Superhydrophobic-Hydrophilic Interface Control of Laser-Processed Fluorine-Doped Graphene Films for Microfluidics

Microfluidic technology is crucial in biomedical and chemical analysis as it manipulates fluids at a microscopic scale using microchannels. In this work, a two-step, maskless laser processing technique was proposed to fabricate fluorine-doped graphene films. The graphene films processed by the first UV laser have the property of superhydrophobicity owing to the doping of fluorine atoms on the graphene surface. However, the superhydrophobic state can be converted into a hydrophilic state once a second
$\text{CO}_2$
laser scan is on the graphene film due to the introduction of microcrack and the removal of most fluorine atoms. Thus, superhydrophobic-hydrophilic interface control of graphene films can be achieved efficiently and controllably. By adjusting laser parameters, fluorine-doped graphene films with different conductivities, surface morphologies, and wettability were prepared without the need of post-processing chemical modifications. Utilizing two types of laser scanning allows for precise control over the superhydrophobic and hydrophilic interfaces on graphene films, offering new strategies and methods for applications in microfluidics, fluid drainage and transport.