A High-Sensitivity Ionization Humidity Sensor Based on Carbon Nanotubes

Monitoring relative humidity accurately is essential for health, comfort, agriculture, food processing, storage, and making electronics. Because of this, it is imperative to know how much water is in different situations and materials in a precise and reliable way. Carbon materials have gained interest in humidity sensing due to their diverse surface chemistry and structural design abilities. Here, a new ionization relative humidity sensor was proposed. It had a carbon nanotube cathode, an extracting electrode, and a collecting electrode. The sensitive mechanism of the humidity sensor is studied based on how water vapor reacts when it collides with ions. The results show that the three-electrode sensor is much more sensitive than the two-electrode, resonant, resistive, and capacitive ionization-based relative humidity sensors. At the same time, the three-electrode humidity sensor has the widest range of detection of all the humidity sensors. At a 90V extraction voltage, single-value sensitive characteristics were obtained in the range of 25–100% RH in nitrogen (N 2 ) and 30–100% RH in air. The maximum sensitivity is 381.67% RH − 1 and 11.83% RH − 1 , respectively. Furthermore, the remarkable consistency indicates broad application possibilities of the three-electrode humidity sensor.