A measuring assembly for detecting particles of a particle flow in a gas flow path, including an ionization stage which has an ionization device by which the particles to be detected can be ionized or are ionized. The measuring assembly further has measuring stage with a detector which detects the ionized particles of the particle flow, the detector has at least one electrode to which particles release the charge received at the ionization device. The released charge can be measured via an electric resistor connected to the at least one electrode. This provides an inexpensive and reliable measuring assembly which has a low susceptibility to errors in that the at least one electrode of the detector is designed as a microsystem. In order to improve the measurement of the charge carried by the ionized gas, the pores of a filter substrate are metallized and electrically connected to the resistor.