Time-Resolved Sweat Collection for Off-Body SERS Analysis: Bridging Wearability and Sensitivity

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Wearable Technology

Background:

• Sweat analysis offers a noninvasive method for physiological monitoring.
• Surface-enhanced Raman scattering (SERS) provides sensitive detection of sweat biomarkers.
• Current wearable SERS systems are limited by bulky equipment.

Purpose of the Study:

• To develop a wearable platform for in situ sweat collection and time-sequenced storage.
• To enable delayed, off-body high-sensitivity SERS detection of sweat biomarkers.
• To overcome the limitations of integrating current SERS technology into wearable devices.

Main Methods:

• Fabricated a Janus microporous membrane with a wettability gradient for directional sweat collection.
• Integrated a microfluidic chip with burst valves for passive, time-sequenced sweat sampling and storage.
• Developed a capillary-based SERS substrate using a silver mirror reaction for biomarker detection.

Main Results:

• Achieved directional and continuous sweat collection from the skin.
• Demonstrated time-sequenced storage of sweat samples during exercise.
• Reached detection limits as low as 1 mM for sodium lactate and urea using SERS.
• Successfully identified characteristic peaks from human sweat samples.

Conclusions:

• The developed wearable platform enables feasible integration of sweat sensing with high-performance spectroscopic analysis.
• This technology offers promising applications for personalized health monitoring and dynamic physiological assessment.
• The system addresses the impracticality of bulky Raman spectrometers in wearable health devices.