Development of optoelectrofluidic on-demand printing system for hydrogel sheets

Abstract

This thesis presents a novel optoelectrofluidic printing system that facilitates not only optoelectrofluidic patterning of microparticles and mammalian cells but also harvesting the patterned microparticles encapsulated within poly(ethylene glycol) dicarylate (PEGDA) hydrogel sheets. Although optoelectrofluidic technology has numerous advantages for programmable and on-demand patterning and feasibility of manipulating single microparticles, practical applications using existing laboratory infrastructure in biological and clinical research fields have been strictly restricted due to the impossibility to recover the final patterned product. In order to address these harvesting limitations, PEGDA was employed to utilize optoelectrofluidic printing system. The concentration of hydrogel precursor and the chamber height were optimized to figure out the suitable harvesting condition of the polymerized PEGDA hydrogel sheet. Also, the Clausius-Mossotti (CM) factor was calculated to investigate the dielectrophoretic mobility of the microparticle and cells. Based on the optimized conditions of the optoelectrofluidic system, three basic abilities of optoelectrofluidic printing system were characterized: Controlling the number of microparticles, controlling distance between microparticle columns, and controlling the ratio of two different microparticles. Furthermore, the optoelectrofluidic patterning and printing of HepG2 cells were demonstrated with minimum resolution of about 10 μm in 5 min. The dielectrophoretic force exerted to cells was verified based on the simulation and the appropriate ranges of frequency was defined experimentally. Finally, optoelectrofluidically cell-patterned hydrogel sheets successfully recovered under a highly viable physiological condition.