The earliest electronic cigarette can be traced to Herbert A. Gilbert, who in 1963 patented a device described as "a smokeless non-tobacco cigarette" that involved "replacing burning tobacco and paper with heated, moist, flavored air". This device heated the nicotine solution and produced steam.
In 2001, a pharmacy graduate Hon Lik was using high-dose nicotine patches to rid himself of the habit of smoking. Hon devised a system on a large console, using food additives as solvents. At the time he was working on vaporization by ultrasound. The droplets formed were too big to resemble tobacco smoke and so he used resistance heating, which got better results. The challenge was managing to scale the mechanism down to a miniature size, suitable for a hand-held cigarette-zed device, and getting the right dose of nicotine, while also getting the right odors from harmless additives.
Hon filed the first patent in 2003 in China for the device. The first electronic cigarette was manufactured that year in Beijing, China using an ultra-sound technology. It didn't have the vaporization system used today but instead based on atomization, which can vaporize liquids through the heating produced by the electricity of the battery.