UV Effect on Indium Oxide Resistive Sensors

In this paper, electrospinning technique has been employed to synthesize In₂O₃/PVP (indium oxide/polyvinylpyrrolidone) composite fibers. The produced In₂O₃ fibers after annealing at 600 °C were investigated as sensitive layer in resistive sensors for monitoring NO₂ at low concentrations in air. By optimizing the spinning conditions and the subsequent annealing treatment, In₂O₃ fibers have been successfully obtained. The annealed samples have a high crystallization degree. Their sensing behavior towards nitrogen dioxide has been then tested both in the dark and under UV light. To analyze in detail the effect of UV radiation, sensing tests have been performed by using three different procedures: without UV illumination, under continuous UV illumination, and under pulsed UV illumination (provided only during the recovery time). It has been proved that the optimal sensing characteristics (higher sensibility and very shorter recovery time) of the sensor occur when the sample is irradiated with pulsed UV light.