Rapid Assembly of Carbon Nanoparticles Into Electrical Elements by Optically-Induced Electroosmotic Flow

We report the rapid assembly of carbon nanoparticles (CNPs) into functional electrical elements utilizing optically-induced electroosmotic flow (OIEF) in a specialized microfluidics chip. Numerical simulations of various optically-induced electrokinetics forces exerted on CNPs were initially performed to ascertain the viable forces that could overcome the Brownian motion and produce sufficient force to manipulate and assemble the CNPs. The results confirmed the theoretical prediction that only the force induced by OIEF could manipulate the CNPs. Subsequently, a series of experiments for assembling CNPs were conducted. This was followed by electrical characterization of the assembled three-dimensional CNP microstructures. The results proved that OIEF could effectively and rapidly assemble CNPs in about 45 s. We used measurements of the current-voltage relationship to validate that the CNP-based microstructures are resistive elements, and their resistance could be controlled by the width and length of the microstructures. We believe that, by using OIEF technique, different nanoparticles of varying electrical properties could be assembled rapidly in a specialized microfluidics chip to create micro-electrical elements in the future, including integrating different nanoparticle elements into functional electrical devices.