Abstract: A particulate matter sensor device comprising an enclosure (21) that comprises a flow inlet (11), a flow outlet (12) and a flow channel (2) extending therebetween, a radiation source for emitting radiation into the flow channel (2) for interaction of the radiation with the particulate matter in the flow (20) of an aerosol sample when guided through the flow channel (2), a radiation detector (4) for detecting at least part of said radiation after interaction with the particulate matter. The sensor device comprises a flow modifying device (511) arranged upstream of the radiation detector (4) and/or of the radiation source (3) for modifying the flow (20) for reducing particulate matter precipitation onto the radiation detector (4) and/or onto the radiation source (3) and/or the channel wall sections in close proximity to the detector (4) and/or source (3). The invention also relates to a method of determining parameters of particulate matter in an aerosol sample by using such a particulate matter sensor device.