Hybrid Piezoelectric/Triboelectric Wearable Nanogenerator Based on Stretchable PVDF–PDMS Composite Films

Abstract

Hybrid piezoelectric/triboelectric nanogenerators combine the merits of piezoelectric nanogenerators (PENGs) and triboelectric nanogenerators (TENGs), possessing enhanced electrical output and sensitivity. However, the structures of the majority of hybrid nanogenerators are rather complex in integrating both functions, limiting their practical application in wearable electronics. Herein, we propose to construct a piezoelectric/triboelectric hybrid nanogenerator (PT-NG) with a simple structure based on a composite film to simultaneously achieve the coupling of piezoelectric charge generation and triboelectrification with improved energy conversion efficiency. The composite film consists of electrospun PVDF nanofibers embedded in the surface of the PDMS film, which not only forms a rough nanomorphology on the surface of PDMS but also provides structural protection to the PVDF nanofibers by PDMS during compressive deformation. The results have shown that the PT-NG can generate much higher electrical outputs than individual TENG and PENG devices. The PT-NG devices exhibit a high level of mechanical-to-electrical energy conversion efficiency with superior performance in charging capacitors and functioning as self-powered wearable sensors for the detection of different signals from finger movement, the recognition of various gestures, and the monitoring of respiration. More importantly, the composite device possesses an impressive structure durability, maintaining its layered structure over 5000 testing cycles without noticing any obvious damage on the nanofibers or detachment between the layers. Our results have demonstrated that the combining of piezoelectric nanofibers and triboelectric substrate is an efficient way to fabricate highly efficient energy harvesting devices for intelligent identification and health monitoring.

Tribo-piezoelectric Hybrid Nanogenerators Based on ZnO Nanorods and CsPbBr3 Nanoparticle/PVDF-HFP Films for Self-Powered Photodetectors

“…Under the influence of this potential, the flow of electrons can be realized to balance the potential. Again, during the recontact of the two layers, the backflow of electrons under the reverse potential can be expected. , Further, the role of the piezoelectric PVDF-HFP layer in enhancing contact electrification was verified upon changing the contacting layer to Al, cellulose paper, nitrile, or Teflon (poly­(tetrafluoroethylene)PTFE). As shown in Figure (d), when different counter layers are in contact with ZnO nanorods, diverse outputs can be obtained depending upon the tendency of the layer to attract electrons.…”

“…For example, Zhang et al reported the development of a flexible self-powered UV photodetector by coupling the triboelectric and photoelectric effects in a ZnO nanowire-based system showing a responsivity of 1.4 mA/W . Chen et al demonstrated a polyvinylidene fluoride (PVDF)–polydimethylsiloxane (PDMS)-based hybrid nanogenerator for the detection of finger movement, gesture recognition, and monitoring respiration …”

Crumpled Nanogenerator Based on Elastic Modulus Design for Fully Self-Powered High-Speed Rail Speed Measurement

“…Energy harvesting and conversion devices using nanotechnology have received increasing attention recently as they may play a crucial role in building and driving self-powered nanodevices and nanosystems. − Nanogenerators are devices that convert thermal and chemical energy into electrical energy, effectively collecting energy from various low-frequency mechanical movements from the environment. − Self-powered sensors based on nanogenerators can be used as data acquisition units for traffic, human movement, meteorological environment, and gas sensors. − In recent years, it has been reported that many wind-driven energy harvesters can be used to capture energy from the surrounding flow field to power sensing nodes or wireless sensing systems for continuous monitoring. − Self-powered sensors are an important application development direction of nanogenerators. The development of fully self-powered systems that do not rely on traditional energy systems such as mains or batteries is of great value to the future design of the IoT. − …”