Highly Ordered 3D Porous Graphene Sponge for Wearable Piezoresistive Pressure Sensor Applications

Wearable sensors with excellent flexibility and sensitivity have emerged as a promising field for healthcare, electronic skin, and so forth. Three-dimensional (3D) graphene sponges (GS) have emerged as high-performance piezoresistive sensors; however, problems, such as limited flexibility, high cost, and low sensitivity, remain. Meanwhile, device-level wearable pressure sensors with GS have rarely been demonstrated. In this work, highly ordered 3D porous graphene sponges (OPGSs) were first successfully prepared and controlled through an emulsion method, and then a device-level wearable pressure sensor with high flexibility and sensitivity was assembled with a gold electrode and polydimethylsiloxane into a reliable package. The pH values were carefully controlled to form a stable emulsion and the OPGSs showed a highly ordered 3D structure with ultralow density, high porosity, and conductivity; this resulted in a gauge factor of 0.79-1.46, with 50 % compression strain and excellent long-term reproducibility over 500 cycles of compression-relaxation. Moreover, the well-packaged pressure sensor devices exhibited ultrahigh sensitivity to detect human motions, such as wrist bending, elbow bending, finger bending, and palm flexing. Thus, the developed pressure sensors exhibited great potential in the fields of human-interactive applications, biomechanical systems, electronic skin, and so forth.