TABLE OF CONTENTS The terms sensor and transducer are generally considered to be interchangeable. They refer to devices that convert physical or chemical variables into electrical signals or, in some instances, convert an electrical signal back to a physical quantity. However, instrumentation specialists consider the term sensor to be more comprehensive and not limited to the conversion of physical quantities. Examples include the conversion of chemical concentrations and composition into a numerical value.
In this section a sensor is defined as a device capable of sensing changes in magnitude of some physical or chemical variable such as frequency, radiation, heat, pressure, or salinity and responding with a proportional electrical output. By contrast, a transducer is any device that converts energy in one form into energy in another form.
A sensor can transmit information, initiate a change, or actuate a switch. That output can control some function directly or be converted and measured to provide accurate measurements of a variable. Sensors can act as interfaces between the physical world and electronics, making it possible for electronic circuitry to "see," "hear," "smell," "taste," and "touch." They are essential for many process and machine controls and measurement systems.
Sensors are in home appliances, office equipment, food and chemical process lines, machine tools, and instruments in ships, aircraft, and automobiles. They are required in telecommunications equipment, computers, robots, and many different scientific and medical instruments. Demand for sensors has grown because of the increasing sophistication of existing instruments and their applications...
