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Wearable sweat analysis possesses significant potential for transforming personalized and precision medicine, by capturing the longitudinal profiles of a broad spectrum of biomarker molecules that are informative of our body’s dynamic chemistry. However, the lack of established physiological criteria to provide personalized feedback, based on sweat biomarker readings, has prevented the translation of wearable sweat-based bioanalytical technologies into health and wellness monitoring applications. Accordingly, scalable sweat sampling tools are required to facilitate large-scale and longitudinal clinical studies focusing on interpreting sweat biomarker readings. However, conventional sweat induction-collection tools are bulky and require multi-step and manual operations. Accordingly, here, we devise a sweat sampling patch, which can be deployed for autonomous diurnal sweat induction-collection. The core of this patch is an addressable array of miniaturized and coupled iontophoresis/microfluidic interfaces that can be activated on- demand or at scheduled time-points to induce/collect sufficient sweat samples for analysis. The iontophoresis interface was designed following an introduced design space centering on sufficient sweat secretory agonist delivery at safe current levels. The microfluidic interface was fabricated following a simple, rapid, and low-cost fabrication scheme. To achieve autonomous operation, these interfaces were extended into an array format and coupled with a custom-developed flexible and wireless circuit board. To inform utility, periodically induced/collected sweat samples of an individual were analyzed in relation to meal intake. 

To track dynamically varying and physiologically relevant biomarker profiles in sweat, autonomous wearable platforms are required to periodically sample and analyze sweat with minimal or no user intervention. Previously reported sweat sensors are functionally limited to capturing biomarker information at one time-point/period, thereby necessitating repeated user intervention to increase the temporal granularity of biomarker data. Accordingly, we present a compact multi-compartment wearable system, where each compartment can be activated to autonomously induce/modulate sweat secretion ( via iontophoretic actuation) and analyze sweat at set time points. This system was developed following a hybrid-flex design and a vertical integration scheme—integrating the required functional modules: miniaturized iontophoresis interfaces, adhesive thin film microfluidic-sensing module, and control/readout electronics. The system was deployed in a human subject study to track the diurnal variation of sweat glucose levels in relation to the daily food intake. The demonstrated autonomous operation for diurnal sweat biomarker data acquisition illustrates the system's suitability for large-scale and longitudinal personal health monitoring applications.