Figure 4.

Application of the strain-based flexible sensor in smart wearables: (a) a schematic diagram of electron transport at the crack edge in a crack-flexible strain sensor [43]; (b) a wearable graphene fabric strain sensor for the detection of various human motions [44]; (c) injection of graphene nano-powders into transparent adhesive pads to fabricate flexible strain sensors with an excellent tensile–strain response [45]; and (d) the sensory performance in response to the bending of the finger and the degree thereof are both reflected in the relative rate of change in the resistance [46].