Enhanced Electroosmotic Mixing in a Wavy Micromixer Using Surface Charge Heterogeneity

Abstract

We investigate the flow and mixing characteristics for an electroosmotic flow through a wavy micromixer using surface charge heterogeneity. The Laplace equation for the external electric field, Poisson–Boltzmann equation for potential distribution, and continuity and momentum equations for fluid flow and species transport equation have been solved by imposing the appropriate boundary conditions using a finite element method-based numerical solver. The results are presented by varying the phase lag of sinusoidal zeta potential between the two walls (Δϕ), Debye parameter (κ), geometrical wave number (n), dimensionless wall amplitude (α), and diffusive Peclet number (Pe). The results reveal that the phase lag has a strong confluence on the flow field and mixing performance together with other physicochemical parameters. The strength of primary flow as well as the size of the recirculation zones increases with Δϕ and κ, and additional recirculation zones are formed in the core of the mixer for Δϕ = 0. The value of mixing efficiency is close to 100% up to a critical value of Pe (Pe Cri), the value of which is greater for the nonuniformly charged surface potential with a nonzero phase lag. For thinner EDL (κ = 150), a fully mixed state based on 90% mixing is achieved up to higher values of Pe with a higher flow rate at Δϕ = π/2 and π. Also, for Δϕ = π/2, the mixing efficiency as well as the flow rate enhances with the amplitude of the channel walls for Pe Cri ≤ Pe ≤323.5. Moreover, for Δϕ = 0, the value of mixing efficiency increases with α for 786 ≤ Pe ≤1000 with a 9.17% decrement in the flow rate for the change in α from 0.05 to 0.25.

A Novel Strategy for Square-Wave Micromixers: A Survey of RBC Lysis for Further Biological Analysis

“…Figure 2A indicates the investigated MUs in this study, including the CDC-conjugated base MU (MU 1), CDC-conjugated semisquare-based-RPDMU (MU 2), CDC-conjugated semihexagon-based-RPDMU (MU 3), CDC-conjugated semioctagon-based-RPDMU (MU 4), and CDC-conjugated semidecagon-based-RPDMU (MU 5). As shown in Figure 2B, six HMPs must be filled with five different MUs, requiring a total number of 5 6 experiments to be investigated, which is not feasible. Hence, a design of experiments (DOE) method should be employed to decrease the total number of experiments.…”

“…Microfluidics, also known as lab-on-a-chip, is the science studying the flow behavior at the microscale. , Flow manipulation within microfluidic devices such as micromixers, − microdroplet generators, − and microseparators − is pursued to achieve the desired output. These systems have found their functionality in various biorelated analyses and engineering. − In many of these applications, efficient and well-controlled mixing is crucial in successfully satisfying the aim of the desired study. , Therefore, micromixers are one of the most pivotal parts of lab-on-a-chip systems.…”

AC Electrothermal Effect Promotes Enhanced Solute Mixing in a Wavy Microchannel

“…A survey of the existing literature unravels that ACET actuation is suitable for electrolytic liquids with higher electrical conductivity (≥0.01 S/m), which are typically used in microfluidic applications. − Considering all of the above aspects, the modulation of the electric field distribution by introducing waviness to the microfluidic surface seems to be an interesting proposition to modify the features of ACET vortex production and the eventual consequence of this phenomenon to augment the underlying mixing. To the best of our knowledge, no studies focusing on the impact of geometrical parameters pertaining to ACET-modulated vortex generation and its effect on the solute mixing characteristics have been reported until this endeavor.…”

Mixing characteristics and pressure drop analysis in a spiral micromixer

“…6,7 Active micromixers are those in which the mixing performance of fluids is enhanced by agitating or stirring the flow using external energy sources other than the main driving potential for flow. These sources can be electrokinetics, [8][9][10][11][12][13] acoustic field, 14 and magnetic field. 15 Active micromixers are difficult and expensive to fabricate because of external driving sources, and it is not easy to integrate them into micromixers.…”