Electromechanical bending behavior study of soft photocurable ionogel actuator using a new finite element method

Abstract

The photocurable ionogel actuator (PIA) is one of the most promising driving mechanisms for the future due to its extraordinary features such as its light weight, flexibility, low-energy consumption and ability to work in open air. However, before the benefits of PIA can be effectively exploited for applications, a mathematical model is required to enhance the understanding of the parameters influencing the actuator electromechanical bending behavior. In this work, a model based on the finite element method (FEM) for the electromechanical bending behavior of PIA is established. It is assumed that the PIA consists of one ionogel layer and two activated carbon electrode layers. With reference to its operational principles, an analogy is drawn between thermal strain and induced strain in the PIA due to the volume change of the activated carbon electrode layer, which is a coupled structural/thermal model and can be solved by FEM. The distribution of net charge in the activated carbon electrode layer is mimicked using temperature distribution, and the electromechanical coupling coefficient is mimicked using the thermal expansion coefficient. Compared with the traditional equivalent bimorph beam model, the proposed model can predict the distribution of the induced strain more exactly. On the basis of the model, experiments are carried out to investigate the impact of selected parameters on the tip displacement, electromechanical coupling coefficient and induced strain of the PIA. The voltage of the input signal, and three geometrical parameters, length, width, and thickness, of the PIA are selected in this work. The experimental and simulation results indicate that the voltage, length, and thickness show significant influence on the electromechanical bending behavior of the PIA, but the width does not. As a whole, these results can be beneficial for providing enhanced degrees of understanding, predictability and control of PIA performance.