Acoustic virtual walls enable open, scalable, and programmable microfluidics.

Microfluidic platforms are widely used across biomedical research, chemical synthesis, diagnostics, environmental monitoring, and materials science for precisely manipulating small volumes of fluids and suspended particles. However, conventional systems rely on narrow physical channels that are prone to clogging, limited volumetric throughput due to high hydraulic resistance, and excessive shear stress that can damage sensitive cells and fragile materials. To overcome these constraints, we introduce acoustic channeling within a wide, open fluid chamber by replacing solid boundaries with acoustic virtual walls. These walls are formed by evanescent acoustic pressure fields generated from an engineered two-dimensional waveguide that suppresses internal wave propagation and produces highly localized subwavelength fields. This architecture minimizes shear stress while guiding particles along precisely defined trajectories. The electronically tunable acoustic field enables programmable, remote, and real-time particle control. Supported by simulations, we demonstrate diverse channeling designs, efficient particle collection, and material-specific separation. Operating at milliliter-per-minute flow rates, two orders of magnitude higher than conventional microfluidic systems, this platform enables scalable, clog-free microfluidics for high-throughput and robust applications.