Method for quantifying Variation in the Resistance of Electronic Cigarette Coils.

Introduction:
This article presents a robust and unbiased method for measuring the resistance of electronic cigarette (e-cigarette) coils, which is crucial for understanding its effect on emissions and enabling comparison across different e-cigarette types, brands, and laboratories. The study uses an apparatus that mimics the geometric configuration and assembly of e-cigarette reservoirs, coils, and power control units.

Key Points:

* The study introduces a two-wire and four-wire configuration for measuring coil resistance, with the four-wire configuration being far less prone to bias error and recommended for universal adoption.
* The study demonstrates a significant difference in coil resistance between two e-cigarette products (aLTO by Vuse and JUUL) and within the same product.
* The authors observed a 0.593 ohm difference in coil resistance (p<0.001) between aLTO and JUUL, with mean resistances and standard deviations being 1.031 (0.067) ohms for aLTO and 1.624 (0.033) ohms for JUUL.
* The variation in coil resistance can significantly impact aerosol emissions.
* The two-wire configuration introduced a positive measurement bias of 0.086 ohms, which is significant for sub-ohm coil designs.
* The study highlights the need for a standardized method for measuring coil resistance, as inconsistencies in reporting can be attributed to the absence of such a standard.

Main Message:
The study emphasizes the importance of a robust and unbiased method for measuring e-cigarette coil resistance, as variations in coil resistance can significantly affect aerosol emissions. The four-wire configuration is recommended for universal adoption due to its reduced bias error compared to the two-wire configuration. The findings also highlight the significant difference in coil resistance between two popular e-cigarette products, aLTO by Vuse and JUUL, and the importance of considering manufacturing variation in coil resistance when assessing e-cigarette emissions.

Saleh qM, hensel EC, Robinson RJ. Method for quantifying Variation in the Resistance of Electronic Cigarette Coils. International journal of environmental research and public health. 2020;17(21). doi:10.3390/ijerph17217779