A Personal, Thermophoretic Sampler for Airborne Nanoparticles

HEPA Filter Critical Flow Orifice A personal, thermophoretic particle sampler was designed to collect airborne nanoparticles in the breathing zone of exposed workers. The thermal precipitator captures aerosol by creating a 1000 ̊C/cm temperature gradient between two aluminum plates (0.1 cm separation distance) using a resistive heater, a thermoelectric cooler, a temperature controller, and two thermistor sensors. The objective was to make the device small, lightweight, and efficient at collecting airborne nanoparticles over an 8 hour workshift. Particle collection efficiency was determined by challenging the sampler with monodisperse aerosols from 15 240 nm at flow rates of 5 and 20 mL/min. The sampler collected particles with 100% efficiency at a 5 mL/min flow rate and with approximately 65% efficiency at a 20 mL/min flow rate. The uniformity of particle deposition across the collection plate varied, but was most representative near the center of the cold plate.