Halochromic textile materials as innovative pH-sensors

Recently, an increasing interest in pH-sensitive textiles is recognized. These chromic textiles can be used as flexible sensors for various applications. The aim of the current research is to develop textile pH-sensors through the application of pH-sensitive dyes on various textile materials using different techniques. The results of our study show that halochromic dyes can be incorporated into conventional textiles by a conventional dyeing technique. Also coating the fabrics with a sol-gel layer layer containing the halochromic dye proved to be successful. The majority of these developed materials showed a clearly visible color change with a pH-variation. The response of the sensors was dependent on the density of the fabric but was generally relatively fast, especially for the sol-gel treated fabrics. The halochromic coloration of nanofibres was realized by directly adding the dyes during the fiber formation, which was shown to be highly effective. Again, a clear halochromic shift was observed. The response of these sensors was fast thanks to the high porosity of nanofibrous non-wovens. Yet, it should be kept in mind that the halochromic behavior of the dyes in the textile matrix altered compared to their behavior in solution which is most likely attributed to dye-fiber interactions. Generally we can conclude that various coloration techniques showed to be effective for the development of innovative textile pH-sensors.