Precision flow focusing in 3D printed microchannels for enhanced impedance spectroscopy

Abstract

Precise particle positioning is critical for achieving high-quality signal acquisition in impedance-based single-particle analysis. We present a novel microfluidic platform that enables tunable three-dimensional (3D) hydrodynamic focusing using a single-layer microchannel fabricated via projection micro stereolithography (PμSL). The design integrates a nozzle structure, vertical sheath flow, and a constricted sensing region. Unlike planar designs where particles often settle on the channel bottom, the nozzle structure elevates the particle stream above the floor, minimizing particle–wall interactions. This configuration enables robust lateral and vertical confinement, with positioning govern..