Facile fabrication of asymmetric surfaces via mechanochemistry

TL;DR

This paper presents a simple mechanochemical method using a stylus to create bidirectional nanowire surfaces on silicon, enabling new ways to manipulate fluids on microfluidic tracks.

Contribution

It introduces a novel, facile technique for fabricating asymmetric silicon surfaces with controllable nanowire orientations using mechanochemistry.

Findings

Successful fabrication of bidirectional silicon nanowires.

Mechanochemical treatment alters etching directions.

Potential for fluid manipulation on asymmetric surfaces.

Abstract

We demonstrate a mechanochemical approach to fabrication of a bidirectional surface on a doped silicon wafer. In the initial step of our fabrication procedure, a high-density polyethylene (HDPE) stylus is pressed and drawn on the Si surface. This rubbing action provides a mechanochemical treatment of the Si surface, which unexpectedly alters the etching direction in the subsequent metal-assisted chemical etching step. Hence, Si nanowires of two different orientations can be patterned conveniently by a rub-write step. The mechanism of bidirectional Si nanowire formation is investigated. This anisotropy is exploited to propel water droplets on a fluidic track.