Analytic modeling and experiments of tri-layer, electro-thermal actuators for thin and soft robotics

By bonding micron-thin polymer layers with an electrically conductive layer, we can utilize the bi-metal effect to create a soft, thin, electrically-activated thermal actuator (ETA), which can be used in printed soft robots. Using ETAs have shown quite remarkable potential in previous works. However, to reveal their true capabilities, we propose to utilize a multi-layered ETA. In this research, we analytically model the actuator for both the bi-, and more importantly, tri-layer ETAs and analyze their behavior. We develop a simple intuitive model to better explain the benefits of the tri-layer actuation and to estimate the optimal design parameters. We verify the models by conducting an experiment to measure the curvature change for different third layer thicknesses. The experiments show a significant improvement in performance of the tri-layer actuators and display a good fit between the simplified analytic model and the full model.