Biomimetic robotic Venus flytrap

Abstract
The work described in this paper is a novel design of a robotic Venus flytrap (VFT) (Dionaea
muscipula Ellis) by means of ionic polymeric metal composite (IPMC) artificial muscles as
distributed nanosensors and nanoactuators. Rapid muscular movements in carnivorous plants,
such as VFT, which are triggered by antenna-like sensors (trigger hair), present a golden key to
study distributed biomolecular motors. Carnivorous plants, such as VFT, possess built-in
intelligence (trigger hairs), as a strategy to capture prey, that can be turned on in a controlled
manner. In the case of the VFT, the prey that is lured by the sweet nectar in the VFT pair of
jaw-like lobes has to flip and move the trigger hairs, which are colorless, bristle-like and
pointed. The dynamically moved trigger hairs then electro-elastically send an electric signal to
the internal ions in the lobe to migrate outwardly for the jaw-like lobes to close rapidly to
capture the prey. The manner in which the VFT lobes bend inward to capture the prey shows a
remarkable similarity with typical IPMCs bending in an electric field. Furthermore, the
mechano-electrical sensing characteristics of IPMCs also show a remarkable resemblance to
mechano-electrical trigger hairs on the lobes of the VFT. The reader is referred to a number of
papers in connection with sensing and actuation of IPMCs in particular. Thus, one can
integrate IPMC lobes with a common electrode in the middle of one end of the lobes to act like
a spine and use IPMC bristles as trigger finger to sense the intrusion of a fly or insect to send a
sensing signal to a solid state relay which then triggers the actuation circuit of the IPMC lobes
to rapidly bend toward each other and close. The two lobes, which form the trap, are attached
to the midrib common electrode which is conveniently termed the spine. The upper surface of
each lobe is dished, and spaced along the free margins of the lobes with some 15–20
prong-like teeth . These are tough and pointed, and are inclined at an inward angle so that
when the trap is sprung shut they will interlock. We have been experimenting with the VFT
closing of its jaw-like lobes that close in about 0.3 s and have gained a lot of knowledge to
report on the ionic and electrical mechanisms involved in the operation of such intelligent
distributed biomolecular motors.

http://iopscience.iop.org/1748-3190/6/4/046004/pdf/1748-3190_6_4_046004.pdf

More about Venus flytrap!

Energetics and forces of the Dionaea muscipula trap closing
Alexander G. Volkov and coworkers


Abstract

The Venus flytrap is the most famous carnivorous plant. The electrical stimulus between a midrib and a lobe closes the Venus flytrap upper leaf in 0.3 s without mechanical stimulation of trigger hairs. Here we present results for direct measurements of the closing force of the trap of Dionaea muscipula Ellis after mechanical or electrical stimulation of the trap using the piezoelectric thin film or Fuji Prescale indicating sensor film. The closing force was 0.14 N and the corresponding pressure between rims of two lobes was 38 kPa. We evaluated theoretically using the Hydroelastic Curvature Model and compared with experimental data velocity, acceleration and kinetic energy from the time dependencies of distance between rims of lobes during the trap closing. The Charge Stimulation Method was used for trap electrostimulation between the midrib and lobes. From the dependence of voltage between two Ag/AgCl electrodes in the midrib and one of the lobes, we estimated electrical charge, current, resistance, electrical energy and electrical power dependencies on time during electrostimulation of the trap.

Journal of Plant Physiology
Volume 169, Issue 1, 1 January 2012, Pages 55-64 

Complete hunting cycle of Dionaea muscipula: Consecutive steps and their electrical properties
Alexander G. Volkov and coworkers

Abstract
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.

Journal of Plant Physiology
Volume 168, Issue 2, 15 January 2011, Pages 109-120 

A novel form of myrmecotrophic mutualism

Setting the trap: cleaning behaviour of Camponotus schmitzi ants increases long-term capture efficiency of their pitcher plant host, Nepenthes bicalcarata

There are more than 600 species of plants worldwide known to capture small animals to obtain extra nutrition. One species in the tropical peat swamp forests of Borneo, the fanged pitcher plant, Nepenthes bicalcarata, not only traps insects, but also provides a home for the highly specialised species of carpenter ant, Camponotus schmitzi.
The plant's leaves are specially modified as cup-shaped insect traps. These pitchers produce sweet nectar to lure insects; slippery surfaces on the upper rim of the pitcher cause them to slide and fall into the pitchers where they are held and digested by the fluid within. Amazingly, the resident Camponotus schmitzi ants appear to be completely immune to the traps; they nest inside hollow stems of the plant, feed on the traps' nectar without falling and "steal" prey from the pitchers by swimming and diving in the digestive fluid.
Many "ant-plants" have evolved close relationships with ants, which can provide protection from leaf-feeding insects and fungal attack, in return for nesting space and food rewards. The fanged pitcher plant is the only known insect-eating ant-plant. Despite a number of studies since its discovery in the late 19th century, it has been unclear what, if anything, the plant gains from the association.
We discovered that the Camponotus schmitzi ants thoroughly clean the slippery trapping surface of their host plant. Even when strongly contaminated by cornflour, the ants' cleaning restored the slipperiness of the trap within a few days. By cleaning the slippery trap, the ants ensure it is maintained in good condition and can continue to capture insects for much longer than if the ants are absent. Indeed, the pitchers of Nepenthes bicalcarata can live and remain active three times longer than pitchers from other Nepenthes species in the area. So, by maintaining the traps of the plant, the ants do more than just clean: they help the plant to be well-fed.

Source:  http://www.functionalecology.org