Graphene-based pressure sensor and strain sensor for detecting human activities

Wearable pressure sensors and strain sensors with high sensitivity and large working range are essential for detecting human motions. However, fabricating wearable sensors, which are capable of detecting pressure or strain signals, still remains challenging. Herein, two kinds of novel sensors, pressure sensors and strain sensors, are fabricated using the same materials and similar fabrication processes. The sensors are fabricated by soaking cotton in graphene inks so as to avoid high temperature and toxic chemicals caused by reduction compared to traditional graphene oxide inks. The pressure sensor shows excellent performance with high sensitivity (0.12-0.41 kPa(-1)) and broad working range (0-20 kPa). The strain sensor also has outstanding sensitivity (gauge factor 22.6-83.7) and large working strain of 27%. These two sensors are further demonstrated to show the ability of detecting human activities such as breathing, wrist pulsing, respiration, etc. The low-cost and scalable fabrication along with the good comprehensive performance of the sensors makes them applicable in wearable electronic devices for human health monitoring and movements.