Microsystems Seminar: Slava Krylov, "Arrays of Micro Oscillators"
Thursday, September 17, 2015
1146 A V Williams Bldg
Parametrically Excited Electrostatically Coupled Arrays of Micro Oscillators
School of Mechanical Engineering
Faculty of Engineering
Tel Aviv University
Resonant micro- and nanoelectromechanical (MEMS/NEMS) devices are core components in biological and chemical sensors, scientific instruments for material characterization and navigation measurement units for consumer, automotive, aerospace and defense applications. Operational principle of these structures is often based on monitoring of their resonant frequencies, which are influenced by the parameters of interest. Among various types of devices, parametrically excited structures are attractive for implementation in sensors due to their ability to generate large resonant responses as well as sharp transition between low-amplitude to large-amplitudes vibrations accompanying changes in system parameters.
In this talk, several approaches to achieve parametric excitation in micro oscillators will be first briefly reviewed. An excitation by direct stiffness modulation, inertia modulation as well as electrostatic operation by fringing fields will be discussed. Next, results of theoretical and experimental investigation of the collective dynamic behavior of large arrays of micro oscillators will be presented. The device is consisting of two sets of partially interdigitated cantilevers. The adjacent beams are coupled mechanically due to clamping compliances, and electrostatically through voltage-dependent fringing fields. In the framework of the reduced order model built using Galerkin decomposition the array is considered as an assembly of single degree of freedom oscillators. Both local and non-local mechanical interactions are accounted for. The non-local interaction matrix is build using the finite elements analysis of the array. The electrostatic forces are approximated by means of fitting the results of three-dimensional numerical solution for the electric fields. The out-of-plane resonant responses of the devices fabricated from the silicon on insulator substrates are visualized by time-averaged temporally aliased video imaging and measured by the laser Doppler vibrometry.
We show that large amplitude collective vibrations of the array can be achieved using parametric excitation while the dynamic properties of the array such as the width of the propagation band as well as the modal patterns can be efficiently tuned by the applied voltage. Our experimental and model results collectively demonstrate that under a slowly varying drive frequency the standing wave patterns remain synchronized within certain frequencies intervals, followed by an abrupt change in the pattern. The ability to control the spectral characteristics using voltage can be useful for individual addressing of different locations of the sensing arrays, in band-pass filters with tunable passband and in diffractive optical devices.
Slava Krylov holds M.Sc. and Ph. D. in applied mechanics, both from the State Marine Technical University of St. Petersburg, Russia. After his graduation he was Colton postdoctoral fellow at the Department of Solid Mechanics, Materials and Systems, Tel Aviv University and CNRS visiting post-doctoral fellow at Laboratoire de Modélisation en Mécanique, Université Pierre et Marie Curie (Paris VI), Paris, France. He spent five years in industry working as a R&D engineer for the Israel Aircraft Industries (IAI) and later as a principal scientist and co-founder of a start-up company developing optical MEMS. Currently he is Professor at the School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University. He was visiting professor of the School of Applied and Engineering Physics and Mary Shepard B. Upson Visiting Professor at The Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY. He’s also a visiting research fellow at the Center for the Nanoscale Science and Technology (CNST) at the National Institute of Standards and Technology (NIST), Gaithersburg, MD. He serves as a consultant and member of an advisory board of several MEMS companies in Israel. His research is focused in the area of modeling, design and characterization of micro- and nano-electromechanical systems (MEMS/NEMS), micro and nano actuators, inertial sensors, dynamics and stability of MEMS/NEMS, nano resonators and polymeric MEMS.