According to the opinion of some experts, a transducer is a device which transforms non-electrical energy into electrical energy or vice versa. Another definition of this term transducer is a device which transforms energy from one domain into another. Typical energy domains are mechanical, electrical, chemical, fluid, and thermal. A transducer can be defined also as a device which transforms energy from one type to another, even if both energy types are in the same domain.

According to the above definitions, transducer is a device that converts a signal from one physical form to a corresponding signal having a different physical form. Therefore it is an energy converter. This means that the input signal always has energy or power.

Transducers may generally be divided into two class – Sensors, which monitor the system – Actuators, which impose a condition on a system. Sensors and actuators are comprehensive classes of transducers. Some transducers can operate as a sensor or as a actuator, but not as both simultaneously.

Sensor examples: – Hotwire anemometers (measure flow velocity) – Microphones (measure fluid pressure) – Accelerometers (measure the acceleration of a structure) – Gas sensors (measure concentration of specific gas or gases) – Humidity sensor – Temperature sensors, etc

Actuator examples – Motors (which impose a torque) – Force heads (which impose a force) – Pumps (which impose either a pressure or a fluid velocity).

Any device converting signal of one kind to signal of a different kind is considered to be a transducer. The output signals can be of any useful physical form. The transducer can be placed as input transducer or output transducer. An input transducer converts physical signal to electric signal while an output transducer converts electric signal to physical signal.

 Another name of input and output transducers are sensor and actuator. Sensor is used to refer to the input transducer while actuator refers to the output transducer. Sensors are intended to acquire information, usually designed to handle low power and intended to consume energy as low as possible. Actuators are designed to power conversion and to handle (relatively) high power.

According to the opinion of some experts, a transducer is a device which transforms non-electrical energy into electrical energy or vice versa. Another definition of this term transducer is a device which transforms energy from one domain into another. Typical energy domains are mechanical, electrical, chemical, fluid, and thermal. A transducer can be defined also as a device which transforms energy from one type to another, even if both energy types are in the same domain.

According to the above definitions, transducer is a device that converts a signal from one physical form to a corresponding signal having a different physical form. Therefore it is an energy converter. This means that the input signal always has energy or power.

Transducers may generally be divided into two class – Sensors, which monitor the system – Actuators, which impose a condition on a system. Sensors and actuators are comprehensive classes of transducers. Some transducers can operate as a sensor or as a actuator, but not as both simultaneously.

Sensor examples: – Hotwire anemometers (measure flow velocity) – Microphones (measure fluid pressure) – Accelerometers (measure the acceleration of a structure) – Gas sensors (measure concentration of specific gas or gases) – Humidity sensor – Temperature sensors, etc

Actuator examples – Motors (which impose a torque) – Force heads (which impose a force) – Pumps (which impose either a pressure or a fluid velocity).

Any device converting signal of one kind to signal of a different kind is considered to be a transducer. The output signals can be of any useful physical form. The transducer can be placed as input transducer or output transducer. An input transducer converts physical signal to electric signal while an output transducer converts electric signal to physical signal.

 Another name of input and output transducers are sensor and actuator. Sensor is used to refer to the input transducer while actuator refers to the output transducer. Sensors are intended to acquire information, usually designed to handle low power and intended to consume energy as low as possible. Actuators are designed to power conversion and to handle (relatively) high power.

Hello Edson,

Many different books (and eventually authors) may express the terms transducers and sensors differently or similarly. But I would make a small attempt to clarify and hopefully simplify the terms.

Let's see the transducer first - the word transducer is derived from the process of transduction - where energy in one form is converted into another form, usually electrical. A transducer may require external or additional energy (power supply) to help/aid this process of transduction. Therefore a transducer acts as a source of energy no matter how small it is such as small voltage or current or for that matter say emf.

A sensor on the other hand changes its own (electrical) characteristics such as resistance, current etc.

Let's now compare a Thermocouple and a Thermistor.

A Thermocouple when exposed to temperature generates tiny thermoelectric emf or potential difference across its output.

But the thermistor on the other hand when exposed to the same temperature, would exhibit a change in resistor rather than generating any emf.

The Actuator can be regarded as another transducer, that most commonly, converts the electrical energy into mechanical energy including kinetic energy as a result of linear or angular motion.

As Jorge has stated above, a transducer acting in sensing application may require little energy (low external power) however, the transducer used as actuator requires high power such as electrical motors, solenoid valves, hydraulic or pneumatic cylinders etc.

I hope this clarifies your doubts.

Best wishes!

-Prasanna Waichal

Hi, Jorge and Prasana,

You are so helpful to clarify to me these terms: Jorge in terms of the translate of the definition for transducer (from latim, "transductore" - trans, ; tuctore, ), and Prasana in terms of energy.

In these way, for example an antena, it is a sensor ("a device that receives and responds to a signal or stimulus", as described in Fraden J.Handbook of Modern Sensors: Physics, Designs, and Applications 5th ed. Springer., 2016, p.1).

For some authors, however, transductor are defined as a dispositive that receives a signal and retransmite it, independent on the type of energy convertion. In this way, my doubt is: if we assume the definition "energy in one form is converted into another form" , how about a convertion in terms of the same type of energy? ( if it is possible).

Best wishes and I Thank you so much for your time!

Edson

In my opinion, this will depend of the definition that you are use for the term transducer.

Hello Edson,

Good to hear from you back again!

Well, if you talk specifically about antenna, then it is not only a sensor but also an actuator!!!

It is well known in the RF field that a transmitting antenna is as good and effective as a receiving antenna or vice a versa.

Having said that, when we use a particular antenna with a receiver, it becomes a sensor converting EM radiations (or energy) into electrical energy. On the other hand, we can also connect the same antenna to a transmitter where it (antenna) acts as an actuator that converts the electrical energy (the amplified RF wave) into electromagnetic excitation of the free space.

Same case is with a piezo-crystal which can be used as both sensor and actuator at a given instance, but as Jorge has stated above, not simultaneously. The Piezo set in medical ultrasound imaging, the antennas in radar systems are few classic examples to state.

Have a nice time!

-Prasanna Waichal

Hi, Prasanna

Good to hear from you to!

In fact my doubt is in terms of the definition of biosensor (a sensor that incorporates a biological recognition element)... In this sense, this kind of reflexion came to me, i. e., the real definition for sensor, actuator and transducer!

In fact, by the IUPAC´s resolution from 2001, I am in agreement with all explanation here!

Your explanations also were so ilustrative for me.

Thank you for your time!

Have a nice day!

Edson

P.S.: In terms of the definition "a transducer is a device which transforms non-electrical energy into electrical energy or vice versa": all sensors are a transducer, but not every transducer is a sensor!!