Gradient‐Driven Droplet Transport Enabled by Anisotropic Surfaces Fabricated via Acoustic Assembly Photopolymerization

ABSTRACT The development of functional surfaces with engineered wetting properties and droplet behaviors has attracted significant interest for applications in biomedical engineering, electronics, and microfluidics. However, achieving precise, localized engineering of surface wettability remains a significant challenge in both fabrication and modeling. In this study, a novel acoustic assembly photopolymerization (AAP) method is introduced for fabricating surfaces with predictable anisotropic and gradient wettability. The relationship between the APP process parameters and the fabricated film properties is established to enable the accurate fabrication of surfaces capable of self‐guided liquid manipulation. Theoretical models of flow dynamics in open capillary grooves are developed to predict the liquid flow behavior within microchannels. By tailoring the process‐property relationship, the droplet motion and droplet transport time can be precisely controlled within a 5–30 s window. Experimental validation confirms that AAP‐fabricated surfaces enable predictable droplet transport with less than 5% mean error from theoretical predictions, demonstrating tunable hydrodynamic performance. This work advances the understanding of microscale fluid dynamics on anisotropic surfaces and presents a scalable approach for manufacturing next‐generation microfluidic devices. Notably, the demonstrated capability for designed, gradient‐driven liquid transport without external energy input opens new avenues for on‐chip chemical synthesis, point‐of‐care diagnostics, and biosensing applications.