Enhanced detection of nitrogen dioxide via combined heating and pulsed UV operation of indium oxide nano-octahedra.

Oriol Gonzalez,Xavier Vilanova,Eduard Llobet,Sergio Roso

doi:10.3762/bjnano.7.144

Abstract

We report on the use of combined heating and pulsed UV light activation of indium oxide gas sensors for enhancing their performance in the detection of nitrogen dioxide in air. Indium oxide nano-octahedra were synthesized at high temperature (900 °C) via vapour-phase transport and screen-printed onto alumina transducers that comprised interdigitated electrodes and a heating resistor. Compared to the standard, constant temperature operation of the sensor, mild heating (e.g., 100 °C) together with pulsed UV light irradiation employing a commercially available, 325 nm UV diode (square, 1 min period, 15 mA drive current signal), results in an up to 80-fold enhancement in sensitivity to nitrogen dioxide. Furthermore, this combined operation method allows for making savings in power consumption that range from 35% to over 80%. These results are achieved by exploiting the dynamics of sensor response under pulsed UV light, which convey important information for the quantitative analysis of nitrogen dioxide.

Highlights

Technological barriers related to sensor performance and power consumption are currently limiting the implementation of widely distributed, smart wireless sensor systems that can be deployed and remain in operation with no further human intervention
When a nitrogen dioxide molecule gets adsorbed on the indium oxide, it traps electronic charge from the conduction band of the nanomaterial, which results in an increase in the resistance of the sensor
At such a low operating temperature, most of the ionosorbed nitrogen dioxide molecules remain attached to the surface on indium oxide during the cleaning phases with dry air, which results in irreversible changes in sensor resistance

Summary

Introduction

Technological barriers related to sensor performance and power consumption are currently limiting the implementation of widely distributed, smart wireless sensor systems that can be deployed and remain in operation with no further human intervention. At such a low operating temperature, most of the ionosorbed nitrogen dioxide molecules remain attached to the surface on indium oxide during the cleaning phases with dry air, which results in irreversible changes in sensor resistance.

Results

Conclusion