Abstract
Relative humidity (RH) sensing properties of zinc oxide nanofibers (ZNF), synthesized using electrospinning technique, were studied by impedance spectroscopy. RH sensors were fabricated with two different electrodes (Au and Ni) using lithography on top of the nanofibers deposited on Si/SiO2 substrate. Compare with the Ni electrode sensor, Au electrode sensor exhibits larger sensitivity and quicker response/recovery. Capacitance, electrical conductivity and electrical modulus were studied at 40%-90% RH as a function of the frequency of the applied AC signal in the frequency range of 10−2-106 Hz. The corresponding response and recovery times are 3s and 5s for Au, and 6s and 10s for Ni electrode sensor, respectively. The sensors exhibited a reversible response with small hysteresis of less than 4% and 12% for Au and Ni electrodes respectively. Stability of the sensor device with Au electrode was confirmed by testing the device for 13 days. The excellent sensing characteristics and comparison of sensors with different electrode materials may offer an effective route for designing and optimizing RH sensors.
Highlights
Nanostructured materials have a significant importance for variety of applications due to their small size, high surface area to volume ratio, unique chemical and photoelectric properties.[1,2] Till variety of one dimensional nanostructured chemical sensors, transistors, ultraviolet detectors and solar cells have been reported.[3]
Relative humidity (RH) sensors were fabricated with two different electrodes (Au and Ni) using lithography on top of the nanofibers deposited on Si/SiO2 substrate
The sensors exhibited a reversible response with small hysteresis of less than 4% and 12% for Au and Ni electrodes respectively
Summary
Nanostructured materials have a significant importance for variety of applications due to their small size, high surface area to volume ratio, unique chemical and photoelectric properties.[1,2] Till variety of one dimensional nanostructured chemical sensors, transistors, ultraviolet detectors and solar cells have been reported.[3] One dimensional metal oxide nanostructures such as TiO2, In2O3, ZnO, WO3 and SnO2 have gained much attention due to their superior properties.[4]. The major applications of humidity sensors are agriculture, food, industrial, environmental and for manufacturing highly sophisticated integrated circuits in semiconducting industry.[5] Automatic control systems, reliable, cheap and sensitive humidity sensors operated at room temperatures are of significant interest these days.[6] In recent times, the sensors based on porous metal ceramic oxides have received much attention due to their chemical and physical stability.[7]
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