Abstract: A wireless network is described including a cluster network and a sensor/actuator network arranged in a hierarchical manner with the cluster head network. The cluster head network includes at least one cluster head and the sensor/actuator network includes a plurality of sensor/actuator nodes arranged in a plurality of node levels.

Abstract: A sensor arrangement for ascertaining the density and the viscosity of a liquid is proposed, having an arrangement comprising at least two basic sensor elements, at least one of which can be wetted with the liquid, and having electro-acoustical transducers (6) in the basic sensor elements for generating and detecting surface acoustic waves with predetermined wave modes, from whose propagation behavior along a measurement path a measure for the density and the viscosity of the liquid can be ascertained. Liquid traps (17) for the liquid, which extend in the applicable measurement path, are disposed in the region of at least one of the basic sensor elements, parallel to the direction of propagation of the surface acoustic wave.

Abstract: An oscillatory micromirror having a cantilevered mirror surface is joined using at least one torsion axis formed by at least one torsion beam mounted on the mirror surface, to a support member that surrounds at least portions of the mirror surface. There is located between at least one of the torsion beams and the support member a flexural beam that performs a flexural oscillation which induces a torsional oscillation of the mirror surface about the torsion axis. At a suitable frequency, large amplitudes of the torsional oscillation may be provided by small amplitudes of the flexural oscillation.

Abstract: A sensor arrangement for ascertaining physical properties of a liquid is proposed, having electro-acoustical converters (6) on a substrate (5) which are wettable with the liquid and are suitable for generating and detecting acoustical surface waves with predetermined wave modes. A Y-rotated quartz slice is used as the substrate (5), and above the substrate (5) is a waveguide layer (16); the standard of the Y rotation of the quartz slice and the material of the waveguide layer (16) are selected such that an extensive temperature compensation within the range of temperature of the liquid to be investigated is obtained.

Abstract: A method and apparatus are proposed for operating a microacoustic sensor arrangement, for example, to determine the physical characteristics of a measurement medium. Acoustic surface waves with predetermined wave modes are generated and detected by electroacoustic transducers (6) and a measurement for the physical characteristics of the measurement medium is determined from their propagation behavior along a propagation path. In addition, a sagittally polarized surface wave is generated in the area of the surface of the substrate (5; 22) on which the measurement medium is located.

Abstract: A sensor which has a bending reed and a piezoelectric resonator. Due to excitation by the piezoelectric resonator, the bending reed can be excited to vibration in a measurable medium. In this context, the vibration frequency and the damping of the bending reed are a function of the density and the viscosity, respectively, of the measurable medium. This can be measured by a piezoresistive element, and thus the density and viscosity of the measurable medium are ascertained.