Feasibility assessment of a piezoresistive sensor based on graphene nanoplatelets for respiratory monitoring

The demand for wearable systems devoted to monitoring respiratory activity is growing more and more. This interest is mainly related to the possibility of remotely monitoring this activity that is both sensitive to several psychological and physiological stressors and correlated to a variety of pathologies. Among several solutions, sensing elements based on nanocomposite films have gained broad interest for instrumenting wearable systems. In this study, we focused on designing and developing a stretchable sensing element realized with graphene nanoplatelets (GNP) ink. The proposed element has been characterized to assess its metrological properties in terms of sensitivity, calibration curve, and hysteresis error. Finally, a pilot study involving two healthy volunteers has assessed its feasibility for estimating respiratory rate. The trials are performed under two respiratory conditions (i.e., eupnea and tachypnea).