Dielectrophoretic characterization and separation of micro-organisms

Markx, Gerard H.; Huang, Ying; Zhou, Xiaoling; Pethig, Ronald

doi:10.1099/00221287-140-3-585

Cited by 215 publications

(145 citation statements)

References 17 publications

(13 reference statements)

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“…One demonstration, from Peter Gascoyne's group at MD Anderson Cancer Center, showed the technique could separate cancer cells spiked into human blood, potentially marking it out as a prognostic technique for the detection of circulating tumor cells; 24 the second, by the Pethig lab at Bangor, where CD34þ hematopoietic stem cells were separated from bone marrow. 25 By this point-30 years after the first demonstration of DEP separation-what could be regarded as the key separation targets in DEP had already been demonstrated; cancer cells from blood, 24 stem cells, 25,26 bacteria of different strains 27,28 and live and dead cells. 2 One final implementation of DEP separation has endured from this period.…”

Section: The Microfabrication Explosionmentioning

confidence: 99%

Fifty years of dielectrophoretic cell separation technology

Hughes

2016

Biomicrofluidics

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In 1966, Pohl and Hawk [Science 152, 647–649 (1966)] published the first demonstration of dielectrophoresis of living and dead yeast cells; their paper described how the different ways in which the cells responded to an applied nonuniform electric field could form the basis of a cell separation method. Fifty years later, the field of dielectrophoretic (DEP) cell separation has expanded, with myriad demonstrations of its ability to sort cells on the basis of differences in electrical properties without the need for chemical labelling. As DEP separation enters its second half-century, new approaches are being found to move the technique from laboratory prototypes to functional commercial devices; to gain widespread acceptance beyond the DEP community, it will be necessary to develop ways of separating cells with throughputs, purities, and cell recovery comparable to gold-standard techniques in life sciences, such as fluorescence- and magnetically activated cell sorting. In this paper, the history of DEP separation is charted, from a description of the work leading up to the first paper, to the current dual approaches of electrode-based and electrodeless DEP separation, and the path to future acceptance outside the DEP mainstream is considered.

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Section: The Microfabrication Explosionmentioning

confidence: 99%

Fifty years of dielectrophoretic cell separation technology

Hughes

2016

Biomicrofluidics

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“…Betts 1994, Suehiro et al 2003) and separation of bacteria of different species (Markx et al 1996) as well as a method of analysing bacterial properties (e.g. Markx et al 1994, Milner 1998, for the analysis of bacterial motors (Washizu et al 1993;Hughes and Morgan, 1998) and for the construction of microbial consortia (Alp et al 2002). Work has been performed on the separation of viable and non-viable bacteria (e.g.…”

Section: Introductionmentioning

confidence: 99%

Dielectrophoretic assay of bacterial resistance to antibiotics

et al. 2003

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The dielectrophoretic collection spectra of antibiotic-sensitive and antibiotic-resistant strains of Staphylococcus epidermidis have been determined. These indicate that in the absence of antibiotic treatment there is a strong similarity between the dielectric properties of sensitive and resistant strains, and that there is a significant difference between the sensitive strain before and after treatment with the antibiotic streptomycin after 24hrs exposure. This method offers possibilities for the assessment of bacterial resistance to antibiotics.

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“…As demonstrated by Markx et al [18], physical separation of a mixture of particles into two populations can be achieved by subjecting the electrode array to a flow of liquid of sufficient pressure to remove particles trapped at field minima leaving the other particles trapped at the electrode tips. The remaining beads can then be removed by switching off the field and flushing fresh liquid across the electrodes.…”

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confidence: 99%

Dielectrophoretic separation of nano-particles

Green

Morgan

1997

J. Phys. D: Appl. Phys.

156

141

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Abstract. We show for the first time that it is possible to separate a population of nanoparticles into two subpopulations solely on the basis of their dielectric properties. Using nanofabricated electrode arrays it has been shown that a solution of 93 nm diameter latex beads with a distribution of surface charge can be separated by the application of non-uniform AC electric fields (dielectrophoresis). The mixture separated into two populations, one experiencing positive dielectrophoresis and the other negative dielectrophoresis.The movement of polarizable particles in non-uniform fields, termed dielectrophoresis by Pohl [1], has been exploited as a rapid non-invasive tool for the diagnosis and separation of mammalian cells and micro-organisms [2]. It has found practical applications in medicine for separating cancer cells from blood [3], enriching CD34+ cells in bone marrow samples [4] and for detecting the viability of pathogenic organisms in water [5].Separation of particles is based on the fact that when placed in a non-uniform AC electric field, polarized particles experience a variable translational force, depending on the applied field frequency. For particles whose polarizability is greater than the medium the net movement is to regions of highest field strength, whereas particles whose polarizability is less than the medium move to the region of lowest field gradient. Because the particle's polarization is frequency dependent, the net force is also frequency dependent. Therefore, by judicious choice of suspending medium conductivity and applied frequency, even particles with very similar dielectric properties can be efficiently separated.The sum total of the forces on a given particle is: F total = F deterministic + F random . The deterministic force is the sum of the sedimentation, hydrodynamic and dielectrophoretic forces. The random force is due to Brownian motion and for particles with a diameter of the order of 100 nm this force is considerable. The mean free path of the movement is inversely dependent on mass, implying that decreases in the particle diameter require significant increases in the applied electrostatic energy (or field strength). The stable trapping of viruses and beads has been demonstrated previously [6][7][8][9]. Here we show that nanometre sized latex spheres can be both stably trapped in nanofabricated electrode arrays and, more importantly, that a heterogeneous mixture can be separated into two populations using dielectrophoresis. Experiments were conducted on charged latex spheres of 93 nm diameter, using planar electrodes manufactured by electron-beam lithography. The applied electric field strength was 2.5 × 10 5 V m −1 and the suspending medium conductivity was 0.018 S m −1 . Large electric field strengths cause localized heating of electrode structures which in turn gives rise to discontinuities in conductivity, permittivity and viscosity of the medium. The result is the inception

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Dielectrophoretic characterization and separation of micro-organisms

Cited by 215 publications

References 17 publications

Fifty years of dielectrophoretic cell separation technology

Fifty years of dielectrophoretic cell separation technology

Dielectrophoretic assay of bacterial resistance to antibiotics

Dielectrophoretic separation of nano-particles

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