Donor–π bridge-acceptor dyes featuring dual chromophoric groups for enhanced sensitivity in wearable sweat sensor

A wearable visual pH sensor was successfully fabricated, showcasing high color sensitivity, robust cyclic stability, and exceptional color fastness. [Display omitted] •Heterocyclic azo dye with two D–π–A system was successfully synthesized.•The synthesized dye exhibits distinct chromatic variations in response to different pH values.•Colorimetric fabric sensors have been successfully prepared to monitor the pH value of sweat.•The fabric sensors exhibited exceptional color fastness against washing, rubbing, and sunlight exposure. The pH value of human sweat serves as a crucial biomarker for disease diagnosis, rendering wearable sweat sensors an innovative tool for monitoring human health. However, the commercialization of these devices is seriously impeded by their low sensitivity, poor wearing comfort, and limited reusability. In this work, a reactive dye capable of color change under pH change has been synthesized. Due to the unique molecular structure, the dye molecule exhibits remarkable color change recognition and high sensitivity. To fabricate a wearable pH sensor, screen printing technology was employed for depositing the color-changing dye onto cotton fabric. The resulting sensor demonstrated excellent performance attributes including high color sensitivity, robust cyclic stability in response to pH changes, and exceptional resistance against washing, friction, and sunlight-induced fading. Therefore, this study presents a highly promising approach for achieving real-time monitoring of human sweat pH levels.