Patent ID: 6881314

Claim:
A method of discriminating a matter using electrophoretic and acoustic forces in field flow fractionation, which method comprises: a) obtaining an apparatus, which apparatus comprises: i) a chamber having at least one inlet port and at least one outlet port said chamber having such structural characteristics that when a carried medium is caused to travel through said chamber, the traveling velocity of said carried medium at various positions within said chamber is different; ii) at least two stationary electrode elements adapted along a portion of said chamber, wherein said electrode elements can be energized via at least one electrical signal provided by a first electrical signal generator to create an electrical field, thereby causing at least one electrophoretic force having components normal to the traveling direction of said carrier medium on a matter in said carrier medium; and iii) at least one stationary piezoelectric transducer adapted along a portion of said chamber, wherein said piezoelectric transducer can be energized via at least one electrical signal provided by a second electrical signal generator to create an acoustic wave, thereby causing at least one acoustic force having components normal to the traveling direction of said carrier medium on a matter in said carrier medium, wherein said first electrical signal generator and said second electrical signal generator are different electrical signal generators; b) introducing a carrier medium containing a matter to be discriminated into the chamber of the apparatus obtained in a) via its inlet port, wherein said introducing causes the carrier medium to travel through the chamber according to a velocity profile; c) applying at least one electrical signal provided by a said first electrical signal generator to the electrode elements, wherein said energized electrode elements create an electrical field, thereby causing at least one electrophoretic force on said matter having components normal to the traveling direction of said carrier medium traveling through said chamber; and d) applying at least another electrical signal provided by said second electrical signal generator to the piezoelectric transducer, wherein said energized piezoelectric transducer creates an acoustic wave, thereby causing at least one acoustic force on said matter having components normal to the traveling direction of said carrier medium traveling through said chamber, whereby said matter is displaced to positions within said carrier medium along a direction normal to the traveling direction of said carrier medium traveling through said chamber and discriminated according to its position within said carrier medium along the direction normal to the traveling direction of said carrier medium traveling through said chamber.