Learning from Self‐Sealing Deformations of Plant Leaves: The Biomimetic Multilayer Actuator

Abstract

During evolution, plants have developed various functional principles for sealing and healing wounds. Prime examples are succulent leaves of Delosperma cooperi that seal external injuries within 60 min. Cross sections of intact leaves show a centripetal multilayer structure consisting of five tissues alternately under tensile and compressive prestress. Injuries destroy this mechanical equilibrium causing a deformation of the entire leaf until a new equilibrium is reached, and the wound edges meet, thereby sealing the fissure. Following this functional principle of D. cooperi leaves, a planar three‐layer materials system consisting of a sheet of shape memory polymer (SMP) with programmed temporary geometry sandwiched between two polydimethylsiloxane (PDMS) sheets is developed. After the individual sheets are bonded at room temperature, the application of heat treatment without mechanical constraints results in a prestressed multilayer system. The damage‐triggered bending behavior of the three‐layer system is described by means of an analytical model and feasibility tests establishing the self‐sealing functionality of the system. Thus, a biomimetic materials system with a self‐sealing function within the framework of a biomimetic biology push process is developed. However, the discussion herein has gone beyond the biological model, because the self‐sealing three‐layer materials system can additionally serve as an actuator.

Le biomimétisme, une voie à explorer pour le Génie des procédés ?

“…-Maillots de bain inspirés de la peau de requin pour réduire le frottement de l'eau ; -Un train à vapeur qui simule le bec du martin-pêcheur ; -Des alternatives plastiques résistantes et biodégradables inspirées de la cuticule des insectes ; -Ventilateurs basés sur la queue de la seiche ; -Radar basé sur l'écholocation des chauves-souris ; -Des panneaux solaires photovoltaïques qui imitent le mouvement du tournesol ; -Des chaussures qui imitent les pieds du gecko ; -Sac à dos en forme de tatou ; -Velcro bio-inspiré par les chardons ; -Une canne pour aveugles qui copie l'écholocation des chauves-souris ; -Des actionneurs à partir de feuilles (Becker et al, 2022) ; -Des textiles (Eadie et Ghosh, 2011).…”

Biomimetics in Botanical Gardens—Educational Trails and Guided Tours

“…The various repair principles are sources of inspiration for engineering materials with self-repairing functions. For example, the wound reaction of the ice plant Delosperma cooperi ( Figure 18 ) has been a model for a multi-layered actuator [ 51 ] and a polymer-based material with a shape memory effect that can heal cracks within 60 min [ 52 ].…”

“…The various repair principles are sources of inspiration for engineering materials with self-repairing functions. For example, the wound reaction of the ice plant Delosperma cooperi (Figure 18) has been a model for a multi-layered actuator [51] and a polymer-based material with a shape memory effect that can heal cracks within 60 min [52]. Plant movements are often overlooked because plants are tied to their location and because the movements of their parts are either too fast for the human eye (e.g., the trapping movements of carnivorous plants such as the Venus flytrap or bladderworts) or too slow (e.g., growth movements).…”

Bio‐Inspired Pressure‐Dependent Programmable Mechanical Metamaterial with Self‐Sealing Ability

“…Becker et al. [ 34 ] developed a biomimetic multilayer actuator with self‐sealing function. Inspired by the pre‐stresses in the Delosperma cooperi leaf, they developed a planar three‐layer material system with built‐in pre‐stresses.…”

“…After 120 minutes, mechanical properties (e.g., stress at break, tensile strain) are restored by more than 80%. Becker et al [34] developed a biomimetic multilayer actuator with self-sealing function. Inspired by the prestresses in the Delosperma cooperi leaf, they developed a planar three-layer material system with built-in pre-stresses.…”