Here we present the fabrication and the performance of a novel, wearable, robust, flexible and disposable micro-fluidic device which incorporates miniature optical components as a detection system, for wireless monitoring in real time mode of sweat pH during an exercise session. This micro-fluidic platform is completely non-invasive, with the great advantage of providing a continuous flow of fresh sweat for continuous real time analysis, ensuring immediate feedback regarding sweat composition to an athlete and/or coach. To the best of our knowledge, this is the first wearable and wireless micro-fluidic device suitable for real time analysis and reporting of the wearer’s physiological state.