Improvement of a microfiber filter for domestic washing machines.

The development of enhanced processes for filtration is one solution for stopping the increasing freshwater and sea pollution caused by microplastic and microfibers. Major contributors to micro-X pollution are domestic devices such as washing machines, which also hold a high technical potential for separating problematic soils from waste water during cleaning cycles. The focus of the present paper are the biomimetic development of a novel concept for filtration and removal of particles such as microfibers in conventional washing machines. To this goal, a TRIZ analysis yielded viable solutions for the major key issues. In a next step, measurements were made with various filters with and without ribbed structures. The results are promising for the incorporation in a filter concept that is easy to operate and cost-effective.

The Protective Role of Bark and Bark Fibers of the Giant Sequoia (Sequoiadendron giganteum) during High-Energy Impacts.

The influences of (1) a high fiber content, (2) the arrangement of fibers in fiber groups, and (3) a layered hierarchical composition of the bark of the giant sequoia (Sequoiadendron giganteum) on its energy dissipation capability are analyzed and discussed regarding the relevance for an application in bioinspired components in civil engineering. The giant sequoia is native to the Sierra Nevada (USA), a region with regular rockfalls. It is thus regularly exposed to high-energy impacts, with its bark playing a major protective role, as can be seen in the wild and has been proven in laboratory experiments. The authors quantify the fundamental biomechanical properties of the bark at various length scales, taking into account its hierarchical setup ranging from the integral level (whole bark) down to single bark fibers. Microtensile tests on single fibers and fiber pairs give insights into the properties of single fibers as well as the benefits of the strong longitudinal interconnection between single fibers arranged in pairs. Going beyond the level of single fibers or fiber pairs, towards the integral level, quasistatic compression tests and dynamic impact tests are performed on samples comprising the whole bark (inner and outer bark). These tests elucidate the deformation behavior under quasistatic compression and dynamic impact relevant for the high energy dissipation and impact-damping behavior of the bark. The remarkable energy dissipation capability of the bark at the abovementioned hierarchical levels are linked to the layered and fibrous structure of the bark structurally analyzed by thin sections and SEM and µCT scans.

Spatio-temporal development of cuticular ridges on leaf surfaces of Hevea brasiliensis alters insect attachment.

Cuticular ridges on plant surfaces can control insect adhesion and wetting behaviour and might also offer stability to underlying cells during growth. The growth of the plant cuticle and its underlying cells possibly results in changes in the morphology of cuticular ridges and may also affect their function. We present spatial and temporal patterns in cuticular ridge development on the leaf surfaces of the model plant, Hevea brasiliensis. We have identified, by confocal laser scanning microscopy of polymer leaf replicas, an acropetally directed progression of ridges during the ontogeny of Hevea brasiliensis leaf surfaces. The use of Colorado potato beetles (Leptinotarsa decemlineata) as a model insect species has shown that the changing dimensions of cuticular ridges on plant leaves during ontogeny have a significant impact on insect traction forces and act as an effective indirect defence mechanism. The traction forces of walking insects are significantly lower on mature leaf surfaces compared with young leaf surfaces. The measured walking traction forces exhibit a strong negative correlation with the dimensions of the cuticular ridges.

Replicating the complexity of natural surfaces: technique validation and applications for biomimetics, ecology and evolution.

The surfaces of animals, plants and abiotic structures are not only important for organismal survival, but they have also inspired countless biomimetic and industrial applications. Additionally, the surfaces of animals and plants exhibit an unprecedented level of diversity, and animals often move on the surface of plants. Replicating these surfaces offers a number of advantages, such as preserving a surface that is likely to degrade over time, controlling for non-structural aspects of surfaces, such as compliance and chemistry, and being able to produce large areas of a small surface. In this paper, we compare three replication techniques among a number of species of plants, a technical surface and a rock. We then use two model parameters (cross-covariance function ratio and relative topography difference) to develop a unique method for quantitatively evaluating the quality of the replication. Finally, we outline future directions that can employ highly accurate surface replications, including ecological and evolutionary studies, biomechanical experiments, industrial applications and improving haptic properties of bioinspired surfaces. The recent advances associated with surface replication and imaging technology have formed a foundation on which to incorporate surface information into biological sciences and to improve industrial and biomimetic applications. This article is part of the theme issue 'Bioinspired materials and surfaces for green science and technology'.