Growth of 2D ZnO Nanowall for Energy Harvesting Application

Here we report a novel and facile way to grow the vertically aligned ZnO nanowall on both sides of the flexible substrate through low- temperature, cost-effective hydrothermal method and their application toward energy harvesting application. The fabricated nanogenerator device structure consists of a ZnO nanowall structure on the both sides of the flexible substrates covered with poly­(methyl methacrylate), and gold (Au) coating on both sides acts as an electrode. The fabricated nanowall nanogenerator produces the maximum output voltage and current of 2.5 V and 80 nA respectively, with maximum power output of 0.2 μW·cm^–2, when folding the device through the finger. Furthermore, we studied the performance of the nanogenerator device with different load resistance. The voltage and current were linearly varied with the load resistance. The maximum power output (37.7 nW·cm^–2) was measured at load resistance of 75 MΩ. The fabricated device showed the capability by driving a commercial green LED and LCD with the help of the capacitor. The experimental results confirmed the ZnO nanowall as a good candidate for energy harvesting application

Exalted Electric Output via Piezoelectric–Triboelectric Coupling/Sustainable Butterfly Wing Structure Type Multiunit Hybrid Nanogenerator

The scalable synthesis of an irregular composite surface impregnated with high-performance piezoelectric 0.3Ba_0.7Ca_0.3TiO₃–0.7BaSn_0.12Ti_0.88O₃ nanoparticles (0.3BCT–0.7BST NPs) for enhancing the power density of hybrid nanogenerators (H-NGs) using a contact–separation structure is reported for the first time. The designed high-performance butterfly wing structure type multiunit system, consisting of four simple arc-shaped H-NGs, has dual functionality as a stand-alone power source for light-emitting diodes and charging Li coin cells and as a self-powered air pressure sensor. Manyfold increments of the open-circuit voltage (<i>V</i>_OC(p–p) = 572 V) and short-circuit current (<i>I</i>_SC(p–p) = 1.752 mA) were observed for H-NG with an irregular surface compared with a piezoelectric nanogenerator (P-NG) (<i>V</i>_OC(p–p) = 53 V, <i>I</i>_SC(p–p) = 2.366 μA). Compared with the power density of a flat surface based H-NG (333 W/m²), the power density of a single arc-shaped H-NG with an irregular surface was 4-fold higher at 1336 W/m², and that with a micropillar surface was twice as high (632 W/m²). A high functional property of fillers along with polydimethylsiloxane matrix improves the surface charge density of the composite film. The surface charge density of the H-NG was greatly influenced by the distance between the active layers, micropores, thickness, relative permittivity, and applied force

Flexible, Hybrid Piezoelectric Film (BaTi_{(1–<i>x</i>)}Zr_<i>x</i>O₃)/PVDF Nanogenerator as a Self-Powered Fluid Velocity Sensor

We demonstrate a flexible piezoelectric nanogenerator (PNG) constructed using a hybrid (or composite) film composed of highly crystalline BaTi_{(1–<i>x</i>)}Zr_<i>x</i>O₃ (<i>x</i> = 0, 0.05, 0.1, 0.15, and 0.2) nanocubes (abbreviated as BTZO) synthesized using a molten-salt process embedded into a poly­(vinylidene fluoride) (PVDF) matrix solution via ultrasonication. The potential of a BTZO/PVDF hybrid film is realized in fabricating eco-friendly devices, active sensors, and flexible nanogenerators to interpret its functionality. Our strategy is based on the incorporation of various Zr⁴⁺ doping ratios into the Ti⁴⁺ site of BaTiO₃ nanocubes to enhance the performance of the PNG. The flexible nanogenerator (BTZO/PVDF) exhibits a high electrical output up to ∼11.9 V and ∼1.35 μA compared to the nanogenerator (BTO/PVDF) output of 7.99 V and 1.01 μA upon the application of cyclic pushing-releasing frequencies with a constant load (11 N). We also demonstrate another exciting application of the PNG as a self-powered sensor to measure different water velocities at an outlet pipe. The average maximum peak power of the PNG varies from 0.2 to 15.8 nW for water velocities ranging from 31.43 to 125.7 m/s during the water ON condition. This study shows the compositional dependence approach, fabrication of nanostructures for energy harvesting, and self-powered devices in the field of monitoring for remote area applications

Self-Induced Gate Dielectric for Graphene Field-Effect Transistor

We report the electronic characteristics of an avant-garde graphene-field-effect transistor (G-FETs) based on ZnO microwire as top-gate electrode with self-induced dielectric layer. Surface-adsorbed oxygen is wrapped up the ZnO microwire to provide high electrostatic gate-channel capacitance. This nonconventional device structure yields an on-current of 175 μA, on/off current ratio of 55, and a device mobility exceeding 1630 cm²/(V s) for holes and 1240 cm²/(V s) for electrons at room temperature. Self-induced gate dielectric process prevents G-FETs from impurity doping and defect formation in graphene lattice and facilitates the lithographic process. Performance degradation of G-FETs can be overcome by this avant-garde device structure

Battery-Free Electronic Smart Toys: A Step toward the Commercialization of Sustainable Triboelectric Nanogenerators

Next-generation toys are designed to entertain and interact with children. Such toys need a power source, generally a battery that must be replaced frequently, leading to increased maintenance costs. Recently, an innovative biomechanical energy harvester called a triboelectric nanogenerator (TENG) was introduced as an eco-friendly generator that scavenges waste energy. Here, in a step toward the commercialization of TENG devices, we present a novel approach that uses TENG technology to develop battery-free electronic smart toys. This robust, eco-friendly, and cost-effective approach for harnessing biomechanical energy can transform a traditional toy into a smart toy. With this innovative idea, we developed a smart clapping toy (SCT-TENG) and a smart duck toy (SDT-TENG) using biocompatible materials. We employed a simple inbuilt circuit with light-emitting diodes that are powered using biomechanical energy. The SCT-TENG and SDT-TENG exhibited output voltages of 65 V_p‑p and 260 V_p‑p, respectively. We believe that the use of TENG technology for battery-free electronic smart toys opens up new possibilities for the commercialization of TENGs and the field of battery-free smart toys

Battery-Free Electronic Smart Toys: A Step toward the Commercialization of Sustainable Triboelectric Nanogenerators

Next-generation toys are designed to entertain and interact with children. Such toys need a power source, generally a battery that must be replaced frequently, leading to increased maintenance costs. Recently, an innovative biomechanical energy harvester called a triboelectric nanogenerator (TENG) was introduced as an eco-friendly generator that scavenges waste energy. Here, in a step toward the commercialization of TENG devices, we present a novel approach that uses TENG technology to develop battery-free electronic smart toys. This robust, eco-friendly, and cost-effective approach for harnessing biomechanical energy can transform a traditional toy into a smart toy. With this innovative idea, we developed a smart clapping toy (SCT-TENG) and a smart duck toy (SDT-TENG) using biocompatible materials. We employed a simple inbuilt circuit with light-emitting diodes that are powered using biomechanical energy. The SCT-TENG and SDT-TENG exhibited output voltages of 65 V_p‑p and 260 V_p‑p, respectively. We believe that the use of TENG technology for battery-free electronic smart toys opens up new possibilities for the commercialization of TENGs and the field of battery-free smart toys

Human Interactive Triboelectric Nanogenerator as a Self-Powered Smart Seat

A lightweight, flexible, cost-effective, and robust, single-electrode-based Smart Seat–Triboelectric Nanogenerator (SS-TENG) is introduced as a promising eco-friendly approach for harvesting energy from the living environment, for use in integrated self-powered systems. An effective method for harvesting biomechanical energy from human motion such as walking, running, and sitting, utilizing widely adaptable everyday contact materials (newspaper, denim, polyethylene covers, and bus cards) is demonstrated. The working mechanism of the SS-TENG is based on the generation and transfer of triboelectric charge carriers between the active layer and user-friendly contact materials. The performance of SS-TENG (52 V and 5.2 μA for a multiunit SS-TENG) is systematically studied and demonstrated in a range of applications including a self-powered passenger seat number indicator and a STOP-indicator using LEDs, using a simple logical circuit. Harvested energy is used as a direct power source to drive 60 blue and green commercially available LEDs and a monochrome LCD. This feasibility study confirms that triboelectric nanogenerators are a suitable technology for energy harvesting from human motion during transportation, which could be used to operate a variety of wireless devices, GPS systems, electronic devices, and other sensors during travel

Sustainable Biomechanical Energy Scavenger toward Self-Reliant Kids’ Interactive Battery-Free Smart Puzzle

Biomechanical energy is a promising renewable energy source and, owing to the demand for portable and smart device power sources, has attracted the attention of researchers in a wide range of disciplines. We present a smart puzzle triboelectric nanogenerator (SP-TENG) based on the contact and separation mode between a surface-modified polydimethylsiloxane film and a paper contact material. The SP-TENG exhibits a simple structure (thin and lightweight), with an output voltage of 70 V and a current of 6.5 μA, which can drive a liquid crystal display at the press of a finger. A systematic investigation of the SP-TENG demonstrated it to be a practical energy harvester with the potential to charge a commercial capacitor and drive a liquid crystal display. The SP-TENG also acts as an instantaneous force sensor with detection sensitivity of 2.605 μA kPa^–1. We fabricated six SP-TENGs as puzzle pieces and formed a self-powered smart puzzle by connecting it to a simple logic circuit. This approach improved a simple traditional puzzle, transforming it into an interactive smart puzzle

Direct In Situ Hybridized Interfacial Quantification to Stimulate Highly Flexile Self-Powered Photodetector

In contrary to the existing externally powered photodetectors, a reliable approach for self-powered photodetection is designed for the first time through an internally integrated concept via coupling of piezotronic with photonic effects. A flexile self-powered photodetector (F-SPPD) developed by one-dimensionally grown floral-like F-ZnO nanorods on a poly­(vinylidene difluoride) substrate conjointly performs the tunability of optical properties through the exploitation of strain-induced piezoelectric potentials (σ⁺, σ^–) at the electrode interfaces. The experimental observation showed an ideal photodetector characteristics with a 1-fold increment in photoresponsivity (<i>R</i>_365nm ∼ 22.76 mA/W) by lowered Schottky barrier heights (Φ_SB1^T, Φ_SB2^T) through externally governed tensile strain (+ε). Further, the self-powered operation mode of F-SPPD exhibited higher spectral sensitivity (5.69 mA/(W cm^–2)) than that of the photodetector (3.47 mA/(W cm^–2)) operated under unstrained condition. This work effectively brings in the direct integration ideology of two different systems into a single module toward the downscaling of device size and weight

Human Interactive Triboelectric Nanogenerator as a Self-Powered Smart Seat

A lightweight, flexible, cost-effective, and robust, single-electrode-based Smart Seat–Triboelectric Nanogenerator (SS-TENG) is introduced as a promising eco-friendly approach for harvesting energy from the living environment, for use in integrated self-powered systems. An effective method for harvesting biomechanical energy from human motion such as walking, running, and sitting, utilizing widely adaptable everyday contact materials (newspaper, denim, polyethylene covers, and bus cards) is demonstrated. The working mechanism of the SS-TENG is based on the generation and transfer of triboelectric charge carriers between the active layer and user-friendly contact materials. The performance of SS-TENG (52 V and 5.2 μA for a multiunit SS-TENG) is systematically studied and demonstrated in a range of applications including a self-powered passenger seat number indicator and a STOP-indicator using LEDs, using a simple logical circuit. Harvested energy is used as a direct power source to drive 60 blue and green commercially available LEDs and a monochrome LCD. This feasibility study confirms that triboelectric nanogenerators are a suitable technology for energy harvesting from human motion during transportation, which could be used to operate a variety of wireless devices, GPS systems, electronic devices, and other sensors during travel