Controllable Multidimensional Rotation of Leidenfrost Droplets on the Femtosecond Laser-Patterned Asymmetric Structures

Abstract Precise manipulation of Leidenfrost droplet motion is essential for the broad practical applications of Leidenfrost effect, yet controllable multidimensional rotation remains a challenge. Herein, we propose a strategy to achieve diversified rotational behaviors of Leidenfrost droplets based on patterned asymmetric structures. Asymmetric structures are easily fabricated on aluminum substrates via femtosecond laser, which can propel Leidenfrost droplets unidirectionally. The design of asymmetric microstructural patterns enables the regulation of asymmetric vapor flow distribution between the levitated droplet and the heated substrate, allowing stable and controllable rotation of Leidenfrost droplets in the horizontal plane, vertical plane, and three-dimensional chaotic rotation. By optimizing the laser processing parameters and heating temperature, a maximum droplet rotational speed of 148 rpm is attained. The practical value of this strategy for energy conversion and chemical synthesis is further demonstrated. The rotation of the Leidenfrost droplets enables the conversion of thermal energy into mechanical energy and subsequently into electrical energy, showing great potential for waste heat recovery. This approach also increases the mixing efficiency to accelerate the synthesis of nanomaterials. This effective method for regulating Leidenfrost droplet motion will significantly broaden the application prospects of the Leidenfrost effect in thermal energy utilization, chemical synthesis, and microfluidic manipulation.