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International patent application published for StopWatch smartwatch-based system for smoking detection.


14 September 2017

An international patent application has recently been published for StopWatch - a smartwatch-based system for automatically detecting cigarette smoking, developed by Andy Skinner, Chris Stone and Marcus Munafò from TARG and the MRC IEU, and Hazel Doughty from the Faculty of Engineering. The patent protects the novel design aspects of the system that allow it to work using just a smartwatch, without the need for additional sensors, a smartphone or a data connection. Having a patent will help us develop industry partnerships to fully realise the potential of the system in measuring and helping to change smoking behaviours.

The StopWatch system uses data from wrist-worn motion sensors to identify the signature hand movements associated with smoking a cigarette. A number of existing systems can already do this, but these require either a bespoke wristband equipped with motion sensors, or pairing with a smartphone with a data connection to perform the analysis of the motion data. These increase both the cost, and the burden of using this kind of system in everyday living.

StopWatch is unique in that it uses the motion sensors in a low-cost, consumer smartwatch, and does all of the data processing necessary to identify smoking gestures on the smartwatch itself, without the need for a smartphone or connection to a data network. Having the system run entirely on a smartwatch keeps the cost of the system low, and leverages the smartwatch manufacturer’s investment in product design, making it more appealing and easier to use than bespoke sensing systems.

The system has two main uses. It can provide researchers and health professionals with detailed measurements of smoking behaviour in free-living conditions, which are free from the recall errors and reporting biases associated with self-reporting of smoking. It can also be used in smoking behaviour change interventions. Its ability to detect when someone is smoking in real time means it has particular potential in interventions helping to prevent relapses leading to a return to smoking, as it enables delivery of intervention messages at precisely the time they are needed.

For more details of StopWatch, see a preprint describing the system at

Further information

Information on the Tobacco and Alcohol Research group can be found here and information on the MRC IEU can also be found here

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