Over the last years, environmental pollution awareness has grown in society. The presence of nitrite in water is an indicative of urban and industrial contamination; nitrite in high concentrations can react with amines and amides generating toxic and cancinogenic nitrosamides. Additionally, the increase of nitrate in water helps in the uncontrolled proliferation of algae, leading to the death of the any organisms present in water. The aim of this work is to improve the characteristics of a nitrite/nitrate microfluidic sensor device, which was recently developed in our lab, based on a fast colorimetric reaction with the Griess reactive. The project aims to improve the analytical properties of the devices, but at the same time make a useful and user-friendly microfluidic device for water analysis.