Bioinspired Bistable Dielectric Elastomer Actuators: Programmable Shapes and Application as Binary Valves

Nature has plenty of imitable examples of bistable thin structures that can actuate in response to mechanical and environmental stimuli, such as touch, light, and moisture. Scientists and engineers have used these as models to develop real-world systems with enhanced shape stability, energy efficiency, and power output. The bistable leaf of the Venus Flytrap (VFT) has a uniquely simple structure that enables exquisite actuation to trap the prey instantly. In this study, we present a strategy, inspired and derived from the VFT, which incorporates dielectric elastomer (DE) layers in a bistable actuator capable of reversible snapping through electrical stimulation. The trilayered laminated actuator is composed of two prestrained layers and a strain-limiting middle layer. The balance between elastic energy and bending energy of the laminates results in bistable shapes. We explore a broad design space of the bistable architecture through analysis and experiments to validate the fabrication parameters. The rapid snap-through between the two stable configurations is activated by a voltage pulse applied on the DE layers that change the laminate's strain field. Whereas a high electric field is used as the actuation trigger, the self-stabilization characteristic of the bistable structure obviates the need for continuous voltage supply. Finally, we recommended a new method of flow control by modulating porosity on curved surfaces through operating bistable dielectric elastomer actuators as binary valves.