Reactive etching of gallium oxide on eutectic gallium indium (eGaIn) with chlorosilane vapor to induce differential wetting.

Differentially wettable surfaces are well sought after in energy, water, health care, separation science, self-cleaning, biology, and other lab-on-chip applications-however, most demonstrations of realizing differential wettability demand complex processes. Herein, we chemically etch gallium oxide (GaO) from in-plane patterns (2D) of eutectic gallium indium (eGaIn) to demonstrate a differentially wettable interface using chlorosilane vapor. We produce 2D patterns of eGaIn on bare glass slides in native air using cotton swabs as paint brushes.