Self-powered Electronic Devices Research Articles

High-output triboelectric nanogenerator based on L-cystine/nylon composite nanofiber for human bio-mechanical energy harvesting

Thanks to the characteristics of lightweight and high-efficiency in low-frequency, triboelectric nanogenerator (TENG) is considered a highly promising technology to effectively harvest human mechanical energy. However, the low output of wearable TENG significantly limits its application in self-powered wearable electronic systems. Herein, we propose a high-output multilayer-structured triboelectric nanogenerator (HM-TENG) fabricated by nylon/L-cystine composite nanofiber film (NCNF), which can efficiently harvest various human bio-mechanical energy. Based on the excellent positive triboelectric performance of L-cystine and the corresponding preparation process research, the fabricated TENG by NCNF with 8 w% L-cystine achieves several times the output performance of TENG with pure nylon nanofiber. Besides, the fabricated HM-TENG obtain a high power density of 11.52 W/m2, which is 5–500 folds higher than previous related research work. Importantly, relied on the designed power management circuit and the installation of a foot mounted HM-TENG, various self-powered wearable electronic devices constructed by harvesting human bio-mechanical energy have been successfully demonstrated. Our research not only provides a novel method for developing high-output TENG but also offers a important solution for the design of self-powered electronic devices.

Humidity-Resistant, Conductive Fabric-Based Triboelectric Nanogenerator for Efficient Energy Harvesting and Human-Machine Interaction Sensing.

With the rapid development of triboelectric nanogenerators (TENGs), the exploration of self-powered, flexible, and wearable electronic devices has attracted widespread attention. However, the choice of tribomaterials and high humidity environment have a significant impact on the triboelectricity of TENG. Therefore, we prepared a composite fabric (HPC) with superhydrophobic and conductive properties, which was used simultaneously as a tribopositive material and electrode for the construction of promising wearable TENGs. Specifically, the loading of polydopamine, carbon nanotubes, and polypyrrole on the surface of the cotton fabric makes it have not only conductivity but also enhanced tribopositive polarity. Then, cetyltrimethoxysilane was selected to modify it to obtain superhydrophobicity. Compared with the common TENGs with a separate tribolayer and electrode, the integrated HPC-TENG shows the advantages of simpler structure and lighter wear. Moreover, compared with the unmodified fabric-based TENG, the performance of the proposed HPC-TENG is improved by nearly 7.2 times, and the maximum power density can reach 2.6 W m-2. This remarkable output can be attributed to the combination of strong electron-giving groups, high electrical conductivity, and abundant micro- and nanorough structure of the HPC fabric. More importantly, due to the water repellency of the fabric surface, the high output performance can be maintained under high humidity conditions. In addition, HPC-TENG has potential applications as pressure sensors for human motion status monitoring and multichannel sensing for smart game blanket entertainment. The newly designed HPC-TENG offers a new strategy for the development of superhydrophobic fabrics with an electrical conductivity, energy harvesting, and self-powered sensor.

Robust integration of energy harvesting with daytime radiative cooling enables wearing thermal comfort self-powered electronic devices

Wearable triboelectric nanogenerators (TENGs) exhibit high flexibility and electric output, and are highly desirable in wearable electronics, soft robotics, and healthcare. Despite significant progress in wearables, achieving versatile integration (e.g. elasticity and permeability) and ensuring thermal comfort when wearing TENGs remain challenging. We mitigate this challenge by fabricating an ultra-stretchable, waterproof, and air/moisture permeable nonwoven textile via the electrospinning of styrene–ethylene–butylene–styrene assisted by electrospraying poly(vinylidene fluoride-co-hexafluoropropylene)/SiO2 to integrate passive radiative cooling technology into the TENG system. The co-deposited PVDF-HFP/SiO2 micro-nanoparticles exhibit excellent triboelectric and radiative cooling performances and can serve as binders and hydrophobic agents. Combining this with the stretchable liquid metal–superlyophilic electrode, our wearable TENG device offers an excellent triboelectric output (114.5 V, 445 mW/m2 under 25 N) that can be used to power small electronics and monitor human movements (e.g. finger tapping and walking). Moreover, the integrated TENG-based radiative cooling textile with high values of Rsolar (83%) and εLWIR (95%) offers cooling by ∼9.5 °C under sunlight as compared with cotton. This study contributes to the development of wearing thermal comfort textile-based TENGs for electricity generation, self-powered sensing, and zero-energy input cooling.

Fabrication of High-Performance Natural Rubber Composites with Enhanced Filler-Rubber Interactions by Stearic Acid-Modified Diatomaceous Earth and Carbon Nanotubes for Mechanical and Energy Harvesting Applications.

Mechanical robustness and high energy efficiency of composite materials are immensely important in modern stretchable, self-powered electronic devices. However, the availability of these materials and their toxicities are challenging factors. This paper presents the mechanical and energy-harvesting performances of low-cost natural rubber composites made of stearic acid-modified diatomaceous earth (mDE) and carbon nanotubes (CNTs). The obtained mechanical properties were significantly better than those of unfilled rubber. Compared to pristine diatomaceous earth, mDE has higher reinforcing efficiencies in terms of mechanical properties because of the effective chemical surface modification by stearic acid and enhanced filler-rubber interactions. The addition of a small amount of CNT as a component in the hybrid filler systems not only improves the mechanical properties but also improves the electrical properties of the rubber composites and has electromechanical sensitivity. For example, the fracture toughness of unfilled rubber (9.74 MJ/m3) can be enhanced by approximately 484% in a composite (56.86 MJ/m3) with 40 phr (per hundred grams of rubber) hybrid filler, whereas the composite showed electrical conductivity. At a similar mechanical load, the energy-harvesting efficiency of the composite containing 57 phr mDE and 3 phr CNT hybrid filler was nearly double that of the only 3 phr CNT-containing composite. The higher energy-harvesting efficiency of the mDE-filled conductive composites may be due to their increased dielectric behaviour. Because of their bio-based materials, rubber composites made by mDE can be considered eco-friendly composites for mechanical and energy harvesting applications and suitable electronic health monitoring devices.

Effect of electrode patterns on piezoelectric energy harvesting property of zinc oxide polyvinylidene fluoride based piezoelectric nanogenerator

Renewable energy generation is one of the key strategies to solve energy shortages and environmental problems. Among various techniques of renewable energy generation and harvesting, piezoelectric energy harvesting receives huge consideration due to the enormous demand in self-powered electronic devices. Therefore, the development of a piezoelectric nanogenerator (PENG) with effective piezoelectric energy harvesting performance is very important. Herein, we develop zinc oxide polyvinylidene fluoride based (ZnO@PVDF PENG) device and study on the effects of electrode patterns on the piezoelectric performances of the device. We also investigate real application of the device in our daily life. The findings show that interdigitated electrode patterned ZnO@PVDF PENG present the highest piezoelectric performance by harvesting output current, voltage, and power density of 1.15 μA, 50 V, and 20.10 mW/m2, respectively at 12 N. The device also scavenges energy that has capacity to light 20 green light emitting diodes (LEDs) and display a liquid crystal display (LCD) timer for 1 s. Moreover, the ZnO@PVDF PENG) device shows excellent cyclic charging and discharging property, which is very important for practical applications. Therefore, this PENG device is promising candidate to harvest green and renewable energy and use to power electronic devices.

High-performance triboelectric nanogenerator based on 2D graphitic carbon nitride for self-powered electronic devices

Triboelectric nanogenerators (TENGs) are a promising technology for harvesting mechanical energy from various sources. In this work, we report on the fabrication and performance of a TENG device using a 2D graphitic carbon nitride (g-C3N4)/silicone hybrid film. The synthesis of g-C3N4 was achieved through a low-cost one-step pyrolysis process using urea as the precursor. The TENG device exhibited a high output voltage ∼ 550 V, current ∼ 110 µA, and a power density of about 4.19 W/m2 when paired g-C3N4/silicone with Kapton. Overall, the TENG device exhibited a multi-fold increment in power density compared to previous g-C3N4-based TENGs.

Uncovering the remarkable electrochemical performance of B2N2 monolayer as a promising candidate for Mg-ion batteries

Nowadays, owing to their potential applications in next-generation self-powered electronic devices, such as energy-harvesting smart garments from body movements and roll-up displays, electrochemical energy storages are enjoying considerable interest. Nonetheless, the development of such technologies has been hindered due to the rarity of high-efficacy electrodes with specific electrochemical performance. Amongst prospective electrodes, researchers have investigated 2D flexible and lightweight materials which have unique physiochemical attributes such as high conductance, high surface metal diffusivity, a hydrophilic surface and mechanical strength. Within this piece of research, a 2D orthorhombic di-boron di-nitride monolayer (o-B2N2ML), which is a boron nitride allotrope, was investigated. Moreover, several determining electronic chemical factors were investigated, such as theoretical capacity, equilibrium voltage and binding strength. Interestingly, the Mg-ion battery had a specific capacity of up to 1125 mAh.g−1. Also, the diffusion of Mg-ions was accelerated due to the presence of a o-B2N2 ring with a diffusion barrier (DB) of 0.26 eV. The low OCV and the low DB of the o-B2N2ML demonstrate that it can be used for practical purposes with long service life and fast rates of charge and discharge. The results also indicated the possible use of the o-B2N2ML as an anode material with high efficiency in MIBs.

Self-strengthening and conductive cellulose composite hydrogel for high sensitivity strain sensor and flexible triboelectric nanogenerator

Triboelectric nanogenerators (TENGs) as promising energy harvesting devices have gained increasing attention. However, the fabrication of TENG simultaneously meets the requirements of green start feedstock, flexible, stretchable, and environmentally friendly remains challenging. Herein, the hydroxyethyl cellulose macromonomer (HECM) simultaneously bearing acrylate and hydroxyl groups was first synthesized and used as a crosslinker to prepare the chemically and physically dual-crosslinked cellulose composite hydrogel for an electrode material of stretchable TENG. Meanwhile, the in-situ polymerization of pyrrole endowed the hydrogel with satisfactory conductivity of 0.40 S/m. More impressively, the synergies of the cellulose rigid skeleton and the construction of the dual-crosslinking network significantly improved the mechanical toughness, and the hydrogel exhibited excellent self-strengthening through cyclic compression mechanical training, the self-strengthening efficiency reached 124.7 % after 10 compression cycles. Given these features, the hydrogel was used as wearable strain sensors with extremely high sensitivity (GF = 3.95) for real-time monitoring human motions. Additionally, the hydrogel showed practical applications in stretchable H-TENG for converting mechanical energy into electric energy to light LEDs and power a digital watch, and in self-powered wearable sensors to distinguish human motions and English letters. This work provided a promising strategy for fabricating sustainable, eco-friendly energy harvesting and self-powered electronic devices.

Experimental feasibility investigation on wearability of cloth-type electronic devices composed of functional polyvinylidene difluoride (PVDF) fibers

In the fabrication of fabric-type electronic devices, especially mobile wearable devices, various electrical functions such as sensing, actuation, and energy harvesting can be realized using complex fibrous electrical components and the associated techniques such as weaving and wiring. This study introduces a hybrid cloth-type electronic device composed of PVDF and ordinary fiber yarns. Moreover, experimental protocols for evaluating the electrical performances of cloth-type electronic devices are used to check the feasibility of the proposed wearable electronic device. The magnitude of the generated voltage signal depending on the weaving pattern and types of functional fibers under impact loading were experimentally investigated, and the most appropriate weaving pattern was suggested. To check the serviceability of the proposed cloth-type wearable device, its performance was tested under various hygrothermal environmental conditions. After conducting several electro-mechanical tests and a washing test, the proposed hybrid cloth-type electronic device was found to have adequate potential for use in self-powered wearable electronic devices.

Highly Sensitive Self-Powered Humidity Sensor Based on a TaS2/Cu2S Heterostructure Driven by a Triboelectric Nanogenerator.

Self-powered humidity sensors with high response and good stability have attracted extensive interest in environmental monitoring, medical and health care, and sentiment detection. Because of its high specific surface area and good conductivity, two-dimensional material has wide application in the field of humidity sensing. In this work, we proposed a novel self-powered high-performance TaS2/Cu2S heterostructure-based humidity sensor driven by a triboelectric nanogenerator (TENG) made with the same structure. The TaS2/Cu2S heterostructure was prepared via the chemical vapor deposition method, and then, electrolytic and ultrasound treatments were introduced to further increase the surface area. The fabricated humidity sensor showed ultrahigh sensitivity (S = 3.08 × 104), fast response (2 s), low hysteresis (3.5%), and great stability. First-principles calculation results demonstrated the existence of an electron transport channel with a low energy barrier (-0.156 eV) from the Cu2S to TaS2 layer in the heterostructure, which improves the surface charge transfer of the material. The TaS2/Cu2S heterojunction-based TENG can generate an output voltage of 30 V and an output current of 2.9 μA. Furthermore, the proposed self-powered humidity sensor verified the potential ability of detecting human respiratory frequency, skin humidity, and environmental humidity. This work provides a new and feasible path for research in the field of humidity sensors and promotes the application development of self-powered electronic devices.

Nonlinear Dynamics and Energy Harvesting of a Two-Degrees-of-Freedom Electromagnetic Energy Harvester near the Primary and Secondary Resonances

Energy harvesting is a useful technique for various kinds of self-powered electronic devices and systems as well as Internet of Things technology. This study presents a two-degrees-of-freedom (2DOF) electromagnetic energy harvester that can use environment vibration and provide energy for small electronic devices. The proposed harvester consists of a cylindrical tube with two moving magnets suspended by a magnetic spring mechanism and a stationary coil. In order to verify the theoretical model, a prototype electromagnetic harvester was constructed and tested. The influence of key parameters, including excitation acceleration, response to a harmonic frequency sweep, and electromechanical coupling on the generated characteristics of the harvester, was investigated. The experimental and theoretical results showed that the proposed electromagnetic energy harvester was able to increase the resonance bandwidth (60–1200 rad/s) and output power (0.2 W). However, due to strong nonlinearity, an unstable region occurred near the main first resonance, which resulted from the Neimark–Sacker bifurcation.

Piezoelectric power generation using vibrations from human heart

In past decades, energy harvesting using piezoelectric materials has offered various opportunities towards implementing self-powered electronic devices. In the direction of wearable devices, this paper is mainly focused towards charging the pacemaker device from human heart vibration using piezoelectric energy harvesting (PEH) technique. Here, a fan-folded piezoelectric energy harvesting (FF-PEH) device has been investigated to meet with the basic power requirement of pacemaker device. Initially, a simulation study has been conducted to observe the voltage-power-frequency response of FF-PEH using COMSOL Multiphysics version 5.4. Further, the behavior of FF-PEH has been optimized for variation in different materials used. It has been observed that by choosing PZT-5H, silicon and platinum as piezoelectric, substrate and rigid beam materials respectively, the FF-PEH device is capable to provide 10.19 μW power at 20 Hz resonant frequency.

High power density energy harvesting and human motion monitoring with [trimethylchloromethyl ammonium][CdCl3]/polymer composite

•High power density energy harvesting with hybrid perovskite composites •Hybrid perovskite piezoelectric sensors are able to monitor delicate human motions •Interfacial molecular interactions between the hybrid perovskite and polymer Piezoelectric hybrid organic-inorganic perovskites (HOIPs) have emerged as promising materials for the development of self-powered electronic devices. These hybrid systems generally have low elastic moduli and are also intrinsically brittle, limiting their applications in mechanical-to-electrical energy conversion. Here, we report the synthesis of TMCM-CdCl3/PDMS (TMCM, trimethylchloromethyl ammonium; Cl, chloride; PDMS, polydimethylsiloxane) composites with high piezoelectricity. The TMCM-CdCl3 micro-rods can adhere with PDMS chains via the C–H···Cl interactions, leading to effective absorption of strain and corresponding efficient conversion to electric polarization. As a result, the energy harvesting devices made by the composite films give a high power density up to 115.2 μW/cm2, catching up with those of the state-of-the-art ceramic counterparts. In addition, the composite devices can harvest human motion energy and sense delicate body gestures. This work demonstrates that the piezoelectric HOIP/polymer composites can serve as promising materials for the development of self-powered flexible and wearable devices. Piezoelectric hybrid organic-inorganic perovskites (HOIPs) have emerged as promising materials for the development of self-powered electronic devices. These hybrid systems generally have low elastic moduli and are also intrinsically brittle, limiting their applications in mechanical-to-electrical energy conversion. Here, we report the synthesis of TMCM-CdCl3/PDMS (TMCM, trimethylchloromethyl ammonium; Cl, chloride; PDMS, polydimethylsiloxane) composites with high piezoelectricity. The TMCM-CdCl3 micro-rods can adhere with PDMS chains via the C–H···Cl interactions, leading to effective absorption of strain and corresponding efficient conversion to electric polarization. As a result, the energy harvesting devices made by the composite films give a high power density up to 115.2 μW/cm2, catching up with those of the state-of-the-art ceramic counterparts. In addition, the composite devices can harvest human motion energy and sense delicate body gestures. This work demonstrates that the piezoelectric HOIP/polymer composites can serve as promising materials for the development of self-powered flexible and wearable devices.

Optimal Design of Wearable Micro Thermoelectric Generator Working in a Height-Confined Space

With the increasing development of self-powered wearable electronic devices, there is a growing interest in thermoelectric generators (TEGs). To achieve more comprehensive and reliable functionality of wearable devices, improving the power generation performance of thermoelectric devices will be the key. It has been shown that integrating a heat sink at the cold end of the TEG increases the effective temperature difference and, thus, maximizes the power output of the thermoelectric device. However, the space left for the power supply is often limited. How to optimize the integrated system of micro-thermoelectric generators and heat sinks in a height-confined space has become the key. In this study, we have established a corresponding model using a numerical calculation method, systematically studied the influence of TEG geometric size on the number of fins and fin height, and determined the optimal number of fins for the highest equivalent convective heat transfer coefficient corresponding to different fin heights. We also conducted the co-design of TEG and fin topological structure to study the effects of the ratio of leg height to fin height (l/H), the width of legs (w), and the number of thermoelectric leg pairs (N) on the maximum output power density per unit area (Pm1) and the maximum output power density per unit mass (Pm2) of the device. When N = 16, w = 0.3 mm, l/H = 2.5 (that is, l = 3.57 mm, H = 1.43 mm), and Pm1 reaches the maximum value of 30.5 μW/cm2; When N = 2, l/H = 0.25 and w = 0.3 mm, and Pm2 reaches a maximum value of 5.12 mW/g. The measured values of the open-circuit voltages of fabricated micro-TEGs with different thermoelectric leg heights (l = 0.49 mm, l = 1.38 mm, and l = 1.88 mm) are basically consistent with the simulated values. When N = 2, l = 0.49 mm, H = 3.74 mm, and w = 0.85 mm, and Pm2 reaches 0.44 mW/g. The results provide insights into the optimal design of wearable micro thermoelectric generator working in a height-confined space and highlight the importance of co-designing TEGs and fin topological structures for optimizing their performance.

Development of an enhanced hybrid bi-catalytic electrode containing bimetallic composite catalyst and immobilized enzyme for complete glucose electrooxidation

We describe an enzymatic fuel cell (EFC) that can electrooxidize glucose completely. The EFC contains the hybrid Ni@Pt-CNT/OxOx bioanode, composed of a bimetallic composite catalyst (Ni@Pt-CNT) and the enzyme oxalate oxidase (OxOx), which can cleave carbon-carbon bonds. Ni@Pt-CNT/OxOx displayed 3-fold higher catalytic activity in the presence than in the absence of glucose (1.3 and 0.4 mA cm−2, respectively), indicating that Ni@Pt-CNT and OxOx acted synergistically. Electrochemical impedance spectroscopy showed that Ni@Pt-CNT/OxOx had higher charge transfer resistance and double layer capacitance than Ni@Pt-CNT. Long-term bulk electrolysis (18 h) revealed that the EFC operating with Ni@Pt-CNT/OxOx presented better current density and stability than the electrochemical cell operating with Ni@Pt-CNT, so deep glucose electrooxidation generated energy. The glucose oxidation products detected by HPLC-UV/RID confirmed that glucose was fully electrooxidized, and that 24 electrons were harvested from it. The hybrid Ni@Pt-CNT/OxOx bioanode developed herein could be used in cascade reactions, to provide an EFC with promising application in self-powered electronic devices.

Current Achievements in Flexible Piezoelectric Nanogenerators Based on Barium Titanate

Harvesting ambient mechanical energy at the nanometric scale holds great promise for powering small electronics and achieving self-powered electronic devices. The current review is focused on kinetic energy harvesters, particularly on flexible piezoelectric nanogenerators (p-NGs) based on barium titanate (BaTiO3) nanomaterials. p-NGs based on nanotubes, nanowires, nanofibres, nanoplatelets, nanocubes or nanoparticles of BaTiO3 fabricated in vertical or lateral orientation, as well as mixed composite structures, are overviewed here. The achievable power output level is shown to depend on the fabrication method, processing parameters and potential application conditions. Therefore, the most widely studied aspects, such as influence of geometry/orientation, BaTiO3 content, poling process and other factors in the output performance of p-NGs, are discussed. The current standing of BaTiO3-based p-NGs as possible candidates for various applications is summarized, and the issues that need to be addressed for realization of practical piezoelectric energy harvesting devices are discussed.

A comparative study on rigid and flexible magnetoelectric composites: Review

This review reports the latest trends in the ceramic composite matrix used for the magnetoelectric (ME) effect. In the last few years, ME composite has become the center of attraction for use in various electrically and magnetically coupled devices. The growth and use of electronic components everywhere have propulsively accelerated the exploration of self-powered electronic and sensor network devices. ME is a feasible technique for addressing difficulties of traditional batteries such as short life span and frequent recharge difficulties. Self-charging multiferroic components have been found for the constant working of mobile electronics that use multiferroic composites in response to magnetoelectric energy transformation. Researchers have rigorously studied the rigid and flexible magnetoelectric composites for their suitability in applications. This paper gives a comparative study between rigid and flexible magnetoelectric composites based on their properties and provides knowledge about the materials for such types of composites. It reviews the latest polymer-based ME materials as well as the related fabrication and polarization methods. The review finally encapsulates the applications in biomedicine, ranging from mechanical energy harvesters to sensors and actuators.

Heat-Driven Iontronic Nanotransistors.

Thermoelectric polyelectrolytes are emerging as ideal material platform for self-powered bio-compatible electronic devices and sensors. However, despite the nanoscale nature of the ionic thermodiffusion processes underlying thermoelectric efficiency boost in polyelectrolytes, to date no evidence for direct probing of ionic diffusion on its relevant length and time scale has been reported. This gap is bridged by developing heat-driven hybrid nanotransistors based on InAs nanowires embedded in thermally biased Na+ -functionalized (poly)ethyleneoxide, where the semiconducting nanostructure acts as a nanoscale probe sensitive to the local arrangement of the ionic species. The impact of ionic thermoelectric gating on the nanodevice electrical response is addressed, investigating the effect of device architecture, bias configuration and frequency of the heat stimulus, and inferring optimal conditions for the heat-driven nanotransistor operation. Microscopic quantities of the polyelectrolyte such as the ionic diffusion coefficient are extracted from the analysis of hysteretic behaviors rising in the nanodevices. The reported experimental platform enables simultaneously the ionic thermodiffusion and nanoscale resolution, providing a framework for direct estimation of polyelectrolytes microscopic parameters. This may open new routes for heat-driven nanoelectronic applications and boost the rational design of next-generation polymer-based thermoelectricmaterials.

First study on harvesting electromagnetic noise energy generated by the frequency converters

This paper proposes a novel environmental energy harvesting process. The source of energy consists of the electromagnetic (EM) noise emitted by the frequency converter system (inverter) and the harvester is composed by a monopole antenna and a full rectifier circuit. The operation of the frequency converter using MOSFET and IGBT switchers produces parasite currents in high frequency (100 KHz to 30 MHz) which are the principal cause of radiated EM noise. We have demonstrated that we can convert this EM noise into useful electrical energy to power wireless sensor nodes (WSNs) and other electronic devices. Experimentally, the EM noise is produced when the system “frequency converter + charge” is in operation mode. Moreover, the harvester has produced an uninterrupted power of 40 mW measured in accredited ISO/IEC 17025 laboratory. Furthermore, we have presented the output power of our device stored in 1 µF capacitor with demonstration examples of loading charges. These results offer opportunities for self-powered WSNs and electronic devices on a very large area of industrial applications with less use of conventional batteries.

Effects of Co-Solvent-Induced Self-Assembled Graphene-PVDF Composite Film on Piezoelectric Application

A persistent purpose for self-powered and wearable electronic devices is the fabrication of graphene-PVDF piezoelectric nanogenerators with various co-solvents that could provide enhanced levels of durability and stability while generating a higher output. This study resulted in a piezoelectric nanogenerator based on a composite film composed of graphene, and poly (vinylidene fluoride) (PVDF) as a flexible polymer matrix that delivers high performance, flexibility, and cost-effectiveness. By adjusting the co-solvent in the solution, a graphene-PVDF piezoelectric nanogenerator can be created (acetone, THF, water, and EtOH). The solution becomes less viscous and is more diluted the more significant the concentration of co-solvents, such as acetone, THF, and EtOH. Additionally, when the density is low, the thickness will be thinner. The final film thickness for all is ~25 µm. Furthermore, the- crystal phase becomes more apparent when graphene is added and combined with the four co-solvents. Based on the XRD results, the peak changes to the right, which can be inferred to be more dominant with the β-phase. THF is the co-solvent with the highest piezoelectric output among other co-solvents. Most of the output voltages produced are 0.071 V and are more significant than the rest.