Smoking alternatives: Do e-cigs provide the optimal alternative? What voltage is optimal?

[JW50]

Below is an abstract of some research that deals with PG. It is found here: ScienceDirect - International Journal of Pharmaceutics : Effect of energy on propylene glycol aerosols using the capillary aerosol generator and deals with “optimal aerosolization” of PG. Thinking of the e-cig as an aerosol generator the question arises as to what voltage (and resistance) of vaping gives the most optimal delivery of nicotine.

Effect of energy on propylene glycol aerosols using the capillary aerosol generator

X. Shen , M. Hindle , and P. R. Byron
Aerosol Research Group, Department of Pharmaceutics, Virginia Commonwealth University, Box 980533, 410 North 12th St., Richmond, VA 23298-0533, USA
Received 13 March 2003; Revised 11 September 2003; accepted 9 February 2004. Available online 27 March 2004.
Abstract
The CAG is being developed for pulmonary drug delivery. Liquids are pumped, heated and vaporized by the CAG, whence they nucleate and condense to form aerosols. This study characterized the effect of energy on the aerosolization process. With increasing energy, the CAG produced an increasing fine particle fraction (FPF) until “optimal aerosolization” was achieved between 40 and 45 J; this energy range agreed with that theoretically required to vaporize the dose of PG. Further increases in energy above this optimal range did not improve PG’s aerosolization efficiency. Based on the energy, FPF and temperature profiles, it was possible to deduce the nature of the liquid flow-boiling during aerosol generation. The aerosol particle size went through a minimum, as energy was increased through the “optimal range.” In the “energy excess” region, where additional energy increased PG vapor temperature and velocity, droplet sizes were increased primarily due to changes in the nucleation rates and supersaturation ratios affecting the nucleation and condensation processes occurring within the vapor jet. The in vitro MMAD of the PG aerosol changed as a function of the applied energy, suggesting that for any pharmaceutical application, the choice of applied energy is critical to deposition profile of the aerosol.
Author Keywords: Author Keywords: Aerosol; Propylene glycol; Vaporization; Energy

Any thoughts or comments about the optimum e-cig wattage that would produce the fastest intake of nicotine? How might the "optimal" be proven?

 

[rolygate]

Standard equipment operates around 4 watts, LR equipment is about 6 watts, and 5 volts produces 8 to 10 watts or so, depending on the exact resistance of the atty/carto used. It is generally accepted that increasing the power (wattage) increases the vapor volume and density, among other things. The liquid is used up faster as well.

Logically, this means there is more of everything in the vapor, including nicotine. Particle size may well be affected but this probably does not have as great an effect as the amount of nicotine supplied, which will most likely be more at higher wattages (it certainly feels that way).

However you also might need to take into account that nicotine is absorbed in the mouth, lungs and nose - not just the lungs. Probably, particle size is irrelevant in the mouth. There is a theory that more nicotine is absorbed in the mouth when vaping because the particle size in vapor is around ten times that of smoke, therefore vapor ingredients (such as nicotine) are not nearly as well absorbed, since the vapor does not penetrate the smallest airways of the lungs. Research that describes this is not easy to find, and it is extremely unlikely that an expansion of the research quoted above, that addresses the exact amount of power supplied to atomizer coils for any given result, will be forthcoming any time soon. This type of research is paid for by pharma and they don't have any reason to do it. The cheapest possible trials of this sort would cost several hundred thousand dollars.

Increase the power of your e-cig and you get more of everything. Nicotine is almost certainly absorbed by the mouth and nose as well as the lungs, so an optimal absorption method would be to hold the vapor in the mouth first, then inhale, then exhale through the nose. In the end, vaping time is probably the most easily adjusted factor, as 6 minutes at 8 watts may be equal to 12 minutes at 4 watts, whatever way you cut it.