Ma. Hemingway et Rc. Brown, A MINIATURE ELECTRET-BASED DEVICE FOR MEASURING THE ELECTRICAL MOBILITY OF AEROSOLS, Journal of aerosol science, 26(2), 1995, pp. 241
A miniature device has been developed, which measures the mean electri
cal mobility of an aerosol using an electric field to precipitate the
aerosol onto parallel plates, between which it is drawn. The electric
field is provided by an electret, and so no powered high voltage sourc
e is required. Measurements on a prototype indicated that the electret
must be long and wide, and separated from a parallel earthed plate by
only a small distance, if the deposition pattern is to be easily obse
rved. A large dynamic range is obtained if the charge on the electret
is made spatially variable so that the aerosol encounters first a weak
and then a strong electric field. The theory of action of the device
is discussed, along with experimental results obtained.