Manipulation of Fractal Nano-Kirigami by Capillary and Electrostatic Forces

Fractals are beautiful forms of geometric patterns, usually having high degrees of freedom of shape change. Recently, fractal and fractal-like designs have aroused great interest in scientific research. Here, fractal-like nano-kirigami structures with rotational symmetries are proposed and demonstrated, in which topological morphologies can be transformed by growing fans and coiling units. Experimentally, the nano-kirigami structures with different fractals are manipulated by using the capillary force-induced 3D deformation process. Benefited from the fractal-like designs, the structral deformations exhibit strong fractal dependence, with which the stress threshold and reflection spectrum can be tailored by changing the number of fans and coiling units. The modulation of fractal nano-kirigami is further demonstrated by using the electrostatic forces when external voltage is applied. The fractal nano-kirigami structures are also envisioned with capability of conveniently generating fractal-dependent optical vortices. The special fractal design strategy in this work can bring new opportunities to functional 3D micro/nano structures with improved optical tunability and customization.