Beyond passive mixing: Geometric evolution and multifunctional applications of staggered herringbone microfluidic devices

Staggered herringbone microfluidic chips are widely used passive systems for enhancing transport and interaction under laminar flow conditions, and have been extensively applied in chemical synthesis, biosensing, and cell-related studies. The performance of these systems is fundamentally governed by their geometric design, which determines mixing efficiency, mass transfer, and flow-induced stimulation. Despite their widespread adoption, the design logic connecting geometric parameters, fabrication constraints, and functional applications has not been systematically clarified. In this review, we summarize and organize the key geometric features of herringbone microstructures and their influence on fluid behavior, fabrication feasibility, and application performance. Representative design strategies are discussed across different application scenarios, ranging from homogeneous reactions and nanoparticle synthesis to surface-interaction enhancement and cell functional regulation. By integrating design principles with practical implementation and application-driven requirements, this review aims to provide a critical overview of the design logic and application-dependent optimization strategies of staggered herringbone microfluidic chips.