Movement of particles using sequentially activated dielectrophoretic particle trapping

#The present invention is directed to PCR sample preparation, particularly to the manipulation of particle in a sample fluid using dielectrophoretic forces to concentrate and move samples in an electrophoretic channel, and more particularly to movement of particles by sequentially activated/deactivated electrodes position along a length of a channel.

#Extensive efforts are being carried out to enable sample preparation for various amplication, such as to provide PCR sample preparation for counter biological warfare applications, as well as for a clinical tool to determine genetic information. A key element of the sample preparation process is to enable controlled concentration and/or movement of DNA, for example, prior to detection.

#The present invention enables manipulation of DNA and cells/spores using dielectrophoretic (DEP) forces to perform sample preparation protocols for polymerized chain reaction (PCR) based assays. The invention utilizes a series of electrodes located along a length of an electrophoretic channel. Since DEP forces induce a dipole in the sample particles, these particles can be trapped in non-uniform fields produced by electrodes located along a length of the channel. By switching on and off sequentially located electrodes, the electric field s produced thereby cause the particles to be moved down a channel and/or concentrated in the channel, with little or no flow. Thus, the invention provides movement of particles using sequentially activated dielectrophoretic particle trapping.

#The accompanying drawings, which are incorporated into and form a part of the disclosure, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

#FIG. 1 is a top view of an embodiment of a patterned set of electrodes or electrode segments located on a top surface of a fluidic channel.

#FIG. 2 is a side view of the fluid channel and electrode of FIG. 1 shown a single electrode on the bottom surface of the fluidic channel.

#The present invention is directed to the manipulation of DNA and cells/spores using dielectrophoretic (DEP) forces to perform sample preparation protocols for polymerized chain reaction (PCR) based assays. More specifically, the invention is directed to movement of particles using sequentially activated DEP particle trapping. The invention enables the movement of materials along a fluidic channel with little or no flow. DEP forces induce a dipole in the particles (a negative charge for example) and these charged particles can be trapped in non-uniform electric fields. The particles are trapped in high electric field strength regions of a first set of several sets of electrodes located along the fluidic channel, and by switching off the electric field in the first set of electrodes and switching on the adjacent downstream set of electrodes, particles can be moved down the fluidic channel. The set of electrodes may comprise a number of smaller electrodes, such as fingers or segments of interdigitated electrodes on the top of the fluidic channel and a long or larger single electrode at the bottom of the channel, or vice versa, and the electric fields are generated between any of the small electrodes or electrode segments and single electrode. Thus, as seen in the drawings and described in detail hereinafter, as the electric field is changed from one small electrode to the next small electrode the particles are drawn down the fluidic channel so as to enable control, concentration, and appropriate movement of the particles for assay purposes.

#A set of small electrodes may be photo-lithographically patterned on the top as shown in FIG. 1, or on the bottom, of a fluidic or flow channel. A single electrode (larger) is patterned on the bottom, as shown in FIG. 1, or on the top of the flow channel. An alternating current (AC) source is connected between the sets of small electrodes and the single electrode such that an AC signal can be placed between any one of the small electrodes on the top of the channel and the single electrode on the bottom, as shown, thereby producing an electric field therebetween. The particles are attracted to the high electric field gradient at the smaller electrode. When it is desired to move a particle along the channel the small electrode will be switched off and the next (downstream) small electrode will be switched on (activated), causing the particle to move to and trapped in the electric field of that next electrode. Thus, the particles can be “walked” down the channel under full control of particle movement, with little or no flow through the channel.

#An embodiment of an electrode configuration is illustrated in FIGS. 1 and 2, with FIGS. 3 and 4 illustrating the electric field change causing movement of the particles through the fluidic or flow channel. FIG. 1 is a top view of an electrode configuration located in the top or upper surface of a channel, while FIG. 2 is a side view of the electrode configuration of Figure.