Characteristics of 2D ZnO-based piezoelectric nanogenerator and its application in non-destructive material discrimination

The present report aims at the application of piezoelectric nanogenerators for non-destructive material discrimination. The detailed characteristics of zinc oxide (ZnO) nanosheet-based piezoelectric nanogenerator and its applications in mechanical energy harvesting and sensing are considered as major objectives of the present study. The nanogenerator is fabricated with ZnO nanosheet film prepared by hydrothermal method with necessary electrodes. The nanogenerator response as a function of different load resistances, different finger-tapping frequencies, different finger-tapping pressures, bending and twisting movements are recorded. The maximum output power of 18 nW is observed at the load resistance of 200 K Omega with 60 mV output voltage. The output voltages of similar to 150 mV, 350 mV, and 200 mV are observed for finger-tapping, bending, and twisting movements, respectively. The output voltages of similar to 76 mV, 100 mV, and 145 mV are observed for low, medium, and high pressures applied by the finger. Nanogenerator is also tested for its stability of the output at different points of time after the device fabrication and found stable over for one year. Further, the nanogenerator is used as an impact sensor for non-destructive material discrimination application. The output voltages of 176 mV, 225 mV, 272 mV, and 300 mV were observed for acrylic, ceramic, marble, glass balls of uniform diameter but with a different mass. The fabricated nanogenerator can discriminate the equal size materials of different densities. Further, ZnO nanosheet-based nanogenerator has potential applications in mechanical sensors due to the high flexibility and mechanical reliability of the ZnO nanosheets.