what causes heating in dielectrophoresis

[seshuiscool]

i have fabricated a multi-staged dielectrophoretic device (micron scale) to separate cells. i know its a pretty old concept, but i am actually a biological science student so i am obviously not very good with the electromechanics.

 

when i tried to test this device the micro flow path is getting over heated, this causes the evaporation of the fluid (mobile phase) and the cells that needs to be separated.

 

can anyone explain me what exactly is causing the heating and what parameters i do i need to modify in order to reduce the heat production and still achieve good dielectrophoretic separation.