Sensors are the key to life and survival - and to the success of modern technology. Nature has provided living creatures with a wealth of sensors for a variety of measurands, such as light, sound, temperature, speed, motion, distance, force, pressure, acceleration, odor and so on - sensors, whose performance and specifications have often not been matched yet by man-made devices. Even at today's high level of electronics and information technology, sensors remain the crucial and decisive interface needed to reliably relate phenomena occurring in the environment to corresponding electric signals that can be processed to obtain the desired information and subsequent correct reaction of systems. Although the literature on sensors is extremely vast, there is one type of sensors which so far has received little attention: the piezoelectric sensor. Certainly, most handbooks on measurement mention briefly this type of sensor yet there is not a single book in the English language dedicated entirelyto piezoelectric sensors and giving a reasonably complete overview. There are only the books by [Gohlke 1955 and 1959] and [Tichy and Gautschi 1980], all in German.