Electrically tunable airborne particle classifier using a virtual impactor

This paper reports an airborne particle classifier based on a virtual impactor (VI) which is capable of actively tuning a cut-off diameter by applying the electric potential. The VI aerodynamically classifies airborne particles according to their size. An electrode pair is integrated in the VI, which make possible to electrically control the cut-off diameter of the VI without additional fabrications. The VI with a cut-off diameter of 1 mu m was designed, and its cut-off characteristics were examined. Thereafter, the cut-off diameter was successfully tuned to from 35 mn to 70 nm by applying electric potentials from 1 kV to 3 kV.