Performance Of Humidity Sensor Research Articles

The influence of Fe 2O 3 in the humidity sensor performance of ZrO 2:TiO 2-based porous ceramics

ZrO 2:TiO 2 ceramics were prepared with different porosity values by two methods: (a) sintering at 1150, 1300 and 1500 °C, corresponding to the temperatures of the first, second and third sintering stages, according to dilatometry results; (b) adding Fe 2O 3 (2.0 and 5.0 mol%) to ZrO 2:TiO 2 powders before sintering. The ZrO 2:TiO 2 specimens were characterized by X-ray diffraction, mercury porosimetry, scanning electron microscopy and impedance spectroscopy. The impedance spectroscopy analysis was carried out under different relative humidities. The bulk electrical resistivity in the low frequency region (10–100 Hz) decreases for increasing relative humidity. Increasing the sintering temperature from the first to the third sintering stage promoted grain growth, as expected, with consequent decrease of the intergranular porosity. The use of Fe 2O 3 as sintering aid reduced the porosity of the specimens, but increased the electrical response under humid environments in comparison with specimens sintered without Fe 2O 3.

Impact of morphology on high-speed humidity sensor performance

Capacitive-based humidity sensors were fabricated using unique nanostructured aluminum-oxide thin films. These sensors exhibited extremely fast desorption response times as short as 42 ms. In this paper, we present the effects of varying the thin-film porosity on sensor performance. Specifically, we look at the capacitive response and the desorption response time of the sensors. It was found that increased porosity tends to decrease the desorption response time and increase the relative humidity where the devices become sensitive.

Performance of operational radiosonde humidity sensors in direct comparison with a chilled mirror dew‐point hygrometer and its climate implication

This study evaluates performance of humidity sensors in two widely used operational radiosondes, Vaisala and Sippican (formally VIZ), in comparison with a research quality, and potentially more accurate, chilled mirror dew‐point hygrometer named “Snow White”. A research radiosonde system carrying the Snow White (SW) hygrometer was deployed in the Oklahoma panhandle and at Dodge City, KS during the International H2O Project (IHOP_2002). A total of sixteen sondes were launched with either Vaisala RS80 or Sippican VIZ‐B2 radiosondes on the same balloons. Comparisons of humidity data from the SW with Vaisala and Sippican data show that (a) Vaisala RS80‐H agrees with the SW very well in the middle and lower troposphere, but has dry biases in the upper troposphere (UT), (b) Sippican carbon hygristor (CH) has time‐lag errors throughout the troposphere and fails to respond to humidity changes in the UT, sometimes even in the middle troposphere, and (c) the SW can detect cirrus clouds near the tropopause and possibly estimate their ice water content (IWC). The failure of CH in the UT results in significant and artificial humidity shifts in radiosonde climate records at stations where a transition from VIZ to Vaisala radiosondes has occurred.

Study and performance of humidity sensor based on the mechanical–optoelectronic principle for the measurement and control of humidity in storehouses

The humidity sensor unit based on the change in the contraction–expansion of black hair vs. humidity was transformed to the change in optoelectronic signal vs. humidity. The humidity measurement equipment based on this kind of sensor may automatically measure, display, store and control the environmental humidity values of the storehouse.

Application of porous glasses for humidity control

We have fabricated and investigated humidity sensors on the basis of silica porous glasses obtained by leaching of initial sodium-borosilicate glasses. Correlation between the performance of humidity sensors and size distribution of voids was revealed and investigated. We observed reproducible changes of electrical resistance three-four orders of magnitude for changes of humidity in the range from 20 to 98%. It was shown that fabricated humidity sensors can operate at temperatures as low as −20°C.