Photocontrol of helix handedness in curled liquid crystal elastomers

In this manuscript, we describe a photo-responsive dual-layer polysiloxane-based liquid crystal elastomer (LCE) soft actuator with switchable handedness of helical curling motions. Benefited from the embedded organic near-infrared (NIR) absorbing dye, the LCE ribbon can perform an impressive one-handed helical curling deformation under NIR light irradiation, meanwhile execute another-handed helical curling deformation under ultraviolet (UV) light irradiation due to the <i>trans-cis</i> isomerisation effect of azobenzene. This work demonstrates that the handedness of helical curling motions of LCE soft actuators can be reversibly altered by modulating the wavelength band of light stimuli (UV vs. NIR), which might have potential applications in control devices.