Light-fueled self-rotation of a liquid crystal elastomer rod enabled by lateral constraint

Recent experiments have found that a liquid crystal elastomer (LCE) rod supported in the middle can rotate continuously under horizontal illumination due to the combined impacts of gravity and light-fueled lateral bending deformation. Similar to traditional gravity-driven systems, it is constrained by the direction of gravity and cannot be applied in microgravity environments. This study introduces a lateral constraint to a liquid crystal elastomer rod system, enabling self-rotation under lighting from any direction, including horizontal and vertical illumination. Through theoretical modeling, the results indicate that the system can steadily rotate under the combined impacts of lateral forces and vertical illumination. Factors like thermal energy flux, thermal conductivity coefficient, the LCE rod length, contraction coefficient, and friction coefficient affect the angular velocity of the self-rotation. The numerical computations align closely with the experimental data. Our proposed steadily self-rotating system features a simple structure with constant self-rotation. It operates independently of gravity direction, making it an excellent choice for special environments, such as the microgravity conditions on the Moon. The lateral constraint strategy presented in this study offers a general approach to expanding the applications of gravity-driven self-sustained motion, with promising potential, especially in microgravity settings, where its versatility under varying lighting conditions could yield valuable insights. © 2025 The Author(s)