Behavior of metal-polymer hybrid colloidal particles in an optoelectrofluidic device has been investigated theoretically and experimentally. In the application of hundreds of kHz ac voltage, a variety of optically induced electrokinetic and electrostatic mechanisms affect the movement of gold-coated polystyrene microspheres. The particles repel from the light pattern, and their mobility increases as the amount of gold increases. We apply this model to develop an optoelectrofluidic immunoassay, in which the corresponding metal-polymer hybrid particles are formed by a reaction of antibody-coated gold nanoparticles, antigens, and antibody-coated polystyrene microspheres. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4790622]