Directional Navigation of Low-Temperature Leidenfrost Droplets on Femtosecond Laser-Textured Superwettable Pattern Surfaces

The Leidenfrost effect enables near-frictionless droplet transport by suspending droplets on vapor layers, making it pivotal for contact-free manipulation in microscale chemical reactions and material transport applications. Traditional ratchet structures that drive Leidenfrost droplet motion require the substrate material to be heated above the higher Leidenfrost point (LFP) critical temperature, which imposes significant demands on energy consumption and material heat resistance. Herein, we proposed a method that integrates femtosecond laser-induced deposition with femtosecond direct writing to fabricate a textured superwettable patterned surface, achieving directional droplet navigation at a notably low temperature of just 155 °C. The surface features uniformly distributed nanoparticle clusters and micro/nanoscale stripe structures. Through combined experiments and simulations, we systematically analyzed low-temperature Leidenfrost droplet dynamics and demonstrated the precise control of braking, uphill climbing, and curved trajectories. This study provides a facile fabrication strategy with robust performance for controlled navigation of Leidenfrost droplets under low-temperature conditions.