An apparatus for concentrating aerosol particles can include: a sample air inlet; an enriched aerosol outlet; an aerosol lean outlet; a flow path connecting the air inlet and aerosol rich and aerosol lean outlets; and a plurality of alternately energized and grounded electrode pairs along the flow path. The aerosol rich outlet can be in fluid communication with an aerosol particle capture device. The apparatus can include a sheath air inlet providing a flow of aerosol free air over surfaces of the alternately energized and grounded electrode pairs. The apparatus can include an elongate focusing chamber having a cylindrical shape containing the alternately energized and grounded electrode pairs that are configured as circular rings. The apparatus can include one or more structures configured to impart tangential, spiral or helical flow to a stream entering through the sample air inlet.