Real-time detection of respiratory activity using an inertial measurement unit

In this paper the use of an inertial measurement unit (IMU) to measure respiratory activity is presented. Movement of the abdomen was recorded by an IMU attached to a belt around the abdomen. The resulting signal was compared with reference measurements of the airflow at the mouth. The results of experimental evaluation show that the method can correctly detect the number of breaths together with the timing of the onsets of expiration and inspiration in real-time. They also indicate that the signal can be used to differentiate between different breathing situations. This novel method could therefore be suitable for use in automatic abdominal stimulation systems to support respiratory activity in tetraplegia where the stimulation is applied depending on the respirator activity of the subject.