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Bioinspiration & Biomimetics

Michael Pieroni, Clara Lagomarsini, Danilo De Rossi, Federico Carpi
Electrically tunable lenses are conceived as deformable adaptive optical components able to change focus without motor-controlled translations of stiff lenses. In order to achieve large tuning ranges, large deformations are needed. This requires new technologies for the actuation of highly stretchable lenses. This paper presents a configuration to obtain compact tunable lenses entirely made of soft solid matter (elastomers). This was achieved by combining the advantages of dielectric elastomer actuation (DEA) with a design inspired by the accommodation of reptiles and birds...
October 26, 2016: Bioinspiration & Biomimetics
Nayeon Lee, M F Horstemeyer, R Prabhu, Jun Liao, Hongjoo Rhee, Youssef Hammi, Robert D Moser, Lakiesha N Williams
In this study a woodpecker's hyoid apparatus was characterized to determine its impact mitigation mechanism using finite element (FE) analysis. The woodpecker's hyoid apparatus, comprising bone and muscle, has a unique geometry compared to those of other birds. The hyoid starts at the beak tip, surrounds the woodpecker's skull, and ends at the upper beak/front head intersection while being surrounded by muscle along the whole length. A FE model of the hyoid apparatus was created based on the geometry, microstructure, and mechanical properties garnered from our experimental measurements...
October 25, 2016: Bioinspiration & Biomimetics
H Lu, K B Lua, Y J Lee, T T Lim, K S Yeo
This paper reports the results of combined experimental and numerical studies on the ground effect on a pair of three-dimensional (3D) hovering wings. Parameters investigated include hovering kinematics, wing shapes, and Reynolds numbers (Re). The results are consistent with the observation by another study (Gao and Lu, 2008 Phys. Fluids, 20 087101) which shows that the cycle-averaged aerodynamic forces generated by two-dimensional (2D) wings in close proximity to the ground can be broadly categorized into three regimes with respect to the ground clearance; force enhancement, force reduction, and force recovery...
October 25, 2016: Bioinspiration & Biomimetics
Kai Yang, Gangfeng Liu, Jihong Yan, Tao Wang, Xinbin Zhang, Jie Zhao
The highly efficient and agile water-surface locomotion of water striders has attracted substantial research attention. Compared with imitating the horizontal rowing motion, imitating the jumping capability of water striders is much more challenging because the strong interaction in the jumping process easily causes the robot to sink. This study focuses on designing a miniature robot capable of continuously jumping on the water surface. A spring-based actuating mechanism is proposed to produce a large jumping force...
October 21, 2016: Bioinspiration & Biomimetics
Federico Pedraja, Rossana Perrone, Ana Silva, Ruben Budelli
Agonistic behaviour related to territorial defence is likely to be costly in terms of energy loss and risk of injury. Hence information about the fighting ability of a potential opponent could influence the outcome of the contest. We here study electric images of the territorial and aggressive weakly electric fish Gymnotus omarorum in the context of agonistic behaviour. We show that passive and active electric images may drive the approach towards an opponent. The likelihood of first attacks can be predicted in these fish based on electric image information, suggesting that aggressive interactions may in fact be triggered through the passive electrosensory information...
October 21, 2016: Bioinspiration & Biomimetics
Roberto Martini, Francois Barthelat
Protective systems that are simultaneously hard to puncture and compliant in flexion are desirable, but difficult to achieve because hard materials are usually stiff. However, we can overcome this conflicting design requirement by combining plates of a hard material with a softer substrate, and a strategy which is widely found in natural armors such as fish scales or osteoderms. Man-made segmented armors have a long history, but their systematic implementation in a modern and a protective system is still hampered by a limited understanding of the mechanics and the design of optimization guidelines, and by challenges in cost-efficient manufacturing...
October 13, 2016: Bioinspiration & Biomimetics
Daniel Van Opdenbosch, Gerhard Fritz-Popovski, Johann Plank, Cordt Zollfrank, Oskar Paris
Living nature and human technology apply different principles to create hard, strong and tough materials. In this review, we compare and discuss prominent aspects of these alternative strategies, and demonstrate for selected examples that nanoscale-precision biotemplating is able to produce uncommon mechanical properties as well as actuating behavior, resembling to some extent the properties of the original natural templates. We present and discuss mechanical testing data showing for the first time that nanometer-precision biotemplating can lead to porous ceramic materials with deformation characteristics commonly associated with either biological or highly advanced technical materials...
October 13, 2016: Bioinspiration & Biomimetics
Maarja Kruusmaa, Guillaume Rieucau, José Carlos Castillo Montoya, Riho Markna, Nils Olav Handegard
So far, actuated fish models have been used to study animal interactions in small-scale controlled experiments. This study, conducted in a semi-controlled setting, investigates robot(5) interactions with a large wild-caught marine fish school (∼3000 individuals) in their natural social environment. Two towed fish robots were used to decouple size, tail motion and speed in a series of sea-cage experiments. Using high-resolution imaging sonar and sonar-video blind scoring, we monitored and classified the school's collective reaction towards the fish robots as attraction or avoidance...
October 6, 2016: Bioinspiration & Biomimetics
Viraj G Damle, Rubin Linder, Xiaoda Sun, Nicholas Kemme, Lucas C Majure, Konrad Rykaczewski
Many varieties of the cabbage family have leaves covered with superhydrophobic epicuticular wax, which provides them with self-cleaning characteristics. Since the wax also lowers insect adhesion, rinsing of the leaves with water should be an effective way of removing the insects. Conversely, we report that superhydrophobicity of tuscan kale increases resistance of aphids to hydrodynamic removal. The exterior surface of the insects is also superhydrophobic and acts as an extension of the leaf's surface. As a result even at moderate impact velocities impinging water drops cannot penetrate under the pests...
October 3, 2016: Bioinspiration & Biomimetics
C Abels, A Qualtieri, M De Vittorio, W M Megill, F Rizzi
To enhance today's artificial flow sensing capabilities in aerial and underwater robotics, future robots could be equipped with a large number of miniaturized sensors distributed over the surface to provide high resolution measurement of the surrounding fluid flow. In this work we show a linear array of closely separated bio-inspired micro-electro-mechanical flow sensors whose sensing mechanism is based on a piezoresistive strain-gauge along a stress-driven cantilever beam, mimicking the biological superficial neuromasts found in the lateral line organ of fishes...
June 2016: Bioinspiration & Biomimetics
Ulrich Tritschler, Igor Zlotnikov, Peter Fratzl, Helmut Schlaad, Simon Grüner, Helmut Cölfen
Bio-inspired Laponite (clay)-liquid crystal (LC) polymer composite materials with high clay fractions (>80%) and a high level of orientation of the clay platelets, i.e. with structural features similar to the ones found in natural nacre, have been shown to exhibit a promising behavior in the context of reduced oxygen transmission. Key characteristics of these bio-inspired composite materials are their high inorganic content, high level of exfoliation and orientation of the clay platelets, and the use of a LC polymer forming the organic matrix in between the Laponite particles...
June 2016: Bioinspiration & Biomimetics
M Percin, B W van Oudheusden, G C H E de Croon, B Remes
The study investigates the aerodynamic performance and the relation between wing deformation and unsteady force generation of a flapping-wing micro air vehicle in hovering flight configuration. Different experiments were performed where fluid forces were acquired with a force sensor, while the three-dimensional wing deformation was measured with a stereo-vision system. In these measurements, time-resolved power consumption and flapping-wing kinematics were also obtained under both in-air and in-vacuum conditions...
June 2016: Bioinspiration & Biomimetics
Rodolphe J Gentili, Hyuk Oh, Alissa V Kregling, James A Reggia
The human hand's versatility allows for robust and flexible grasping. To obtain such efficiency, many robotic hands include human biomechanical features such as fingers having their two last joints mechanically coupled. Although such coupling enables human-like grasping, controlling the inverse kinematics of such mechanical systems is challenging. Here we propose a cortical model for fine motor control of a humanoid finger, having its two last joints coupled, that learns the inverse kinematics of the effector...
June 2016: Bioinspiration & Biomimetics
R Penta, K Raum, Q Grimal, S Schrof, A Gerisch
UNLABELLED: Recent experimental data revealed a stiffening of aged cortical bone tissue, which could not be explained by common multiscale elastic material models. We explain this data by incorporating the role of mineral fusion via a new hierarchical modeling approach exploiting the asymptotic (periodic) homogenization (AH) technique for three-dimensional linear elastic composites. We quantify for the first time the stiffening that is obtained by considering a fused mineral structure in a softer matrix in comparison with a composite having non-fused cubic mineral inclusions...
June 2016: Bioinspiration & Biomimetics
Ulrich Tritschler, Helmut Cölfen
Designing bio-inspired, multifunctional organic-inorganic composite materials is one of the most popular current research objectives. Due to the high complexity of biocomposite structures found in nacre and bone, for example, a one-pot scalable and versatile synthesis approach addressing structural key features of biominerals and affording bio-inspired, multifunctional organic-inorganic composites with advanced physical properties is highly challenging. This article reviews recent progress in synthesizing organic-inorganic composite materials via various self-assembly techniques and in this context highlights a recently developed bio-inspired synthesis concept for the fabrication of hierarchically structured, organic-inorganic composite materials...
June 2016: Bioinspiration & Biomimetics
Michael Kappl, Farzaneh Kaveh, W Jon P Barnes
Tree frogs have become an object of interest in biomimetics due to their ability to cling to wet and slippery surfaces. In this study, we have investigated the adhesion and friction behavior of toe pads of White's tree frog (Litoria caerulea) using atomic force microscopy (AFM) in an aqueous medium. Facilitating special types of AFM probes with radii of ∼400 nm and ∼13 μm, we were able to sense the frictional response without damaging the delicate nanopillar structures of the epithelial cells. While we observed no significant adhesion between both types of probes and toe pads in wet conditions, frictional forces under such conditions were very pronounced and friction coefficients amounted between 0...
June 2016: Bioinspiration & Biomimetics
Victoria A Webster, Emma L Hawley, Ozan Akkus, Hillel J Chiel, Roger D Quinn
In robotics, there is a need for small scale, compliant actuators for use in medical applications or minimally invasive environmental monitoring. Biohybrid devices offer one solution to this need by using muscle cells to actuate compliant scaffolds. Such devices typically use biocompatible synthetic polymers as compliant scaffolds, which require additional processing steps to promote cellular alignment and attachment. Instead, electrocompacted and aligned collagen (ELAC) can be used as a completely organic scaffold, requiring no additional processing steps, with alignment being innately promoted by the topography...
June 2016: Bioinspiration & Biomimetics
Olivier Poncelet, Guillaume Tallier, Sébastien R Mouchet, André Crahay, Jonathan Rasson, Ratan Kotipalli, Olivier Deparis, Laurent A Francis
The unique architecture of iridescent Morpho butterfly scales is known to exhibit different optical responses to various vapours. However, the mechanism behind this phenomenon is not fully quantitatively understood. This work reports on process developments in the micro-fabrication of a Morpho-inspired photonic structure in atomic layer deposited (ALD) materials in order to investigate the vapour optical sensitivity of such artificial nanostructures. By developing recipes for dry and wet etching of ALD oxides, we micro-fabricated two structures: one combining Al2O3 and TiO2, and the other combining Al2O3 and HfO2...
June 2016: Bioinspiration & Biomimetics
Alwina Lübke, Joachim Enax, Karolin Wey, Helge-Otto Fabritius, Dierk Raabe, Matthias Epple
Synthetic composite materials that mimic the structure and composition of mammalian tooth enamel were prepared by mixing fluoroapatite rods (diameter 2-3 μm, thickness about 0.5 μm) and methylmethacrylate (MMA), followed by polymerization either during or immediately after ultracentrifugation, using either a tertiary amine/radical initiator for polymerization at room temperature or a radical initiator for thermal polymerization. This led to mineral-rich composites (mineral content between 50 and 75 wt%). To enhance the mechanical stability and the interaction between fluoroapatite and polymer matrix, small amounts of differently functionalized MMA monomers were added to the co-monomer mixture...
June 2016: Bioinspiration & Biomimetics
Sung-Hyuk Song, Min-Soo Kim, Hugo Rodrigue, Jang-Yeob Lee, Jae-Eul Shim, Min-Cheol Kim, Won-Shik Chu, Sung-Hoon Ahn
This paper presents a biomimetic turtle flipper actuator consisting of a shape memory alloy composite structure for implementation in a turtle-inspired autonomous underwater vehicle. Based on the analysis of the Chelonia mydas, the flipper actuator was divided into three segments containing a scaffold structure fabricated using a 3D printer. According to the filament stacking sequence of the scaffold structure in the actuator, different actuating motions can be realized and three different types of scaffold structures were proposed to replicate the motion of the different segments of the flipper of the Chelonia mydas...
June 2016: Bioinspiration & Biomimetics
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