The ability to monitor health and disease status transdermally via analysis of sweat obviating the need for a blood draw is a medical goal and unmet need. Present sweat monitoring technology remains limited as a largely experimental practice, relying on lab-based systems. Further, these approaches are unsuitable for monitoring changes during dynamic fitness, athletic and army activities. Herein, we introduce epidermal, flexible, conformal microfluidic devices—patches, with integrated wireless communication electronics, that allow collection and point-of-care analysis of sweat. Constructed devices offer advanced biomechanical capabilities affording reliable skin adhesion, in situ sweat collection via perspiration, and thus the determination of local sweat rate and volume as well as biomarker content under dynamic conditions. Optimized microfluidic channel design (shape, width and height), which satisfy with stretchability, stability, and permeability for sweat patch application, was suggested. Representative biomarkers—glucose, lactate, chloride, and pH were analyzed via quantitative colorimetric analysis and interrogated to a smartphone utilizing near-field communication electronics. Two human studies were conducted with the devices to demonstrate assessment of perspiration: (1) temperature and humidity controlled indoor mild cycling; and (2) real-world outdoor use of the patches during a long distance cycling race.