Development of a Transfer Function for a Personal, Thermophoretic Nanoparticle Sampler

Effective assessment of nanoparticle exposures requires accurate characterization of the aerosol. Of increasing concern is personal exposure to engineered nanoparticles that are specifically designed for use in the nanotechnology sector. This manuscript describes the operation and use of a personal sampler that utilizes thermophoretic force to collect nanoparticles onto a standard TEM (transmission electron microscope) grid. After collection, nanoparticles on the TEM grid are analyzed with an electron microscope, and the resultant data used to determine the characteristics of the nanoparticle aerosol sampled. Laboratory experiments were conducted to determine the inlet losses and collection efficiency of the thermophoretic sampler for particles between 20 and 600nm in diameter. These results are used together with theory for thermophoretic velocity to form a transfer function that relates the properties of the collected particles to the properties of the sampled aerosol. The transfer function utilizes a normalization factor, F(d), which is larger than unity for very small particles but approaches unity for particles larger than about 70nm. Copyright 2014 American Association for Aerosol Research