Highly-sensitive potassium-tantalum-niobium oxide humidity sensor

• Published in: Sensors and actuators. A. Physical. 2019-08, Vol.295, p.133-140
• Main Authors: Ravikant, Singh, Sheshamani, Gupta, Gaurav, Yadav, Sanjay, Dubey, P.K., Ojha, V.N., Kumar, Ashok
• Format: Article
• Language: English
• Subjects: Configurations; Displays; Ferroelectric materials; Ferroelectricity; Ferroelectrics; Humidity; Humidity sensor; Niobium oxides; Polarity; Potassium; Relative humidity; Reproducibility; Resistance; Sensitivity; Sensors; Water vapor
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2019.05.023

Bulk polar resistive humidity sensor with giant sensitivity (˜ 4600), large current hysteresis under small bias electric field, and many order of change in current/resistance in the range of relative humidity from 15% to 95% [Display omitted] •A novel low cost polar resistive humidity sensor with a giant sensitive and long-term reproducibility.•The resistance of the sensor varies from GΩ to kΩ with a change in humidity from 15% to 95%.•An abrupt change in humidity sensing current with a change in polarity of bias voltage.•A digital display unit along with electronic circuitry developed to show the relative humidity. We report moisture sensitive properties of ferroelectric niobium-rich potassium tantalate KTa0.2 Nb0.80.99Mn0.01O3 (KTN) which shows giant humidity response with excellent reproducibility and repeatability of data as a function of exposure time and humidity contents. Many fold change in resistance was observed with change in the relative humidity (Rh) from 15% to 95% which provides maximum sensitivity (˜ 4600) at 298 K in the presence of Rh 95%. It also shows polarity dependent change in resistance with nearly 310 to 513 mV in-built potential depending on the device configuration. The polar KTN humidity sensor shows a decrease in resistance with an increase in Rh% which favors the Grotthuss mechanism responsible for humidity effects. To improve the sensitivity, a particular device configuration has implemented for the homogeneous interaction of the water vapor molecule with a maximum active sensor-surface area. The electronics with the digital display unit was designed and developed to represent the relative humidity in the form of digital display.