A Multidomain Magnetic Passive Aerosol Sampler: Development and Experimental Evaluation

Abstract

An innovative "quarter-sized" multidomain magnetic passive aerosol sampler (MPAS) has been developed, mainly for determining particle penetration through personal protective ensembles. The MPAS is a 28 mm disc with a height of 8.6 mm. It consists of 186 small magnets with about 140 on the collection area, arranged in an alternating N and S pole pattern. In contrast to conventional passive samplers, it uses magnetic force to collect a quantifiable amount of surrogate Fe 3 O 4 particles within a substantially shortened sampling time. This article presents detailed design, principles of operation, performance evaluation, and the development of a deposition velocity model for the MPAS. Performance of the MPAS was evaluated under various test conditions, including different particle sizes ranging from 95 to 350 nm and wind speeds ranging from 0.48 to 1.17 m/s. A previously developed recirculation aerosol wind tunnel was employed to evaluate its performance. Experimental results show that the dimensionless deposition velocity increased with increasing particle size (e.g., about 5-fold greater for 300 nm particles than 100 nm particles at 0.48 m/s) and slightly decreased with increasing wind speeds. Our results show that this Address correspondence to Pengfei Gao, National Institute for Occupational Safety and Health, National Personal Protective Technology Laboratory, 626 Cochrans Mill Road, Pittsburgh, PA 15236, USA. E-mail: PGao@cdc.gov sampler is promising for the measurement of particle penetration through protective ensembles for which high collection efficiency is needed.

Collection of Aerosol Particles in a Single-Stage, High Gradient Magnetic Collector

“…In a magnetic collector, particles are separated based on both their size and magnetic susceptibility, simultaneously. 16,17 A recent example of the development of a passive aerosol sampler using permanent magnets was reported by Hsiao et al 23 The sampler used 186 small magnets arranged in an alternating pole configuration to collect particles as they deposited onto the collection substrate though no collection efficiency data were reported. 23 An active aerosol sampler designed using a 3-stage high-gradient permanent magnetic separation (HGPMS) array was first reported by Cheng et al 16 The authors demonstrated the effective capture of nanoparticles by configuring the permanent magnets as reversed pole pairs and adding a paramagnetic matrix such as stainless-steel wool to create the high-gradient magnetic field.…”