Development of novel room temperature ozone sensors for health and safety applications

Abstract

A new type of highly sensitive ozone (03) metal oxide gas sensor has been developed. Various mixtures of In203, ZnO and SnO2 were deposited on alumina substrates containing indigitated electrodes by means of Vacuum Thermal Evaporation (VTE). Deposition rate of the sensing layer was variedfrom 0.3 nm/s -1.4 nm/s. The highest sensitivity of the sensors was found at a deposition rate of 1.2 nm/s -1.4 nm/s. In addition the 03 sensors were found to perform best with a 40 nm thick sensing layer. With such sensors, environmentally relevant ozone concentrations can be measured (0 -500 ppb (parts per billion)). Different combinations of this material were investigated and compared focusing on the sensitivity and performance when exposed to ozone. Most of the current metal oxide ozone sensors on the market have the disadvantage of requiring operation at elevated temperatures (200°C -600°C) [1]. Room temperature operation has some major advantages over elevated temperature operation such as, reduced fabrication costs, reduced operating costs, as well as ease of implementation into portable/handheld devices.

Fundamental Review to Ozone Gas Sensing Using Optical Fibre Sensors

“…Absorption of light by a molecule at a given frequency is caused by electron resonance at that given frequency [5,30]. Light absorption by ozone gas in ultra violet (UV) region (200 to 400 nm, 6.2 to 3.0 electron volt ((eV)) as well as in the visible region (400 to 780 nm, 3.1 to 1.6eV) of the light spectrum [5,31] is caused by excitation of valence electrons in the atoms of molecules. Light absorption in microwave region (0.3 to 300 cm,) is due to a change in rotation of the bonds in a molecule.…”