US Patent 7178380 Virtual impactor device with reduced fouling

A virtual impactor device having reduced fouling includes injection ports within the separation zone to redirect particles that otherwise tend to impact the walls of the separation zone and produce fouling. The virtual impactor device preferably also includes an acceleration zone having concave and convex sections, which reduces fouling in that area. The virtual impactor device can be combined with various downstream components such as collectors, atomizers and various analytical devices.