The Micro Vertex Detector (MVD) of the future Compressed Baryonic Matter (CBM) experiment at FAIR will have to provide a spatial precision of ∼5μm in combination with a material budget of 0.3%–0.5%X0 for a full detector station. Simultaneously, it will have to handle the rate and radiation load of operating the fixed target experiment at an average collision rate of 100kHz (4–10AGeV Au+Au collisions) or 10MHz (up to 28GeV p-A collisions). The harsh requirements call for a dedicated detector technology, which is the next generation CMOS Monolithic Active Pixel Sensor MIMOSIS. We report about the requirements for the sensor, introduce the design approach being followed to cope with it and show first test results from a first sensor prototype called MIMOSIS-0 .