When talking torque measurement, ‘analogue’ or ‘digital’ become hardly essential, being just a matter of approach to operation, and that it must be the actual physical principles which can be all-important.
Classification of sensors
In discussing sensing devices one has to decide if you should classify them in accordance with the physical property they normally use (like piezoelectric, photovoltaic, etc.) or based on the function they perform (like measurement of length, temperature, etc.). Within the former case one can present a reasonably integrated look at the sensing process, but it is a little disconcerting when one wishes to compare the merits of, say, two kinds of temperature sensors, if one has to examine separate sections on resistive, thermoelectric and semiconductor devices to help make the comparison.
Alternatively, to attempt to differentiate devices by function often is usually a relatively boring catalogue of numerous unrelated devices. The important thing about them is signals are transformed from a single form to a different. Additionally it is possible to discuss button load cell from your functional viewpoint, under headings like length, temperature, etc., appropriate for somebody who actually wants to select or use a sensor for a particular application rather than just read across the subject.
The phrase ‘sensors’ and ‘transducers’ are generally widely used within the description of measurement systems. The first kind is popular in the us whereas the second is more often used in Europe. The option of words in science is quite important. Lately there has been an inclination to coin new words or even to misuse (or misspell) existing words, and this might lead to considerable ambiguity and misunderstanding, and has a tendency to diminish the preciseness from the language. The challenge has become very apparent inside the computer and microprocessor areas, where preciseness is particularly important, and may seriously confuse persons entering the subject.
The word ‘sensor’ hails from sentire, meaning ‘to perceive’ and ‘transducer’ comes from transducere meaning ‘to lead across’. A dictionary definition Chambers Twentieth Century) of ‘sensor’ is ‘a device that detects a change in a physical stimulus and turns it right into a signal which can be measured or recorded’; a corresponding definition of ‘transducer’ is ‘a device that transfers power from one system to a different inside the same or even in different form’.
A sensible distinction is to apply ‘sensor’ for the sensing element itself, and ‘transducer’ for the sensing element plus any associated circuitry. For example, thermistors are sensors, because they respond to a stimulus (changes its resistance with temperature), but only become transducers when connected in a bridge circuit to convert alternation in resistance to alternation in voltage, considering that the complete circuit then transduces through the thermal towards the electrical domain. A solar cell is both a sensor as well as a transducer, as it responds to your stimulus (generates a current or voltage responding to radiation) as well as transducer from your radiant to the electrical domain. It can not require any associated circuitry, though in reality an amplifier would usually be utilized. All transducers thus hkjrzk a sensor, and lots of (though its not all) sensors will also be transducers.
The difference is pretty small, and the moment one actually uses a sensor (by applying capability to it) it might be weight sensor. An interesting classification of devices can be accomplished by thinking about the many forms of energy or signal transfer.
The phrase ‘actuate’ means ‘to placed into, or incite to, action’ and actuators are devices that make the display or observable output in a measurement system like a light-emitting diode (LED) or moving coil meter. They are obviously transducers used for output purposes, since they transduce in one domain to another (ie. electrical to radiant for LEDs).