"Our mission is to 'obsolete' cigarettes, " said Craig Weiss, chief executive of NJOY, the leading US e-cigarette maker by market share.

CNN: Sales of e-cigarettes continue to soar

Upstarts such as NJOY, Vapor and Logic are spending more on marketing and advertising, to make the case for their products as a viable smoking alternative.

CNN: Sales of e-cigarettes continue to soar