Dielectrophoresis-based particle exchanger for the manipulation and surface functionalization of particles

Abstract

We present a microfluidic device where micro- and nanoparticles can be continuously functionalized in flow. This device relies on an element called "particle exchanger", which allows for particles to be taken from one medium and exposed to some reagent while minimizing mixing of the two liquids. In the exchanger, two liquids are brought in contact and particles are pushed from one to the other by the application of a dielectrophoretic force. We determined the maximum flow velocity at which all the particles are exchanged for a range of particle sizes. We also present a simple theory that accounts for the behaviour of the device when the particle size is scaled. Diffusion mixing in the exchanger is also evaluated. Finally, we demonstrate particle functionalization within the microfluidic device by coupling a fluorescent tag to avidin-modified 880 nm particles. The concept presented in this paper has been developed for synthesis of modified particles but is also applicable to on-chip bead-based chemistry or cellular biology.

Dielectrophoretic focusing of particles in a microchannel constriction using DC‐biased AC flectric fields

“…Other than this flowassisted method, a variety of sheathless focusing approaches have also been demonstrated. For example, particle focusing has been achieved by applying an external force field, such as optical [16], acoustic [17], electrophoretic [18], and AC dielectrophoretic [19][20][21][22], to manipulate particles directly to their equilibrium positions in the pressure-pumping particulate stream. In addition, particle focusing has also been achieved by using hydrodynamic filtration [23,24], hydrophoresis [25,26], DC dielectrophoresis [27], and inertia [28][29][30][31] etc.…”

Bioanalytical separations using electric field gradient techniques

“…The device was able to separate peptide ligands bound to beads from unbound peptides and beads. An additional DEP technique functionalized small particles (880 nm avidin-modified latex) in continuous flow with a ''particle exchanger'' [107]. In the device, AC DEP force was utilized to extract a particle from a starting medium and expose it to a different reagent.…”

A dielectrophoretic continuous flow sorter using integrated microelectrodes coupled to a channel constriction

“…These packaging steps significantly increased the fabrication complexity and costs. Other devices used sidewalls [7] or photoconductive [8] electrodes for manipulating [9,10], trapping [11], sorting [12], and/or releasing [13] latex beads or bioparticles.…”