Bioinspired superwetting surfaces for fog harvesting fabricated by picosecond laser direct ablation

Fog harvesting has been considered as a promising method for solving water crisis in underdeveloped regions. To mimic and optimize the alleged natural fog harvesting ability of the stenocara beetle, hybrid superhydrophobic (hydrophobic, superhydrophilic)/hydrophilic patterns are processed on stainless steel via picosecond laser direct writing. Basically, after laser processing, the surfaces of stainless steel change from hydrophilic to superhydrophilic. Then, after chemical and heat treatment, the superhydrophilic surfaces become superhydrophobic with ultra-low adhesion, and superhydrophobic (hydrophobic) with ultra-high adhesion, respectively. This work systematically examines the fog harvesting ability of picosecond laser treated surfaces (LTS), pristine surfaces (PS), laser and chemical treated surfaces (LCTS), laser and heat-treated surfaces (LHTS). Compared with the PS, the as-prepared surfaces enhanced the fog harvesting efficiency by 50%. This work provides a fast and simple method to fog collectors, which offer a great opportunity to develop water harvesters for real world applications.