Human skin-inspired multiresponsive actuators based on graphene oxide/polydimethylsiloxane bilayer film: bi-directional transformation of semi-tube into plane sheet/tube under different stimuli

Abstract

Multiresponsive soft actuators comprised of carbon nanostructured-polymer hybrid smart materials have received enormous attention recently. However, it is always desirable and interesting to explore new types of stimuli which can trigger actuation in such materials. Inspired by human skin which can respond to multiple stimuli, we report here multiresponsive soft actuators based on graphene oxide (GO)-polydimethylsiloxane (PDMS) bilayer structure. These actuators exhibit reversible actuation under different stimuli viz. infrared (IR) light, acetone vapors and temperature. The actuation behavior under the influence of temperature is further investigated with its values in the heating as well as cooling modes. Therefore, the use of the different stimuli imparts the functionalities of photomechanical, vapomechanical, thermomechanical and cryomechanical actuation, respectively to these actuators. The actuators are realized by spin coating of PDMS film (200 μm) on GO film (15 μm) followed by curing at 120 °C. The thermal residual stress generated during curing process causes the structure to become tubular upon release which was then sliced to form semi-tube so that its bi-directional actuation could be observed. The semi-tubular actuators reversibly get transformed into plane sheet shape under the influence of IR light, heating and acetone vapors within about 4, 5 and 1 s, respectively which causes change of curvature from 2.1 to 0 cm−1. Further, it is transformed into full tube shape under the influence of cooling within about 12 s that changes the curvature from 2.1 to 4.2 cm−1. Finally, the actuators are utilized to demonstrate one of the prototype applications as IR light-driven soft gripper. It is believed that these actuators may also find potential applications in the fields of biomimics and realization of artificial intelligence components for military/industrial use.