A novel particle feeding system capable of pneumatically dispensing dispersed particles at low and consistent feed rates has been developed. The feeder is based on a rotating brush that continually cleans the outlet orifice in a hopper filled with particles. The system was designed specifically for biomass particles that have been milled and sieved to less than 150 mu m as a feedstock for laboratory scale aerosol flow reactors. This feedstock often contains a large fraction of high aspect ratio particles that form obstructions in many conventional feeding systems. In addition to biomass, the feeder has successfully fed all particles less than 150 mu m that have been tested. Feed rates varying from 4.25 to 2420 mg/min have been obtained with spray dried algae at a constant carrier gas flow of 0.75 slpm, and steady and consistent feeding with milled switchgrass has been demonstrated. The design, construction, and preliminary testing of the feeding system are presented in this paper. (C) 2012 Published by Elsevier B.V.