Large-Area Vertical Silicon Nanocolumn Arrays for Versatile Cell Interfaces

Despite the facile fabrication of geometry-controlled vertical silicon nanocolumn arrays (vSNAs), metal-assisted chemical etching (MACE) showed critical limitations for producing vSNAs, particularly, with very low densities, high aspect ratios, and arbitrary spatial patterns. Herein, we report an approach to fundamentally resolve the intrinsic mass transport issue during the wet silicon etching by introducing two-stage nanosphere lithography based on two different-sized polystyrene beads. First, we thoroughly examined the silicon-etching kinetics in two-stage nanosphere lithography-assisted MACE. Then, we confirmed that the proposed technique enables the unprecedentedly wide-range modulation of nanocolumn density down to 0.1–1 per square micrometer and the scalable production of low-density vSNAs with high aspect ratios up to ∼30. Furthermore, it was demonstrated that the arbitrary spatial patterns of vSNAs could be easily obtained on sizable substrates even without the conventional photolithography technique and utilized for cellular interface experiments. In combination with low-cost, large-scale, and reproducible fabrication, the exceptional flexibility in terms of nano- to microscale geometric control permits vSNAs to serve as well-defined versatile cellular interfaces for intracellular delivery, topographic stimulation, cell capturing, electrophysiological recording, etc.