Integrated Strain Sensors with Stretchable Vertical Graphene Networks for Non-invasive Physiological Assessment

Flexible piezoresistive sensors, which attract considerable research interest, have been extensively investigated by many efforts from material and structural methodologies. However, practical applications for physiological assessment, apart from the monitoring of joint motion and recording of pulse, have been rarely reported. In this work, vertical graphene (VG) nanowalls were synthesized, characterized, and adopted to fabricate flexible strain sensors. Routine measurements, such as strain responsion, were exerted. Then, the radial and carotid pulses and the respiratory rate of subjects were collected by these flexible piezoresistive sensors to evaluate the pulse rate, the rhythm of pulse, and the respiratory rate for risk assessment of cardiac bradycardia, arrhythmias, arrest, and artery stiffening. Furthermore, a wearable circuit was also designed and fabricated in this work to integrate with the flexible sensor for portable physiological monitoring. The convenient noninvasive platform makes it extremely suitable for wide applications at community levels, which help to raise and sustain awareness of the importance of vital signs.