Page 100 - An Introduction to Microelectromechanical Systems Engineering

CHAPTER 4
MEM Structures and Systems in Industrial

and Automotive Applications

“…for I believe that his device had tremendous advantages and unless there be other
systems of equal merits which are unknown to me, I am of the opinion that he has
the most remarkable system in existence.”
—David Sarnoff on E. Howard Armstrong’s radio receiver, 1914.
Quoted in the Empire of the Air, by Tom Lewis.

Armed with an understanding of the fabrication methods, it is time to examine vari-
ous types of microelectromechanical (MEM) structures and systems. It is apparent
that with a vast and diverse set of fabrication tools, creativity abounds. Indeed, the
list of MEM structures and devices continues to grow daily as more applications
prove to benefit from miniaturization. But just as necessity is mother of all
inventions, it is economics that ultimately determine the commercial success of a
particular design or technology. Demonstrations of micromachined devices are
innumerable, but the successful products are few. MEMS technology is only a
means to achieve a solution for a particular application. A quest for its perfection
should not entail an oversight of the end objective: the application itself.
The next four chapters review a select set of MEMS-based commercial products
with applications in multiple diverse markets. This chapter is specific to those prod-
ucts with utility in industrial and automotive applications. It also includes a short
introduction on the general methodology of the design process and a listing of com-
monly used sensing and actuation techniques. The following three chapters address
products for optical, life sciences, and RF electronic applications.
Three general categories form the total extent of MEMS: sensors, actuators, and
passive structures. Sensors are transducers that convert mechanical, thermal, or
other forms of energy into electrical energy; actuators do the exact opposite. Passive
structures include devices where no transducing occurs, including both mechanical
and optical components. A complete listing of all MEMS demonstrations is not
sought in this book; rather, the theme is to illustrate the state of the technology by
providing sufficient examples of structures and systems that have proven their com-
mercial viability or show promise to do so in the near future.

General Design Methodology

Starting with a list of specifications for the MEM device or system, the design
process begins with the identification of the general operating principles and overall

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