UC Berkeley

Fast crystallization of solid-phase materials in liquid medium is a crucial pre-requisite to achieve the aims of a number of applications for micro-and nano-manufacturing, bio-chemical sensing technology and fundamental colloidal science. Corresponding mechanical systems for those applications are required to accommodate and take advantage of the virtue of multi-phase (liquid, gas, and solid phases) flow phenomenon to accomplish "crystallization" part for complete functioning. In this dissertation, evaporation-driven fast crystallization of micro-and nano-particles is demonstrated via micro mechanical systems in order to inspire potential implementation of those systems to existing mechanical systems. Various fast crystallizing behaviors of micro, nanoparticles are demonstrated by multi-phase flow in the micro-mechanical systems. Evaporative flows such as open-channel flow, thin liquid-flim flow, and fast, micro-scale evaporative liquid flow on hydrophobic surface are driving fast crystallization of the particles in micro-mechanical systems with sub-5 minute scale. Critical parameters for the analysis of colloidal motions in evaporative flows are identified by conventional thermo-coupled fluid mechanics and numerical values of those parameters were accurately calculated by particle-dynamic incorporated-computations to provide accounts for particle effects in evaporative self-assembly. Finally, electrical and optical characterizations of crystallized 3D lattices are performed to demonstrate the feasibility of the developed systems for rapid, direct characterization of various target species. Experimental, analytical and computational parts of the dissertation complement each other with active cross-talks and reinforce the thesis argument that evaporation-driven multi-phase flow can be applied for the improvement of micro-and nano-manufacturing technologies, bio-chemical assay technologies and the development of platforms for fundamental colloidal sciences.