Piezoresistive Sensors Based on rGO 3D Microarchitecture: Coupled Properties Tuning in Local/Integral Deformation

Abstract

device, [7] which possesses a satisfactory sensitivity and stretchability simultaneously. [8] However, the polymer precursor infiltration process should be well controlled to preserve the surface roughness of the conductive network, [9] which is the key to achieving high sensor response. [10] And the polymer fully filled bulk structure provides little free space for deformation of the conductive network, making it difficult to form or rupture the filler-filler contacts with a small deformation variation. Such undesirable composite morphology may result in the poor sensor sensitivity.On the basis of previous research, the sensitivity of this conductive elastomer composite can be improved by optimizing the electrical property or mechanical property. For simplification, the electrical property refers to the electrical conductivity, usually using the resistance of the composite. The mechanical property is defined as static mechanical elasticity, which refers to the quality that the composite is able to stretch and return to its original shape. On the one hand, it is a common strategy to increase the device sensitivity by decreasing the conductivity of the composite. [11] On the other hand, increasing the ratio of conductive filler ratio (exceeds the percolation threshold) perhaps improves the overall mechanical elasticity of the strain sensor, thus increasing the sensitivity and stretchability. [12] Obviously, these two properties are normally interdependent in composite materials, because they can be influenced by the conductive filler ratio simultaneously. For example, when one tries to decrease the conductivity of the composite by decreasing the ratio of the conductive micro/nanomaterials, the relative increasing of polymer must lead to the decreasing of mechanical elasticity, which turned out harmful to the device sensitivity and working region (the maximum strain of the composite that electronic signal can be measured steadily and repeatedly). Due to such coupled tuning effect of the electrical and mechanical properties, we have not found the ideal state of equilibrium between the high sensitivity and wide working region (satisfactory strain limit). A general composite structure based on a simple process and low cost is urgently required, which can be used to rigorously investigate the coupled properties tuning of electrical and mechanical properties for different application potential.Here, we demonstrate a collaborative 3D microarchitecture based on conductive reduced graphene oxide (rGO) foams and insulated fibrous framework, which can realize the coupled properties tuning by varying the rGO weight fraction. At the An ideal flexible piezoresistive sensor should possess high sensitivity as well as wide sensing range, and provide a stable and excellent response under different deformation, such as local and integral strain. However, these properties are difficult to achieve simultaneously with conventional all-polymer-filled composite, as tuning of one material component always causes the unpredictable change o...

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