Page 63 - The Mechatronics Handbook

5

An Introduction

to Micro- and

Nanotechnology

5.1 Introduction
The Physics of Scaling • General Mechanisms of
Electromechanical Transduction • Sensor and Actuator
Michael Goldfarb Transduction Characteristics
Vanderbilt University 5.2 Microactuators
Electrostatic Actuation • Electromagnetic Actuation
Alvin Strauss
5.3 Microsensors
Vanderbilt University
Strain • Pressure • Acceleration • Force • Angular Rate
Eric J. Barth Sensing (Gyroscopes)
Vanderbilt University 5.4 Nanomachines
5.1 Introduction

Originally arising from the development of processes for fabricating microelectronics, micro-scale devices
are typically classified according not only to their dimensional scale, but their composition and manu-
facture. Nanotechnology is generally considered as ranging from the smallest of these micro-scale devices
down to the assembly of individual molecules to form molecular devices. These two distinct yet over-
lapping fields of microelectromechanical systems (MEMS) and nanosystems or nanotechnology share a
common set of engineering design considerations unique from other more typical engineering systems.
Two major factors distinguish the existence, effectiveness, and development of micro-scale and nano-
scale transducers from those of conventional scale. The first is the physics of scaling and the second is
the suitability of manufacturing techniques and processes. The former is governed by the laws of physics
and is thus a fundamental factor, while the latter is related to the development of manufacturing
technology, which is a significant, though not fundamental, factor. Due to the combination of these
factors, effective micro-scale transducers can often not be constructed as geometrically scaled-down
versions of conventional-scale transducers.
The Physics of Scaling

The dominant forces that influence micro-scale devices are different from those that influence their
conventional-scale counterparts. This is because the size of a physical system bears a significant influence
on the physical phenomena that dictate the dynamic behavior of that system. For example, larger-scale
systems are influenced by inertial effects to a much greater extent than smaller-scale systems, while smaller
systems are influenced more by surface effects. As an example, consider small insects that can stand on
the surface of still water, supported only by surface tension. The same surface tension is present when

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