Colorimetric sensor for bad odor detection using automated color correction

Abstract

Colorimetric sensors based on color-changing dyes offer a convenient approach for the quantitative measurement of gases. An integrated, mobile colorimetric sensor can be particularly helpful for occasional gas measurements, such as informal air quality checks for bad odors. In these situations, the main requirement is high availability, easy usage, and high specificity towards one single chemical compound, combined with cost-efficient production. In this contribution, we show how a well stablished colorimetric method can be adapted for easy operation and readout, making it suitable for the untrained end user. As an example, we present the use of pH indicators for the selective and reversible detection of NH3 in air (one relevant gas contributing to bad odors) using gas-sensitive layers dip coated on glass substrates. Our results show that the method can be adapted to detect NH3 concentrations lower than 1 ppm, with measure-to-result times in the range of a few minutes. We demonstrate that the color measurements can be carried out with the optical signals of RGB sensors, without losing quantitative performance.

Computer Technology and Innovation

“…An integrated mobile colorimetric sensor can be particularly useful for occasional gas measurements, such as informal air quality checks for odors. In these situations, the main requirement is high availability, ease of use and high specificity towards a single chemical compound, combined with cost-effective production (Schmitt, K., Tarantik, K., Pannek, C., Benito-Altamirano, I., Casals, O., Fabrega, C., ... & Prades, J. D., 2017).…”

Machine-Readable Pattern for Colorimetric Sensor Interrogation

“…Then, we transferred the colorimetric indicator to well-defined areas using screen-printing. The response to gases of the machine-readable patterns was investigated exposing them to different NH3 concentrations (0-100 ppm in humid air, 50% RH), and acquiring their colors with a digital camera under illumination conditions with adjustable color temperature [3].…”

How to implement a selective colorimetric gas sensor with off the shelf components?

“…This is the most simple and cheap approach, but bothersome and prone to human error. Alternatively, camera-based methods offer the chance of monitoring color changes automatically with the information available on a picture [14,15]. The challenge is avoiding external influences on the color appearance due to, e.g.…”