resonator working as a mass sensor for which the deposition and evaporation of a water droplet have been detected. [ABSTRACT FROM AUTHOR]

Abstract: Thermal-electrical energy converters based on pyroelectric effect are investigated for energy harvesting and possible use in ultralow-power sensor modules. Different elements based on thick films of lead zirconate titanate (PZT) sandwiched between metal electrodes deposited on alumina substrate were fabricated and characterized. The charge extracted was stored into a capacitor comparing performances offered by different rectifying circuits. Results show that the harvested energy can be compatible with use in autonomous sensors working in low-duty-cycle switched-supply mode. [ABSTRACT FROM AUTHOR]

Abstract: Distributed architectures for industrial applications are a new opportunity to realize cost-effective, flexible, scalable and reliable systems. Direct interfacing of sensors and actuators to the industrial communication network improves the system performance, because process data and diagnostics can be simultaneously available to many systems and also shared on the Web. However, sensors, especially low-cost ones, cannot use standard communication protocols suitable for computers and PLCs. In fact, sensors typically require a cyclic, isochronous and hard real-time exchange of few data, whereas PCs and PLCs exchange a large amount of data with soft real-time constrains. Looking at the industrial communication systems, this separation is clearly visible: several fieldbuses have been designed for specific sensor application areas, whereas high-level industrial equipments use wired/wireless Ethernet and Internet technologies. Recently, traditional fieldbuses were replaced by Real-Time Ethernet protocols, which are “extended” versions of Ethernet that meet real-time operation requirements. Besides, real-time wireless sensor networking seems promising, as demonstrated by the growing research activities. In this paper, an overview of the state-of-art of real-time sensor networks for industrial applications is presented. Particular attention has been paid to the description of methods and instrumentation for performance measurement in this kind of architectures. [Copyright &y& Elsevier]