Water droplet rapid spreading transport on femtosecond laser-treated photothermal and superhydrophilic surface

Rapid water droplet spreading transport on responsive surfaces has attracted much recent interest. Most current methods for transporting water droplets rely on external electric or magnetic fields, which limits their practical application. Here, a photothermal and superhydrophilic stainless steel surface is prepared by femtosecond laser direct writing technology. By virtue of the synergistic functions of the light absorption and superhydrophilicity, water droplet rapid spreading transportation can be achieved on the as-prepared surface by simply exposing to light. Moreover, the relationship between water droplet spreading transportation time and cycles, droplet volumes, temperatures were systemically investigated, respectively. And the spreading transportation mechanism is discussed. This finding offers a simple method for fabricating a light-responsive interface material for rapid water droplet spreading transportation, which would be useful in microfluidics and water treatment.