Simon Poppinga

Ultra-fast underwater suction traps

Carnivorous aquatic Utricularia species catch small prey animals using millimetre-sized underwater suction traps, which have fascinated scientists since Darwins early work on carnivorous plants. Suction takes place after mechanical triggering and is owing to a release of stored elastic energy in the trap body accompanied by a very fast opening and closing of a trapdoor, which otherwise closes the trap entrance watertight. The exceptional trapping speed—far above human visual perception—impeded profound investigations until now. Using high-speed video imaging and special microscopy techniques, we obtained fully time-resolved recordings of the door movement. We found that this unique trapping mechanism conducts suction in less than a millisecond and therefore ranks among the fastest plant movements known. Fluid acceleration reaches very high values, leaving little chance for prey animals to escape. We discovered that the door deformation is morphologically predetermined, and actually performs a buckling/unbuckling process, including a complete trapdoor curvature inversion. This process, which we predict using dynamical simulations and simple theoretical models, is highly reproducible: the traps are autonomously repetitive as they fire spontaneously after 5–20 h and reset actively to their ready-to-catch condition.

A methodology for transferring principles of plant movements to elastic systems in architecture

In architecture, kinetic structures enable buildings to react specifically to internal and external stimuli through spatial adjustments. These mechanical devices come in all shapes and sizes and are traditionally conceptualized as uniform and compatible modules. Typically, these systems gain their adjustability by connecting rigid elements with highly strained hinges. Though this construction principle may be generally beneficial, for architectural applications that increasingly demand custom-made solutions, it has some major drawbacks. Adaptation to irregular geometries, for example, can only be achieved with additional mechanical complexity, which makes these devices often very expensive, prone to failure, and maintenance-intensive.Searching for a promising alternative to the still persisting paradigm of rigid-body mechanics, the authors found inspiration in flexible and elastic plant movements. In this paper, they will showcase how todays computational modeling and simulation techniques can help to reveal motion principles in plants and to integrate the underlying mechanisms in flexible kinetic structures. By using three case studies, the authors will present key motion principles and discuss their scaling, distortion, and optimization. Finally, the acquired knowledge on bio-inspired kinetic structures will be applied to a representative application in architecture, in this case as flexible shading devices for double curved facades. Plant movements.Kinetic structures.Biomimetics.Facade shading.Compliant mechanisms.

Faster than their prey: new insights into the rapid movements of active carnivorous plants traps.

Plants move in very different ways and for different reasons, but some active carnivorous plants perform extraordinary motion: Their snap-, catapult- and suction traps perform very fast and spectacular motions to catch their prey after receiving mechanical stimuli. Numerous investigations have led to deeper insights into the physiology and biomechanics of these trapping devices, but they are far from being fully understood. We review concisely how plant movements are classified and how they follow principles that bring together speed, actuation and architecture of the moving organ. In particular, we describe and discuss how carnivorous plants manage to execute fast motion. We address open questions and assess the prospects for future studies investigating potential universal mechanisms that could be the basis of key characteristic features in plant movement such as stimulus transduction, post-stimulatory mechanical answers, and organ formation.

Catapulting Tentacles in a Sticky Carnivorous Plant

Among trapping mechanisms in carnivorous plants, those termed ‘active’ have especially fascinated scientists since Charles Darwin’s early works because trap movements are involved. Fast snap-trapping and suction of prey are two of the most spectacular examples for how these plants actively catch animals, mainly arthropods, for a substantial nutrient supply. We show that Drosera glanduligera, a sundew from southern Australia, features a sophisticated catapult mechanism: Prey animals walking near the edge of the sundew trigger a touch-sensitive snap-tentacle, which swiftly catapults them onto adjacent sticky glue-tentacles; the insects are then slowly drawn within the concave trap leaf by sticky tentacles. This is the first detailed documentation and analysis of such catapult-flypaper traps in action and highlights a unique and surprisingly complex mechanical adaptation to carnivory.

Trap diversity and evolution in the family Droseraceae

We review trapping mechanisms in the carnivorous flowering plant family Droseraceae (order Caryophyllales). Its members are generally known to attract, capture, retain and digest prey animals (mainly arthropods) with active snap-traps (Aldrovanda, Dionaea) or with active sticky flypaper traps (Drosera) and to absorb the resulting nutrients. Recent investigations revealed how the snap-traps of Aldrovanda vesiculosa (waterwheel plant) and Dionaea muscipula (Venus’ flytrap) work mechanically and how these apparently similar devices differ as to their functional morphology and shutting mechanics. The Sundews (Drosera spp.) are generally known to possess leaves covered with glue-tentacles that both can bend toward and around stuck prey. Recently, it was shown that there exists in this genus a higher diversity of different tentacle types and trap configurations than previously known which presumably reflect adaptations to different prey spectra. Based on these recent findings, we finally comment on possible ways for intrafamiliar trap evolution.

Abstraction of bio-inspired curved-line folding patterns for elastic foils and membranes in architecture

Today’s architectural foils and membranes amaze with their superior strength-toweight ratio and are often implemented as lightweight building envelopes or shading devices. Most claddings, however, are optimized for high tensile strength, which reduces the design possibilities to pre-stressed inflexible shapes. Only a few projects are exploring the potential inherent in the membrane’s low bending stiffness. Nowadays, new materials and manufacturing methods allow for customized pliability of semi-rigid thin-shell structures, which fully tap the potential of reversible elastic deformation. While this concept has hardly been used in architecture, convertible surfaces are rampant in nature. Therefore, the aim of this paper is to review in general how nature’s soft, flexible, and forceadaptive structures may inspire the development of technical membrane structures and outline their architectural potential in particular. Focusing on bio-inspired pliable systems that show distinct curved-line folding principles will be the framework for a close collaboration among architects, engineers, and biologists. Examining the flower opening of Ipomoea alba will clarify the drawbacks and opportunities of elastic kinematics. Therefore, the first part of the study will introduce this nocturnal flower, whose environmentally responsive petals adapt their geometry in a circadian rhythm. Morphological and anatomical analyses will secondly lead to a better understanding of their primarily

Plant movements as concept generators for deployable systems in architecture

Plants, apparently not capable of complex movements, have always fascinated scientists when proving the contrary. A multitude of movements in plants have been revealed, showing a broad spectrum of motion sequences and underlying principles. Interestingly, many of these movements show high elasticity and flexibility of the respective structures and allow reversible deformations. With the investigation of suitable biological role models and the use of new construction materials, such as fibre-reinforced polymers (FRPs), the authors are developing deployable technical structures without local hinges. In this presentation the first steps of the applied biomimetic working process are described: the selection of role models, investigation and basic abstraction of plant movements. An overall screening through the plant kingdom has led to a wide-ranged matrix comprising many different types of plant movements, which constitutes the basis for our investigations. We distinguish between autonomous and non-autonomous movements. Active autonomous movements are characterized by motor organs, e.g. pulvini driven by a change of turgor pressure. Passive autonomous movements occur due to changing physical circumstances, e.g. bending through desiccation. Non-autonomous movements are mostly reversible deformations caused by a release of stored elastic energy after an external trigger or by direct application of mechanical forces. In a case study we applied morphological and anatomical investigations on the valvular pollination

Elastic architecture: nature inspired pliable structures

At the interfaces of our mostly stationary architecture and surrounding nature we need to make constructions adaptable to ambient changes. Adaptability as a structural response to changing climate conditions, such as the intensity and direction of sun radiation, can be realised with deployable systems. These systems are often based on the combination of stiff compression members and soft tension members connected with hinges and rollers. Deployable systems in nature are often based on flexibility. This can be observed especially in plant movements. New construction materials such as fibre-reinforced polymers (FRP) can combine high tensile strength with low bending stiffness, allowing large elastic deformations. This may enable a completely new interpretation of convertible structures which work on reversible deformation, here referred to as elastic or pliable structures. In a current research project the kinematics for such systems are derived from certain applicable plant movements. This paper will focus on the biomimetic workflow used to develop elastic kinetic structures based on such movements. The abstraction and optimisation methods will be described from an engineering point of view, focusing on the technical approaches of converting the conceptual results of a first level abstraction into higher level abstractions and finally to physical design.

Biomimetic Deployable Systems in Architecture

The high elasticity of plant structures represents the basis of many plant movements and also allows for reversible deformations. By analyzing suitable biological role models and using new construction materials bio-inspired deployable technical structures without local hinges can be developed. The selection, investigation and basic abstraction of nastic plant movements are the first steps of the applied biomimetic working process. A broad screening of the plant kingdom has revealed a wide range of types of these movements, which can be distinguished in autonomous and non-autonomous movements. Active autonomous movements are driven by motor organs or cells, e.g. by a change of turgor pressure. Passive autonomous movements are typically caused by a change of the physical circumstances in cells or sub-cellular structures, e.g. movement caused by changes of humidity in cell walls. Non-autonomous movements are mostly reversible and occur due to a release of stored elastic energy after an external trigger or by application of mechanical forces. As these deformations show clearly defined actuating elements and mechanics, our investigation concentrates on the latter kinetic systems. Model plants are analyzed morphologically and biomechanically, e.g. by bending, tensile and pressure tests. In a close collaboration between biologists and engineers these kinetic systems are verified with the help of physical models, computer simulations and additional abstraction steps are performed which finally lead to technical applications in biomimetic deployable systems in architecture.

Fallenbewegungen fleischfressender Pflanzen

Langsame Pflanzenbewegungen laufen vornehmlich mit hydraulischen “Motoren” ab, d. h. die auftretenden Verformungen werden durch eine Verschiebung von Wasser zwischen Zellen und Geweben hervorgerufen. Vor allem bei großen und schnellen Strukturen (zum Beispiel den Schnappfallen der carnivoren Venusfliegenfalle) treten elastische Instabilitäten auf und beschleunigen den Bewegungsvorgang deutlich. Die bei den vorgestellten carnivoren Pflanzen zur Anwendung kommenden mechanischen “Tricks” lassen sich in abstrahierter Form mittels einfacher physikalischer Handmodelle veranschaulichen und tragen zum Verständnis der involvierten Prozesse bei.