Dielectrophoretic separation of biological samples in a 3D filtering chip

Abstract

A field-flow dielectrophoretic separation method in a 3D filtering chip has been developed in this work. The separation method was possible due to the special configuration of the DEP filtering chip, which has a structure similar to a classical capacitor with two parallel plate electrodes (realized by using a stainless steel mesh) and a dielectric medium (defined by a suspension of 100 µm diameter silica beads in buffer solution). The dielectrophoretic phenomenon is generated by the non-uniformities of the dielectric media, which produce a gradient of the electric field and, as a consequence, a DEP force. If a suspension medium with cells flows through the filter, the DEP force can trap these cells around the contact points between the silica beads (if the cells exhibit positive DEP) or they are repelled into the space between the beads (if the cells exhibit negative DEP). It is shown that for two different cell populations, the frequency of the electric field and permittivity of the media can be tuned in such a way that one population will exhibit positive DEP and the other one negative DEP. The population that expresses negative DEP can be easily flushed out due to the hydrodynamic force which is larger at the center point between the beads. In such a way two cell populations can be separated. The working principle was verified with both live and dead yeast cells. Best results for the separation of viable and nonviable cell populations were achieved at an applied voltage of 150 V in a frequency range between 10 kHz and 20 kHz for flow rates of 0.1 ml min −1 and 0.2 ml min −1 . With a few of these devices cascaded in series, higher efficiency could be achieved. As a result, this device and the associated proposed separation method can be very useful tools for bio-pharmaceutical industries since continuous flow separation at relatively high flow rates is both time and cost saving.

Exploitation of physical and chemical constraints for three-dimensional microtissue construction in microfluidics

“…55,56 Lewpiriyawong et al 57 proposed a microfluidic H filter fabricated in PDMS that induced a nonuniform electric field, generating a nDEP force on the particles. The iDEP method has been used for separating two different cell populations like viable and dead cells using HeLa cells 58 or yeast cells 59 as models. This method can potentially be applied to sort out two live cell populations and trap and concentrate them for microtissues construction on a chip.…”

Particle Manipulation by Miniaturised Dielectrophoretic Devices

“…used to manipulate cells, virus, DNA, and polystyrene particles by many researchers 16,[18][19][20][21][22][23][24] . Recently, Iliescu 25 , et al proposed a novel 3-D dielectrophoretic chip where two planar electrodes were made from a stainless steel mesh, and bonded on both sides of a glass frame which is filled with round silica beads, as shown in Fig. 5.…”

A handheld preconcentrator for the rapid collection of cancerous cells using dielectrophoresis generated by circular microelectrodes in stepping electric fields

“…12 An approach for the DEP field-flow separation of cells utilizing a DEP chip filter, in which a non-uniform electric field is generated by the insertion of dielectric silica beads between two wire-meshed parallel plates, has been proposed. 13 A microfluidic device composed of a series of microchannels constructed with insulating microstructures for the concentration of micro=nanoparticles using direct current (DC) dielectrophoresis in a continuous fluid flow was proposed by Chen and Du.…”