Self-Heating of Top-Down Manufactured ITO Sensors for Accurately Monitoring ppb-Level O₃

Wafer-scale fabrication of high-performance metal oxide semiconductor (MOS) gas sensors, with good reproductivity/uniformity, is essential for their batch deployments as either selective sensors or smart electronic noses, but it remains a big challenge. In this work, we propose a top-down approach for manufacturing O₃ sensors from commercial indium tin oxide (ITO) glasses, which mainly involves laser patterning (etching) and Ar/H₂ plasma treatment. Increased surface roughness induced by Ar/H₂ plasma treatment (60 min) and localized heating (180 °C) via self-heating enable an exceptional O₃ sensing performance, including a drastically improved O₃ response, good selectivity, weak humidity interference and long-term stability. The present ITO sensor enables real-time precise monitoring of ambient O₃ from background-level ∼25 to 200 ppb, verified by the UV photometric ozone analyzer. Moreover, wafer-scale fabrication of sensor arrays with uniform O₃ sensing performance has been demonstrated, raising the hope of smart O₃ sensors for ambient ppb-level O₃ monitoring.