Impact of Droplet Splashing on Biological and Medical Materials Relevant to Clinical Settings

Despite numerous studies of droplet impact onto substrates, the splashing dynamics of droplets on biological material surfaces and its implications for infection transmission have rarely been studied. It is hypothesized that the splashing mechanism is influenced by the droplet size, the impact velocity, and the substrate wettability and morphology. The transmission of contamination from initial droplets or liquid films to biofilms upon impact is experimentally investigated. Splashing mechanisms involving biological droplets (e.g., water, urine, blood, and saliva) on a range of biological substrates (e.g., bone, meat, eye, skin, hair, nail, and tooth) and medical surfaces across a range of droplet velocities are comparatively analyzed. The study demonstrates that contaminants located in either an initial droplet or a liquid biofilm can be transmitted by splashing when the droplet impacts onto the biofilm. The Weber number, a descriptor of secondary droplet splashing, expressed as a function of the surface roughness (R _a) is considered. For a droplet of radius R, the prominence of the surface curvature (R _a /R) is highlighted through comprehensive experimentation, underscoring the importance of using tailored surface materials within clinical environments.Developing advanced biomaterials and designs can thus help reduce droplet splashing and promote safer medical procedures.