Research progress on droplet impact based on multifunctional surfaces

Droplet impact is ubiquitous in numerous applications and plays an important role in fields such as anti-icing, pesticide spraying, and inkjet printing. With the advancement of high-speed imaging and surface fabrication technologies, an increasing variety of multifunctional surfaces have been developed and utilized, deepening our understanding of the dynamic characteristics and energy changes during droplet impact. This paper first introduces the basic parameters of droplet impact, including the maximum spreading coefficient, contact time, and a list of relevant dimensionless numbers. Next, the kinetic and dynamic characteristics of droplet impact on single-functional and multifunctional surfaces are discussed. Multifunctional surfaces, typically possessing two or more different functionalities, exhibit unique motion phenomena such as lateral migration, self-splitting, and self-rotation due to their anisotropy during droplet impact. This paper categorizes these multifunctional surfaces based on their topological and chemical characteristics, including surfaces with micro-physical structural adjustments, macro-special shaped multifunctional surfaces, and externally coupled multifunctional surfaces. The kinetic and dynamic behaviors of droplet impact on these surfaces are described in detail, providing theoretical models and practical applications. This work aims to provide theoretical support and technical guidance for the optimized design of multifunctional surfaces and their applications across various fields through a comprehensive exploration of droplet impact dynamics.