News Column

"Microfluidic Dielectrophoresis System" in Patent Application Approval Process

May 20, 2014

By a News Reporter-Staff News Editor at Life Science Weekly -- A patent application by the inventor DORRER, Christian (Stuttgart, DE), filed on January 6, 2014, was made available online on May 8, 2014, according to news reporting originating from Washington, D.C., by NewsRx correspondents (see also Robert Bosch Gmbh).

This patent application is assigned to Robert Bosch Gmbh.

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to a microfluidic dielectrophoresis system, in particular for the accumulation and/or concentration of dielectric, polarizable particles from a liquid medium, the use thereof, and a method for performing a dielectrophoresis, in particular for the accumulation and/or concentration of polarizable particles from a liquid medium, in particular using a microfluidic dielectrophoresis system.

"An important area of application of dielectrophoresis is the concentration and separation of polarizable particles from a suspension. The particles may be manipulated in a fluidic channel, which is equipped with electrodes, as a flow cell. An inhomogeneous electrical field is produced by the electrodes during the dielectrophoresis by applying an AC voltage. A dipole moment, which interacts with the applied field, is induced by the inhomogeneous electrical field in the polarizable particles. The particles move either into areas of higher (positive DEP) or lower (negative DEP) field strength gradients due to a dielectrophoretic force field and may be accumulated therein in a 'field cage' if necessary. Inter alia, a method has been established for the concentration of particles in which the polarizable particles are held back by positive dielectrophoresis (pDEP), while new sample volume is continuously conducted through the flow cell. After the electrode voltage, and therefore the dielectrophoretic force, is turned off, the particles may be flushed out in collected form. Because of the short range of the electrical field, microfluidic systems suggest themselves in particular for implementing the described functional principle. A typical construction of such a microfluidic system includes a microfluidic chip, which is equipped with a dielectrophoretically active channel part, which is equipped with electrodes, as a flow cell and with supply line channels. Such constructions are described, for example, in the technical publications 'Strategies for dielectrophoretic separation in laboratory-on-a-chip systems' (Hughes, M. P. Electrophoresis 2002, 23, 2569) and 'High-Throughput Positive-Dielectrophoretic Bioparticle Microconcentrator' (Gadish, N.; Voldman, J. Anal. Chem. 2006, 78, 7870) and the literature cited therein. A microfluidic channel system may be contacted with further components via flexible tubing. The sample volumes may be supplied from a reservoir using injector pumps or peristaltic pumps. Liquid which is no longer required may be conducted into a waste reservoir.

"Such dielectrophoresis (DEP) chips, which may allow the selective separation and concentration of polarizable particles, for example, polymer particles or bioparticles, such as viruses, bacteria, or cells, possibly from complex substance mixtures, for example, for a subsequent analysis, are currently of interest in research and development. With respect to biotechnological applications, the problem often exists that bacteria, viruses, or cells must be extracted from a comparatively large sample volume. In order to conduct large liquid quantities (milliliters) through a microfluidic system in an acceptable time, comparatively large channel cross-sections and therefore large channel volumes are required. As a result, not all particles are reached by the dielectrophoretic force field and the liquid quantity required for the final flushing of the particles out of the particular channel is in turn relatively large, which limits the achievable particle concentration, and reduces the efficiency of the concentration in relation to a channel having smaller volume.

"A device for the sequencing of polynucleotides is proposed in published international patent application document WO 97/07245, in which the samples may be fed using a distributor unit into separation channels which are operated in parallel and may be processed simultaneously therein, for example, separated."

In addition to the background information obtained for this patent application, NewsRx journalists also obtained the inventor's summary information for this patent application: "The present invention proposes providing a dielectrophoresis system which includes at least one supply device for a liquid medium having particles contained therein, N.gtoreq.2 microfluidic, dielectrophoretically active channels K.sub.n, which are equipped with electrodes, where 1.ltoreq.n.ltoreq.N, lines for the fluidic connection of the supply device to the channels, for the connection of the channels to one another, and for the drainage of the medium and/or the particles from the channels, and valves for setting the flow direction of the medium in the lines,

"the dielectrophoretically active channels being situated and being connected by lines in such a way that they may be operated connected in parallel and in series by switching the valves in relation to the flow direction of the medium, and the electrodes of the various channels being activatable independently of one another.

"In other words, the dielectrophoretically active channels of the dielectrophoresis system of the present invention may be operated both in a parallel connection and also, alternatively thereto, in a series connection, in relation to the flow of the medium. The changeover between the parallel connection and the series connection may be controlled in a targeted manner according to the present invention via the valve setting.

"According to the present invention, a higher throughput of sample volume, i.e., the medium having polarizable particles contained therein, may be made possible using the parallel connection of the dielectrophoretically active channels. In an accumulation phase, the accumulation of polarizable particles in the microfluidic channels may additionally occur at higher efficiency. It is possible through the possible series connection of these channels and the independent control of the electrodes and thus of the individual dielectrophoretic force fields to selectively release the particles accumulated in the individual channels by turning off the voltage at the electrodes and to collect the particles in a channel connected downstream in the flow direction, in which the dielectrophoretic force is still active. The particles which are accumulated and concentrated once again in this manner may be flushed out in collected form from this channel. In other words, an additional concentration effect may be achieved in a separate concentration phase.


"The present invention is explained hereafter on the basis of exemplary embodiments in connection with the figures, without being restricted to the embodiments shown.

"FIG. 1 shows a schematic construction of a microfluidic dielectrophoresis system according to the present invention having channels connected in parallel.

"FIG. 2 shows a schematic view of a microfluidic dielectrophoresis system according to the present invention from FIG. 1 having channels connected in series."

URL and more information on this patent application, see: DORRER, Christian. Microfluidic Dielectrophoresis System. Filed January 6, 2014 and posted May 8, 2014. Patent URL:

Keywords for this news article include: Robert Bosch Gmbh.

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Source: Life Science Weekly

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