High-performance strain sensors based on functionalized graphene nanoplates for damage monitoring

Electro-Mechanical Properties of Multilayer Graphene-Based Polymeric Composite Obtained through a Capillary Rise Method

“…The deterioration of the piezoresistive properties of polymer composites filled with carbon nanostructures during cyclic mechanical tests with incremental strain level has been already observed in [10,38,39]. In particular Zha et al [10] report that during incremental cyclic tensile loadings, even after the third cycle, $\Delta R/R_0$% does not return to its initial value, demonstrating the unstable drift of the piezoresistive response.…”

“…In particular Zha et al [10] report that during incremental cyclic tensile loadings, even after the third cycle, $\Delta R/R_0$% does not return to its initial value, demonstrating the unstable drift of the piezoresistive response. Actually, we assume that in this type of sensor, incremental strain induces primarily a partially-irreversible change of the morphology of the agglomerates located over the lamina surface, in which nanostructures are kept together by weak forces, with a consequent increase of the distance between nanoparticles, resulting in the break-up of conductive networks.…”

“…These sensors rely on different physical properties, such as optical, piezoelectric and piezoresistive effects [3,4,5]. Recently, piezoresistive strain gauges based on polymer matrix filled with carbon nanostructures, such as carbon nanotubes (CNT) [6,7], reduced graphene oxide (rGO) [8,9], graphene nanoplatelets (GNP) or multilayer graphene nanoplatelets (MLG) [10,11,12,13,14,15], have gained considerable attention from both academia and industry due to their high sensitivity, mechanical compatibility with the host structures, isotropic response and size scalability. These types of sensor are typically made of polymer composites filled with carbon nanostructures, which create a percolating electrical network, whose resistance is dependent on the distance between particles and on the piezoresistivity of the particles themselves [16].…”

“…These defects result in a progressive deterioration of the mechanical properties of the composite for increasing or repetitive load cycles, and they limit the use of such composites in strain sensor applications because of the continuous increase of the electrical resistance of the material under stress [13,25,26]. The investigation of the role that the composite microstructure plays on the cyclic piezoresistive response and on the hysteretic behavior of strain sensors has attracted considerable research efforts [9,10,13,19,27]. Recently Zha et al have produced a strain sensor based on functionalized GNP/epoxy composite for in situ damage monitoring of structural composites by a resin casting method [10].…”

“…The investigation of the role that the composite microstructure plays on the cyclic piezoresistive response and on the hysteretic behavior of strain sensors has attracted considerable research efforts [9,10,13,19,27]. Recently Zha et al have produced a strain sensor based on functionalized GNP/epoxy composite for in situ damage monitoring of structural composites by a resin casting method [10]. The composite sensor has shown a relatively good sensitivity, with a gauge factor ( GF ) of ~45 and a Young's modulus of ~2.2 GPa.…”