Fast water flow in laser micromachined microgrooves with nonuniform surface wettability

Abstract

Fast water flow on solid surfaces is desired in many applications. In this paper, surfaces with microgrooves and nonuniform wettability were fabricated, and fast water flow with an average velocity of 47.6 mm/s was achieved. The proposed method included three steps: fabricating V-shaped microgrooves on copper surfaces by a pulsed laser, storing laser-processed samples in an organic-rich vacuum environment and partially soaking the samples in H2O2 solution. The morphology and composition changes during the three steps were analyzed using SEM, 3D laser microscopy, XRD, XPS and EDS, and the water flow on various surfaces was studied. Our results indicated that the presence of a suitable wettability difference at the front edge of a superhydrophilic surface can accelerate water flow on the surface. Our results may provide new ideas for the fabrication of high-performance heat pipe or water harvesting surfaces.