Highly sensitive strain sensors based on hollow packaged silver nanoparticle-decorated three-dimensional graphene foams for wearable electronics.

Flexible strain sensors possess a great potential for applications in wearable electronic devices for human motion detection, health monitoring, implantable medical devices and so on. However, the development of highly sensitive strain sensors remains a challenge in the field of wearable electronics. Herein, we prepared a highly sensitive strain sensor, which was composed of a three-dimensional reduced graphene oxide foam decorated with silver nanoparticles (Ag NPs) to enhance the conductivity. Then, half-cured polydimethylsiloxane was employed to get a special "hollow packaged" structure. Thanks to the synergistic conductive effect of Ag NPs and the reduced graphene oxide flakes as well as the special "hollow packaged" structure, the as-prepared flexible strain sensor not only possessed a dramatic gauge factor of 1588 (at 50% sensing strain), but also exhibited high stability in 500 cycles of 30% strain. The mechanism of the enhancement of the sensitivity with the special "hollow packaged" structure was discussed as well. Meanwhile, the detection of the bending and rotation of wrists and the bending of fingers and arms was demonstrated, showing attractiveness in human motion detection.