Making Sweat Measurable: Induction, Sampling, and Refreshment in Wearable Biofluid Sensing

Area of Science:

• Biomedical Engineering
• Wearable Technology
• Biosensing

Background:

• Sweat is a promising biofluid for noninvasive wearable health monitoring, offering continuous access to biomarkers.
• Current limitations in sweat monitoring stem from challenges in sweat induction, collection, and transport, rather than sensing chemistry.
• Low, transient, and heterogeneous sweat secretion outside of strenuous activity hinders continuous monitoring.

Purpose of the Study:

• To reframe sweat sampling as an integrated engineering pipeline for improved wearable health monitoring.
• To analyze strategies for sweat induction, capture, transport, and refreshment for reliable biomarker accessibility.
• To outline design principles for quantitative, long-duration sweat monitoring in real-world applications.

Main Methods:

• Review of sweat gland physiology and biomarker dynamics.
• Comparison of whole-body, localized thermal, and cholinergic sweat induction methods.
• Analysis of microfluidic architectures for sustained temporal resolution under variable sweat flux.

Main Results:

• Sweat availability and management are critical constraints for continuous monitoring.
• System-level integration of programmable induction and controlled fluid handling enables quantitative monitoring.
• Effective sweat sampling requires optimizing the entire pipeline from induction to refreshment.

Conclusions:

• Shifting focus from sensing chemistry to induction-sampling integration is crucial for reliable sweat monitoring.
• Design principles for integrated sweat collection systems are needed for real-world wearable applications.
• Optimized sweat management is essential for making sweat a dependable biofluid for continuous health monitoring.