VitalPod: A Low Power In-Ear Vital Parameter Monitoring System

Monitoring of physiological parameters support early detection, prevention, and management of adverse health-care related events. In-ear wearable sensor nodes that track changing bio-physiological signals can be advantageous over traditional monitoring methods in being compact, unobtrusive, and inconspicuous, increasing their appeal. However, in-ear ergonomics place rigid constraints on a device's physical design and size, limiting battery lifetime and restricting the incorporation of multiple sensor modules. This work presents the design and implementation of the wireless hearable VitalPod, an in-ear multi-vital sign monitor that measures heart rate (HR), respiratory rate (RR), blood oxygenation (SpO2), skin temperature and activity. The VitalPod is designed with low power and energy efficiency in mind, using novel sensing integrated circuits and processing modules that achieve operational longevity of up to 42 hours using a small form factor 32mAh rechargeable Liion polymer battery. It has a compact design and form factor, similar to many commercial wireless earbuds, featuring hardware required for wireless music playback using a standard balanced armature driver in addition to vital sign monitoring sensors. Experimental results show high performance in estimating vital signs for HR (-0.061± 1.12 beats per minute), RR (0.87±1.48 breaths per minute) and change in SpO2 (0.21±0.82 %). Additionally, the presented work also evaluates the positional placement of sensors in the ear to reduce the effect of motion induced artifacts.