Classification and Condensation of Nano-Sized Airborne Particles by Electrically Tunning Collection Size

This paper demonstrates a hybrid particle classification and condensation device based on both aerodynamics and electrostatics using a micro virtual impactor (¿VI). The ¿VI is capable of classifying the nanoparticles according to their size and condense their number concentration that we are interested. The ¿VI was fabricated using polymer micromachining. Its classification efficiency was examined using solid particles, polystyrene latex (PSL) ranging from 80 to 250 nm in diameter. Thereafter, specific-sized nanoparticles, NaCl of 50 nm in diameter, were condensed by applying an electric potential of 1.1 kV. As a result, the electric signal detected was amplified by 4 times higher than that when no electric potential was applied. The output signal was amplified by 4 times (before condensation: 4 fA, after condensation: 16 fA).