Linear piezoresistive strain sensor based on graphene/g-C ₃ N ₄ /PDMS heterostructure

Abstract

Here we report a novel hybrid material consists of 2D graphitic carbon nitride (g-C₃N₄) and graphene heterostructure that exhibits piezoresistivity superior to graphene and potentially being used as a strain sensor. The g-C₃N₄ that contains periodically spaced triangular nanopores is used for improving the piezoresistivity of the sensor imparting change in the polarization upon application of strain. In this work, we have investigated graphene/g-C₃N₄ interfaced materials and quantified its piezoresistive effects through experimental analysis and density functional theory (DFT) based computational studies provide insights into the electronic structures of the hybrid interfaces. We have observed a linear response in electrical resistance for a wide range of uniaxial strains up to ∼25%. The observed increase in resistance upon application of strain corroborates with our computational finding of strain-dependent band gap opening. Further, it has been realized that band-gap opening occurs exclusively in the graphitic layer of the composite materials under strain. However, the g-C₃N₄ bands remain intact at the interface. The linearity and a considerably small gauge factor (1.89) make graphene/g-C₃N₄ a promising heterostructure material unlike conventional metal gauge sensor in wide strain pressure sensor devices.