Facile large-scale alignment and assembly of conductive micro/nano particles by combining both flow shear and electrostatic interaction

Abstract We introduce a facile approach to align various conductive micro/nano particles in a large area using both flow shear and electrostatic interaction. The complicated three-dimensional (3D) microcoils are chosen to investigate the assembly behavior and effectiveness of the multi-physical field induced alignment in polydimethylsiloxane (PDMS) pre-polymer; and the forcing mechanism and motion behavior of the microcoils are also analyzed: the flow shear could orient the major axis of microcoils, and then the electrostatic interaction between these oriented microcoils results in their self-assembly into chains. Besides, the processing parameters are also optimized, including the gap between the polyethylene terephthalate (PET) plates of ∼100 μm, the shearing speed of ∼40 mm/s, PET plate voltage of ∼20 kV, and microcoil weight fraction of ∼2%. And the order parameter S could reach up to ∼0.96 and more than ∼70% of the particles were assembled into a chain-like structure. Furthermore, we also demonstrate the universality of this method to other conductive micro/nano particles' assembly, including silver-coated glass spheres, carbon nanotubes (CNTs), and graphene. This approach may pave the way for the large-scale fabrication of functional composites based on well-ordered conductive micro/nano particles.