Porous biocompatible colorimetric nanofiber-based sensor for selective ammonia detection on personal wearable protective equipment

Colorimetric sensors are economical and power-free devices for gas detection. Ammonia is used in several industries and overexposure can lead to death. In this study, we demonstrate a simple, single-step fabrication of a sensitive and selective colorimetric ammonia sensor. This sensor is based on simple pH-indicator immobilized electrospun mat and was able to detect ammonia concentrations as low as 0.5 ppm with a fast response time of 10 s. The core-shell bi-polymer nanofiber mat was produced using single nozzle electrospinning with a PDMS shell for selectivity. We overcome the main weakness of colorimetric ammonia sensing which is its response to pH liquids and aerosol by the addition of PDMS shell making it suitable for personal protective equipment (PPE) in industrial environments. The detection range is adjustable by controlling the thickness of the PDMS shell without compromising the other performances of the sensor. Smart PPEs with integrated colorimetric sensors could potentially be used by workers in industrial settings to detect the presence of toxic ammonia gas in a visual way.