Enhanced triboelectric properties of Eu2O3-doped BaTiO3/PVDF-HFP nanofibers.

Because triboelectric nanogenerators (TENGs) convert mechanical energy into electricity, they are sustainable energy sources for powering a diverse range of intelligent sensing and monitoring devices. To enhance the electrical output of polymer-based TENGs, nanofillers are commonly incorporated into polymers. In this study, we developed a simple low-temperature process for preparing high-performance ceramic powder-based TENGs comprising electrospun fibrous surfaces based on poly(vinylidene difluoride-co-hexafluoropropylene) (PVDF-HFP) and dispersed Eu2O3-doped BaTiO3 nanofillers. Herein, we discuss the effect of the modified dielectric properties and transferred charge of the electrification film on the performance of the TENGs. After incorporating the Eu2O3-doped BaTiO3 nanofiller, the maximum output voltage of the 10 wt% Eu2O3-BaTiO3/PVDF-HFP electrospun-nanofiber TENG reached as high as 1004 V with a corresponding current density of 9.9 µA cm-2. The enhancement in the triboelectric properties of the Eu2O3-BaTiO3/PVDF-HFP electrospun-nanofiber TENGs was due to their high amounts of interface polarization and transferred charge, suggesting improved capture and storage of triboelectric electrons. These Eu2O3-BaTiO3/PVDF-HFP electrospun-nanofiber TENGs could harvest mechanical energy and power electronic devices; they were robust and not affected by the operating temperature or humidity. Furthermore, we used a fabricated device as a sensor for application as a light-emitting diode dimmer switch and for the tracking of leg movement.

Biowaste Eggshell Membranes for Bio-triboelectric Nanogenerators and Smart Sensors.

In this study, we used a simple and cost-effective method to fabricate triboelectric nanogenerators (TENGs) based on biowaste eggshell membranes (EMs). We prepared stretchable electrodes with various types of EMs (hen, duck, goose, and ostrich) and employed them as positive friction materials for bio-TENGs. A comparison of the electrical properties of the hen, duck, goose, and ostrich EMs revealed that the output voltage of the ostrich EM could reach up to 300 V, due to its abundant functional groups, natural fiber structure, high surface roughness, high surface charge, and high dielectric constant. The output power of the resulting device reached 0.18 mW, sufficient to power 250 red light-emitting diodes simultaneously, as well as a digital watch. This device also displayed good durability when subjected to 9000 cycles at 30 N at a frequency of 3 Hz. Furthermore, we designed an ostrich EM-TENG as a smart sensor for the detection of body motion, including leg movement and the pressing of different numbers of fingers.

Creating hot spots within air for better sensitivity through design of oblique-wire-bundle metamaterial perfect absorbers.

Better sensitivity of a biosensor could boost up the detection limit of analytes, thus a must in the fields of bio-sensing and bio-detection. To further enhance the sensitivity of a biosensor, in this work, we design an oblique-flat-sheet metamaterial perfect absorber (MPA) to concentrate the hot spots within air between the oblique flat sheet and the continuous ground metal, thus enabling fully interaction between analytes and hot spots. The corresponding field distributions in simulation corroborated our assumption and its sensitivity could be up to 1049 nm/RIU. Then, we fabricated the sample by e-beam lithography process for a seed layer and simply tilting the sample during deposition to obtain oblique flat sheets. When considering the stochastic nature of the deposited multiple oblique flat sheets, we modified the metallic upper resonator of the MPA from the single oblique-flat-sheet into randomly distributed oblique-wire-bundle (OWB) and in simulation, its sensitivity is boosted up to 3319 nm/RIU. In experiments, the measured sensitivity is 1329 nm/RIU under different concentrations of glucose solutions that is four times larger than the 330 nm/RIU of the planar MPA. The higher sensitivity was attributed to that the OWB MPA could provide hot spots within air not only between OWB and grounded metal but also among wires. Moreover, the OWB could also trap and concentrate the analytes locally.

Electrospun P3HT/PVDF-HFP semiconductive nanofibers for triboelectric nanogenerators.

This paper describes a simple electrospinning approach for fabricating poly(3-hexylthiophene) (P3HT)/poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) semiconductive nanofiber mat triboelectric nanogenerators (TENGs). Measurements of the electrical properties of the P3HT/PVDF-HFP semiconductive nanofiber TENGs revealed that the output voltage could be enhanced up to 78 V with an output current of 7 µA. The output power of the device reached 0.55 mW, sufficient to power 500 red light-emitting diodes instantaneously, as well as a digital watch. The P3HT/PVDF-HFP semiconductive nanofiber TENG could be used not only as a self-powered device but also as a sensor for monitoring human action. Furthermore, it displayed good durability when subjected to 20,000 cycles of an external force test.