Continuous Particle Trapping, Switching, and Sorting Utilizing a Combination of Dielectrophoresis and Alternating Current Electrothermal Flow

Abstract

We propose a simplified multifunctional traffic control approach that effectively combines dielectrophoresis (DEP) and alternating current electrothermal (ACET) flow to realize continuous particle trapping, switching, and sorting. In the designed microsystem, the combined DEP and ACET effects, which are symmetrically generated above a bipolar electrode surface, contribute to focus the incoming colloidal particles into a thin beam. Once the bipolar electrode is energized with an electric gate signal completely in phase with the driving alternating current (AC) signal, the spatial symmetry of the electric field can be artificially reordered by adjusting the gate voltage through fieldeffect traffic control. This results in a reshapable field stagnant region for precise switching of particles into the region of interest. Moreover, the integrated particle switching prior to the scaled particle trapping experiment is successfully conducted to demonstrate the feasibility of the combined strategy. Furthermore, a mixture of two types of particle sorting (i.e., density, size) with quick response performance is achieved by increasing the driving voltage with a maximum gate voltage offset, thus, extending the versatility of the designed device. Finally, droplet switching and filtration of the satellite droplets from the parent droplets is performed to successfully permit control of the droplet traffic. The proposed traffic control approach provides a promising technique for flexible manipulation of particulate samples and can be conveniently integrated with other micro/nanofluidic components into a complete functional on-chip platform owing to its simple geometric structure, easy operation, and multifunctionality.

AC Electrothermal Effect in Microfluidics: A Review

“…More details of different strategies for implementation of ACEO in microfluidics can be found in [54,55]. DEP and ACET effects can be combined [13,56,57,58,59] to improve particle manipulations, as DEP has difficulty in manipulating submicron particles, and also is weak in areas far from electrodes where ACET is strong [13,56].…”

AC Electroosmosis Effect on Microfluidic Heterogeneous Immunoassay Efficiency

“…DEP is greatly used in biological applications for the separation of virus particles [15,16], the separation of nanoparticles [17], droplet manipulation [18], and trapping and manipulation of single cells and particles [19]. Dielectrophoresis (DEP) and alternating current electrothermal (ACET) flow are also combined to realize continuous particle trapping, switching, and sorting [20]. ACEO is used to move fluids with low conductivity.…”

Buoyancy-Free Janus Microcylinders as Mobile Microelectrode Arrays for Continuous Microfluidic Biomolecule Collection within a Wide Frequency Range: A Numerical Simulation Study

“…In terms of the physical origin of the relevant charge layers, the primary electrical force exerting on microscale solid entities suspended in aqueous electrolytes includes electrophoresis (EP) [27][28][29], nonlinear induced-charge electrophoresis (ICEP) [30][31][32][33][34][35], and dielectrophoresis [36][37][38]. Directed "force-free" electrophoretic delivery of microspheres in a constant DC electric field is caused by the linear electroosmosis fluid stress on the surface of the natively charged particles, which is due to the interaction between an imposed tangential field and the natural diffuse screening cloud adjacent to the target sample suspended in aqueous electrolyte [39].…”