Model to Model: Understanding the Venus Flytrap Snapping Mechanism and Transferring it to a 3D-printed Bistable Soft Robotic Demonstrator

The Venus flytrap (Dionaea muscipula) does not only serve as the textbook model for a carnivorous plant, but also has long intrigued both botanists and engineers with its rapidly closing leaf trap. The trap closure is triggered by two consecutive touches of a potential prey, after which the lobes rapidly switch from their concave open-state to their convex close-state and catch the prey within 100-500 ms after being triggered. This transformation from concave to convex is initiated by changes in turgor pressure and the release of stored elastic energy from prestresses in the concave state, which accelerate this movement, leading to inversion of the lobes bi-axial curvature. Possessing two low-energy states, the leaves can be characterized as bistable systems. With our research, we seek to deepen the understanding of Venus flytrap motion mechanics and apply its principles to the design of an artificial bistable lobe actuator. We identified geometrical characteristics, such as dimensional ratios and the thickness gradient in the lobe, and transferred these to two 3D-printed bistable actuator models. One actuator parallels the simulated geometry of a Venus flytrap leaf, the other is a lobe model designed with CAD. Both models display concave-convex bi-stability and snap close. These demonstrators are the first step in the development of an artificial Venus flytrap that mimics the mechanical behavior of the biological model and can be used as a soft fast gripper.