Electrophoresis

Dielectrophoresis (DEP), the phenomenon of directed motion of electrically polarizable particles in a nonuniform electric field, is promising for applications in biochemical separation and filtration. However, quantification methods of the DEP force on individual particles with the pico-Newton resolution required for the development of theories and design of device applications are lacking. Using optical tweezers-based force transducers already developed in our laboratory, we have results that quantify the frequency-dependent DEP force and the crossover frequency of individual particles with this new experimental method.

 

 

 

 

 

 

 

 

 

 

 

 

A diagram depicting the potential well formed by OT. Under an AM DEP force the particle executes an oscillatory motion centered at the point off-set from the center of the optical trap.

 

 

 

 

 

 

 

The DEP force (left) and displacement phase (right) as a function of frequency for four different sizes of polystyrene particles with diameters ranging from 0.998 to 2.1 um.