The Venus Flytrap as a model for a biomimetic material with built-in sensors and actuators

In the present paper a model is presented for the dynamic response of a family (Droseraceae) of carnivorous plants such as the Venus Flytrap (Dionaea Muscipula Ellis) and the Waterwheel Plant (Aldrovanda Vesiculosa) to external dynamic disturbances. The goal of the present investigation is to apply such modelling to the molecular design of biomimetic materials with sensors and actuators. In modelling the dynamic response of such plants (or their flowers, to be exact) to external disturbances it is worth noting that these plants are capable of trapping and capturing their prey, usually small insects and flies, by the stimulation of a number of built-in trigger hairs or whisker-type sensors, which may be electro-elastic. The trapping and capturing action is quite muscular in the sense that, for example in the case of the Venus Flytrap, the flower, which is in the form of twin-lobed leaf blades closes quite quickly, upon stimulation of its trigger hairs, to trap the prey. These petals or valves are normally held ajar like an open spring trap. A victim entering the compass of the valves trips a trigger mechanism, whereupon the valves snap together with often surprising speed like a pair of jaws, and the victim is securely held within. The Venus Flytrap and Waterwheel Plant are closely related, though the former is terrestrial while the latter is aquatic. They belong to the same family as the Sundews (Droseraceae). The purpose of the present paper is to present a model for such intelligent structures with built-in sensors and muscular actuators in the hope of being able to fabricate similar intelligent materials (biomimetics) and intelligent structures for practical applications. Another remarkable property of the Venus Flytrap is that it is indeed possible to spring the trap without touching the trigger hairs — by repeated rubbing or scratching of the surface of the lobes for example — but the insect always does so by touching one or more trigger hairs. Based on a number of experimental observations in our laboratory we present a model for sensing and actuation of the Venus Flytrap. Our model is based on redistribution of ions and in particular Ca2+ and H+ ions in the tissue volumes. Generation of action potential simulation of trigger whiskers creates an ionic membrane type depolarization wave that propagates throughout the flower tissues.