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Table 1 Aerosol generators

From: Aerosol generation and characterization of multi-walled carbon nanotubes exposed to cells cultured at the air-liquid interface

Type Principle Material type Size range Maintainable duration Concentration range Ref
Nebulizer Droplets are formed with an atomizer or in a fountain formed by ultrasonic sound. Dried droplet residue forms the particles. Liquids containing dissolved or suspended solids 0.43–16.2 μm Optimal for 6-h durations 0.01–5 mg/m3 [34]
Electro spray Generator High voltage is applied to a metal capillary end containing flowing liquid. Expelled charged droplets fragment when electrostatic forces exceed surface tension. Dried droplet residue forms the particles. Liquids containing dissolved or suspended solids 2- 100 nm Optimal for 4 h 5 ng/cm2/min for in vitro and 2 mg/m3 for in vivo [35]
Fluidized bed Small beads are fluidized by air, and the turbulent motion and bead interaction disperses powder added to the bed. Solid 20–500 μm Greater than 3 h 0.5–40 mg/m3 [31], [36]
Acoustic Includes an acoustic energy source and a diaphragm(s) that produce a pressure gradient. Solid Same as the original particle size Greater than 30 h 15 mg/m3 or more [37]
Brush feed Composed of a screw feeder, rotating brush, and a cyclone designed to remove larger particles to aerosolize carbon fibers. Solid Same as the original particle size In 6 h increments 5 mg/m3 [38]
Dust feeder The surface of a cake of compacted powder is scraped at a controlled rate, by mechanical scraping and blown by compressed air. Solid Same as the original particle size >20 h Concentration of the output aerosol can be controlled by adjusting the air-flow rate [27, 39], [40]
  1. The table provides a brief description of aerosol generators that are applicable to MWCNTs, including the principle of aerosol generation, the type of material that can be aerosolized, the size and concentration of the aerosolized particle, and the duration of exposure to the aerosolized particles