Magnesium chromate–TiO2 spinel tape cast thick film as humidity sensor

Impedance characteristics of carbon nitride films for humidity sensors

“…However, organic humidity sensors have some disadvantages such as low operating temperature, low long-term stability and swelling. Carbon nitride humidity sensor has higher linearity than other humidity sensors based on inorganic materials which have a high sensitivity at low humidity range and a low sensitivity at high humidity [15,16]. When water molecules adsorb on carbon nitride film, the hydrogen attack in carbon nitride film could easily break the C N and C N bonds and form C H and N H bonds [9].…”

Humidity sensor based on Ga2O3 nanorods doped with Na+ and K+ from GaN powder

“…Generally, response time and recovery time are defined as the time taken to reach 90% of the total impedance change [34] . The response time is about 6 s and the recovery time is about 21 s. The recovery time is much longer than response time, indicating that the water vapor adsorption is endothermic process, and it will take a longer time to desorb from the sensor membrane [35] .…”

Humidity sensor based on electrospun (Na0.5Bi0.5)0.94TiO3–Ba0.06TiO3 nanofibers

“…With increasing the RH (75%, 85%, and 95%), more and more water molecules are adsorbed, and the leak conduction is appeared [38]. The capacitance C can be represented by using the following expression [39]:…”

“…Generally, the time taken by a sensor to reach 90% of the total impedance change is defined as the response time or recovery time [40]. The response time (as the humidity changes from 11% to 95% RH) is about 2 s and the recovery time (as the humidity changes from 95% to 11% RH) is about 50 s. The adsorption and desorption processes of water vapor are corresponding to the exothermic and endothermic processes, and the endothermic speed is slower than exothermic speed [39]. Hence, the recovery time was longer than the response time.…”