Use of Virtual Impactor (VI) Technology in Biological Aerosol Detection

Detecting biological threat aerosol is difficult in that a small cloud lasting only a few seconds at a point location may contain sufficient material to infect large numbers of exposed individuals. Clinical analytical methods require relative large amounts of the sample in liquid form to facilitate positive measurements. Biological agents may be fragile because of their lipid membranes that can be susceptible to harsh sample collection treatment. Damaged organisms may render subsequent analyses to be invalid. Virtual impaction (VI) sample collectors have been theorized to provide usable concentration rates yet are sufficiently gentle with the aerosol particles to preserve cellular viability. This review will discuss different implementations of VI technology and examine their merits. Outstanding issues will be outlined to aid future experimentation.