Patent ID: 7516019

Claim:
A method of estimating the number of nanoparticle aerosol aggregates having a primary particle size a in a gas using a differential mobility analyzer for measuring spherical particles, comprising: a) passing a volume of a gas containing entrained nanoparticle aerosol aggregates through the differential mobility analyzer for measuring spherical particles; b) obtaining the primary particle size a of the aggregates; c) obtaining a mobility diameter d m of the aggregates; d) counting a total number of aggregates n sph that pass through the differential mobility analyzer; e) equating a migration velocity of an aggregate to that of a spherical particle having the same mobility diameter d m to obtain a number N of primary particles in the aggregate particle; f) determining a fraction of aggregates η agg that are singly electrically charged by the differential mobility analyzer; and g) estimating the number of aggregates n agg in the volume of gas from the counted total number of aggregates n sph and the charge fraction η agg .