Dielectrophoresis (DEP) is an excellent tool for manipulating small particles within a liquid or gas medium. However, when the size of the particles is too small, such as with quantum dots (QDs), it is difficult to manipulate the particles using DEP because the dielectrophoretic force (FDEP) depends on the volume of the particles and is therefore too weak to achieve particle migration. Herein, we demonstrate a novel method for controlling nanoscale QD particles using DEP by introducing photopolymerized reactive mesogen (RM) bead vehicles. The size of an RM bead is well-controlled by the RM concentration in the medium, and when the size is approximately 0.2 μm or larger, the RM beads can be arbitrarily manipulated using DEP under moderate electric fields. Interestingly, during photopolymerization, QD particles are easily absorbed by polymerized RM beads and most of the QDs are embedded within the RM beads. Hence, we can fabricate periodic QD arrays by manipulating the RM beads containing such dots. In addition, we can fabricate multicolor QD arrays by repeating the processes using different QD particles. The shape of a DEP-assisted QD-RM network pattern can be precisely predicted by calculating the gradient of the square of the electric field (∇E2) and the corresponding FDEP. This new technology may be useful for the fabrication of optical devices, displays, photonic crystal devices, and bioapplications.
Keywords: dielectrophoresis; photopolymerization; polymer particles; quantum dot arrays; quantum dot assembly; reactive mesogen.