Highly Specific and Wide Range NO₂ Sensor with Color Readout

We present a simple and inexpensive method to implement a Griess-Saltzman-type reaction that combines the advantages of the liquid phase method (high specificity and fast response time) with the benefits of a solid implementation (easy to handle). We demonstrate that the measurements can be carried out using conventional RGB sensors; circumventing all the limitations around the measurement of the samples with spectrometers. We also present a method to optimize the measurement protocol and target a specific range of NO₂ concentrations. We demonstrate that it is possible to measure the concentration of NO₂ from 50 ppb to 300 ppm with high specificity and without modifying the Griess-Saltzman reagent.