When the humidity increases, the material absorbs water molecules, leading to an increase in refractive index. This change is detected by the optical fiber, allowing the sensor to measure humidity levels. Humidity plays a crucial role in various industries, including agriculture, healthcare, food processing, and electronics manufacturing. Accurate and. The measurement of relative humidity (RH) is an important part of heating, ventilation, air conditioning, and refrigeration (HVACR), which provides quality control in numerous aspects of daily life., paints/coatings, construction. DHT11 has two forms: sensor and module. DHT11 sensor has four pins: DHT11 module has three pins: Some manufacturers provide DHT11 sensor in module form with three pins: GND, VCC and DATA pins (or alternatively: -, +, and OUT pins). In sensor form, A resistor from 5K to 10K Ohms is required to keep.