Abstract:

The effect of metal (Ti, Ni, and Au) electrodes on humidity sensing properties of electrospun TiO₂ nanofibers was investigated in this work. The devices were fabricated by evaporating metal contacts on SiO₂ layer thermally grown on silicon substrate. The separation between the electrodes was 90 μm for all sensors. The sensors were tested from 40% to 90% relative humidity (RH) by AC electrical characterization at room temperature. When sensors are switched between 40% and 90% RH, the corresponding response and recovery time are 3 s and 5 s for Ti-electrode sensor, 4 s and 7 s for Ni-electrode sensor, and 7 s and 13 s for Au-electrode sensor. The hysteresis was 3%, 5% and 15% for Ti-, Ni-, and Au-electrode sensor, respectively. The sensitivity of Ti, Ni, and Au-electrode sensors are 7.53 MΩ/%RH, 5.29 MΩ/%RH and 4.01 MΩ/%RH respectively at 100 Hz. Therefore Ti-electrode sensor is found to have linear response, fast response and recovery time and higher sensitivity as compared with those of Ni- and Au-electrode sensors. Comparison of humidity sensing properties of sensors with different electrode material may propose a compelling route for designing and optimizing humidity sensors.

Key words: Titanium dioxide, Nano?bers, Metal electrodes, Humidity sensor