A self-powered vibration sensing element based on three-dimensional graphene field effect transistor

摘要

Piezoelectricity of two-dimensional layered materials is of great significance for electromechanical coupling applications in nanoelectrome-chanical systems. The nanoscale devices based on graphene have attracted intense interest due to its excellent electronic and mechanical properties. However, the centrosymmetric crystal structure in intrinsic graphene severely restricts its applications in mechanical sensors, transducers, and energy harvesters. In this paper, a self-powered vibration sensing element based on rolled-up single-layer graphene is proposed and demonstrated, which realizes the conversion from mechanical vibrations into electrical signals. In contrast to previous pioneering works requiring silica cavities or Si/SiO_2 calibration grating substrate to support the graphene, a three-dimensional (3D) non-closed tubular structure is adopted to develop the piezoelectricity in single-layer graphene, where the inversion symmetry of single-layer graphene is broken via self-rolled-up process induced strain. Hence, apparent piezoresponse from the 3D non-closed tubular graphene field effect transistor is observed. Moreover, a peak-to-peak amplitude for the piezoelectric current up to 4.2 is achieved, corresponding to the periodicity of mechanical vibration, and the value can increase to 10.8 nA by applying a small source-drain voltage of 6 mV. The device is also sensitive to mechanical vibration with different frequencies and shows similar currents. The electromechanical coupling in rolled-up graphene provides a basis for the applications in sensing, actuating, and energy harvesting.