Abstract
Exhaled breath condensate (EBC) offers a non-invasive window into respiratory and systemic metabolism, yet wearable EBC systems are constrained by unstable moisture harvesting, short sensor lifetimes in humidity and battery dependence. Here we present EBClite, a battery-free smart mask for multiday EBC biomarker monitoring, using lactate as a model analyte. The platform integrates a regenerable antidrying porous hydrogel that achieves sustained and reactivatable breath condensation over several days, extending operational lifetime while reducing material cost. EBClite further incorporates a long-term stable electrochemical lactate sensor and an ultrathin quasi-two-dimensional perovskite solar cell with a power-to-weight ratio of 10āWāgā1 and a power conversion efficiency exceeding 30% under ambient indoor illumination, enabling autonomous operation across diverse lighting conditions. Human studies demonstrate strong correlations between EBC and blood lactate levels during exercise and carbohydrate intake, enabling real-time tracking of metabolic fluctuations. EBClite provides a sustainable, user-friendly platform for continuous respiratory and metabolic monitoring.
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Acknowledgements
This work was supported through the Heritage Medical Research Institute (W.G.), the Horizon 2020 research and innovation programme of the European Union under grant agreement number 101016411 āSoft Milli-robots-SOMIROā (M.K.). The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript. We acknowledge N. Dalleska for help with ICP-MS.
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W.G., M.K., W.H. and C.P. initiated the concept and designed the studies; W.H., C.P. and W.T. led the experiments and collected the overall data; W.H., W.T., J.M., G.K., C.W., M.-J.K. and Y.C. contributed to EBClite characterization, validation and sample analysis. C.P., L.E.L, B.H., S.D. and M.S. contributed to solar module development, fabrication and characterization. C.P. and E.R. contributed to experimental design and characterization of VOC test for the solar module. W.G., M.K. and Z.F. supervised the studies. W.H., C.P., L.E.L., W.G. and M.K. cowrote the paper. All authors contributed to the data analysis and provided the feedback on the paper.
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Heng, W., Putz, C., Tang, W. et al. A battery-free smart mask for long-term exhaled breath biochemical sensing. Nat. Sens. (2026). https://doi.org/10.1038/s44460-026-00041-3
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DOI: https://doi.org/10.1038/s44460-026-00041-3
