From drop impact to cellular response: Transient interfacial force fields, contact-line physics, and mechanotransduction in complex biofluids

Drop impact is a classical problem in fluid mechanics, yet its implications for biological systems remain largely unexplored. Upon impact, droplets generate transient interfacial force fields composed of localized pressure, shear, and extensional stresses that evolve over microsecond-to-millisecond timescales. In complex biofluids and at soft interfaces, these stresses are not simply dissipated, but are redistributed and transformed through structure–flow coupling, dynamic wetting, contact-line motion, and interfacial compliance. This Perspective develops a multiscale physical framework linking drop-impact hydrodynamics to microstructural dynamics in complex fluids and to the transmission of mechanical signals across soft biological interfaces. Particular emphasis is placed on the physics of stress localization near the advancing contact line, the role of classical and soft-matter dimensionless groups in governing impact response, and the conditions under which transformed stresses may perturb cellular mechanosensitive pathways. To quantify this coupling, an impact–mechanotransduction number is introduced as a dimensionless measure relating transmitted impact stress to characteristic cellular prestress. Within this framework, drop impact is recast not only as a transport and deformation process, but also as a source of impulsive mechanical forcing in soft matter and biointerface systems. These ideas define a new direction, impact-driven mechanobiology, and establish a physically grounded basis for future theoretical, experimental, and translational studies of fluid–biological interactions.