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

A new type of highly sensitive ozone (O₃) metal oxide gas sensor has been developed. Various mixtures of ln₂O₃, 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 varied from 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 O₃ 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 (200degC-600degC). 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.