Study Of A Biological Actuator And Sensor: The Mimosa Pudica

Abstract

The Mimosa Pudica is an action plant that closes its leaves when given a stimulus. The plant integrates both sensing and actuating mechanisms, and the distinctive motion is about a hinge-like point, the pulvinus, making the characterization of the motion attractive. In this project, experiments were set up to measure the characteristics of the plants in the goal to estimate the possibility to produce micro-actuator based on a similar principle. The signal speed, the sensitivity, the actuator speed, the power, the torque produced by the plant were measured by using different sensors. The results showed that the torque is dependent on the diameter of the pulvinus and that actuator could reach a top angular velocity of 1 rad/s. We developed a phenomenological model to describe the behavior of the plant that could match experimental results and propose an original physical description of the mechanism inside the plant by considering a phase transition behavior instead of the classical ion channel model. Finally, the plant actuator energy density is also compared with other known micro-actuators and the possibility to use the plant as a micro-actuator is discussed.