Sensors

An electronic sensor detects and measures a physical phenomenon, such as temperature, pressure, force, or acceleration, and provides a corresponding output signal, usually in the form of an electrical, mechanical, magnetic, etc. The actuating unit consists of an actuator and optionally a power supply and a coupling mechanism. Sensors and actuators are broadly termed as transducer devices which convert one form of energy into another form of energy.

Furthermore, sensors are classified as analog or digital based on the type of output signal. Analogue sensors produce a continuous output signal or voltage which is generally proportional to the quantity being measured. Physical quantities such as Temperature, Speed, Pressure, Displacement, Strain etc are all analogue quantities as they tend to be continuous in nature. Microcontroller are used to sense the analog signals, sometimes high resolution ADC’s are interfaced externally to get precision and accuracy (where microcontroller does not supports) and do the required processing and send the output.

Digital Sensors produce a discrete digital output signals or voltages that are a digital representation of the quantity being measured. Digital sensors produce a binary output signal in the form of logic “1” or logic “0”. Compared to analogue signals, digital signals or quantities have very high accuracies and can be both measured and “sampled” at a very high clock speed. The accuracy of the digital signal is proportional to the number of bits used to represent the measured quantity.

There are various types of sensors that are classified by their measurement objectives. Linear/Rotational sensors, Acceleration sensors, Force torque and pressure sensor, Flow sensors, Temperature sensors, Proximity sensors, Light sensors, Smart material sensors, Micro- and Nano-sensors, Level sensors, Ultrasonic Sensor, Vibration Sensor. Sensors can also be classified as passive or active, In passive sensors the power required to produce the output is provided by the sensed physical phenomenon itself (such as a thermometer) whereas the active sensors require external power source (such as a strain gage).