3D Printing-Assisted Nanoparticle Assembly for Multifunctional Applications

Nanoparticle (NP) assembly is critical where NPs are organized into complex superstructures through direct and indirect interactions. Long-range NP orders have nanoscale locational selectivity, orientational alignment, and scalable micropatterning, which are indispensable for enabling multiple functionalities and improving the performances of different systems. Though nanoparticles can self-assemble into organized nanostructures via simple drying thermodynamics, scalability has been a primary issue. Thus, this research focuses on more scalable manufacturing for directed NP assembly. First, 3D printing was used for template fabrications with varying topology features. Next, nanoparticle engineering with colloidal and surface studies leads to desirable NP packing on template surfaces. Finally, the processed devices will also demonstrate a few applications of surface micropatterning with nanoscale particle orders. Specifically, a few manufacturing procedures involve (i) stereolithography (SLA)/layer-by-layer dip coating, (ii) continuous liquid interface projection (CLIP)/ink writing, (iii) fused deposition melting (FDM)/direct ink writing, and (iv) multiphase direct ink writing (MDIW)/wet etching. To demonstrate the applicability of hybrid manufacturing, a broad range of nanoparticles, including carbon nanofibers (CNFs), MXene nanoflakes, and boron nitride nanoplatelets (BNNPs) were studied in this research. With well-managed template physics and NP dispersion control, nanoparticle orientational alignment and positional preferences are driven by short- and long-range intermolecular interactions (e.g., convective, van der Waals, capillarity, shear, and other secondary bonding). The printed devices displayed multifunctional properties, i.e., anisotropic conductivity, piezoresistive and chemical sensitivity, mechanical durability, and heat dissipation capabilities, for microelectronic applications. This fabrication technique shows enormous potential for rapid, scalable, and low-cost manufacturing of hierarchical structures, especially for micropatterning of nanoparticles not easily accessible through conventional processing methods.