A microfluidic chip for focussing a stream of particulate containing fluid comprises a sample microfluidic channel configured to receive the stream of particulate containing fluid, a guidance microfluidic channel having a polygonal cross-sectional area and configured to receive a stream of guidance fluid, and a common microfluidic channel having a polygonal cross sectional area formed by the merging of the sample microfluidic channel and the guidance 10 microfluidic channel at an oblique angle along only part of one or more sides of the guidance microfluidic channel, and a detection zone disposed in the common microfluidic channel having one or more sensors. The merging of the sample microfluidic channel and the guidance microfluidic channel is configured to provide a composite fluid stream containing a focussed beam of particulates that is disposed asymmetrically in the common microfluidic channel 15 adjacent a corner or side of the common microfluidic channel and wherein the one or more sensors are configur
