When the artificial leaf is exposed to sunlight, these nanotubes are locally heated, causing the polymer to contract. Areas not exposed to direct sunlight remain in an expanded form, which results in the leaf “bending” towards a light source.
This process effectively keeps the leaf automatically facing the light source without the need for motors or other devices. According to the researchers, this mechanism is similar to how plants, especially aquatic ones like Micranthemum glomeratum, track the sun.