Dielectrophoresis of Electroless Gold Plating Polystyrene Microspheres

Micro spheres with perfect conductive surface have many advantages in biosensor and MEMS devices research. Polystyrene micro spheres were coated gold shell perfectly using electroless gold plating method and the scanning electron microscope (SEM) images were obtained detailedly. Dielectrophoresis (DEP) model of single sphere and signal shell sphere were set up and the real part of the Clausius-Mossotti factor for the two kinds of micro spheres were calculated. Experiments on the DEP characterization for the native polystyrene micro spheres and gold coated polystyrene micro spheres (GCPM) were measured and the results show that the GCPM can only be acted by positive DEP force when the order of the frequency is below 10¹² Hz. The experimental results and the theory prediction have a good agreement.