Poly(vinyl alcohol)-Mediated Graphene Aerogels with Tailorable Architectures and Advanced Properties for Anisotropic Sensing

Three-dimensional graphene (3DG) aerogels possessing superior elasticity and conductivity are prerequisite to achieve high sensitivity and reliability in flexible sensors. However, conventional 3DG aerogels with brittle structure and small recoverable deformation often do not possess excellent sensing performance. Herein, 3DG-poly(vinyl alcohol) (3DG-PVA) composite aerogels with controlled structures and properties are designed and prepared by PVA-mediated self-assembly of graphene oxide nanosheets combining the hydrothermal reaction and freeze-drying processes. The resulting aerogels exhibit robust structurewith high porosity, superior elastic deformation, decent electrical conductivity, and outstanding electromechanical performances including a high sensitivity of 0.34 kPa(-1), a fast response time of 63.9 ms, and an excellent signal stability of over 5000 times of cycling. To demonstrate their potential applications in the field of piezoresistive sensing, the wearable sensors are designed and fabricated by using 3DG-PVA aerogels, which exhibit the anisotropic sensing capabilities and ultrasensitive performances confirmed by practical applications in monitoring the motions of human joints with different orientations, as the sensing part.