Figure 1.

Experimental setup and analysis approach. (A) The motion sensor used in this study is integrated into an in-ear vital-sign monitor: the triaxial accelerometer is embedded in the processing unit behind the auricle, while the optical sensors for vital-sign monitoring are located on the sensor earplug that goes into the outer ear canal. (B) The participants walked across a 6.7 m pressure-sensitive gait mat synchronized with the ear-worn motion sensor at slow, preferred, and fast walking speeds. (C) Definition of spatial gait characteristics: Stride length is defined as the distance between two successive heel contacts of the same foot; stride width is defined as the perpendicular distance of one heel contact to the line connecting two successive heel contacts of the opposite foot. Abbreviations: acc: acceleration; ML: medio-lateral axis; AP: anterior–posterior axis; IF: inferior–superior axis.