Peristaltic flow of electrically conducting nanofluid under the action of Joule and radiative heat within an asymmetric microchannel

The proposed mathematical model is based upon the peristaltic flow of an electrical conducting nanofluid within an asymmetric microchannel. The flow takes place under the action of dissipative heat energy due to the occurrence of the magnetic field that is basically known as Joule heating and radiative heat proposed as thermal radiation along with the additional heat source. Moreover, the impact of upper/lower wall zeta potential and the expression for the electric potential is presented using the Poisson Boltzmann equation and Debey length approximation. The well-known numerical practice is used for distorted governing equations with appropriate boundary conditions. Further, computation of the pressure gradient is obtained for the associated physical parameters. The graphical illustration shows the characteristics of the pertinent parameters on the flow problem and the tabular result represents the simulated values for the rate coefficients. In the significant examination, the study reveals that the mobility parameter due to the occurrence of the electric field vis-à-vis time parameter encourages the velocity distribution within the center of the channel furthermore significant retardation occurs near the wall region.

Hydrodynamic Microparticle Separation Mechanism Using Three-Dimensional Flow Profiles in Dual-Depth and Asymmetric Lattice-Shaped Microchannel Networks

We herein propose a new hydrodynamic mechanism of particle separation using dual-depth, lattice-patterned asymmetric microchannel networks. This mechanism utilizes three-dimensional (3D) laminar flow profiles formed at intersections of lattice channels. Large particles, primarily flowing near the bottom surface, frequently enter the shallower channels (separation channels), whereas smaller particles flowing near the microchannel ceiling primarily flow along the deeper channels (main channels). Consequently, size-based continuous particle separation was achieved in the lateral direction in the lattice area. We confirmed that the depth of the main channel was a critical factor dominating the particle separation efficiencies, and the combination of 15-μm-deep separation channels and 40-μm-deep main channels demonstrated the good separation ability for 3–10-μm particles. We prepared several types of microchannels and successfully tuned the particle separation size. Furthermore, the input position of the particle suspension was controlled by adjusting the input flow rates and/or using a Y-shaped inlet connector that resulted in a significant improvement in the separation precision. The presented concept is a good example of a new type of microfluidic particle separation mechanism using 3D flows and may potentially be applicable to the sorting of various types of micrometer-sized objects, including living cells and synthetic microparticles.

Microparticle Inertial Focusing in an Asymmetric Curved Microchannel

Inertial microfluidics offers high throughput, label-free, easy to design, and cost-effective solutions and is a promising technique based on hydrodynamic forces (passive techniques) instead of external ones, which can be employed in lab-on-a-chip and micro-total-analysis-systems for focusing, manipulation, and separation of microparticles in chemical and biomedical applications. The current work, studies the focusing behavior of microparticles in an asymmetric curvilinear microchannel. For this purpose, focusing behavior, including position and band width, of microparticles of diameters of 10, 15 and 20 µm, which served as representatives of different cells, in an asymmetric curvilinear microchannel with curvature angle of 280° was experimentally studied at flow rates from 400 to 2700 µL/min (corresponding to Reynolds numbers between 30 and 205). The results revealed that the largest distance between focusing bands of 20 µm and 10 µm microparticles as well as between focusing bands of 15 µm and 10 µm was obtained at Reynolds number of 121. For the case of microparticles of diameters 20 µm and 15 µm, the largest distance was seen at Reynolds number of 144. The focusing band width became smaller in the asymmetric microchannel so that focusing could be more clearly observed in this configuration.