Templated self-assembly over patterned electrodes by an applied electric field: Geometric constraints and diversity of materials

This paper expands the scope and usefulness of a process to assemble dry micrometer-sized particles into arrays over a templated electrode by a high-voltage dc bias. Using the predictions from a theoretical model for the process of assembly, the experimental scope and limitations of this technique were explored and related to the predictions of the model. The range of bead size that can be assembled (20-750 μm) and the effects of changing the ratio of the size of the features in the templated electrode to the size of the particles being assembled were experimentally determined and compared to the theory. It was also demonstrated that: 1) the assembled spheres can be made of materials that are either dielectrics (glass and polystyrene), semiconductors (silicon), or conductors (copper); 2) the material for the electrode can either be gold, silver, copper, or amorphous silicon; and 3) the dielectric substrate only needs to be able to support the applied voltage without breaking down. The experimental results, in general, were predicted and supported by the model.