We have developed a simple, inexpensive and flexible method to automatically manipulate and assemble micro-/nano-entities using optically-induced dielectrophoretic (ODEP) force. Instead of using traditional fixed metal microelectrodes to generate non-uniform electric field, dynamic optical images designed by an animator software and projected through a microscope lens are used as “virtual electrodes” to generate real-time-varying electric fields in a fluidic medium to manipulate/assemble micro-/nano-scale particles and biological entities. Moreover, the induced ODEP force field can also be used to focus polymer molecules locally to generate 3D micro-polymer structures. Thus far, we have demonstrated the manipulation/assembly/fabrication of 1) 500nm to 100μm polystyrene beads, 2) 50nm carbon nanoparticles, 3) 100nm Au nanoparticles, 4) 10μm pigmented human skin cells, and 5) polymer structures with 7μm lateral and 100nm thickness resolution. These results indicate that ODEP technology may potentially become a new paradigm for automating micro/nano manipulation, assembly, and fabrication processes.