Dielectrophoretic behaviour of Micrococcus lysodeikticus and its protoplast

Inoue, Takashi; Pethig, Ronald; Al-Ameen, T A K; Burt, Julian P.H.; Price, Jonathan A.R.

doi:10.1016/0304-3886(88)90030-7

Cited by 22 publications

(17 citation statements)

References 8 publications

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“…At low frequencies the electrical properties of bacteria were concluded (Carstensen & Marquis, 1968 ;Einolf & Carstensen, 1969) to be dominated by the relatively high conductivity of the cell wall, with the cell interior being screened from low frequency imposed electric fields by the insulating inner plasma membrane (Pethig, 1979). These results were confirmed by dielectrophoretic measurements on M. bsodeikticzls (Inoue et al, 1988). Carstensen and co-workers (Carstensen et al, 1965 ;Carstensen & Marquis, 1968) also found that the electrical properties of the cell wall changed significantly with culturing conditions and culture age, which is an aspect we have not addressed here.…”

Section: Discussionsupporting

confidence: 58%

Dielectrophoretic characterization and separation of micro-organisms

Markx¹,

et al. 1994

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The effective electrical conductivity values for a variety of Gram-negative and -positive bacteria have been determined in the frequency range 10 kHz to 100 kHz. This information enabled experimental conditions to be selected where micro-organisms of different species can be separated using dielectrophoresis -the movement of particles induced by non-uniform AC electric fields. Mixtures of micro-organisms of different species were separated locally on a microscope slide using micro-electrodes of polynomial geometry, and their physical isolation into two separate suspensions was accomplished using a dielectrophoresis chamber that incorporated interdigitated, castellated micro-electrodes.

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Section: Discussionsupporting

confidence: 58%

Dielectrophoretic characterization and separation of micro-organisms

Markx¹,

et al. 1994

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“…PALS will overcome the disadvantages of tedious microscopic measurements by computerization as well as statistical significance at short measuring times. In contrast to conventional optical approaches (Talary and Pethig, 1994;Inoue et al, 1988), dynamic light scattering methods allow a direct detection of the frequency dependence of particle motion and avoid particle-particle interactions.…”

Section: Discussionmentioning

confidence: 99%

Introducing phase analysis light scattering for dielectric characterization: measurement of traveling-wave pumping

Gimsa¹,

Eppmann²,

Prüger³

1997

Biophysical Journal

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Phase analysis light scattering (PALS) was applied to characterize a high-frequency traveling-wave (TW) micropump. Field strength and frequency characteristics were measured for aqueous solutions up to 40 MHz and conductivities of 16 mS/m. The TW field was generated by an ultramicroelectrode array of intercastellated electrodes, which were driven by square-topped signals. Pumping exhibited one major relaxation peak, which strongly increased for conductivities above 4 mS/m. The conductivity dependence of the peak frequency showed an unexpected nonlinear behavior. Around 20 MHz an additional peak caused by electronic resonance was found. Additional coils or capacitors shifted the resonance peak and allowed us to determine the electronic properties of the array. Analysis of distortions in the pump spectra caused by the harmonic content of the driving signals showed that the pump direction is determined by the traveling direction of the field. For measurement of AC-field-induced particle translations, the advantage of PALS over the commonly used microscopic analysis is that it offers an objective method for statistically significant, computerized registration of extremely slow motions. Thus, for dielectric characterization, low field strengths can be used, which is advantageous not only for analyzing liquid pumping, but also for measuring particle translations induced by dielectrophoresis or TW dielectrophoresis.

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“…K(ω) can theoretically have a value that ranges between +1.0 and −0.5. At low frequencies K(ω) has the limiting value given by [11]…”

Section: The Theorymentioning

confidence: 99%

“…To obtain a non-uniform electric field in which particles could be levitated, AC voltages were applied between interdigitated electrodes as outlined in figures 1 and 3. Gold electrodes of various widths (5-240 µm) were deposited onto a microscope slide by photolithography [11], with the distance between adjacent electrodes being the same as the width of an electrode.…”

Section: The Levitation Devicementioning

confidence: 99%

The dielectrophoretic levitation of latex beads, with reference to field-flow fractionation

Markx

Pethig²,

Rousselet³

1997

J. Phys. D: Appl. Phys.

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103

114

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Interdigitated microelectrodes have been used to investigate the passive dielectrophoretic levitation of latex beads as a function of the frequency and voltage of the applied electrical signal, the suspending medium conductivity, bead size and characteristic dimensions of the electrodes. The variations of the electric field strength E and of the factor ∇E 2 as functions of the height above the electrode plane were determined by computer-aided modelling. As predicted from a simple theory based on the balancing of the gravitational settling force with the negative dielectrophoretic force, the height of levitation was found to be independent of the bead size and at 1 MHz, at which the levitation was at its largest, to be only weakly dependent on the conductivity of the suspending medium. The frequency dependence of the levitation height was found to be in close agreement with theory, based on the known dielectric properties of the beads and on previously determined electrode polarization effects. Apart from using this method to investigate the dielectric properties of particles, a particularly important application is envisaged to be that of particle separation, based on differences in dielectric properties, using dielectrophoretic levitation in combination with field-flow fractionation techniques.

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Dielectrophoretic behaviour of Micrococcus lysodeikticus and its protoplast

Cited by 22 publications

References 8 publications

Dielectrophoretic characterization and separation of micro-organisms

Dielectrophoretic characterization and separation of micro-organisms

Introducing phase analysis light scattering for dielectric characterization: measurement of traveling-wave pumping

The dielectrophoretic levitation of latex beads, with reference to field-flow fractionation

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