Figure 1.

Sensor specification and distribution of activity classes. (A) The in-ear wearable vital sign monitor: optical sensors are located on the sensor earplug that goes into the outer ear canal, while the triaxial accelerometer is located in the processing unit behind the auricle. (B) Low-dimensional embedding of the 6 activity classes (lying, standing/sitting, walking, ascending stairs, descending stairs, running) via UMAP. Abbreviations: AP: anterior–posterior axis; ML: medio-lateral axis, IF: inferior–superior axis; UMAP: Uniform Manifold Approximation and Projection.