title: Fast, high-throughput creation of size-tunable micro/nanoparticle clusters via evaporative self-assembly in picoliter-scale droplets of particle suspension.
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).
authors.affiliation: Berkeley Sensor and Actuator Center (BSAC), University of California at Berkeley, Berkeley, California 94720, United States. sunchoi@eecs.berkeley.edu
authors.forename: Sun
authors.initials: S
authors.lastname: Choi
authors.forename: Arash
authors.initials: A
authors.lastname: Jamshidi
authors.forename: Tae Joon
authors.initials: TJ
authors.lastname: Seok
authors.forename: Ming C
authors.initials: MC
authors.lastname: Wu
authors.forename: Tarek I
authors.initials: TI
authors.lastname: Zohdi
authors.forename: Albert P
authors.initials: AP
authors.lastname: Pisano