A new approach to photochromic nanofiber‐based ultraviolet sensors with grayscale adaptation

Abstract

The purpose of UV sensors is to detect ultraviolet radiation, which is crucial for various applications, such as skin protection, environmental monitoring, and industrial processes where UV exposure poses risks. These sensors provide real‐time data to ensure safety and optimize performance in relevant fields. In this context, the aim of this study was to develop easy‐to‐use UV sensors using photochromic nanofibrous materials. Photochromic nanofibers were obtained by electrospinning thermoplastic polyurethane and a spirooxazine dye. Two solvent systems (only dimethylformamide and a dimethylformamide:dichloromethane mixture) and three dye concentrations (0.5%, 2%, and 5%) were used to produce the nanofibers. Uniform and bead‐free nanofibers were obtained using a dimethylformamide:dichloromethane solvent system. The fatigue resistance of the photochromic nanofibers was tested, revealing a maximum color loss of 14% after 20 on‐off UV cycles. Nanofibers produced with a dimethylformamide:dichloromethane solvent system and a 0.5% dye concentration were chosen for UV sensor design due to their high total color difference. These photochromic nanofibers served as UV indicators, and a grayscale‐ adapted scale was used for evaluation. A UV sensor prototype capable of accurately determining UV exposure levels was successfully developed using photochromic nanofibers. This spectrally selective UV sensor can offer remarkable potential in managing the impact of UVR in our day‐to‐ day life.Highlights Bead‐free, uniform nanofibers were obtained using a DMF:DCM solvent system. The nanofibers returned to their original colorless state in 5 min. The photochromic nanofibers showed high fatigue resistance. The nanofiber color indicated the UV intensity by comparing via adapted grayscale.