Sensors ubiquitously surround human existence. Deeply embedded into the fabrics of everyday life in systems–consumer electronics, civil and medical infrastructure, cars, homes, business and office buildings, and smart phones–they gather a vast amount of useful information that can be used for various purposes. Providing an exhaustive review of the applications of sensors is beyond the scope of this chapter. Instead, it focuses on a handful of emerging applications that use ubiquitous (wireless) sensing and can be considered representative of both the opportunities and challenges associated with ubiquitous sensing. These applications are:
- civil infrastructure monitoring
- medical diagnosis and monitoring
- water-quality monitoring.
The idea is to illustrate the diversity of sensing, the novelty of the applications, and the various design issues and challenges that have to be dealt with when designing, developing, and deploying sensors.
2.1 Civil Infrastructure Monitoring
In civil infrastructure monitoring, accelerometers, gyroscopes, tilt sensors, and piezoresistive sensors have been widely employed to measure the response of bridges and buildings to ambient and forced excitations. Ambient excitations are produced by natural causes such as earthquakes, wind, or the movement of cars, whereas forced excitations are intentionally produced by impact hammers and shakers or by placing bumpers on bridges to determine the response of a structure. Tilt sensors, gyroscopes, ...