Fast, High-Throughput
Creation of Size-Tunable
Micro/Nanoparticle Clusters via Evaporative Self-Assembly in Picoliter-Scale
Droplets of Particle Suspension
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Abstract
We report a fast, high-throughput method to create size-tunable
micro/nanoparticle clusters via evaporative assembly in picoliter-scale
droplets of particle suspension. Mediated by gravity force and surface
tension force of a contacting surface, picoliter-scale droplets of
the suspension are generated from a nanofabricated printing head.
Rapid evaporative self-assembly of the particles on a hydrophobic
surface leads to fast clustering of micro/nanoparticles and forms
particle clusters of tunable sizes and controlled spacing. The evaporating
behavior of the droplet is observed in real-time, and the clustering
characteristics of the particles are understood based on the physics
of evaporative-assembly. With this method, multiplex printing of various
particle clusters with accurate positioning and alignment are demonstrated.
Also, size-unifomity of the cluster arrays is thoroughly analyzed
by examining the metallic nanoparticle cluster-arrays based on surface-enhanced
Raman spectroscopy (SERS)