Due to substantial health effects, particulate matter emitted by motor vehicles is limited by legislation. To determine the emissions, the current legislation requires particle number concentration measurements during the type approval procedure for new vehicle types. Recently, it was shown that these tests do not reflect the real emission behavior of motor vehicles during their normal usage. Alternative examination methods like emission monitoring via Periodical Technical Inspections (PTI) or on-board emission testing (referred to as Real Driving Emissions (RDE)) would be much more reliable. However, due to a lack of appropriate measurement instrumentation, research on reliable as well as traceable sensor systems has to be done before the aforementioned methods can be applied. The aim of this project is to develop and validate a sensor principle for the determination of particle number concentration, which is based on electrical charging of the particles. As a result of the project, a sensor prototype that is lightweight, robust, energy efficient, cost-efficient and mobile should be designed.