Fig. 2: Design and fabrication of interface-enhanced micro-rockets by 3D printing.

a Schematic of the 3D microprinting process. Direct laser writing for 3D microprinting with a nanoscale resolution; the 3D structures are acquired after developing the uncross-linked SU-8 photoresist; a gold layer with a thickness of 100 nm is coated onto the micro-rocket; and the micro-rockets are transferred via micro-manipulation to the liquid solution for further light-driven motion. b SEM images of the micro-rocket array. Inspired by the interface enhancement in nature, the micro-rocket is designed with three tubes with a diameter of 20 µm and a wall thickness of 2 µm. The lengths of the central tube and two symmetrical tubes are 45 µm and 22.5 µm, respectively. c The top view and side view of the energy dispersive X-ray spectrum (EDS) mapping of the micro-rockets