Materials science

Artificial muscle

Robotics

Robot

Artificial intelligence

Power (physics)

Percolation threshold

Percolation (cognitive psychology)

Physics

Neuroscience

Nanotechnology

Biology

Quantum mechanics

Electrical resistivity and conductivity

Graphene

Computer science

Mechanical energy

Actuator

Soft robotics

Nature Nanotechnology

Artificial muscles are indispensable components for next-generation robotics capable of mimicking sophisticated movements of living systems. However, an optimal combination of actuation parameters, including strain, stress, energy density and high mechanical strength, is required for their practical applications. Here we report mammalian-skeletal-muscle-inspired single fibres and bundles with large and strong contractive actuation. The use of exfoliated graphene fillers within a uniaxial liquid crystalline matrix enables photothermal actuation with large work capacity and rapid response. Moreover, the reversible percolation of graphene fillers induced by the thermodynamic conformational transition of mesoscale structures can be in situ monitored by electrical switching. Such a dynamic percolation behaviour effectively strengthens the mechanical properties of the actuator fibres, particularly in the contracted actuation state, enabling mammalian-muscle-like reliable reversible actuation. Taking advantage of a mechanically compliant fibre structure, smart actuators are readily integrated into strong bundles as well as high-power soft robotics with light-driven remote control.

Human-muscle-inspired single fibre actuator with reversible percolation