Index of content:
Volume 116, Issue 5, November 2004
- TRANSDUCTION 
116(2004); http://dx.doi.org/10.1121/1.1798331View Description Hide Description
The paper contains an analysis of the viscous damping in perforated planar microstructures that often serve as backplates or protecting surfaces in capacitive microsensors. The focus of this work is on planar surfaces containing an offset system of periodic oval holes or its limit cases: a system of circular holes or of slits. The viscous damping is calculated as the sum of squeeze film and the holes’ resistances. The optimum number of holes is determined which minimizes the total viscous damping for a given percentage of open area. Graphs and formulas are provided for designing these devices. In the case the open area is higher than 15% the numerical results show that the influence of the holes’ geometry (circular or oval) has a slight influence on viscous damping. As the planar structures containing oval holes assure a better protection against dust particles and water drops, they should be preferred in designing protective surfaces for microphones working in a natural environment. The obtained results also can be applied in designing other MEMSdevices that use capacitive sensing such as accelerometers, micromechanical switches, resonators, and tunable microoptical interferometers.
116(2004); http://dx.doi.org/10.1121/1.1804631View Description Hide Description
Many works have been devoted to the estimation of cross-talk effects in one-dimensional ultrasound probes. The main aspect limiting the interest of these works concerns the lack of control of the electrical boundary conditions applied to the array which may dramatically affect the results of cross-talk measurements. In this paper the concept of mutual admittances is recalled. Computations based on a periodic finite-element analysis are performed, jointly to measurements of cross talks in the case of a 1-3 connectivity piezoelectric composite. Quantitative comparisons show the capability of the proposed approach to predict almost all the contributions experimentally observed in a large frequency range.