The earliest electronic cigarette can be traced to Herbert A. Gilbert,[20] 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 1967, Gilbert was approached by several companies interested in manufacturing it, but it was never commercialized and disappeared from the public record after 1967.[21][22][23][24][25][26]
Hon Lik, a Chinese pharmacist, is widely credited[27][28][29] with the invention of the first generation electronic cigarette.[30] In 2000, he came up with the idea of using a piezoelectric ultrasound-emitting element to vaporise a pressurized jet of liquid containing nicotine diluted in a propylene glycol solution.[31] This design produces a smoke-like vapour that can be inhaled and provides a vehicle for nicotine delivery into the bloodstream via the lungs. He also proposed using propylene glycol to dilute nicotine and placing it in a disposable plastic cartridge which serves as a liquid reservoir and mouthpiece.
