Light driven Microfluidics

Optical techniques are very versatile in manipulating matter from far away. We like to show how light can be used to move fluids in an unstructured environment. Precise methods to control properties of fluids, like flow fields or the concentration of solutes would be a powerful tool for the controlled manipulation and investigation of chemical, biological and even cellular processes. A prominent technical example for a fluidic system is the so-called Lab-on-a-chip technology. These microchips miniaturize chemical or biological analyses down to a few millimeters to obtain fast results with only little amount of substrates. A major advantage is the possibility to perform multi parallel analyses. But controlling fluids at these small scales is a difficult task. Fluid flow is laminar and the implementation of valves, mixing fluids and driving the flow require complex chip designs and need many connections to external macroscopic pumps. In this paper, we will present a new approach to drive and control fluid flow in such small systems. Instead of applying pressure from outside in order to generate the flow, it is locally induced by a focused laser. This method allows to control fluid flows in closed compartments like vesicles or living cells. The fluid flows transport solved particles together with the surrounding liquid.