In automatic models, when a user inhales through the device, air flow is detected by a sensor, which activates a heating element that vaporizes a nicotine solution stored in the mouthpiece. On manual models, the user must depress a button to activate the heating element to produce vapor which is then inhaled by the user. On most models an LED
on the opposite end of the device is also activated during inhalation,
which serves as an indicator of use. Several LED colors are available
from various manufacturers.
A disassembled cigarette-styled electronic cigarette.
A. LED light cover
B. battery (also houses circuitry)
C. atomizer (heating element)
D. cartridge (mouthpiece)
The mouthpiece is a small disposableplastic
cup-like piece affixed to the end of the tube. Inside the mouthpiece is
a smaller plastic cup which holds an absorbent material that is
saturated with a flavored liquid solution that may contain nicotine.
This inner cup is made such that air is able to flow around it and
through a hole in the end of the outer piece; this is necessary for the
device to provide the ability for suction to move the vapor into the
user's mouth. The mouthpiece is referred to in the industry as a
"cartridge". When the liquid in the cartridge has been depleted, it can
either be refilled by the user or replaced with another pre-filled
As an alternative to the traditional plastic mouthpiece, some
manufacturers have created dedicated mouthpieces just for dripping, such
as Super-T manufacturing's stainless steel T-Tip drip tip.
Another alternative to using cartridges is the direct dripping method
using drip tips. By removing the absorbent material, one is able to
simply remove the plastic mouthpiece and drip several drops of e-liquid
directly onto the atomizer bridge. To further ease dripping, some
manufacturers have created specialty mouthpieces made of stainless steel
or plastic that are intended just for dripping and do not require
removal each time you drip.
Heating element ("atomizer")
The heating element serves to vaporize the liquid in the mouthpiece
so that it can be inhaled. This component is referred to in the industry
as an "atomizer". Atomizers have a finite life of about one month (on
average) and are one of the recurring expenses associated with
electronic cigarettes. Some models combine an atomizer and pre-filled
disposable component referred to as a "cartomizer".
Battery and electronics
An electronic cigarette battery connected to a USB charger.
Most electronic cigarettes employ a lithium-ion
rechargeable battery to power the heating element. Battery life varies
depending on the battery type and size, frequency of use, and operating
environment. Many different battery charger types are available, such as wall outlet, car, and USB chargers. The battery is generally the largest component of an electronic cigarette.
Some electronic cigarettes employ an electronic airflow sensor to
automatically activate the heating element upon inhalation, while other
models require the user to press a button while inhaling. Various other
electronic circuits are usually employed as well, such as a timed cutoff
switch to prevent overheating and a colored LED to signal activation of the device.
Traditionally, electronic cigarettes have utilized an electronic
means of activation. This involved the use of small tactile switches,
vacuum switches and the related wiring and electronics necessary to run
them. Users soon discovered these could be unreliable. With the advent
of "mods", several manufacturers have created all mechanical electronic
cigarettes that eliminate the use of any wiring, solder or electronics
in an effort to improve switch reliability.
While some larger electronic cigarette models employ a
user-replaceable standard-size battery cell, many models are too small
to house a standard-size cell and instead require a proprietary
component made by the electronic cigarette manufacturer. For those
models, the battery and electronic components are housed within a single
replaceable part, which is still generally referred to in the industry
simply as the "battery".
Nicotine solutions sold separately for use in refillable cartridges
are sometimes referred to as "e-liquid" or "e-juice", and commonly
contain some amount of flavoring, with several different flavors
available. They consist of nicotine dissolved in propylene glycol (PG) and/or glycerin (glycerol). Both PG and glycerin are common food additives.
Solutions are also available in differing nicotine concentrations, to
let the user decide the amount of nicotine to be taken in.
Concentrations range from Zero Nicotine, low and midrange doses
(6–8 mg/ml and 10–14 mg/ml respectively), to high and extra-high doses
(16–18 mg/ml and 20–54 mg/ml respectively). The concentration ratings
are often printed at the e-liquid bottle or cartridge, although the
standard notation "mg/ml" often gets abbreviated to just "mg". Solutions
are also available that contain no nicotine at all.
Some flavor varieties attempt to resemble traditional cigarette types, such as regular tobacco and menthol, and some even attempt to mimic specific cigarette brands, such as Marlboro or Camel. Fruit and other flavors are also available, such as vanilla, caramel, and coffee.