Thomas Speck

Thomas Speck
University of Freiburg | Albert-Ludwigs-Universität Freiburg · Botanical Gardens

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815
Publications
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9,520
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Publications

Publications (815)
Article
Full-text available
Biomechanics The snap traps of the (in)famous carnivorous Venus flytrap (Dionaea muscipula) exhibit different snapping and reopening mechanics during their hunting cycle. The intrinsic biomechanics underlying leaf movement in these plants serve as promising concept generators for the development of versatile biomimetic compliant systems for e.g., s...
Article
Full-text available
The field of plant-inspired robotics is based on principles underlying the movements and attachment and adaptability strategies of plants, which together with their materials systems serve as concept generators. The transference of the functions and underlying structural principles of plants thus enables the development of novel life-like technical...
Article
Full-text available
The opening and closing of pine cones is based on the hygroscopic behavior of the individual seed scales around the cone axis, which bend passively in response to changes in environmental humidity. Although prior studies suggest a bilayer architecture consisting of lower actuating (swellable) sclereid and upper restrictive (non‐ or lesser swellable...
Article
Full-text available
Auxetic metamaterials exhibit a negative Poisson's ratio and superior energy dissipation characteristics under dynamic (impact) loading. This makes them attractive candidates for components that provide crash or impact protection (such as crumple zones) in automotive and aerospace applications. However, little prior work on the effect of boundary c...
Article
Full-text available
Every ecosystem shows multiple levels of species interactions, which are often difficult to isolate and to classify regarding their specific nature. For most of the observed interactions, it comes down to either competition or consumption. The modes of consumption are various and defined by the nature of the consumed organism, e.g., carnivory, herb...
Article
Full-text available
Fast snapping in the carnivorous Venus flytrap (Dionaea muscipula) involves trap lobe bending and abrupt curvature inversion (snap‐buckling), but how do these traps reopen? Here, the trap reopening mechanics in two different D. muscipula clones, producing normal‐sized (N traps, max. ≈3 cm in length) and large traps (L traps, max. ≈4.5 cm in length)...
Article
During the evolution of land plants many body plans have been developed. Differences in the cross-sectional geometry and tissue pattern of plant axes influence their flexural rigidity, torsional rigidity and the ratio of both of these rigidities, the so-called twist-to-bend ratio. For comparison, we have designed artificial cross-sections with vari...
Article
Full-text available
This study analyzes the impact behavior of lemon peel (Citrus x limon) and investigates its functional morphology compared with the anatomy of pomelo peel (Citrus maxima). Both fruit peels consist mainly of parenchyma structured by a density gradient. In order to characterize the lemon peel, both energy dissipation and transmitted force are determi...
Article
The ectoparasitic lifestyle of the Mediterranean medicinal leech (Hirudo verbana) requires reliable functioning of its attachment organs (i.e. anterior and posterior suction discs) on multiple habitat- and host-specific surfaces under both normal and shear stresses. In addition to some intrinsic properties of the attachment devices, however, only a...
Article
Full-text available
The European Mistletoe (Viscum album) is an epiphytic hemiparasite that attaches to its host by an endophytic system. Two aspects are essential for its survival: the structural integrity of the host-parasite interface must adapt to host growth and the functional integrity of the interface must be maintained during ontogeny and under mechanical stre...
Article
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Soft robotics aims at creating systems with improved performance of movement and adaptability in unknown, challenging, environments and with higher level of safety during interactions with humans. This Roadmap on Soft Robotics covers selected aspects for the design of soft robots significantly linked to the area of multifunctional materials, as the...
Chapter
The chapter is open access and can be downloaded for free at the editor house: https://www.degruyter.com/document/doi/10.1515/9783110562064/html
Article
Plants are exposed to various environmental stresses. To mechano-stimulation, such as wind and touch, leaves immediately respond by bending and twisting or acclimate over a longer time period by thigmomorphogenetic changes of mechanical and geometrical properties. We selected the peltate leaves of Pilea peperomioides for a comparative analysis of m...
Article
Full-text available
The plant cuticle is a multifunctional barrier that separates the organs of the plant from the surrounding environment. Cuticular ridges are microscale wrinkle-like cuticular protrusions that occur on many flower and leaf surfaces. These microscopic ridges can help against pest insects by reducing the frictional forces experienced when they walk on...
Article
Full-text available
Arboreal habitats are characterized by a complex three-dimensional array of branches that vary in numerous characteristics, including incline, compliance, roughness, and diameter. Gaps must often be crossed, and this is frequently accomplished by leaping. Geckos bearing an adhesive system often jump in arboreal habitats, although few studies have e...
Article
Full-text available
From a mechanical viewpoint, petioles of foliage leaves are subject to contradictory mechanical requirements. High flexural rigidity guarantees support of the lamina and low torsional rigidity ensures streamlining of the leaves in wind. This mechanical trade-off between flexural and torsional rigidity is described by the twist-to-bend ratio. The sa...
Article
Full-text available
During biological evolution, plants have developed a wide variety of body plans and concepts that enable them to adapt to changing environmental conditions. The trade-off between flexural and torsional rigidity is an important example of sometimes conflicting mechanical requirements, the adaptation to which can be quantified by the dimensionless tw...
Article
Full-text available
The Opuntioideae include iconic cacti whose lateral branch–branch junctions are intriguing objects from a mechanical viewpoint. We have compared Opuntia ficus-indica, which has stable branch connections, with Cylindropuntia bigelovii, whose side branches abscise under slight mechanical stress. To determine the underlying structures and mechanical c...
Preprint
Water fleas of the family Daphniidae are keystone species in many lentic ecosystems and, as most abundant filter feeders, link the primary production to higher trophic levels. As a response to the high predatory pressures, water fleas have evolved a range of defenses, including inducible defenses against animal predators. Here we show in Ceriodaphn...
Article
The climbing passionflower Passiflora discophora features branched tendrils with multiple adhesive pads at their tips allowing it to attach to large diameter supports and to flat surfaces. We conducted tensile tests to quantify the performance of this attachment system. We found that the force at failure varies with substrate, ontogenetic state (tu...
Article
Full-text available
During the last few decades, biomimetics has attracted increasing attention in both basic and applied research and in various fields of industry and building construction [...]
Article
Premise: Among the sophisticated trap types in carnivorous plants, the underground eel-traps of corkskrew plants (Genlisea spp., Lentibulariaceae) are probably the least understood in terms of their functional principle. Here, we provide a detailed analysis of structural and hydraulic features of G. hispidula traps, contributing to the ongoing deb...
Data
Supporting Information For In Situ Investigation of Adhesion Mechanisms on Complex Microstructured Biological Surfaces
Article
A current trend observed in the Anthropocene is the search for bioinspired solutions. Since it became possible to change the quality of the boundary between living and technical systems, more and more life-like technical products have been developed in recent years. Using five plant-inspired developments of motile technical systems for architecture...
Article
Full-text available
The European mistletoe (Viscum album) is a dioecious epiphytic evergreen hemiparasite that develops an extensive endophyte enabling the absorption of water and mineral salts from the host tree, whereas the exophytic leaves are photosynthetically active. The attachment mode and host penetration are well studied, but little information is available a...
Article
Full-text available
Biomimetics is an interdisciplinary field of science that deals with the analysis and systematic transfer of biological insights into technical applications. Moreover, the development of biomimetic products helps to improve our understanding of biological concept generators (reverse biomimetics). What does this mean for the education of kindergarte...
Article
Plants translate wind energy into leaf fluttering and branch motion by reversible tissue deformation. Simultaneously, the plant's outermost structure, i.e., the dielectric cuticula, and the inner ion-conductive tissue, can be used to convert mechanical vibration energy into electricity by surface contact electrification and electrostatic induction....
Article
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This paper presents a material programming approach for designing 4D‐printed self‐shaping material systems based on biological role models. Plants have inspired numerous adaptive systems that move without using any operating energy; however, these systems are typically designed and fabricated in the form of simplified bilayers. This work introduces...
Article
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The technical transfer of plant movement principles offers vast potentials for the development of novel, autonomously actuated structures. Article number 2100411 by Tiffany Cheng, Achim Menges, and co-workers introduces a design and material programming approach for 4D-printing adaptive material systems through a case study of biomimetic design. Ba...
Article
Friction on biological-like micro-structured surfaces has been investigated. Using a bio-replication technique, complex surface morphologies found in plant leaves were transferred onto viscoelastic substrates. A nano-indenter was modified, permitting in-situ real contact junctions visualisation. Effects of applied normal load and sliding speed on t...
Article
Full-text available
The abstraction and implementation of plant movement principles into biomimetic compliant systems are of increasing interest for technical applications, e.g., in architecture, medicine, and soft robotics. Within the respective research and development approaches, advanced methods such as 4D printing or 3D-braiding pultrusion are typically used to g...
Article
Full-text available
Through their anisotropic cellular mesostructure and differential swelling and shrinking properties, hygroscopic plant structures move in response to changes in the environment without consuming metabolic energy. When the movement is choreographed in sequential time steps, either in individual structures or with a coordinated interplay of various s...
Article
Full-text available
In the field of soft robotics, pneumatic elements play an important role due to their sensi-tive and adaptive behavior. Nevertheless, the rapid prototyping of such actuators is still challenging since conventional 3D printers are not designed to fabricate airtight objects or to specify their bending behavior by combining materials of different stif...
Article
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Since most plant movements take place through an interplay of elastic deformation and strengthening tissues, they are thus ideal concept generators for biomimetic hingeless actuators. In the framework of a biomimetic biology push process, we present the transfer of the functional movement principles of hollow tubular geometries that are surrounded...
Article
Full-text available
Although both the petiole and lamina of foliage leaves have been thoroughly studied, the transition zone between them has often been overlooked. We aimed to identify objectively measurable morphological and anatomical criteria for a generally valid definition of the petiole–lamina transition zone by comparing foliage leaves with various body plans...
Article
Learning from living organisms has emerged from a mainly curiosity‐driven examination, where helpful functions of biological structures have been copied, into systematic biomimetic approaches that transfer a targeted function and its underlying principles from the biological model to a technical product. Plant biomimetics is based on functional mor...
Chapter
Suctions cups are widely used in industrial applications for handling various goods. In the animal kingdom, a multitude of analogous structures has evolved, e.g. in octopuses and leeches, which allow the respective organisms to securely attach and detach from various substrates. To date, the biological suction cups outperform their technical counte...
Chapter
In nature and technology, liquids are transported and distributed in a directed manner via pumping systems. Technical pumps often show signs of wear due to abrasion on moving parts, erosion and liquid contamination, which can lead to damage and unwanted noise. Innovative pump systems for electro mobility applications should have particularly low no...
Article
In the course of biological evolution, plant stems have evolved mechanical properties and an internal structure that makes them resistant to various types of failure. The mechanisms involved during damage development and failure in bending are complex and incompletely understood. The work presented builds on a theoretical framework outlined by Enno...
Article
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Comprising ca. 28,000, species the Orchidaceae constitute one of the most species-rich plant families. Orchids differ from other monocotyledons i.a., in the formation of so-called pollinaria, which are entities consisting of pollen grains aggregated into compact pollinia and accessory structures, a viscidium and mostly also a pollinium stalk. The v...
Book
The chapter is open access and can be downloaded for free at the editor house: https://www.degruyter.com/document/doi/10.1515/9783110562064/html
Chapter
Biohybrid approaches harnessing living systems and biological tissue to accumulate electrical energy have potential to contribute green and autonomous power sources. We recently discovered that the cuticle-cellular tissue bilayer in higher plant leaves functions as an integrated triboelectric generator that is capable of converting mechanical stimu...
Chapter
A rising trend can be observed in robot development towards the usage of flexible materials, whose properties resemble their biological counterparts. This way of design promises machines that are more adaptive, energy efficient and cost effective. One of the biggest challenges in this growing research field is the fabrication of functional elements...
Preprint
Full-text available
During biological evolution, plants have developed a wide variety of body plans and concepts that enable them to react or adapt to changing environmental conditions. Their morphological-anatomical and mechanical adaptations to conflicting conditions are especially interesting. A good example is the trade-off between flexural and torsional rigidity,...
Article
Full-text available
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...
Article
Full-text available
Premise Because of their own weight and additional wind forces, plants are exposed to various bending and torsional loads that sometimes require contradictory structural characteristics and mechanical properties. The resulting trade‐off between flexural and torsional rigidity can be quantified and compared using the dimensionless twist‐to‐bend rati...
Conference Paper
Vacuum handling is a widespread technology in automated production systems for gripping of workpieces. Unfortunately, this solution accounts for a considerable share of industrial energy consumption. This consumption is mainly due to the losses in the involved steps like air compression, distribution, vacuum generation and gripper suction. However,...
Article
Nodes are interfaces between stems and leaves. Vascular bundles originate here and elongate into leaves and internodes. In Marantaceae, internodal bundles are highly diverse, including inverted bundles in the climbing genus Haumania. The objective of this paper is to characterize bundle forms, their position across the stem and their connection to...
Article
Background and aims: The endangered aquatic carnivorous waterwheel plant (Aldrovanda vesiculosa) catches prey with 3-5 mm long underwater snap-traps. Trapping lasts 10-20 ms, which is 10-fold faster than in its famous sister, the terrestrial Venus flytrap (Dionaea muscipula). After successful capture, the trap narrows further and forms a 'stomach'...
Article
Within the Aizoaceae, the genus Delosperma exhibits a vast diversification colonizing various ecological niches in South-Africa and showing evolutionary adaptations to dry habitats that might include rapid self-sealing. Leaves of Delosperma react to external damage by the bending or contraction of the entire leaf until wound edges are brought into...
Article
Full-text available
Applications in remote inspection and medicine have motivated the recent development of innovative thin, flexible-backboned robots. However, such robots often experience difficulties in maintaining their intended posture under gravitational and other external loadings. Thin-stemmed climbing plants face many of the same problems. One highly effectiv...
Article
Recently, plant surfaces have attracted attention given their fascinating functionalities, particularly adhesive properties, which largely result from their diverse surface structuring. This paper contributes to the adhesion mechanics investigation on complex biological surface morphologies. Elastomeric replica of three different plant leaves, comp...