Aerosol Particle Collection Efficiency of Holey Carbon Film-Coated TEM Grids

Abstract

A simple sampling method to collect aerosol particles for transmission electron microscope (TEM) analysis was developed by R'mili and others in 2013. The method involves passing air through a holey carbon film-coated copper mesh TEM grid (holey carbon grid) and sampling particles by filtration. In this study, we proposed a modified calculation method to represent the collection efficiencies of holey carbon grids, taking into consideration the porosity of the copper mesh. We then evaluated the particle collection efficiencies of holey carbon grids both theoretically and experimentally. We tested the collection efficiency of two types of holey carbon grids, with nominal pore sizes of 1.2 and 0.6 μm, using particles of monodispersed polystyrene latex (PSL) and potassium chloride. The overall collection efficiency of each grid (E grid ) was determined by the downstream/upstream concentration ratio measured by condensation particle counters (CPCs). In addition, for PSL particles, the collection efficiency of the holey carbon film (E film ) was determined by the ratio of the number of particles on the film (counted on a scanning electron microscope) to the number of inflow particles (counted by a CPC). We compared model calculations against the experimental results obtained in this study and those reported by R'mili and others in 2013. These data showed that the calculated E grid values were in reasonably good agreement with the experimental E grid values. However, although the model calculation indicated that E film ≈ E grid , there was an inconsistency between the experimental E film and E grid , which requires further investigation in order to determine its cause.

Surface-collection efficiency of Nuclepore filters for nanoparticles

“…Actually, the moderate inertia effect may explain the difference in the experimental surface collection efficiencies between 30 nm PSL and Ag particles shown in Figure 5. The value of Stk for the 30 nm Ag particle under the test conditions in Figure 5 seemed to be moderate (Stk D 0.02; from Equation (18) of Ogura et al 2014), while the value of Stk for the 30 nm PSL particle seemed to be low (Stk D 0.002). For this reason, it is considered that the 30 nm Ag particle was affected by the moderate inertia effect while the 30 nm PSL particle was almost unaffected.…”

“…The E I and E D can be calculated using the popular models proposed by Pich (1964) and Manton (1979), respectively. The details of those equations were summarized in Ogura et al (2014). For calculating E R , various expressions have been proposed (Spurny et al 1969;Smith et al 1976;John et al 1978;Marre and Palmeri 2001).…”

“…Manton (1978) therefore calculated the collection efficiency due to the combined mechanisms of impaction and interception on the filter (E IR ) from the computed trajectories of particles, and proposed an approximate expression for E IR as a function of an inertia parameter I. The details of the equations with a slight modification (i.e., with consideration for the Cunningham slip correction factor) were summarized in Ogura et al (2014).…”

Investigation into the Presence or Absence of Solid Particles Generated from Thermal Processes in the Aerosol from an Electrically Heated Tobacco Product with and without Filter Elements

“…The particulate matter sampling was performed directly from the aerosol flow by passing a sample flow of 0.5 L min -1 through the grid -a pump coupled with a critical orifice was used to generate and control the aerosol flow. The main collection mechanism for particulate matter was diffusion to the grid surface (Ogura et al, 2014).…”

Uncertainty assessment for the airborne nanoparticle collection efficiency of a TEM grid-equipped sampling system by Monte-Carlo calculation

“…Recently, a low-cost, portable, and easy used instrument, TEM grid-equipped Mini Particle Sampler, was developed by Institute National de l'Environnement Industrial et des Risques (INERIS) and commercialized by the company Ecomesure, , as shown in Fig. 1 [15][16][17]. Researches on powder structure characterization [18][19] and nanomaterial exposure assessment [20][21][22][23][24] have validated the applicability of the MPS.…”