Fabrication of conical pits via nanoindentation-induced electrochemical etching

Conical micro-pits are of significant importance in a wide range of advanced applications, including space exploration, surveillance systems, biomedical engineering, earth science research, defense technologies, and material processing. However, the fabrication methods of conical micro-pits still need to be further investigated to meet the increasing demand for advanced optics. Nanoindentation combined with electrochemical etching demonstrates powerful ability in micro-pits manufacturing; however, the underlying mechanisms of this method remain unclear, which hinders further development of the fabrication for micro-pits. This study develops a controllable fabrication strategy for conical micro-pits via synergistic nanoindentation and electrochemical etching. Key findings reveal that nanoindentation-induced crystal damage zones act as preferential initiation sites for electrochemical etching, enabling precise control of micro-pit dimensions by tuning mechanical parameters (normal load, cycle number) and electrochemical conditions (voltage, time). This method achieves independent regulation of conical pit diameter and depth, overcoming the limitations of conventional single-mechanism methods. Integrated with PDMS nanoimprinting, the process enables high-fidelity and rapid replication of conical pist arrays on polymer surfaces.