MicroSweat: A Wearable Microfluidic Patch for Noninvasive and Reliable Sweat Collection Enables Human Stress Monitoring

Abstract

Stress affects cognition, behavior, and physiology, leading to lasting physical and mental illness. The ability to detect and measure stress, however, is poor. Increased circulating cortisol during stress is mirrored by cortisol release from sweat glands, providing an opportunity to use it as an external biomarker for monitoring internal emotional state. Despite the attempts at using wearable sensors for monitoring sweat cortisol, there is a lack of reliable wearable sweat collection devices that preserve the concentration and integrity of sweat biomolecules corresponding to stress levels. Here, a flexible, self-powered, evaporation-free, bubble-free, surfactant-free, and scalable capillary microfluidic device, MicroSweat, is fabricated to reliably collect human sweat from different body locations. Cortisol levels are detected corresponding to severe stress ranging from 25 to 125 ng mL −1 averaged across multiple body regions and 100-1000 ng mL −1 from the axilla. A positive nonlinear correlation exists between cortisol concentration and stress levels quantified using the perceived stress scale (PSS). Moreover, owing to the sweat variation in response to environmental effects and physiological differences, the longitudinal and personalized profile of sweat cortisol is acquired, for the first time, for various body locations. The obtained sweat cortisol data is crucial for analyzing human stress in personalized and clinical healthcare sectors.

Dermal-fluid-enabled detection platforms for non-invasive ambulatory monitoring

“…Microfluidic technology has been successful in significantly increasing sweat collection volume by utilizing a smart combination of hydrophilic and hydrophobic materials. 231 MN technology has immense potential for non-invasive monitoring in ISF at a small scale; however, its utility in comparison to conventional blood sampling presently is impaired. An ideal monitoring system must be able to sample ≥1 μL of ISF as sub-microliter volumes are prone to dilution errors and noise affecting the correlations.…”

Flexible and Wearable Biosensors for Monitoring Health Conditions

“…The patch is one of the ideal choices for wearable sensors due to the feature of bendability and fitness to the skin surface. A bunch of patch-type wearable sensors was fabricated to realize various functions for health monitoring [ 101 , 102 , 103 ]. A skin patch was prepared using a microfiber membrane with sodium polyacrylate microgels to measure sweat rate and pH [ 101 ].…”

Screen-Printed Textile-Based Electrochemical Biosensor for Noninvasive Monitoring of Glucose in Sweat

“…Pressure-driven microfluidics can empower a consistent sweat flow, and fresh microliter sampling volumes can be guided to the sensor surface to minimize old and new sweat mixing issues [63]. Therefore, a microfluidic-integrated wearable biosensing platform has been emerging to achieve much more reliable wearable analyte monitoring with excellent practicability [64,65].…”