Page 10 - Mechanics of Microelectromechanical Systems

PREFACE

This book offers a comprehensive coverage to the mechanics of
microelectromechanical systems (MEMS), which are analyzed from a
mechanical engineer’s viewpoint as devices that transform an input form of
energy, such as thermal, electrostatic, electromagnetic or optical, into output
mechanical motion (in the case of actuation) or that can operate with the
reversed functionality (as in sensors) and convert an external stimulus, such as
mechanical motion, into (generally) electric energy. The impetus of this
proposal stems from the perception that such an approach might contribute to
a more solid understanding of the principles governing the mechanics of
MEMS, and would hopefully enhance the efficiency of modeling and
designing reliable and desirably-optimized microsystems. The work
represents an attempt at both extending and deepening the mechanical-based
approach to MEMS in the static domain by providing simple, yet reliable
tools that are applicable to micromechanism design through current
fabrication technologies.
Lumped-parameter stiffness and compliance properties of flexible
components are derived both analytically (as closed-form solutions) and as
simplified (engineering) formulas. Also studied are the principal means of
actuation/sensing and their integration into the overall microsystem. Various
examples of MEMS are studied in order to better illustrate the presentation of
the different modeling principles and algorithms.
Through its objective, approach and scope, this book offers a novel
and systematic insight into the MEMS domain and complements existing
work in the literature addressing part of the material developed herein.
Essentially, this book provides a database of stiffness/compliance models for
various spring-type flexible connectors that transmit the mechanical motion in
MEMS, as well as of the various forces/moments that are involved in
microtransduction. In order to predict their final state, the microsystems are
characterized by formulating, solving and analyzing the static equilibrium
equations, which incorporate spring, actuation and sensing effects.
Chapter 1 gives a succinct, yet comprehensive review of the main
tools enabling stiffness/compliance characterization of MEMS as it lays the
foundation of further developments in this book. Included are basic topics
from mechanics of materials and statics such as load-deformation, stress-
strain or structural members. Presented are the Castigliano’s theorems as basic
tools in stiffness/compliance calculation. Straight and curved line elements
are studied by explicitly formulating their compliance/stiffness characteristics.
Composite micromembers, such as sandwiched, serial, parallel, and hybrid
(serial-parallel) are also treated in detail, as well as thin plates and shells. All
the theoretical apparatus presented in this chapter is illustrated with examples
of MEMS designs.
Chapter 2 is dedicated to characterizing the main flexible components
that are encountered in MEMS and which enable mechanical mobility through