Fig. 4.
Photo-driven actuating behaviour of Janus film. a Schematic illustration and SEM image of EGaIn droplets in CNFs-rich layer. b Photo-thermal effect at different NIR power densities. Rectangular film of 20 × 10mm2; EGaIn/CNFs layer thickness: 9/10 μm/μm. NIR wavelength: 808 nm. Bulk EGaIn was used as the control. c Visual observation (Top) and repeatability (Bottom) of actuating behaviour under NIR irradiation. Power density of NIR: 0.8 W cm−2. d Displacement and actuating speed at different NIR power densities. e Photo-driven self-twisting (Top) and origami (Bottom). The inset (top right) shows twisted Vigna Radiata pods. f Photo-driving floating displacement in water. Energy density of radiation: 0.8 W cm−2