Patent ID: 8627732

Claim:
A device for characterizing a size distribution of electrically-charged airborne particles in an air flow, comprising: a particle charging unit arranged to create the size distribution of electrically-charged airborne particles by electrically-charging airborne particles entering the device, a first particle precipitation unit located downstream from the particle charging unit, arranged to, for each size larger than a first particle size limit, partially reduce the concentration of electrically-charged airborne particles having said each size, and to generate a first output signal corresponding to the precipitation of electrically-charged airborne particles inside the first particle precipitation unit, a second particle precipitation unit located downstream from the first particle precipitation unit, arranged to precipitate substantially all entering electrically-charged airborne particles, and to generate a second output signal corresponding to the precipitation of electrically-charged airborne particles inside the second particle precipitation unit, a data evaluation unit arranged to calculate, based on the first output signal and the second output signal, a particle number concentration and an average diameter of airborne particles having a size larger than the first particle size limit.