We present a novel microfluidic optical chip and corresponding sensor setup for continuous particle detection using light scattering. With the proposed device it is possible to visualise sub-micron and nanometre sized particles in liquid in order to quantify their number without the need for fluorescent labelling. The chip contains a microchannel structured in dry film resist which is crossed by a laser beam so that particles in the flow cross the beam and scatter a portion of the incident light which is recorded at 90 degrees angle. Scattering sub-micron particles appear as clearly visible bright spots of several micrometres in diameter on the video and can individually be counted. (C) 2012 Elsevier Ltd....Selection and/or peer-review under responsibility of the Symposium Cracoviense Sp. z.o.o.