Phys.org May 20, 2021
Inspired by the shape of cactus spines, a team of researchers in the US (Caltech, University of Minnesota) has developed a hydrogel which combines the two water harvesting methods, namely, Fog collection and Solar-steam generation in one device. The hydrogel itself is a polyvinyl alcohol/polypyrrole (PVA/PPy) composite gel, a non-toxic and flexible material used in numerous applications. They used the gel to build a network of spines. Due to their tiny size, they can be printed onto a wafer-thin membrane. During the day, the hydrogel membrane absorbs sunlight to heat up water trapped beneath it, which becomes steam. The steam then recondenses onto a transparent cover, where it can be collected. During the night, the transparent cover folds up and the hydrogel membrane is exposed to humid air to capture fog. As such, the material can harvest water from both steam and fog. In a test conducted during the night, samples of the materials ranging from 55–125 square centimeters in area were able to collect about 35 milliliters of water from fog. In tests during the day, the material could collect about 125 milliliters from solar steam…read more. Open Access TECHNICAL ARTICLEÂ
Fabrication and structure characterization of microstructured PVA/PPy gel membranes. Credit: Nature Communications volume 12, Article number: 2797 (2021)Â