Electronic cigarettes (CBD electronic cigarettes) include a broader product sub-category, described as personal atomizers (PV), advanced personal atomizers (APV) or electronic nicotine delivery systems (ENDS). These products have a series of designs. Full characterization of the design features of e-cigarettes is necessary to assess the potential risks and benefits associated with their use.
A systematic literature search was conducted in October 2013 to identify research related to e-cigarettes and electronic nicotine delivery systems. Search ten reference databases (Web of Knowledge, PubMed, SciFinder, Legacy Tobacco Documents Library, Embase, EBSCOhost, Espacenet, Google Scholar, Google Patent, and US Patent Office) using a set of related search terms used alone or in combination. Search conditions include the following: "thermal runaway" or "battery fire" or "battery explosion" or "lithium battery explosion" or "electronic nicotine device" or "electronic nicotine delivery system" or "e-cigarette" or "e-cigarette" or 'Electronics' and'cigarettes'.
To be considered for inclusion, the clause or patent (grant and application) must (1) be written in English; (2) publicly released; (3) partly or exclusively deal with engineering design or operation, or lithium battery fire or explosion. The search yielded a total of 296 e-cigarette articles or documents that met the inclusion criteria. Then filter the relevance of the article title and abstract (the title provides insufficient detailed information). In addition, thousands of batteries and patent documents were identified; about 100 documents and 460 patents related to battery operation were screened out. In total, the search yielded 54 articles and 28 full-text reviewed patents, including a manual search of the reference list of selected articles to identify other relevant publications.
After the full text review, 14 articles and documents and 16 patent documents were considered to be directly related to the analysis. These articles and patent documents were published between 2004 and 2013. The effectiveness and intensity of each study is determined based on a qualitative assessment of the depth and breadth of the analysis, the uniqueness and relevance of the engineering problem.
Other documents considered for review include conference reports/posters, reports not published in peer-reviewed journals, national and international standards, and government reports. Cite three documents from online sources or meeting minutes. Two websites that provide information on the design and operation of e-cigarettes are also cited. Although not peer-reviewed, these sites and documents provide valuable insights into product design and operation.
Basic design and operation
The design of electronic cigarettes is usually similar in size to traditional cigarettes, and to some extent similar to graphic designs. The common components of most e-cigarettes include aerosol generators, flow sensors, batteries and solution (or e-liquid) storage areas (as shown below)
Typical electronic cigarette configuration. This shows the wick/heater as an aerosol generator, with gauze saturated with e-liquid, a microprocessor for control operation (optional) and an LED for imitating burning coal (optional).
Electronic cigarettes are currently classified as disposable or reusable. Disposable devices do not have rechargeable batteries and are generally not rechargeable. They may have light emitting diodes (LEDs). The e-liquid container or box can be separated from the aerosol generator or atomizer; the combined atomizer and cartridge are called the cartridge atomizer. Currently commercially available electronic cigarettes usually have an aerosol generator with a metal or ceramic heating element wound around the core bundle.
E-cigarettes can use a variety of materials. They include metals, ceramics, plastics, rubber, fibers and foams. Some of the materials can be aerosolized, which may have side effects on health.
Although the complexity of e-cigarettes is different, the basic operations of the first-generation e-cigarettes are described below:
1. The user uses an electronic cigarette, and the electronic cigarette activates the airflow sensor.
2. The airflow sensor detects the pressure change and prompts the current of the LED and heating element.
3. The e-liquid saturates the core through capillary action, and then atomizes through the heating element.
4. Subsequently, the atomized droplets of e-liquid flow into the user's mouth and lungs.