Geometry is a determining factor for thermal performance in both biological and technical systems. While biology has inspired thermal design before, biomimetic translation of leaf morphology into structural aspects of heat exchangers remains largely unaddressed. One determinant of plant thermal endurance against environmental exposure is leaf shape, which modulates the leaf boundary layer, transpiration, evaporative cooling, and convective exchange. Here, we lay the research groundwork for the extraction of design principles from leaf shape relations to heat and mass transfer. Leaf role models were identified from an extensive literature review on environmentally sensitive morphology patterns and shape-dependent exchange. Addressing canopy sun–shade dimorphism, sun leaves collected from multiple oak species exceeded significantly in margin extension and shape dissection. Abstracted geometries (i.e., elongated; with finely toothed edges; with few large-scale teeth) were explored with paper models of the same surface area in a controlled environment of minimal airflow, which is more likely to induce leaf thermal stress. For two model characteristic dimensions, evaporation rates were significantly faster for the dissected geometries. Shape-driven transfer enhancements were higher for the smaller models, and finely toothed edges reached local cooling up to 10 °C below air temperature. This investigation breaks new ground for solution-based biomimetics to inform the design of evaporation-assisted and passively enhanced thermal systems.

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Function is a key central concept to the practice of biomimicry. Many published models of the biomimicry process include steps to identify, understand, and translate function of biological systems. Examples include functional modeling, decomposition, or abstraction with tools specifically designed to facilitate such steps. A functional approach to biomimicry yields a semantic bridge between biology and engineering, enabling practitioners from a variety of backgrounds to more easily communicate and collaborate in a biomimicry design process. Although analysis of function is likely a necessary part of biomimicry design, recent work suggests it is not sufficient without a more systematic understanding of the complex biological context in which a function exists (e.g., scale and trade-offs). Consequently, emerging tools such as ontologies are being developed that attempt to capture the intricacies of biological systems (including functions), such as their complex environmental and behavioral interactions. However, due to the complexity of such tools, they may be under-utilized. Here, we propose a solution through a computer-aided user interface tool which integrates a biomimetic ontology with a thesaurus-based functional approach to biomimicry. Through a proof of concept illustrative case study, we demonstrate how merging existing tools can facilitate the biomimicry process in a systematic and collaborative way, broadening solution discovery. This work offers an approach to making existing tools, specifically the BioMimetic Ontology, more accessible and encompassing of different perspectives via semantic translation and interface design. This provides the user with the opportunity to interface and extract information from both the Engineering-to-Biology Thesaurus and the BioMimetic Ontology in a way that was not possible before. The proposed E2BMO tool not only increases the accessibility of the BioMimetic Ontology, which ultimately aims to streamline engineers' interaction with the bio-inspired design process, but also provides an option for practitioners to traverse biological knowledge along the way, encouraging greater interdisciplinary collaboration and consideration when conducting biomimicry research.

Evaporative interfaces help process heat and substances in a variety of technical realms, from electronic to architectural applications. Because geometry affects the hydraulics, thermal properties and aerodynamics of evaporative devices, their performance can be tuned through design. While non-smooth interfaces are widely exploited to enhance transfer passively, surface area extension in packed volumes is a predominant line of research. This leaves aerodynamic structure-transfer relations and the impact of geometry itself unclear. Meanwhile, protrusions in leaves such as lobes and toothed margins have been associated with enhanced vapor dissipation. This experimental study explores the design space of leaf-inspired structures with evaporating protrusions. Three sets of water-absorbing models with fixed evaporating surface area and unlimited hydraulic supply were tested: (1) paper strips with dimension-equivalent protrusions of varied shape and degree of elongation; (2) cellulose sponges with the same designs as their cross-sectional profile, extruded three-dimensionally; (3) ceramic tiles with grooves of varied cross-section, conceived as building elements for evaporative cooling. Overall, results demonstrate that protrusions affect mass transfer rate and surface temperatures and can be integrated in the design of evaporative exchangers with non-smooth geometries. For the paper models, evaporation rate correlated with protrusion aspect ratio, supporting a functional interpretation of leaf design and its utilization in low-wind plate-fin exchangers. However, the same transfer enhancement was not regained from simply extruding an effective design into three-dimensions. For the ceramic tiles, geometry-driven differences in evaporation depended on the aerodynamic roughness and size of the grooved pattern, and on ventilation. Their outdoor thermal behavior was complex due to a multifaceted interaction with the environment and geometry-related factors such as self-shading and thermal mass. Ultimately, this design effort illustrates the potential of structured interfaces for evaporative exchange and thermoregulating the built environment.

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