Research On The Fabrication And Motion Of The Superhydrophobic Mini-boat Propelled By Water Droplet

Self-propelled devices,which can be moved without any external motor,have become a research hotspot for scholars because of their potential applications in cleaning sewage,removing oil,destroying chemical weapons and targeting drug delivery.These devices can be classified into bubble propulsion and phoresis propulsion depending on the mechanism of motion.However,these self-propelled devices require the application of chemical reactions,two-phase liquids,electrical energy,thermal energy,which limits their practical application.In this paper,a new self-propelled device,which propelled by Laplacian Force that is never used around the whole world is proposed.The Laplace pressure generated by the surface tension of the droplet is used as the driving force to move the mini-boat,which is a new and cleaning self-propelled mechanism using a single liquid without any external energy and realizes the conversion of the surface energy of the droplet into the kinetic energy.A superhydrophilic through-pore in the realm of hundred micron scale was fabricated on a superhydrophobic surface,of which the material is aluminum plate with thickness of 0.59 mm and the whole fabricating process was using nanosecond laser to etch the aluminum plate.The water droplets dripping on the pore can be injected into the water under the Laplace pressure,which can produce a mushroom-like jet.When the pore has a certain inclination angle of 45°,the jet can be ejected obliquely in the water while generating a reverse thrust to the plate,which can be used as a driving force to move the mini-boat on the water.Due to the mode of movement,the mini-boat can be devided into two types,which are translational and rotary.Subsequently,the effects of the water droplet volume and the pore diameter on the motion performance of the mini-boat was researched.The results showed that the energy generated by the mushroom-like jet can propelled the mini-boat.When the initial volume of the water droplet was certain,the initial acceleration of the mini-boat increase but the propelling distance decrease with the increase of the pore size,When pore size was certain,the initial acceleration of the mini-boat decrease but the propelling distance increase with the increase of the initial volume of the water droplet,Then the dynamic analysis was done to the mini-boat,which showed that the Laplace pressure is the only propelling force and water resistance is the drag force during the motion process of the mini-boat.Finally,several application of the mini-boat was designed to realize the continuous and long-distance motion.In summary,the paper provides a new propelling mini-boat,which is expected to be applied in the fields of directional transportation,cargo handling,and micro-generators.