Fig. 4: GGFF flexible pressure sensors.
a Schematic for the elementary unit of GGFF and corresponding equivalent circuit (inset), depicting the hierarchical conductive model constructed in GGFF. R0 is the intrinsic resistance of each fiber, Rc1 is the contact resistance between neighboring fibers, and Rc2 is the contact resistance between the warp and weft yarns. b Relative resistance variation under different pressure contact resistance between the warp and weft yarns. Inset: corresponding equivalent circuit under the pressure, where the faded orange color of Rc1 and Rc2 denotes the resistance decreasing. c Pulse signal detection with GGFF sensor. Inset: wrist attached with GGFF sensor (left), and the magnified image of a single pulse presenting the typical P-, T-, and D-waves (right). d Human vocal signal detection with GGFF sensor, presenting the featured peak shapes responding to the phonation of “graphene”, “glass”, and “fiber” with high repeatability. Inset: throat attached with GGFF sensor. e ΔR/R0 of GGFF sensor attached on a loudspeaker playing an audio file (bottom), showing good consistency with the original audio signals (up).
