sensor

A sensor or a sensor or a receptor is a physical system, technical device or, in a broader sense, also a biological organ, reacting to changes in the measured quantity (physical, chemical) immediately, or reacting to the time course of the change.

The most common sensors are electrical, transforming information about the measured quantity into another physical area, most often into an electrical signal or an electrical parameter. They enable the transformation of a non-electric quantity into electrical signals.

The use
Nowadays, sensors are used in practically all kinds of industrial products and systems, as well as in process automation, measurement and regulation. A few examples: medicine and medical devices, industry and manufacturing, robotics, consumer electronics, household products, vehicles, automobiles, manufacturing, agriculture and food.

Basic characteristics of sensors
unambiguity - each value of the measured quantity corresponds to exactly one value of the output quantity
unambiguous dependence of the output value on the input value (linear, logarithmic)
sensitivity - the value of the change in the measured quantity at which a noticeable change in the output quantity still occurs
inertia - time delay of the output signal after a change in the input quantity
constancy - the sensor data does not change if the input quantity does not change
operational reliability, accuracy, easy maintenance.
nonlinearity and hysteresis
resolution
allowed error
zero shift and drift,
noise,
response time,
frequency characteristic.
Overview
Most sensors are electrical or electronic, although there are other types. Sensors are a type of transducer. Sensors either directly display values (e.g. mercury thermometers) or are connected to an indicator (they can also be indirect, e.g. through an analog or digital converter, or a computer and display) so that they are human-readable. Technical processes make it possible to produce more and more sensors with MEMS technology. In most cases, this increases the possibility of increasing sensitivity.

Development
The world market for sensors is growing dynamically. There are more than a hundred thousand different types of sensors on the market in Europe. This figure illustrates the wide range of uses of sensors, as well as the fact that selecting a sensor for a specific application is not an easy task. A certain reason for increasing interest in sensors is the miniaturization of these devices. The constant progress in the development of technologies compatible with information technologies is responsible for this trend. Currently, sensors based on silicon or similar technology are available for almost every quantity, and there is still room for development in this area.

Division
Since the essential change involves the exchange of energies, we can divide the sensors according to what kind of energy they transfer or detect. According to the input measured quantity, we reclassify sensors of mechanical, thermal, acoustic, magnetic, light, electrical quantities, nuclear radiation, etc. and the corresponding sensors:

distance - measures the length of a straight line between two defined points
position - measures the coordinates of the specified point of the object in the specified reference
system

displacement - measures the change in position in relation to the reference point,
proximity - detects the sign (positive or negative) of the linear distance between
an object point and a fixed reference point,

level gauge - measures the distance to the top of the liquid or bulk substance in the tank
with respect to the specified horizontal reference surface,

protractor - measures the rotation angle with respect to the reference position,
inclinometer - measures the angle with respect to the perpendicular to the ground,
tachometer - measures peripheral speed,
vibration sensor - measures the movement of a vibrating object, expressed as displacement, speed or
acceleration,

accelerometer - measures acceleration.
Force sensors and similar quantities include:

pressure sensor - measures the pressure difference with respect to the vacuum or to the reference pressure (overpressure or underpressure),
force sensor - measures normal or shear force
torque sensor - measures torque,
strain gauge - measures linear proportional elongation
the tactile sensor measures the effect of touch,
matrix tactile - measures the distribution of normal or shear forces
According to the electrical output signal, we divide the sensors into:

active - under the influence of an input quantity, they behave as a source of electrical energy: induction, thermoelectric, photoelectric, piezoelectric sensors
passive - parametric - any of the sensor parameters changes due to the action of the input quantity: resistance, inductance, capacitance
According to the physical principle used:

dilatory
deformation
piezoelectric
thermoelectric
photoelectric
Hall