Design of Spring Coupling for High-Q High-Frequency MEMS Filters for Wireless Applications

A second-order microelectromechanical systems (MEMS) filter with high selectivity and sharp rolloff is required in wireless transceivers used in dense wireless sensor networks (WSNs). These sensors are expected to replace existing wired sensors used in industrial-plant management and environmental monitoring. These filters, together with MEMS-based oscillators and mixers, are expected to replace off-chip components and enable the development of a single-chip transceiver. Such a transceiver will leverage the integrated MEMS componentsÕ characteristics to operate at lower power and, hence, longer battery life, making autonomous WSNs more feasible in a wider range of applications. As a result, this paper presents the design and optimization of the coupling beam of wineglass-mode micromechanical disk filters using simulated annealing. The filter under consideration consists of two identical wineglass-mode disk resonators, mechanically coupled by a flexural-mode beam. The coupled two-resonator system exhibits two mechanical-resonance modes with closely spaced frequencies that define the filter passband. A constraint is added on the beam length to eliminate the effect of the coupling-beammass on the filterÕs resonant frequency. A new process flow is proposed to realize self-aligned overhanging coupling beams designed in this paper.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87260/4/Saitou6.pd

Sintering Kinetics of Plasma-Sprayed Zirconia TBCs

A model of the sintering exhibited by EB-PVD TBCs, based on principles of free energy minimization, was recently published by Hutchinson et al. In the current paper, this approach is applied to sintering of plasma-sprayed TBCs and comparisons are made with experimental results. Predictions of through-thickness shrinkage and changing pore surface area are compared with experimental data obtained by dilatometry and BET analysis respectively. The sensitivity of the predictions to initial pore architecture and material properties are assessed. The model can be used to predict the evolution of contact area between overlying splats. This is in turn related to the through-thickness thermal conductivity, using a previously-developed analytical model