Figure 1. Diagram of custom e-cigarette apparatus.
Air passed through a ceramic heater encased in 2” diameter PVC pipe, where it was heated to a controlled temperature of 300F. The heated air passed through a small orifice and over a ½” diameter ball of non-ferromagnetic metallic wool, which was saturated with 0.45mL of smoke juice (Johnson Creek, nominal 18 mg/mL nicotine). The resulting heated vapor passed through a one-way check valve along a 12” section of flexible tubing and into the user's mouth. Inhaled airflow was measured in mL/min.