Tunable thickness and uniform drop deposition of graphene oxide on porous anodic aluminum oxide and a reliable thickness measurement technique

Abstract

The pinned contact line of sessile droplets containing micro/nanoparticles on a substrate results in nonuniform depositions with noncontrollable thicknesses, thereby producing the coffee-ring effect. In this study, we demonstrated that the thickness of graphene oxide (GO) films can be engineered using porous anodic aluminum oxide (AAO) substrates to fabricate uniform GO films. The outstanding thickness controllability and uniformity of GO films were obtained via tailorable hydrodynamic flow in a sessile droplet due to the pores of the AAO substrate. Furthermore, we developed a novel approach for measuring the micro/nanoscale thicknesses of GO films using an optical microscope. The thicknesses of the deposited GO film, measured via optical microscopy, demonstrated good agreement with those obtained via atomic force microscopy. These findings are beneficial for GO film applications, such as in wearable sensors, filtration, inkjet printing.