Atmospheric water harvesting for humidity control in medical devices for global health

Atmospheric water harvesting (AWH), which captures water from air, either by condensing humid air or by using sorbents that bind and release water vapour, is being explored as a decentralized source of clean water where piped supply is absent, intermittent or unsafe^1-5. Here we highlight the role of AWH as a reversible vapour sorption and controlled condensation strategy to regulate humidity and water activity (the effective availability of water) within biomedical devices. AWH can buffer local hydration and generate small liquid volumes for sampling, improving the robustness of wearables, point-of-care assays and respiratory monitoring in environments where conventional humidity control is unavailable.