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

Abstract

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.

Emergent Soft Lithographic Tools for the Fabrication of Functional Polymeric Microstructures

“…These methods overcome critical challenges related to the production of 3D PMs and highlight the important role that dynamic, selfforming masters will play in expanding the reach of soft lithography to different fields and technologies. These techniques support a diverse range of applications, including, but not limited to: microelectronics, [91,130,144] superhydrophobic surfaces, [73,89,90,[104][105][106] micro-lenses, [93,95] open channel microfluidics, [92] structural color, [104,105,115,124,125] cellular growth environments, [137,145,146,153] and triboelectronics. [82][83][84]128] We anticipate that this list will continue to grow as more scientists adopt the strategies represented by these new fabrication techniques.…”

“…possess a range of desired properties/functions (e. g., superhydrophobicity, structural color, water harvesting, etc.) [104][105][106] that are derived from their structures and numerous efforts to replicate these structures through soft lithography have been undertaken. The replication of natural materials in synthetic polymers is an extension of 3D replica molding and is a convenient approach for achieving complicated structures with desired attributes that circumvents the design and production of masters using traditional lithographic procedures.…”

“…[107] Large-scale applications, such as fog harvesting and anti-icing coatings ( Figure 4E), are possible because of the scalability of PMs fabricated from naturally available and (in many cases) abundant materials. [106]…”

“…Adapted with permission from Refs. [105] and [106], respectively. E) These replicates can be used for fog harvesting at a rate comparable or beyond the natural material templates.…”

Large-scale efficient water harvesting using bioinspired micro-patterned copper oxide nanoneedle surfaces and guided droplet transport

“…In the recent decade, efficient fog collection capability of multiscale hierarchical surfaces in various ora and fauna has inspired researchers to develop synthetic bioinspired fog collection surfaces. [7][8][9][10][11][12][13][14][15] Specically, these surfaces take advantage of the combination of the unique micro and nanostructures which are bioinspired from the biological structures such as multilevel combination of micro and nanostructures of Gladiolus dalenii and microstructured slippery surfaces of the pitcher plant. 16 Among the specic structures, conical spine-like structures, [17][18][19] bumps of beetles, 11,20 micro-structured spindle knot surfaces of spider silk, 21,22 along with others endow the structures with water collection ability.…”