Fiber-based hydrophobic and stretchable UV-photochromic textile

Abstract

Wearable sensors composed of fabric have attracted considerable research interest as they can detect various environmental factors that affect the human body, such as ultraviolet (UV) radiation, temperature, and humidity. Among these sensors, color-conversion sensors are especially valuable as they can provide a visual representation of data without the need for additional electrical devices. For a sensor to be used on the human body, it must maintain its sensing capabilities even when exposed to solutions such as rainwater, sweat, and various cleansing liquids or when subjected to mechanical deformation. Therefore, this study was aimed at fabricating a UV-photochromic fiber that can maintain its color-change reaction to UV light even when exposed to chemical and physical stressors. To this end, UV-photochromic pigment was infused into porous and hydrophobic silica aerogels to create UV-photochromic aerogels, which were then placed between the inner strands of spandex fibers. During the drying process, the UV-photochromic aerogels adhered firmly to the spandex strands and were not separated even when the fibers were stretched and contracted up to 100 times under 200% tensile conditions. The resulting UV-photochromic fibers initially appeared white but transformed to magenta when exposed to UV light. This color change persisted through seven repeated on–off cycles of UV light. Moreover, the hydrophobic nature of the fibers ensured that the color-change reactivity remained stable even under exposure to water, artificial sweat, and detergent solutions. Overall, the proposed UV-photochromic fibers, with enhanced reversibility, stability, and reliability, can promote the commercialization of wearable-based colorimetric sensors.