High speed random separation of microobject in microchip by laser manipulator and dielectrophoresis

Abstract

We developed a new system for high speed random separation of a microobject, such as a microbe, in a microfluidic device by optical radiation pressure and dielectrophoretic force control under a microscope. An arbitrary single microbe can be isolated speedily in a microchannel, even though there are a large number of these microbes in solution. Once the target microbe is trapped at the focal point of the laser manipulator, we can easily realize exclusion of excess microbes by controlling the electric field, while keeping the target trapped at the focal point. To realize an efficient separation system, we made a new separation cell by microfabrication. We show experimental results on our system. We also propose indirect manipulation methods by the micro-tools to avoid direct laser radiation to the target. Some preliminary experiments are conducted to show the effectiveness. Our method is extremely useful in the pure cultivation of the targeted microbe and will be a promising method for biologists in discovering a new microbe or for bio-remediation.