Laser texturing and non-hazardous chemical treatments for high-throughput droplet microarrays with precise superhydrophilic patterns on superhydrophobic aluminum surface

Droplet microarrays (DMAs) consist of superhydrophilic spots separated by superhydrophobic borders, enabling the formation of hundreds of nanoliter-sized droplets with controlled geometries and positions. This study investigates the fabrication of DMAs on aluminum alloy surfaces using an eco-friendly approach that combines laser processing and non-hazardous chemical treatments. The aim is to control the wettability and precision of the superhydrophilic spots by adjusting the laser parameters for droplet generation without cross-contamination, addressing the challenge of maintaining pattern accuracy in the superhydrophilic regions. The effect of laser input energy on the wettability and precision of the superhydrophilic surface was investigated. The minimum distance for the superhydrophobic barrier was found to be 250 µm, and a DMA was designed with an array density of 333 droplets/cm². The stability of the DMAs was tested under extended exposure to air, fresh water, and intense heat. The study highlights the potential for creating DMAs and complex patterns on disposable aluminum dishes and foils, as required for on-demand printing, disposable usage, and high-throughput in biomedical applications.