A Textile-Based, Battery-Free, Electrochromic Platform for Visual Epidermal Sweat Biosensing

Noninvasive wearable sweat sensors are promising for personalized health management, yet their widespread adoption is hindered by complex multi-component architectures, reliance on rigid batteries, and a lack of intuitive visual feedback. Herein, we propose a sweat-powered metabolism-to-visual transduction mechanism that utilizes sweat as both an energy source and a detection target. A fabric-based sweat electricity harvester is fabricated, which harnesses sweat energy to yield a stable power output, enabling battery-free sensing operation. Coupled enzymatic sensing electrode-electrochromic display system translates sweat glucose concentration into directly perceptible color change. To overcome the subjective errors inherent in traditional colorimetry, a neural network-based smartphone application is employed to provide precise quantitative visual readouts, achieving highly accurate estimation of sweat glucose (R² = 0.997) comparable to commercial assay kits in on-body evaluation on human subjects. By successfully decoupling wearable sensors from rigid power sources while fusing self-powered electrochromic displays with AI-assisted digital readouts, this lightweight textile platform establishes an on-demand strategy for user-friendly, and intelligent metabolic monitoring.