Droplet impacting multi-layer soap bubbles on patterned surfaces

Abstract

Droplet-bubble interactions have a significant impact on the efficiency and quality of work in hydrogen energy cells, drug development, microfluidic chips and wastewater treatment. However, due to the complexity of the flow state of droplet-bubble interactions, it's still a great challenge to reveal the mechanism of action and laws of the impact process. This work prepares patterned surfaces by laser etching and fluorosilane (FAS) , reveals the wetting mechanism and the shape diffusion laws of soap bubbles on patterned surfaces, obtains the flow map of droplet impacting single-layer soap bubbles, realizes the controlled impact of droplets on multilayer bubbles, and demonstrates the application potential of multilayer soap bubbles as microreactors. The results show that the increase of the volume of soap bubbles on the patterned surface to 1<D/dn<3 will course their continuous diffusion from the superhydrophilic region to the superhydrophobic region; the controllable impact of droplets on soap bubbles can be realized by adjusting the Weber number We and the angle of incidence θl, and in addition to bounce, tumble, and penetration with the critical point of We=13 and θl=102.5°, the impact behaviors show fusion. With the help of multilayer annular patterned surface and the droplet-bubble impact law, it's possible to manipulate the droplets and deliver different liquids with θl=110° and We =17, 25, and 35 to different regions of multilayer bubbles with volumes of 0.8 mL, 6 mL, and 14.5 mL, demonstrating its potential application as a microreactor.