A Flexible and Stretchable Bending Sensor Based on Hydrazine-Reduced Porous Graphene for Human Motion Monitoring

In this work, we developed a flexible and stretchable bending sensor that is made of graphene film decorated with dense pores and sealed with both polyethylene terephthalate (PET) and elastic rubber layers. The graphene film was laid on a PET substrate to disperse the stretching stress and then covered by another smooth PET layer for reducing shear force. Platinum-catalyzed silicone rubber was employed for protecting the graphene film and providing the stretchability of the whole structure. Properties of the graphene film were investigated through the scanning electron microscope (SEM), Raman spectrometer, X-ray diffraction, and mechanical evaluations. Results indicate that the sensitivity of the proposed bending sensor reaches 1.092 mV/deg with excellent linearity and the resolution achieves 1°. Satisfactory repeatability was also observed with a mean square error of 0.105 of ignorable distortion after 1000 cycles of bending. On-human experiments verified that the bending sensor could accurately sense the bending angles of different human joints without additional structural modification. The results lead us to believe that the proposed method is a promising path for fabricating flexible and stretchable sensors with high performance and stability.