Modeling and experimental verification of common dielectrophoresis on platinum microelectrodes

Abstract

The motion of neutral matter induced by non-uniform electric fields, i.e. common dielectrophoresis, has become the basic phenomenon of microchips intended for medical, biological and chemical assays, especially when they imply biological and artificial microparticle manipulation. This paper describes the modeling and experimental verification of an interdigitated castellated microelectrode array intended to handle biological objects, based on the dielectrophoretic effects. The proposed design, a whole microsystem including electrical, optical and fluidic interfaces, was developed employing platinum deposited by liftoff, silicon micromachining, and photoresin patterning techniques. The fabricated electrodes have typical dimensions of 50, 70 and 90 μm, and were tested by means of polystyrene microspheres of 4.2 μm in diameter. Positive and negative dielectrophoresis were clearly observed, and the microparticle behavior was coherent with that predicted by the homogeneous particle model as well as with the electric field distributions assessed by the finite element method. The most relevant results are reported here.