Laser-induced thermocapillary flow manipulation of microparticles with obstacle avoidance in a non-patterned fluidic environment

This paper proposes a technique for manipulating microparticles toward a desired position in a non-patterned fluidic environment, avoiding the possible obstacles that it may encounter along its path. Infrared laser pulses were used to generate thermocapillary convection flows, within the fluidic environment, which dragged the particles in a controlled manner. In order to avoid the obstacles in real time, an improved artificial potential method (IAPM) was implemented. Experiments were performed to obtain the optimal parameters involved in this optofluidic-based manipulation technique. Different sized of glass beads in the range from 40 μm to 100 μm were manipulated avoiding single and multiple virtual obstacles. This technique could contribute to the manipulation of micro-objects in non-patterned fluidic environments such as in the assembly of microcomponents, where the environment could not be patterned as an assembly factory, and/or the manipulation of biological cells inside a fluidic system without microchannels and chambers.