Handbook of Modern Sensors

Since publication of the previous, the 3rd edition of this book, the sensor technologies have made a remarkable leap ahead. The sensitivity of the sensors became
higher, the dimensions – smaller, the selectivity – better, and the prices – lower.
What have not changed, are the fundamental principles of the sensor design. They
still are governed by the laws of Nature. Arguably one of the greatest geniuses ever
lived, Leonardo Da Vinci had his own peculiar way of praying. It went like this,
“Oh Lord, thanks for Thou don’t violate Thy own laws.” It is comforting indeed that
the laws of Nature do not change with time, it is just that our appreciation of them
becomes refined. Thus, this new edition examines the same good old laws of Nature
that form the foundation for designs of various sensors. This has not changed much
since the previous editions. Yet, the sections that describe practical designs are
revised substantially. Recent ideas and developments have been added, while
obsolete and less important designs were dropped.
This book is about devices commonly called sensors. The invention of a
microprocessor has brought highly sophisticated instruments into our everyday
life. Numerous computerized appliances, of which microprocessors are integral
parts, wash clothes and prepare coffee, play music, guard homes, and control room
temperature. Sensors are essential components in any device that uses a digital
signal processor. The processor is a device that manipulates binary codes generally
represented by electric signals. Yet, we live in an analog world, where such devices
function among objects that are mostly not digital. Moreover, this world is generally
not electrical (apart from the atomic level). Digital systems, however complex and
intelligent they might be, must receive information from the outside world. Sensors
are the interface devices between various physical values and electronic circuits
that “understand” only a language of moving electrical charges. In other words,
sensors are eyes, ears, and noses of silicon chips.
In the course of my engineering work, I often felt a strong need for a book which
would combine practical information on diversified subjects related to the most
important physical principles, design and use of various sensors. Surely, I could
find almost all I had to know by surfing Internet or browsing library bookshelves
in search for texts on physics, electronics, technical magazines, manufacturer’s
catalogues and websites. However, the information is scattered over many publications, and almost every question I was pondering required substantial research
work. Little by little, I have been gathering practical information on everything,
which in anyway was related to various sensors and their applications to scientific
and engineering measurements. Soon, I realized that the information I collected
might be quite useful to more than one person. This idea prompted me to write this
book and this 4th edition is the proof that I was not mistaken.
In setting my criteria for selecting various sensors for the new edition, I
attempted to keep the scope of this book as broad as possible, opting for many
different designs described briefly (without being trivial, I hope), rather than fewer
treated in greater depth. This volume attempts (immodestly perhaps) to cover a very
broad range of sensors and detectors. Many of them are well known, but describing
them is still useful for students and those who look for a convenient reference. It is
the author’s intention to present a comprehensive and up-to-date account of the
theory (physical principles), design, and practical implementations of various
(especially, the newest) sensors for scientific, industrial, and consumer applications.
The topics included in the book reflect the author’s own preferences and interpretations. Some may find a description of a particular sensor either too detailed or too
broad or, on the contrary, too brief. In most cases, the author tried to strike a balance
between a detailed description and simplicity of coverage.
It is clear that one book cannot embrace the whole variety of sensors and their
applications, even if it would be called something like “The Encyclopedia of
Sensors.” This is a different book and the author’s task was much less ambitious.
Here, an attempt has been made to generate a reference text, which could be used by
students, researchers interested in modern instrumentation (applied physicists and
engineers), sensor designers, application engineers and technicians whose job is to
understand, select and/or design sensors for practical systems.
The prior editions of this book have been used quite extensively as desktop
references and textbooks for the related college courses. Comments and suggestions
from the sensor designers, professors, and students prompted me to implement
several changes and correct errors. I am deeply grateful to those who helped me to
make further improvements in this new edition. I owe a debt of gratitude and many
thanks to Drs. Ephraim Suhir and David Pintsov for assisting me in mathematical
treatment of transfer functions and to Drs. Todd E. Mlsna and Sanjay V. Patel for
their invaluable contribution to the chapter on chemical sensors.
Even though the book is intended for the scientific and engineering communities,
as a rule, technical descriptions and mathematic treatments do not require a
background beyond a high school curriculum. Simplicity of description and intuitive approach were the key requirements that I set for myself while working on the
manuscript. My true goal was not to pile up a collection of information but rather to
entice the reader into a creative process. As Plutarch said nearly two millennia ago,
“The mind is not a vessel to be filled but a fire to be kindled…”