NANODEV Research Group

Humidity Sensors

The demand for highly effective humidity sensors has become ascending in domestic environment with rapid development of society as; automobile industry, medical field, agriculture, etc. The aim of this study is to achieve resistance-type humidity sensor by using zeolites and zeo-type materials due to their well-defined porous structure, moisture holding capacity and ionic conduction properties. First, nano-sized Engelhard titanosilicate (ETS-10) and Y type Faujasite were synthesized. Then, gold electrode printed borosilicate glass substrate were coated with synthesized ETS-10 and zeolite Y crystals by using spin-coating method. To test thin films as a humidity sensor, saturated salt solutions were prepared.  The saturated salt solutions of lithium chloride, magnesium chloride, magnesium nitrate, sodium chloride, potassium chloride, potassium nitrate and  potassium sulfate were prepared to obtain relative  humidity  (%  RH)  of  % 11.30 ± 0.27, 32.78 ± 0.16, 52.89 ± 0.22, 75.29 ± 0.12, 84.34 ± 0.26, 93.58 ± 0.55, and 97.30 ± 0.45 at 25 °C, respectively. A homemade system was designed to attach the thin films to the cap of closed vessel of saturated salt solutions. The conductivity measurements were carried out by using impedance spectroscopy at each % relative humidity environment. The results showed that stable, sensitive, and cheap resistive  type humidity sensors that  operate  in wide  range of  % relative humidity values can be designed by using titanosilicate ETS-10 and Y type Faujasite films prepared via spin coating method.