Methods and System Design for Programmable Micro/Nanoscale Assembly, Manipulation, and Concentrating
Optically assisted assembly of nanoparticles via photothermally generated microbubbles is a low-cost method for fabrication and modification of plasmonic sensing platforms. A point laser was focused on a Nano Porous Gold Disk (NPGD) patterned substrate immersed in a solution. Heat generated from plasmonic excitation caused boiling and the formation of gas/water vapor bubbles capable of collecting surrounding hydrophobic and hydrophilic particles. Upon deactivation of the laser, the microbubble shrank and the adhered particles formed a new structure on the NPGD surface. Removing air molecules from the medium via degassing inhibited any formation of hydrophobic particle assembly while leaving hydrophilic particles unaffected. A Spatial Light Modulator (SLM) to project the laser in arbitrary patterns produced arrays of nanoparticle clusters for use as plasmonic sensing units. These aggregates were studied using optical microscopy, scanning electron microscope, hyperspectral localized surface plasmon resonance and hyperspectral Raman spectroscopy.
Associate Professor, Electrical Engineering