What is the difference between sensor and transducer?

Question

What is the difference between sensor and transducer?

Answer 1

A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument

A transducer is a device, usually electrical, electronic, electro-mechanical, electromagnetic, photonic, or photovoltaic that converts one type of energy or physical attribute to another for various purposes including measurement or information transfer

Answer 2

The words 'sensor' and 'transducer' are both widely used in the description of measurement systems. The former is popular in the USA whereas the latter has been used in Europe for many years.

A dictionary definition of 'sensor' is `a device that detects a change in a physical stimulus and turns it into a signal which can be measured or recorded; a corresponding definition of 'transducer' is 'a device that transfers power from one system to another in the same or in the different form'.

A sensible distinction is to use 'sensor' for the sensing element itself and 'transducer' for the sensing element plus any associated circuitry. All transducers would thus contain a sensor and most (though not all) sensors would also be transducers.