Single, binary and successive patterning of charged nanoparticles by electrophoretic deposition

Deposition of nanoparticles on a substrate in a controlled manner leads to the formation of multifunctional surfaces and therefore devices. Electrostatic forces can be utilized to manipulate different types of materials such as magnetic, insulating, conducting, semiconducting, organic and inorganic, without altering the chemistry of the surface. However, simultaneous and successive electrophoretic deposition (EPD) methods are not fully utilized for nanoparticles with different characteristics. In this work, electrostatic forces are applied to direct and position charged nanoparticles suspended in aqueous dispersions on desired areas of the surface. Assemblies of particles are obtained by electrostatic attraction generated by gold electrodes of sizes from 500 nm to 50 µm that are fabricated by thermal evaporation. Different types of charged nanoparticles were simultaneously attracted towards different locations of the surface by means of EPD; as a result, alternating nanoparticle patterns and particle deposition on the same designated areas for forming composite areas are obtained. Assemblies formed from positively charged silver nanoparticles and negatively charged fluorescent latex and silica nanoparticles are demonstrated. The position of metallic-, polymeric- and inorganic-based nanoparticles is controlled by the design of electrode geometry.