Magnetic Non‐Spherical Particles Inducing Vortices in Microchannel for Effective Mixing

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2023-05, Vol.19 (19), p.e2207383-n/a
• Main Authors: Feng, Shi, Pan, Cunliang, Ye, Hongfei, Liu, Wendong, Yang, Wenbo, Lv, Yingdi, Tao, Shengyang
• Format: Article
• Language: English
• Subjects: Efficiency; Fluid flow; magnetic particles; Microchannels; microfluid; micromixing; Mixers; Nanotechnology; Particle image velocimetry; Vortices
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202207383

Mixing in microfluidic channels is dominated by diffusion owing to the absence of chaotic flow. However, high‐efficiency microscale mixing over short distances is desired for the development of lab‐on‐chip systems. Here, enhanced mixing in microchannels achieved using magnetic nonspherical particles (MNSPs), is reported. Benefiting from the nonspherical shape of the MNSPs, secondary vortices exhibiting cyclical characteristics appear in microchannels when the MNSPs rotate under an external magnetic field. Increasing the rotation rate enlarges the secondary vortices, expanding the mixing zone and enhancing the mixing, resulting in a mixing efficiency exceeding 0.9 at Re of 0.069–0.69. Complementary micro‐particle image velocimetry (µPIV) for flow field analysis clarifies the mixing mechanism. In addition, a chaotic vortex area is generated in the presence of two MNSPs, which shortens the distance required for achieving an appropriate mixing efficiency. This study demonstrates the potential of employing MNSPs as efficient mixers in lab‐on‐chip devices. Novel magnetic nonspherical particles (MNSPs) are fabricated to achieve mixing in microchannels. Diverse MNSPs are fabricated based on microfluidics, and a high mixing efficiency is achieved via rotation of the MNSPs under an external magnetic field. In addition, the MNSPs are used for accelerated detection of Hg(II) in microfluidic chips.