Multi-Modal Contractive Forces of Wools as Actuator.

Wool has a long history of use in textiles throughout human civilization. Many smart functions such as reversible shape changes to various stimuli have been demonstrated in the last few years. However, the force-related characteristics are still imperfectly recognized, although they are expected to be used as actuators due to their biological origins and broad applications. Herein, we investigated the feasibility of wools in performing actuating ability through its intrinsic structures and fabrication methods. The diverse modes of contractive forces were obtained in wool materials including platform-like, double-peak, and slope-like shapes, where a molecular model was also presented to trace the origins of stress evolution. After that, a polymeric blend was created to modify the wool materials and a dissimilar performance of stress production was achieved, a square stress mode with stable manner and maintenance, for broad applications in a more efficient way. It is believed that these actuating properties extracted from natural hairs have a large potential in current smart applications and lay down new inspiration in designing actuators.