Dielectrophoretic concentration of particles under electrokinetic flow

In a microfluidic device using electrokinetic/electroosmotic flow to sweep particles down a microfluidic channel section for dielectrophoretic concentration of particles under and collecting said particles in said microfluidic channel section using a combination of dielectrophoresis and electrokinetic/electroosmotic flow, said microfluidic channel section having a first end, a second end and an inner section, an improvement comprising:

• means for producing said electrokinetic/electroosmotic flow in said microfluidic channel section by producing a DC voltage across said first end and said second end of said microfluidic channel section, said means for producing said electrokinetic/electroosmotic flow in said microfluidic channel section by producing a DC voltage across said first end and said second end of said microfluidic channel section comprising
• a positive electrode connected to said first end of said microfluidic channel section and a negative electrode connected to said second end of said microfluidic channel section and a DC power supply connected to said positive electrode and said negative electrode,
• interdigitated electrodes patterned on said inner surface of said microfluidic channel section, said interdigitated electrodes comprising a first electrode plate having first electrode projecting legs and a second electrode plate having second electrode projecting legs, said first electrode projecting legs and said second electrode projecting legs interlaced, and
• means for producing said combination of dielectrophoresis and electrokinetic/electroosmotic flow by applying an AC voltage across said interdigitated electrodes to set up a non-uniform electric field capable of trapping said particles using a dielectrophoretic force as said particles are swept down the microfluidic channel electrokinetically said means for producing said combination of dielectrophoresis and electrokinetic/electroosmotic flow comprising
• an AC power supply connected to said first electrode plate having first electrode projecting legs and said second electrode plate having second electrode projecting legs which sets up said non-uniform electric field proximate said first electrode plate having first electrode projecting legs and said second electrode plate having second electrode projecting legs, said non-uniform electric field trapping said particles.

A method for concentrating particles under flow, comprising:

• forming at least one pair of interdigitated electrodes on a fluidic microchannel having a multiplicity of first electrode projecting legs and a second multiplicity of electrode electrode projecting legs,
• positioning at least one pair of interdigitated electrodes so that said first electrode projecting legs and said second electrode projecting legs are interlaced, and
• sweeping said particles through said fluidic microchannel by
• applying an AC voltage across the interdigitated electrodes to establish a non-uniform electric field capable of trapping particles using an dielectrophoretic force,
• controlling said voltage applied to each pair of interdigitated electrodes, and
• applying a DC voltage across ends of the fluidic microchannel to initiate an electrokinetic/electroosmotic flow field.