Progress and Current Status of Materials and Properties of Soft Actuators

Abstract

In this chapter, brief history and current status of soft actuators made of various materials driven by different stimuli are described with typical references as milestones of the progress. The soft actuators originated from unique characteristics of cross-linked polymer gels for understanding their physical and chemical properties of dimensional changes and phase transitions induced by various environmental stimuli such as pH, salt, solvent, heat, light, and electric field. The ‘explosion’ of research and development of soft actuators in the 1990s extended over a variety of materials such as conductive polymers, elastomers, carbon nanotubes, and biomaterials, which had driven further progress in soft actuators not only from the fundamental viewpoint of basic science and materials chemistry and physics but also from the engineering viewpoint for the practical applications to light-weight, low-cost, no-noise, less-pollution, and high-efficiency micro- and macro-artificial muscles and soft robotic systems.