Multiscale effects and capillary interactions in functional biomimetic surfaces for energy conversion and green engineering

Abstract

Biological surfaces (plant leaves, lizard and insect attachment pads, fish scales, etc.) have remarkable properties due to their hierarchical structure. This structure is a consequence of the hierarchical organization of biological tissues. The hierarchical organization of the surfaces allows plants and creatures to adapt to energy dissipation and transition mechanisms with various characteristic scale lengths. At the same time, an addition of a micro-/nanoscale hierarchical level, for example of surface roughness, can change qualitatively the properties of a system and introduce multiple equilibriums, instability and dissipation. Thus, small roughness has a large effect. In particular, a small change of surface roughness can lead to a large change in the capillary force. The capillary effects are crucial for small-scale applications. Multiscale organization of the biomimetic surfaces and their adaptation to capillary effects make them suitable for applications using new principles of energy transition (e.g. capillary engines) and environment-friendly technologies (e.g. self-cleaning oleophobic surfaces).

Designing biomimetic antifouling surfaces

“…Many organisms have evolved surface topographies that deter settlement, for example, pilot whale skin (Baum et al 2002), mussel/bivalve surfaces (Scardino & de Nys 2004), crabs and eggshell casings (Bers & Wahl 2004). The roughness scale of a coating significantly influences its wettability (Nosonovsky & Bhushan 2009). Microtopography replicas are rarely as effective as the organism in situ, inferring that other contributors to AF behaviour are active in the organism's lifetime.…”

“…In particular, a small change of surface roughness can lead to large changes in the capillary force. The capillary effects are crucial for small-scale applications and the functionality of engineered devices, such as micro-/nano-electromechanical systems (Nosonovsky & Bhushan 2009). Alternatively, the shell of the blue mussel Mytilus edulis can remain free of fouling organisms as long as it possesses an intact periostracum, which is a multiple AF defence that comprises a ripple-like microtopography and the production of chemical AF compounds (Bers et al 2006).…”

Green tribology: principles, research areas and challenges

“…As opposed to the traditional engineering approach, biological materials are grown without the final design specifications, but by using the recipes and recursive algorithms contained in their genetic code. The difference of natural versus engineering design is the difference of growth versus fabrication (Fratzl 2007;Nosonovsky & Bhushan 2008, 2009a. Hierarchical organization and the ability of biological systems to grow and adapt also provide a natural mechanism for the repair or healing of minor damage in the material.…”

The spatial emergence of laser-induced periodic surface structures under lateral displacement irradiation conditions

“…In general, wettability is determined by the chemo-physical [14] and topographical [15,16] properties of the surface. In particular, hydrophobicity can be enhanced with structures having a micro-and nanometre scale [17].…”

“…With respect to the selected temporal conditions, this sequence of translations can be analysed as a sequence of lateral displacements 17) where n denotes the number of the pulse, x 0 the absolute displacement increment in x direction between two successive pulses and N 1 to N 6 the boundaries for the number of pulses. The movements along x direction are assumed to cover multiple irradiation locations and the movements along y direction one, which requires to move an increment y 0 .…”