In this paper, we present a method to form large-area, close-packed, self-assembled monolayers using diatom frustules of Coscinodiscus sp. With these frustules, ranging from 50 pm to 70 pm in diameter, we achieved up to 0.8 cm 2 of close-packed frustule monolayers on wafer surfaces. The orientation of these frustules was uniformly controlled with the concave side facing downwards by blowing N-2 gas bubbles below the water-diatom interface. The method introduced herein, taking advantage of diatom frustules' orientation and hierarchical structures, has the potential for large-scale fabrication of micro/nano structures, which may be applicable to a variety of practical technological applications.