Abstract
Continuous microfluidic focusing of particles, both synthetic and biological, is significant for a wide range of applications in industry, biology and biomedicine. In this study, we demonstrate the focusing of particles in a microchannel embedded with glass grooves engraved by femtosecond pulse (fs) laser. Results showed that the laser-engraved microstructures were capable of directing polystyrene particles and mouse myoblast cells (C2C12) towards the center of the microchannel at low Reynolds numbers (Re < 1). Numerical simulation revealed that localized side-to-center secondary flows induced by grooves at the channel bottom play an essential role in particle lateral displacement. Additionally, the focusing performance proved to be dependent on the angle of grooves and the middle open space between the grooves based on both experiments and simulation. Particle sedimentation rate was found to critically influence the focusing of particles of different sizes. Taking advantage of the size-dependent particle lateral displacement, selective focusing of micrometer particles was demonstrated. This study systematically investigated continuous particle focusing in a groove-embedded microchannel. We expect that this device will be used for further applications, such as cell sensing and nanoparticle separation in biological and biomedical areas.
Highlights
Microfluidics is the science and technology of systems that studies fluid physics in channels with dimensions of tens to hundreds of micrometers [1,2]
This study systematically investigated the particle focusing in low Re-number flows, showing application potential in contact imaging, lifetime-resolved imaging, cell sensing and particle separation in biological and biomedical areas
Simplified 3D models were established with the software COMSOL Multiphysics 5.4 based on the groove dimensional data in scanning electron microscopy (SEM) images, which simulated fluid motion dynamics caused by the groove structures
Summary
Microfluidics is the science and technology of systems that studies fluid physics in channels with dimensions of tens to hundreds of micrometers [1,2]. Features such as small size [3], low reagent consumption [4], fast analysis [5], and low cost [6] make it suitable for various applications in different fields, such as drug delivery [7], point-of-care diagnosis [8], single cell virology [9], cell separation [10] and polymer synthesis [11]. Femtosecond pulse (fs) laser-based high-speed separation of fluorescence-activated human lung cancer A549 cells [25] and Raman image-activated separation of microalgal cells [26] based on intracellular metabolites have been achieved
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