(417d) Artificial Thermalization of Non-Brownian Microparticles for the Fabrication of Close-Packed Colloidal Crystals

Colloidal crystals have been explored in the literature for applications in molecular electronics, photonics, sensors, and drug delivery. However, much of the research on colloidal crystals has been focused on nano-sized particles with limited attention directed towards building blocks with dimensions ranging from tens to hundreds of microns. This can be attributed, in part, to the fact that large-scale particles are less prone to assemble in an organized fashion due to the relative absence of thermalizing forces. Nevertheless, ordered arrays of large particles are of interest both as a basis for the production of hierarchically structured materials as well as for tissue engineering scaffolds due to large pore sizes. In this work, ultrasonic agitation is being explored as a means of artificially “thermalizing” these particles in order to overcome kinetic barriers to packing in the creation of close packed, highly ordered, crystalline structures from large microparticles (18-750um). Using this process, we have been able to create and characterize both two- and three-dimensional structures by adjusting properties of the system and observing the changes using a variety of microscopy techniques. We are currently investigating the significance of various substrate and solution properties such as surface tension, viscosity, particle concentration and particle composition both experimentally and computationally. The interactions between the constituent particles within these colloidal formations can be estimated and analyzed, ideally providing insight into, and control over the formation of desired crystal structures.