Gladiolus dalenii Based Bioinspired Structured Surface via Soft Lithography and Its Application in Water Vapor Condensation and Fog Harvesting

Water collection via heterogeneous condensation and fog harvesting has important implications in everyday life and in several industrial applications. Recently, the unique combination of surface morphology and wettability exhibited by natural and biological species is receiving increasing attention from the scientific community. Surface morphology of such species exhibits unique micro- and nanostructure arrangements, which play a paramount role in water vapor condensation and fog harvesting. In this work, we focus on the design and replication of the bioinspired surface Gladiolus dalenii (G. dalenii) using inexpensive, facile and scalable soft lithography fabrication technique. The extent of micro- and nanostructure surface replication is evaluated using scanning electron microscopy and 3D laser optical microscopy. In addition, we compare the performance of G. dalenii leaf and its bioinspired replica during droplet condensation at the microscale using environmental scanning electron microscopy and optical microscopy and also its fog harvesting behavior. Droplet nucleation and growth is investigated in detail and correlated with the unique surface micro- and nanostructures arranged in a hierarchical manner on such surfaces when compared to smooth control sample. In addition, the different water collection performance on fixated and on replicated G. dalenii, as well as on the smooth control sample is compared and demonstrated by the surface energy analysis proposed. To conclude, by taking advantage of the unique G. dalenii surface morphology, this work successfully demonstrates the excellent condensation heat transfer and fog harvesting behavior of bioinspired functional surfaces fabricated using soft lithography when compared to the flat configuration. In addition, we also demonstrate the near-accurate replication of the microsurface structures and of the governing mechanisms behind condensation and fog harvesting.