Engineering of graphene/epoxy nanocomposites with improved distribution of graphene nanosheets for advanced piezo-resistive mechanical sensing

Abstract

Conductive nanostructured composites combining an epoxy and graphene have been explored for application as high-performance piezo-resistive mechanical sensor.

Recent Advances in Sensing Applications of Graphene Assemblies and Their Composites

“…Many approaches have been explored to address this problem using macroscopic graphene films, graphene fibers, graphene aerogels, graphene‐based composites as potential solutions for enhancing the sensitivity. In these cases, the sensing mechanism is more complicated when disconnectivity, microcrack propagation, and tunneling effects are included . Conductive fibers (1D), conductive films (2D), and macroscopic structures (3D) made of graphene platelets can allow electrons to flow through the overlapped graphene sheets within the percolation network .…”

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

“…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].…”

“…Moreover, Tung et al have developed a piezoresistive sensor made of rGO/epoxy composite at 2 wt %, with a GF of 12.8. Surface functionalization of the filler enabled the improvement of the filler-matrix interface, which is critical for the sensing performance of the rGO/epoxy composite [9]. The reversibility and the damage detection capability of the sensor were monitored as a function of increasing mechanical strain through measurements of the resistance variation under cyclic loading.…”

“…The reversibility and the damage detection capability of the sensor were monitored as a function of increasing mechanical strain through measurements of the resistance variation under cyclic loading. When the strain exceeded the value of the elastic domain boundary of the epoxy matrix, the resistance started deviating from the linear curve probably due to the degradation of the graphene-based composite caused by microcracks at the matrix-filler interface [9]. In a previous study, we proposed a new method to estimate the average size and dimensions of GNP agglomerates in epoxy-based composites, and we demonstrated the degradation of the mechanical properties of the composite due to the presence of filler agglomerates through dynamic thermo-mechanical analysis [28].…”