Validation of a high Flow Rate Puff Topography System Designed for Measurement of Sub-Ohm, Third Generation Electronic Nicotine Delivery Systems.

Introduction:
This text provides an overview of a study that aimed to develop and validate a puff topography system capable of measuring the puff topography of sub-ohm, third generation (3G) electronic nicotine delivery systems (ENDS) as used by vapers in a naturalistic setting. The study used a differential pressure flow cell based on Bernoulli equation that can measure very high flow rates (0-70 L/min) and that imparted minimal flow resistance (~2%). The system was designed to fit between the user's atomizer and mouthpiece and was tested using ten replicate 3D printed flow cells.

Key Points:

* The study used a Bernoulli flow cell designed to fit between the user's atomizer and mouthpiece.
* Ten replicate 3D printed flow cells were used to characterize the reproducibility of the fabrication process.
* a digital manometer was used to measure pressure differential, and a best fit regression was used to form a prediction equation representing all flow cells.
* a quadratic regression of the square root of pressure was used to balance the residuals, resulting in a R2= 0.9991.
* Two ranges of pressure sensors were selected for the data acquisition system: a "low" pressure sensor for low flow measurements and a "high" pressure sensor for high flow measurements.
* Known-volume challenge puffs were generated with a 3-L spirometry calibration syringe and used to evaluate the robustness of the multi-range pressure sensor array.
* The system was found to be accurate at both low and high flow rates for 0.71 L, 2.00 L, and 3.00 L puffs.

Main Message:
The study demonstrates the successful development and validation of a puff topography system capable of measuring the puff topography of sub-ohm, third generation ENDS as used by vapers in a naturalistic setting. The system uses a Bernoulli flow cell that can measure very high flow rates and imparts minimal flow resistance, and is designed to fit between the user's atomizer and mouthpiece. The study used ten replicate 3D printed flow cells to characterize the reproducibility of the fabrication process, and found the system to be accurate at both low and high flow rates for a range of puff volumes. This system has the potential to be a valuable tool for researchers and regulators seeking to understand the use behaviors, nicotine delivery, and toxicant profiles of sub-ohm, third generation ENDS.

Floyd E, Oni T, Cai C, Rehman B, hwang J, Watson T. Validation of a high Flow Rate Puff Topography System Designed for Measurement of Sub-Ohm, Third Generation Electronic Nicotine Delivery Systems. International journal of environmental research and public health. 2022;19(13). doi:10.3390/ijerph19137989