A novel particle emission sensor based on particle charging and electrical detection is presented. The sensor charges the particles and measures the current carried by the particles exiting the sensor. The measurement is carried out without collecting the particles. Thanks to this principle, the mechanical construction of the sensor can be such that the sensor is not prone to fouling. The intended application of the sensor is the measurement of particle emission of diesel vehicles. The sensor is placed directly in to the exhaust flow of the tested vehicle, and because of that there is no need for any sampling or dilution of the exhaust gas. This together with the electrical measurement method allows rapid time response, and consequently, real time measurement of test cycles or on-road driving. The sensor was tested in the laboratory and a theoretical model was build to predict the response of the instrument. The model can be used for converting the measured signals to the particle concentration or emission rate. Good correlation with a reference instrument was obtained in a diesel test cycle measurement.