— Sensors are changing the way people live and considerable efforts are under way for their integration into daily devices. Recently, much attention has been given to sensor fields for flexible and printed electronics. Among all the processes, ultrasonic spray deposition is a simple and precise technique giving enormous potential for applications with low cost production, low waste of material and thin film uniformity. In this work, we are focusing on Zinc Oxide nanoparticles deposited by ultrasonic spray on a flexible substrate as sensitive layer for air quality monitoring. The flexible platform consists of Ti/Pt interdigitated electrodes for gas detection and a micro-heater device, both on Kapton HN substrate. A brief description of the process steps will be provided. Gas sensing properties have been investigated and the flexible sensors present repeatable responses toward ammonia (NH 3) and ozone (O 3) with fast responses and recovery times in a wide range of gas concentrations. The optimum working temperatures were experimentally determined at 300 °C for NH 3 and 200 C° for O 3. Overall, this work highlights the ultrasonic spray potential for fast processing flexible gas sensors based on zinc oxide solution.