Solar-driven atmospheric water harvesting in the Atacama Desert through physics-based optimization of a hygroscopic hydrogel device

Moisture-capturing hydrogels are promising material candidates for atmospheric water-harvesting (AWH) systems, potentially addressing the increasingly global challenge of water scarcity. However, despite material-level performance improvements, optimal system integration of hydrogels remains a major limitation to deploying cost-effective, high-performance devices. Here, we design, optimize, and demonstrate deployment of polyacrylamide-lithium chloride (PAM-LiCl) hydrogels in a passive AWH device to provide liquid water with high thermal efficiency. First, a comprehensive heat and mass transport model is developed to enable optimal device architecture design. We then validate this design through fabrication and testing in a variety of extreme environmental conditions. Overall, we present a holistically optimized sorption system and demonstrate water production up to 1.7 L/m 2 /day with 16% thermal efficiency. This work highlights the potential for system-level improvement of AWH devices and provides initial design guidelines for producing optimal systems with regards to both material performance and environmental conditions.