Biomimetics

10517 KiB

Open AccessArticle

A Note on the Depth-from-Defocus Mechanism of Jumping Spiders

by Aleke Nolte, Daniel Hennes, Dario Izzo, Christian Blum, Verena V. Hafner and Tom Gheysens

Biomimetics 2017, 2(1), 3; https://doi.org/10.3390/biomimetics2010003 - 14 Mar 2017

Cited by 1 | Viewed by 6613

Jumping spiders are capable of estimating the distance to their prey relying only on the information from one of their main eyes. Recently, it has been shown that jumping spiders perform this estimation based on image defocus cues. In order to gain insight [...] Read more.

Jumping spiders are capable of estimating the distance to their prey relying only on the information from one of their main eyes. Recently, it has been shown that jumping spiders perform this estimation based on image defocus cues. In order to gain insight into the mechanisms involved in this blur-to-distance mapping as performed by the spider and to judge whether inspirations can be drawn from spider vision for depth-from-defocus computer vision algorithms, we constructed a three-dimensional (3D) model of the anterior median eye of the Metaphidippus aeneolus, a well studied species of jumping spider. We were able to study images of the environment as the spider would see them and to measure the performances of a well known depth-from-defocus algorithm on this dataset. We found that the algorithm performs best when using images that are averaged over the considerable thickness of the spider’s receptor layers, thus pointing towards a possible functional role of the receptor thickness for the spider’s depth estimation capabilities. Full article

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4672 KiB

Open AccessArticle

Fabrication of Mechanically Stable Superhydrophobic Aluminium Surface with Excellent Self-Cleaning and Anti-Fogging Properties

by Priya Varshney, Soumya S. Mohapatra and Aditya Kumar

Biomimetics 2017, 2(1), 2; https://doi.org/10.3390/biomimetics2010002 - 23 Feb 2017

Cited by 43 | Viewed by 8435

Abstract

The development of a self-cleaning and anti-fogging superhydrophobic coating for aluminium surfaces that is durable in aggressive conditions has raised tremendous interest in materials science. In this work, a superhydrophobic Al surface was synthesized by employing chemical etching technique with a mixture of [...] Read more.

The development of a self-cleaning and anti-fogging superhydrophobic coating for aluminium surfaces that is durable in aggressive conditions has raised tremendous interest in materials science. In this work, a superhydrophobic Al surface was synthesized by employing chemical etching technique with a mixture of hydrochloric and nitric acids, followed by passivation with lauric acid. The surface morphology analysis revealed the presence of rough microstructures on the coated Al surface. Superhydrophobicity with water contact angle of 170 ± 3.9° and sliding angle of 4 ± 0.5° was achieved. The surface bounced off the high-speed water jet, indicating the excellent water-repellent nature of the coating. It also continuously floated on a water surface for four weeks, showing its excellent buoyancy. Additionally, the coating maintained its superhydrophobicity after undergoing 100 cycles of adhesive tape peeling test. Its superhydrophobic nature withstood 90° and 180° bending and repeated folding and de-folding. The coating exhibits an excellent self-cleaning property. In a low temperature condensation test, almost no accumulation of water drops on the surface showed the excellent anti-fogging property of the coating. This approach can be applied to any size and shape of Al surface, and hence has great industrial applications. Full article

(This article belongs to the Special Issue Micro- and Nano-Structured Bio-Inspired Surfaces)

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2641 KiB

Open AccessArticle

Plasma-Textured Teflon: Repulsion in Air of Water Droplets and Drag Reduction Underwater

by Rosa Di Mundo, Francesco Bottiglione, Michele Notarnicola, Fabio Palumbo and Giuseppe Pascazio

Biomimetics 2017, 2(1), 1; https://doi.org/10.3390/biomimetics2010001 - 23 Jan 2017

Cited by 11 | Viewed by 5942

Abstract

A superhydrophobic behavior can be obtained by properly modifying the surface topography of Teflon or other fluorinated polymers having an inherent hydrophobic character. According to this strategy, we have micro/nanotextured Teflon both as plane material (sheets) and as three-dimensional (3D) object (spheres) with [...] Read more.

A superhydrophobic behavior can be obtained by properly modifying the surface topography of Teflon or other fluorinated polymers having an inherent hydrophobic character. According to this strategy, we have micro/nanotextured Teflon both as plane material (sheets) and as three-dimensional (3D) object (spheres) with a single step plasma process. The obtained textured Teflon samples were compared with those made of pristine Teflon in air, in terms of repulsion of impacting water droplets, and underwater, in terms of air layer behavior under static and dynamic conditions. The latter case was investigated by subjecting the spheres to a vertical fall in water. Modified surfaces present nanofilaments on the top of micrometric vertical structures, which can increase the air retaining capacity, resulting in a biomimicry effect due to a similarity with the Salvinia molesta leaf. On this surface, repulsion of impacting water droplets can be as fast as previously reached only on heated solids. Also, the air layer over the modified spheres underwater is shown to play a role in the observed reduction of hydrodynamic drag onto the moving object. Full article

(This article belongs to the Special Issue Micro- and Nano-Structured Bio-Inspired Surfaces)

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Biomimetics, Volume 2, Issue 1 (March 2017) – 3 articles

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