Wetting Dynamics of a Water Droplet on Micropillar Surfaces with Radially Varying Pitches

Unidirectional liquid transport without any need of external energy has drawn worldwide attention for its potential applications in various fields such as microfluidics, biomedicine and mechanical engineering. In nature, numerous creatures have evolved such extraordinary unidirectional liquid transport ability, such as spider silk, Sarracenia’s trichomes, and Nepenthes alata’s peristome, etc. This review summarizes the current progresses of natural unidirectional liquid transport on 1-Dimensional (1D) linear structure and 2-Dimensional (2D) surface structure. The driving force of unidirectional liquid transport which is determined by unique structure exist distinct differences in physics. The fundamental understanding of 1D and 2D unidirectional liquid transport especially about hierarchical structural characteristics and their transport mechanism were concentrated, and various bioinspired fabrication methods are also introduced. The applications of bioinspired directional liquid transport are demonstrated especially in fields of microfluidics, biomedical devices and anti-icing surfaces. With newly developed smart materials, various liquid transport regulation strategies are also summarized for the control of transport speed, direction guiding, etc. Finally, we provide new insights and future perspectives of the directional transport materials.

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“…9b) [70] , radially distributed microstrips with gradually enlarged stripe spacing (Fig. 9c) [71] , or radially distributed micro pillars [72] .…”

Section: Gradient and Patterned Wettability Surfacesmentioning

confidence: 99%

Bioinspired Unidirectional Liquid Transport Micro-nano Structures: A Review

et al. 2021

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“…These simpler geometries are easier to model and from a practical point of view, such surfaces are easier to fabricate by conventional, widespread nano/micromachining techniques, such as focused ion beam (FIB), electron beam lithography, and photo lithography. 70 The generic model that was employed to examine the correlation between the thin-film lifetime and the virus survival time in Sec. III will be applied herein to analyze the model surface configurations depicted in Fig.…”

Section: Designing Antiviral Surfacesmentioning

confidence: 99%

Designing antiviral surfaces to suppress the spread of COVID-19

et al. 2021

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Surface engineering is an emerging technology to design antiviral surfaces, especially in the wake of COVID-19 pandemic. However, there is yet no general understanding of the rules and optimized conditions governing the virucidal properties of engineered surfaces. The understanding is crucial for designing antiviral surfaces. Previous studies reported that the drying time of a residual thin-film after the evaporation of a bulk respiratory droplet on a smooth surface correlates with the coronavirus survival time. Recently, we [Chatterjee et al. , Phys. Fluids. 33 , 021701 (2021)] showed that the evaporation is much faster on porous than impermeable surfaces, making the porous surfaces lesser susceptible to virus survival. The faster evaporation on porous surfaces was attributed to an enhanced disjoining pressure within the thin-film due the presence of horizontally oriented fibers and void spaces. Motivated by this, we explore herein the disjoining pressure-driven thin-film evaporation mechanism and thereby the virucidal properties of engineered surfaces with varied wettability and texture. A generic model is developed which agrees qualitatively well with the previous virus titer measurements on nanostructured surfaces. Thereafter, we design model surfaces and report the optimized conditions for roughness and wettability to achieve the most prominent virucidal effect. We have deciphered that the optimized thin-film lifetime can be gained by tailoring wettability and roughness, irrespective of the nature of texture geometry. The present study expands the applicability of the process and demonstrates ways to design antiviral surfaces, thereby aiding to mitigate the spread of COVID-19.

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“…Number of publications on passive wetting gradients vs year of publication. The papers listed here correspond to refs − , , − , , − .…”

Section: Introductionmentioning

confidence: 99%

Survey of Micro/Nanofabricated Chemical, Topographical, and Compound Passive Wetting Gradient Surfaces

et al. 2021

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Surface wetting gradients are desirable due to their ability to passively transport liquid droplets without the aid of gravity. Such surfaces can be prepared through topographical or chemical methods or a compound approach involving both methods. By altering the surface free energy across a surface, a droplet that contacts such a surface will experience an actuation force toward the hydrophilic region. Such transport properties make these surfaces attractive for a range of applications from thermal management to microfluidics to the investigation of biomolecular interactions. This paper reviews passive wetting gradients that have been demonstrated over the last three decades, focusing on the types of surfaces that have been developed to date along with the materials that have been used. The corresponding wetting ranges and physical lengths over which droplet mobility has been achieved on these various types of gradient surfaces are compared to guide future developments.

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Wetting Dynamics of a Water Droplet on Micropillar Surfaces with Radially Varying Pitches

Cited by 28 publications

References 53 publications

Bioinspired Unidirectional Liquid Transport Micro-nano Structures: A Review

Bioinspired Unidirectional Liquid Transport Micro-nano Structures: A Review

Designing antiviral surfaces to suppress the spread of COVID-19

Survey of Micro/Nanofabricated Chemical, Topographical, and Compound Passive Wetting Gradient Surfaces

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