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Automated dripping devices for vapers: RDTAs, bottomfeeders, squonk mods and dripboxes
  1. Paul Truman Harrell1,2,
  2. Thomas Eissenberg3
  1. 1 Division of Community Health & Research, Department of Pediatrics, Eastern Virginia Medical School, Norfolk, Virginia, USA
  2. 2 Department of Psychiatry & Behavioral Sciences, Eastern Virginia Medical School, Norfolk, Virginia, USA
  3. 3 Department of Psychology, Center for the Study of Tobacco Products, Virginia Commonwealth University, Richmond, Virginia, USA
  1. Correspondence to Dr Paul Truman Harrell, Department of Pediatrics, Eastern Virginia Medical School, 855 W. Brambleton Ave, Norfolk, Virginia, USA; harrelpt{at}

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The standard e-cigarette involves an electric heating coil that vaporises a liquid solution consisting of propylene glycol and/or vegetable glycerin, flavourants and, frequently, nicotine. Typically, the liquid is delivered to the heating coil via saturated wicking material. However, ‘dripping’ is another method that involves the application of liquid to the coil of a direct drip atomiser or rebuildable dripping atomiser.1 2 Users report that dripping provides greater vapour yields, stronger throat hit and a better flavour.3

Dripping is not without drawbacks. Notably, the higher temperatures involved may increase toxicant yield, although an update examining more contemporary designs may be needed.1 4 Additionally, dripping is time consuming. It requires transferring liquid from a separate container to the coil.1 This process must be repeated every few puffs to avoid ‘dry puffs’, as the liquid is vaporised and the heating coil dries out. Dry puffs yield more toxicants and may be accompanied by an aversive taste.1 5 Avoiding dry puffs by adding more liquid is challenging, as too much liquid ‘floods’ the coil, preventing vapour production. Furthermore, monitoring the amount of liquid consumed sometimes was challenging.

Automated dripping devices

To circumvent the inconvenience of direct dripping, e-cigarette users and manufacturers have developed several novel technologies, referred to here …

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  • Contributors PTH wrote the original draft. TE provided feedback and suggestions. Both authors reviewed and approved the final manuscript.

  • Funding PTH effort is supported by the National Cancer Institute of the National Institutes of Health under award number R03CA195124 and the Center for Tobacco Products of the US Food and Drug Administration. TE effort is supported by the National Institute on Drug Abuse of the National Institutes of Health under award number P50DA036105 and the Center for Tobacco Products of the Food and Drug Administration. The content is solely the responsibility of the authors and does not necessarily represent the views of the NIH or the FDA.

  • Competing interests PTH does not have any competing interests to declare. TE is a paid consultant in litigation against the tobacco industry and is named on a patent application for a device that measures the puffing behaviour of electronic cigarette users.

  • Provenance and peer review Not commissioned; externally peer reviewed.