This poster presents a novel In: SnO₂/PHB nanocomposite, a material that holds great promise for the future of gas sensing. The integration of indium-doped tin oxide (In: SnO₂) with poly(3-hydroxybutyrate) (PHB) for ethanol gas sensing is a significant step forward in sensor technology. The introduction of indium lowers the operating temperature by introducing oxygen vacancies. The biodegradable PHB matrix provides a lightweight, flexible, and eco-friendly platform compared to conventional rigid substrates. These features, combined, position the In: SnO₂/PHB nanocomposite as a leading candidate for next-generation portable and sustainable gas sensors, offering a bright future for sensor development. The In: SnO₂/PHB  nanocomposite is safe to use, requires a lower operating temperature, and is biodegradable. Its eco-friendly and flexible design supports sustainable sensor development while maintaining high performance for ethanol detection. This work aligns with SDG 11 (Sustainable Cities and Communities) and SDG 12 (Responsible Consumption and Production), highlighting its potential as a green solution for next-generation portable gas sensors.