fig1

Figure 1. Schematic of a layered wearable microfluidic optical sweat sensing platform. The structure comprises (from bottom to top): a skin-conformal adhesive layer with sweat collection apertures; a flexible substrate (e.g., PDMS, hydrogel, textile, or paper) integrating a microfluidic network for sweat transport; an optical sensing zone (e.g., colorimetry, SERS, fluorescence, and ECL); and an encapsulation layer. Arrows indicate the path of optical signal transmission and the flow direction for analytical data output. Created in BioRender. Chu Wang. (2026) https://BioRender.com/dtltj3c, Adobe Illustrator, and Maxon Cinema 4D R21. PDMS: Polydimethylsiloxane; TPU: thermoplastic polyurethane; SERS: surface-enhanced Raman spectroscopy; ECL: electrochemiluminescence.