Abstract :
Summary form only. Sensors are devices or systems that yield an electrical output from a physical or chemical quantity. Sensors rely on materials whose properties depend on the sensed quantity or on geometry changes produced by that quantity. Sensor development used to follow demands from process control, particularly from mid 20th century. Early industrial sensors were but a robust implementation of contrivances used in experimental science since the last decades of the 19th century, and were based on physical laws discovered at that time. Those macrosensors (potentiometers, RTDs, LVDTs, and thermocouples) were labor-intensive to manufacture, bulky, and heavy, often used expensive materials, and their installation and maintenance costs were high. Sensor evolution is currently fostered by applications that place sensors in products, packages and our environment. Sensors developed for specific markets often create unexpected markets. Progress in sensors is clearly reflected in their lower cost and their improved performance, namely, better sensitivity, higher accuracy, wider measurement range, low susceptibility to interference and higher reliability. This progress has been enabled by materials and IC manufacturing technology, and benefits from both classical and novel sensing principles. MEMS, ceramics, thin films, organic polymers, and fiber optics have yielded sensors that are both displacing legacy sensors and opening new application areas formerly out from our reach. The increasing number of sensors used in a variety of applications would not be feasible without the availability of electronic interfaces able to integrate them in systems controlled by a digital processor.
