换能器是将一种形式的能量转化成另一种形式的器件。这些能量形式包括（但不限于）电能、机械能、电磁能（包含光能）、化学能、声能和热能。虽然“换能器”这一术语一般表示一种传感器，事实上任何能够转化能量的器件都可以被认为是一种换能器。换能器被广泛用于测量仪表中。

A transducer is a device that converts one form of energy to another. Usually a transducer converts a signal in one form of energy to a signal in another.

Transducers are often employed at the boundaries of automation, measurement, and control systems, where electrical signals are converted to and from other physical quantities (energy, force, torque, light, motion, position, etc.). The process of converting one form of energy to another is known as transduction.