The DHT11 sensor is a basic, ultralow-cost digital temperature and humidity sensor. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air. The sensor provides humidity values in percentage of relative humidity (20 to 90% RH) and temperature values in degrees Celsius (0 to 50 °C).

The temperature measurement is carried out by a thermistor, a type of resistor whose resistance changes significantly with temperature. The DHT11 measures the resistance of the thermistor and converts it into temperature data.

For humidity, the DHT11 uses a capacitive humidity sensor. Capacitive humidity sensors measure relative humidity by placing a thin strip of metal oxide between two electrodes. The metal oxide’s electrical capacity changes with the atmosphere’s humidity levels and these changes are converted into humidity readings.

The sensor gives a calibrated digital signal output of the temperature and humidity measurements, which can be easily read using a microcontroller.

In terms of applications, this sensor is utilized in various areas such as measuring humidity and temperature values in heating, ventilation, and air conditioning systems, weather stations, home automation systems, and more.

Find more information: How to Connect DHT11 Sensor With an Arduino