Flexible indium oxide gas sensors with enhanced sensitivity and room temperature operation via natural oxidation techniques

Indium oxide is a widely used transparent conductive oxide known for its excellent electrical conductivity and transparency. These properties make indium oxide suitable for various applications, such as lighting displays and chemical sensors, particularly for detecting toxic gases like NO₂ due to its high sensitivity to gas molecules. However, the inherent brittleness of indium oxide limits its use in flexible devices. In this study, we present a novel method for producing ultrasensitive, flexible NO₂ gas sensors through the natural oxidation of indium, which can also be easily textured to enhance sensitivity. We utilized the dewetting characteristics of indium to create micropatterns on the surface, significantly improving the sensor's sensitivity. Comprehensive gas sensing analysis demonstrated the sensors' ultra-sensitivity and rapid response to NO₂ molecules, with a resistance change of up to ∼5200 %. This work offers a simple, cost-effective approach for fabricating flexible gas sensors that operate at room temperature.