APBN New Site

APBN Developing Site

Graphene-based Actuator Swarm Enables Programmable Complex Deformation

Moisture-responsive, self-healing graphene actuator swarm provides programmable 3D deformation, achieved by integrating SU-8 pattern arrays with graphene oxide.

Actuators – a component of a machine responsible for moving and controlling a mechanism – that can convert environmental stimuli such as humidity, light and pH to mechanical changes have great potential for developing smart devices such as soft robotics. To realize reversable and controllable deformation, bilayer structures are widely used, where the active layer may swell or shrink under external stimuli whereas the inert layer would remain unchanged.

Recently, graphene and graphene oxide (GO) have emerged as a new type of smart material for actuator design due to outstanding properties such as high electrical/thermal conductivity, good mechanical flexibility, excellent biocompatibility and good stability. However, graphene-based bilayer actuators are currently only capable of simple deformation such as bending.

Inspired by the collective coupling and coordination of living cells, scientists at Jilin University and Tsinghua University have developed a moisture-responsive, self-healing graphene actuator swarm that enables programmable 3D deformation by integrating SU-8 pattern arrays with GO. The results are published in the Beijing-based National Science Review.

SU-8 micropattern arrays with specific geometries and orientations were fabricated on a continuous GO film, forming a swarm of bimorph actuators in which an individual SU-8/GO bilayer can serve as an actuator “cell”. Under external stimulation, each actuator cell deforms individually, and the deformation of the entire structure is the collective coupling and coordination of the swarm. A series of complex deformations including bending, twisting, coiling, and 3D folding was thus achieved by making different SU-8 patterns.

Moreover, unlike previously published works, the SU-8/GO bimorph actuator swarm shows moisture-triggered self-healing property, revealing robustness for practical usage. As a proof-of-concept, the researchers further developed several moisture-responsive paper robots that could realize multiform deformations, including smart “dancer robots” that dance with humidity change and a smart “caterpillar robot” which mimics the crawl of caterpillars. The present method may open up a new way for precisely controlling the deformation of graphene-based actuators. [APBN]

Source: Ma, J. N. et al. (2020). Programmable deformation of patterned bimorph actuator swarm. National science review7(4), 775-785.