Temperature sensors are devices designed to measure temperature and convert this measurement into an electrical signal.


Several types of temperature sensors, each with its own principles of operation, accuracy, and
applications:

â–ª Thermocouples: 
These sensors work on the principle, where a voltage is generated when two different metals are joined at two junctions and subjected to different temperature.



â–ª RTDs (Resistance Temperature Detectors): 
RTDs use the principle that the electrical resistance of certain metals or alloys changes predictably with temperature.




â–ª Thermistors: 
These are temperature-sensitive resistors made of semiconductor materials. They have a higher sensitivity to temperature changes compared to RTDs but might have a more limited temperature range and stability.



Digital Temperature and Humidity Sensor - DHT Series (DHT11, DHT22)

"DHT" stands for "Digital Humidity and Temperature".



Humidity Sensing:

• Sensor has moisture-sensitive substrate with a thin-film capacitor.
• Changes in humidity cause the substrate to absorb or release moisture, altering the capacitance of the substrate.
• Change in capacitance is then converted into an electrical signal.


Temperature Sensing:

• Sensors also incorporate a thermistor, a type of resistor whose resistance changes with temperature.
• By measuring the resistance of the thermistor, the sensor determines the ambient temperature.