Sensors

Sensors 

The sensor is a structurally isolated primary measuring transducer from which the signals of the measuring information come from (it "gives" information).

Notes: The sensor can be removed at a considerable distance from the measuring instrument that receives its signals. In the field of measurements of ionizing radiation, the term detector is used.

Example: Sensors of a launched meteorological radiosonde transmit measurement information about temperature, pressure, humidity and other atmospheric parameters.

Sensor:

What is it? 

The term "sensor" in the general case means a cheap but reliable receiver and converter of a measurable quantity, which has moderate accuracy and is suitable for serial production.
By definition, to the sensors all the main nodes of the electronic circuit for measuring non-electric quantities, located directly at the object. The need to convert the measured non-electric quantity into an adequate electrical signal later served as the basis for the introduction of the term "measuring transducer", recommended by the state system for ensuring the uniformity of measurements instead of the term "sensor".

Sensors are measuring instruments containing not only primary transducers, but also elements of measuring circuits in which these transducers are included (amplifiers, functional transducers, interface devices with subsequent measuring and automation tools). Currently, sensors are implemented on the basis of various physical phenomena and various technologies. This makes it possible to make them both multifunctional, that is, providing, through a single sensor, the conversion of many physical quantities, and "intelligent", allowing you to identify when converting a certain magnitude of the influence of other quantities that distort the result of the conversion.
The values ​​of these quantities, converted to electric, can be used to correct the result of measurement of the measured value. For example, when measuring pressure, a significant influence is exerted by a change in the temperature of the medium in which this pressure is measured. Therefore, if there is a pressure sensor that, under certain conditions, also converts temperature, the measurement result of the latter being used to correct the pressure measurement result, there is not only multifunctionality, but also completely new sensor properties, in particular the self-correction property, that is, it " intellectualization.

The technical means with normalized metrological characteristics, which is used to convert the measured value into another value or a measuring signal, convenient for processing, storage, further transformations, indication or transmission, is called a measuring transducer. A measuring transducer directly affected by a measured physical quantity, i.e. the first transducer of the measuring circuit (channel) of the measuring instrument is referred to as a primary measuring transducer or a simple primary transducer. Primary transducers can be integrated into a measuring device or measuring device, as well as structurally isolated. In the latter case, it is recommended to call such a primary converter a sensor (since it allegedly receives measuring signals from it, that is, it “gives” information).
The fate of this term is quite “dramatic”. Not only that, in a number of applications it is referred to (by the way, as well as the primary converter!) As a sensor, then a detector, or simply a sensitive element.  In recent years, the ban has been lifted, the term “sensor” has been recognized as metrologically sound, and it is stipulated that it can be carried out at a considerable distance from the measuring instrument that receives its signals.
A sensor is an element of a measuring device that converts a controlled quantity (temperature, pressure, power, flow, displacement, humidity, speed, etc.) into a signal convenient for recording, transmission, storage, and exposure to controlled processes. For temperature control, temperature sensors are used,

resistance thermometers, thermocouples, thermistors, bimetallic and dilatometric thermometers. 

for pressure control - various pressure gauges; consumption - flow meters; displacements - induction, rheostatic, capacitive, radiophysical sensors.

 speeds - tachometers (tachogenerators), 

amounts of electric energy - counters, voltmeters and ammeters;
frequencies - frequency meters.

humidity - electric, radioactive, superhigh-frequency and other moisture meters. 

sensor is a device that, when exposed to a physical measured quantity, produces an equivalent signal, usually of an electrical nature (charge, current, voltage or impedance), which is a function of the measured quantity: s = F (m).

Here s is the output value of the sensor, and m is the input value. By measuring the value of s, one can thereby determine the value of m. The ratio s = F (m) expresses in a general theoretical form the physical laws underlying the operation of the sensors.
Being expressed numerically, these laws determine the choice of structures (geometry and dimensions) and materials for their manufacture, acceptable environmental characteristics under which the sensors can operate, and application conditions.
 

A sensor is a device that receives a measured parameter and generates an appropriate signal in order to transmit it for future use or recording.

Often in the technical literature the concepts of sensors and measuring transducers are not shared and measuring transducers are simply called sensors. Although from the functional point of view the concepts of the measuring transducer and the sensor are the same, in design practice, the sensor should be understood as a primary measuring transducer enclosed in a housing and equipped with devices for its installation and fixation on the object, as well as a cable for signal transmission and corresponding connectors.

Thus, a measurement transformation is a reflection of one physical quantity using another physical quantity or a set of such physical quantities. The sensor that performs the measurement conversion works in real production conditions, often very difficult, associated with high pressures and temperatures under the influence of aggressive environments.

The sensor is simultaneously affected by a large number of parameters. Among these parameters, only one is a measurable quantity, and all the rest are external parameters characterizing the production environment. These external parameters are in this case interference.

Each sensor should, against the background of interference, respond best to the measured input quantity by generating an appropriate output quantity or code for the output quantity.