Optical tweezers assisted controllable formation and precise manipulation of microdroplet

Abstract

We demonstrate an optical method to realize controllable formation and precise manipulation of microdroplet using optical tweezers (OT). With the irradiation of a highly focused laser into the mixture of inorganic phosphate buffered saline (PBS) and organic solvent isopropanol, a microdroplet was gradually formed at the center of the trap. The size and the growth rate of the microdroplet could be precisely controlled by regulating the laser power and the proportion of two solvents in the mixture. Furthermore, the microdroplet could be manipulated by OT to build microstructures on the slide. We also discuss the possible mechanism behind our observations and the potential usage of such discoveries.