A tough and stretchable colorimetric sensor based on a curcumin-loaded polyurethane electrospun fiber mat for hazardous ammonia gas detection

In this study, a flexible colorimetric sensor is developed to detect harmful ammonia gases using curcumin, a natural pH indicator. By applying an electrospinning method, the flexibility of polyurethane (PU) and the colorimetric characteristics of curcumin were simultaneously expressed in each nanofiber constituting the mat sensor. The physical properties of the mat according to the loaded curcumin concentration were investigated. And, the gas detection behavior was confirmed by the color change response of the mat to ammonia gas. Through the above process, the optimal conditions for fabricating a flexible colorimetric gas sensor with excellent tensile strength and elastic strain were established. The sensor fabricated with the curcumin loading of 30 wt% demonstrated approximately 3.5 times higher tensile strength and strain at break than the pure PU fiber mat. In addition, the color of the mat sensor changed from orange to red in proportion to the concentration of ammonia gases. Finally, the newly developed curcumin-PU mat could effectively withstand repeated external physical stress and was suitable for warning of dangerous toxic gas situations through immediate visual detection, even when repeatedly exposed to harmful gas.