Droplet Sizes of Electronic Cigarette Aerosols - A poster at DDL27
December 06, 2016
Droplet Sizes of Electronic Cigarette Aerosols - A poster presentation at DDL27, Edinburgh 2017.
The objective of this research project was to measure the inter-liquid effect on the size distributions of droplets produced from a commercial EC using laser diffraction, which is a technique for testing inhaled products, with a view to compare ECs with pharmaceutical inhalers in the future.
Introduction: Electronic cigarettes (ECs), or e-cigarettes, are devices that produce aerosols through heating and vaporising solutions, called e-liquids, that may or may not contain nicotine . A user inhales through the mouthpiece; power is supplied to the heating element to heat the e-liquid; the e-liquid is soaked from the reservoir into a wick that is in contact with the heating coil . The heating can be triggered by an internal airflow sensor that detects the inhalation airflow or by an external manual switch. The heated e-liquid will evaporate and travel through the mouthpiece. In general there is a single air path over the heater with cooling in the space post-heater. In some designs, ambient air is channelled into the mouthpiece during inhalation through small holes on the sides of the ECs that maintain the airflow and pressure drop . Upon cooling, the e-liquid vapour condenses into droplets that are inhaled. The effects of the e-liquid formulation (e.g. solvent and excipient composition etc) and device operation factors (e.g. heating temperature and duration, airflow rate etc) on the aerosol properties have not been extensively studied. E-liquids are solutions that are comprised of a solvent vehicle and solutes. The solvent base can be a mixture of glycerol, propylene glycol, ethanol, and water . The solutes include nicotine and food flavourings. Several hundred flavours are available on the market. E-liquids may or may not contain all four solvents listed above. The relationship between droplet size distribution and the formulation composition has not been studied for ECs so it is worth to investigate.
Conclusion: The Kimree V12 EC produced respirable droplets from a range of solutions containing various amounts of glycerol and propylene glycol. There was relatively high variation in the sizes of the large droplets but overall the distributions were comparable between the different liquids. EC technology may be investigated further to gain insights that may be useful for the development of novel inhaled products.
A copy of the poster can be found here: http://www.slideshare.net/progueda/16-12-06-ddl-27-poster-ecigarettes-kwok-rogueda-aedestra
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