Measuring chest circumference change during respiration with an electromagnetic biosensor

In this paper, an off-the-shelf DC motor is modified into a chest belt and used to successfully measure circumference change on a mechanical chest model, while simultaneously harvesting significant power. Chest circumference change can provide information on tidal volume, which is vital in assessing lung function. The chest circumference change is calculated from the motor's voltage output. Calculated values are within 0.95mm of measured circumference changes, with a standard deviation of 0.37mm. The wearable motor can also harvest at least 29.4µW during normal breathing.