An acoustic wave consists of two elements, the acoustic pressure and the acoustic flow. Up to now one has to measure the pressure and calculate the flow to determine the acoustic flow, so it would be convenient to have a sensor that is able to measure acoustic flows. At the University of Twente a novel device has been developed which fulfils this need. In this paper a short introduction to the governing principles of this dynamic flow sensor, the fabrication process, the electronics and some of its interesting applications will be presented. This micromachined device measuring acoustic flows is called the microflown or μ-flown.