Fabrication and Manipulation of Non-Spherical Particles in Microfluidic Channels: A Review

Millifluidic magnetophoresis-based chip for age-specific fractionation: evaluating the impact of age on metabolomics and gene expression in yeast

A novel millifluidic process introduces age-based fractionation of S. pastorianus var. carlsbergensis yeast culture through magnetophoresis. Saccharomyces yeast is a model organism for aging research used in various industries. Traditional age-based cell separation methods were labor-intensive, but techniques like magnetic labeling have eased the process by being non-invasive and scalable. Our approach introduces an age-specific fractionation using a 3D-printed millfluidic chip in a two-step process, ensuring efficient cell deflection in the magnetic field and counteracting magnetic induced convection. Among various channel designs, the pinch-shaped channel proved most effective for age differentiation based on magnetically labeled bud scar numbers. Metabolomic analyses revealed changes in certain amino acids and increased NAD+ levels, suggesting metabolic shifts in aging cells. Gene expression studies further underlined these age-related metabolic changes. This innovative platform offers a high-throughput, non-invasive method for age-specific yeast cell fractionation, with potential applications in industries ranging from food and beverages to pharmaceuticals.

Dynamics of non-spherical particles in viscoelastic fluids flowing in a microchannel

The migration and orientation dynamics of prolate spheroidal particles suspended in a viscoelastic liquid flowing in a square microchannel is experimentally investigated under inertialess flow conditions. The suspending fluid is an aqueous solution of PolyEthylene Oxyde at relatively high concentration characterized by a high level of elasticity and shear-thinning. Fluid viscoelasticity drives the spheroids towards the channel central region at relatively low flow rates when the particles explore the constant viscosity region of the fluid, without showing a preferential orientation. As the flow rate increases and the fluid enters in the shear-thinning region, a smaller fraction of particles migrates at the central channel region, reducing the focusing efficiency. The focused spheroids rotate sufficiently fast to attain a stable orientation with major axis aligned along the flow direction.

The Physics and Manipulation of Dean Vortices in Single- and Two-Phase Flow in Curved Microchannels: A Review

Microchannels with curved geometries have been employed for many applications in microfluidic devices in the past decades. The Dean vortices generated in such geometries have been manipulated using different methods to enhance the performance of devices in applications such as mixing, droplet sorting, and particle/cell separation. Understanding the effect of the manipulation method on the Dean vortices in different geometries can provide crucial information to be employed in designing high-efficiency microfluidic devices. In this review, the physics of Dean vortices and the affecting parameters are summarized. Various Dean number calculation methods are collected and represented to minimize the misinterpretation of published information due to the lack of a unified defining formula for the Dean dimensionless number. Consequently, all Dean number values reported in the references are recalculated to the most common method to facilitate comprehension of the phenomena. Based on the converted information gathered from previous numerical and experimental studies, it is concluded that the length of the channel and the channel pathline, e.g., spiral, serpentine, or helix, also affect the flow state. This review also provides a detailed summery on the effect of other geometric parameters, such as cross-section shape, aspect ratio, and radius of curvature, on the Dean vortices' number and arrangement. Finally, considering the importance of droplet microfluidics, the effect of curved geometry on the shape, trajectory, and internal flow organization of the droplets passing through a curved channel has been reviewed.

Recent Progress of Droplet Microfluidic Emulsification Based Synthesis of Functional Microparticles

The remarkable control function over the functional material formation process enabled by droplet microfluidic emulsification approaches can lead to the efficient and one-step encapsulation of active substances in microparticles, with the microparticle characteristics well regulated. In comparison to the conventional fabrication methods, droplet microfluidic technology can not only construct microparticles with various shapes, but also provide excellent templates, which enrich and expand the application fields of microparticles. For instance, intersection with disciplines in pharmacy, life sciences, and others, modifying the structure of microspheres and appending functional materials can be completed in the preparation of microparticles. The as-prepared polymer particles have great potential in a wide range of applications for chemical analysis, heavy metal adsorption, and detection. This review systematically introduces the devices and basic principles of particle preparation using droplet microfluidic technology and discusses the research of functional microparticle formation with high monodispersity, involving a plethora of types including spherical, nonspherical, and Janus type, as well as core-shell, hole-shell, and controllable multicompartment particles. Moreover, this review paper also exhibits a critical analysis of the current status and existing challenges, and outlook of the future development in the emerging fields has been discussed.

Pneumatically Driven Microfluidic Platform and Fully Automated Particle Concentration System for the Capture and Enrichment of Pathogens

In this study, we developed a pneumatically driven microfluidic platform (PDMFP) operated by a fully automated particle concentration system (FAPCS) for the pretreatment of micro- and nano-sized materials. The proposed PDMFP comprises a 3D network with a curved fluidic chamber and channel, five on/off pneumatic valves for blocking fluid flow, and a sieve valve for sequential trapping of microbeads and target particles. Using this setup, concentrated targets are automatically released into an outlet port. The FAPCS mainly comprises solenoid valves, glass reservoirs, a regulator, pressure sensor, main printed circuit board, and liquid crystal display touch panel. All pneumatic valves in the microfluidic platform as well as the working fluids in the glass reservoirs are controlled using FAPCS. The flow rate of the working fluids is measured to demonstrate the sequential programed operation of the proposed pretreatment process using FAPCS. In our study, we successfully achieved rapid and efficient enrichment using PDMFP-FAPCS with fluorescence-labeled Escherichia coli. With pretreatment-10 min for the microbead concentration and 25 min for target binding-almost all the target bacteria could be captured. A total of 526 Gram-negative bacteria were attached to 82 beads, whereas Gram-positive bacteria were attached to only 2 of the 100 beads. Finally, we evaluated the PDMFP-FAPCS for SARS-CoV-2 receptor-binding domain (RBD)-based outer membrane vesicles (OMVs) (RBD-OMVs). Specific probes involved in PDMFP-FAPCS successfully isolated RBD-OMVs. Thus, PDMFP-FAPCS exhibits excellent enrichment of particles, including microbes and nanovesicles, and is an effective pretreatment platform for disease diagnosis and investigation.