Measurement Systems for Non-Electrical Quantities

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. For example, a mercury thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass tube. A thermocouple converts temperature to an output voltage which can be read by a voltmeter. For accuracy, all sensors need to be calibrated against known standards. Sensors are used everywhere such as touch sensitive mobile phones, laptop's touch pad, touch controller light, etc. Examples of daily applications are in the field of medicine, machines, cars, aerospace, robotics and manufacturing plants. Sensors are selected based on the requirement and the sensitivity. The sensitivity of the sensors is the change of sensor's output when the measured quantity changes. To measure very small changes, the sensors should have very high sensitivity. 

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 (generally electrical or mechanical) for various measurement purposes including measurement or information transfer (for example, pressure sensors). The term transducer is commonly used in two senses; the sensor, used to detect a parameter in one form and report it in another (usually an electrical or digital signal), and the audio loudspeaker, which converts electrical voltage variations representing music or speech to mechanical cone vibration and hence vibrates air molecules creating sound

TYPICAL SENSOR APPLICATIONS

 APPLICATIONS OF TRANSDUCER

The following are the application of the transducers.

1. It is used for detecting the movement of muscles which is called an acceleromyograph.
2. The transducer measures the load on the engines.
3. It is used as a sensor for knowing the engine knock.
4. The transducers measure the pressure of the gas and liquid by converting it into an electrical signal.
5. It converts the temperature of the devices into an electrical signal or mechanical work.
6. The transducer is used in the ultrasound machine. It receives the sound waves of the patient by emitting their sound waves and pass the signal to the CPU.
7. The transducer is used in the speaker for converting the electrical signal into acoustic sound.
8. It is used in the antenna for converting the electromagnetic waves into an electrical signal.