Artificial muscle actuators that can exchange information

convert energy and actuate by mimicking natural muscles have been the focus of developing new materials. Smart polymer exhibiting shape changes in response to environmental stimuli is an excellent candidate for fabricating artificial muscles which have wide-ranging adaptations in robots and the intelligent mechanical system

thus being an important branch of muscle-like actuator investigations. In this review

we mainly summary the recent progress in electromechanical polymer artificial muscles materials including electrostatic actuation

electrothermal actuation

and moisture/relative humidity actuation. Key factors that may affect the actuation process are discussed in order to shed light on possible future research of artificial muscles materials.