Separation of nanoparticles by a nano-orifice based DC-dielectrophoresis method in a pressure-driven flow

Abstract

A novel DC-Dielectrophoresis (DEP) method employing pressure-driven flow for the continuous separation of micro/nanoparticles is presented in this paper. To generate the DEP force, a small voltage difference is applied to produce the nonuniformity of the electric field across a microchannel via a larger orifice of several hundred microns on one side of the channel wall and a smaller orifice of several hundred nanometers on the opposite channel wall. The particles experience DEP force when they move with the flow through the vicinity of the small orifice, where exits the strongest electrical field gradient. Experiments were conducted to demonstrate the separation of 1 µm and 3 µm polystyrene particles by size by adjusting the applied electrical potentials. In order to separate smaller nanoparticles, the electrical conductivity of the suspending solution is adjusted so that the polystyrene nanoparticles of a given size experience positive DEP while the polystyrene nanoparticles of another size experience negative DEP. Using this method, the separation of 51 nm and 140 nm nanoparticles and the separation of 140 nm and 500 nm nanoparticles were demonstrated. In comparison with the microfluidic DC-DEP methods reported in the literatures which utilize hurdles or obstacles to induce the non-uniformity of electric field, a pair of asymmetrical orifices on the channel side walls is used in this method to generate strong electrical field gradient and has advantages such as capability of separating nanoparticles, and locally applied lower electrical voltages to minimize Joule heating effect.

Microfluidic Techniques for Analytes Concentration

“…Lewpiriyawong et al [ 118 ] utilized a microfluidic constriction to generate nonuniform electric fields for insulator-based DEPT of particles and cells. Zhao et al [ 119 ] recently proposed a novel design of using asymmetric orifices on opposite channel walls to generate nonuniform electric fields. Such design was shown to greatly reduce the magnitude of voltages required for insulator-based DEPT.…”

<p>Development and Clinical Prospects of Techniques to Separate Circulating Tumor Cells from Peripheral Blood</p>

“…The PDMS chip also has a serpentine mixed channel that promotes CTC and lining. Huang, 81 Moon, 82 Cheng 83 Cen 84 Zhao 85 Kang 86, Bhattacharya 87 Chuang, 88 Another enrichment technology based on immunomagnetic nanoparticles is the magnetic cell separation system (MACS). 7,40 This method involves high-gradient magnetic separation to capture CTC that are labeled using magnetic nanoparticles coupled with EpCAM antibodies.…”

Simultaneous and continuous particle separation and counting via localized DC-dielectrophoresis in a microfluidic chip

“…Dielectrophoresis (DEP) is a well-known electrical method for particle manipulation at micro and nano scales. [1][2][3][4][5] Recently, there have been some investigations on integrating DEP with some detection means to improve detection sensitivity or achieve selective detection. One popular approach is to integrate DEP with an impedance detection system.…”