Centrifugal Spinning of Conductive Filler-Enhanced PVDF Nanofibers for Energy Harvesting and Sensing Applications

Centrifugal Spinning of Conductive Filler-Enhanced PVDF Nanofibers for Energy Harvesting and Sensing Applications | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Centrifugal Spinning of Conductive Filler-Enhanced PVDF Nanofibers for Energy Harvesting and Sensing Applications MANIKANDAN G K, JEYANTHI S This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7710086/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Graphical Abstract Abstract Centrifugal spinning is a very rapid and scalable method for generating PVDF nanofibers, especially if the nanofibers are doped with conductive fillers (like MWCNT, GO and PANI), that enhance the piezoelectric and electrical properties of PVDF, and that allow these composites to use in energy harvesting and sensing applications. In this study, a solvent combination of DMF and acetone was used to prepare a homogeneous PVDF solution which was spun at 7000–7500 RPM; the increased β-phase content was desired to maximize piezoelectric activity in the polymer. Characterization techniques including SEM, FTIR and XRD showed that there was a uniform fiber formation and strong β-phase content in the fibers, which indicated good dispersion of the fillers. The pristine PVDF electrical conductivity was also tested, which was at 3.6 × 10⁻⁶ S/cm, compared to the 1.667 × 10⁻⁴ S/cm with fillers. Acoustic tests on the composites indicated that the PVDF/MWCNT composite produced the highest voltage output, confirming better sensing performance in this composite. Overall, results indicate that centrifugal spinning fabrication of flexible, self-powered sensing materials is a valid and promising option. Physical sciences/Energy science and technology Physical sciences/Engineering Physical sciences/Materials science Physical sciences/Nanoscience and technology PVDF Nanofibers Centrifugal Spinning Piezoelectric Nanogenerators Energy Harvesting Triboelectric Devices Wearable Sensors Biomedical Applications Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction This study investigates PVDF nanofiber webs produced through electrospinning as polymer membranes, emphasizing their piezoelectric properties and use as energy harvesting and sensing devices. The research demonstrates the influence of fiber shape and crystallinity on the materials performance, and therefore the importance of fiber (shape and crystallinity) in maximizing the efficacy of these nanofiber membranes [ 1 ]. PVDF nanofibers based flexible touch sensors are gaining popularity for wearable applications based on their piezoelectric characteristics and flexibility. Recent developments have even been dedicated to enhance sensitivity and overall performance through various new fabrication techniques like electro spinning and blow spinning; this allows these sensors to be integrated with more diverse health-wellness monitoring systems and interactive devices [ 2 ]. This study optimizes the electrospinning conditions to enhance the piezoelectric properties of PVDF nanofibers. More specifically, the study investigates how voltage, flow rate and polymer concentration influence the β-phase formation within the fibers, and the morphology. Ultimately, the goal is to enhance the functional performance of the nanofibers for various applications, through tuning of the electro spinning conditions [ 3 ]. The article examines the advancements piezoelectric PVDF (polyvinylidene difluoride) nanofibers and their pivotal applications, structural characteristics, and production methods. It examined the advancements made previously to improve the piezoelectric performance of the PVDF nanofibers, which are typically used in sensing and energy harvesting applications. In addition, there was depth exploration into new processing technologies and novel material modifications which show promise for different areas of technology and usage of PVDF nanofibers [ 4 ]. PVDF nanofibers can be used to make pliable and sensitive flow sensors because they have excellent piezoelectric properties, mechanical flexibility, and biocompatibility. These properties allow for responsive sensors, meaning they can accurately track the fluid dynamics in biomedical and industrial applications [ 5 ]. In this study the development and characterization of electrospun PVDF nanofibers for piezoelectric applications. The study examines processing parameters that influence the morphology of the as-spun fibers and degree of β-phase as well as their use in energy harvesting and sensing applications. The goal of the study is to connect processing parameters with the resulting properties of the nanofibers and offer the potential to harness these nanofibers into engineered structures and applications [ 6 ]. Flexible capacitive sensors utilizing electrospun PVDF nanofibers exhibit varying performance based on nanofiber shape, which influences sensitivity and durability. Research highlights the importance of fiber morphology in optimizing sensor characteristics for applications in wearable technology and tactile sensing. [ 7 ]. PVDF-MWCNT nanofibers produced through near-field electrospinning demonstrate enhanced piezoelectric properties due to their β-phase composition. These characteristics make them suitable for energy harvesting applications, as studies indicate improved electrical performance and potential for self-powered devices[ 8 ].This work investigates the impact of multi-walled carbon nanotubes (MWCNT) content on the mechanical and piezoelectric characteristics of PVDF nanofibers. It emphasizes how varying MWCNT concentrations influence tensile strength, β-phase development and overall piezoelectric performance. The findings aim to provide insights into optimizing the composite material for enhanced functionality in various applications[ 9 ]. This research explores the mechanical and electrical characteristics of PVDF-based nanofibers to better understand their potential for energy harvesting and sensing applications. It addresses the effects of material composition and production conditions on the performance properties of the nanofibers, aiming to identify optimal parameters that enhance their functionality in various technological applications [ 10 ]. This work examines the mechanical and dielectric characteristics of aligned PVDF nanofibers, focusing on their potential applications in energy storage and sensing. It evaluates the effects of fiber alignment on polarization, structural characteristics and overall performance highlighting how alignment can enhance the functional properties of the nanofibers for improved efficiency in energy-related applications[ 11 ]. This dissertation discusses the exceptional qualities of PVDF-based nanofibers, with particular attention to their mechanical strength, piezoelectric response and potential applications. It emphasizes the impact of changes in fabrication methods and material modifications aimed at enhancing energy harvesting and sensing capabilities. The findings aim to provide a comprehensive understanding of how these factors contribute to the performance and applicability of PVDF nanofibers in advanced technologies[ 12 ]. The structural, mechanical and electrical features of carbon fibers are the main topics of this paper presentation of a wet-spinning method. It draws attention to the benefits of this process for producing high-performance carbon fibers for cutting-edge uses[ 13 ]. The current inquiry investigates how to optimize the structural and electrical characteristics of electrospun PVDF-MWCNT-based nanogenerators in order to increase power production. It draws attention to how MWCNT dispersion and processing parameters might increase the efficiency of piezoelectric energy harvesting[ 14 ]. Although there are many uses for nanofibers, the efficiency and scalability of conventional production techniques are problematic. One quick and affordable method for producing nanofibers on a big scale is centrifugal spinning [ 15 ]. This study shows that SIBS fibers made by centrifugal spinning were smoother and produced much faster than those made by electrospinning. The fibers were highly water-repellent and could easily absorb oil, making them useful for separating oil from water[ 16 ]. Piezoelectric, electromagnetic, metamaterial, and resonator-based processes are used in acoustic energy harvesting to transform sound or noise into electrical energy that can be used. Acoustic metamaterials are a promising option for effective energy conversion and noise reduction in small-scale electronic applications, according to recent developments[ 17 ]. Applications in energy harvesting, sensing, and noise monitoring are made possible by nanogenerators' ability to capture acoustic energy from vibrations or sound waves. Their performance and versatility are greatly enhanced when combined with AI and ML, opening the door for intelligent, self-powered acoustic devices[ 18 ]. An intelligent self-powered sound-sensing element (ISSE) with improved piezoelectric output can be developed thanks to three-dimensional near-field electrospun PVDF nano-microfiber architectures. With its ability to capture sound energy and identify throat vibrations, this incredibly thin and inexpensive gadget has potential uses in implantable technologies, wearable electronics, and voice control[ 19 ]. In this study, electrospun PVDF nanofiber membranes are introduced as acoustic sensing devices that convert sound waves into frequency-and amplitude-dependent electrical outputs. Their piezoelectric performance is demonstrated in the study, which also emphasizes their potential as an inexpensive way to capture acoustic energy from various sound sources[ 20 ]. For discrete speech sensing, a mask-integrated triboelectric nanogenerator (CS-TENG) is created, which transforms airflow vibrations into electrical signals for precise speech and identity recognition. The system's over 90% accuracy, which is attained through sophisticated signal processing and deep learning, allows for safe, discrete communication in peaceful settings[ 21 ]. Self-polarized PVDF nanofibers with a high β-phase content and improved piezoelectric response are produced using a simple centrifugal spinning technique. Centrifugal spinning is a promising path for scalable, high-efficiency energy harvesting devices, as demonstrated by the exceptional output performance of the resulting flexible nanogenerator[ 22 ]. The creation of one-dimensional nanostructures from polymers, ceramics, and composites with core-sheath, hollow, and porous architectures has been made possible by recent developments in electrospinning. The goal of these advancements is to improve fiber performance, functionality, and uniformity for a range of device applications[ 23 ]. Recent developments in centrifugal spinning are highlighted in this review, with particular attention paid to the structures, characteristics, and functionality of centrifugally spun fibers for uses in drug delivery, energy storage, and filtering. In order to improve this adaptable fiber fabrication method, it also addresses present issues and potential research avenues[ 24 ]. This work describes the electrospinning process used to create PEG/GO composite phase-change fibers, which resulted in improved stability, phase-change performance, and thermal conductivity. Excellent thermal regulation, dependability, and shape stability are demonstrated by the optimized fibers containing 0.5 weight percent GO, which qualifies them for sophisticated thermo-regulated applications[ 25 ]. A high-throughput, safer substitute for electrospinning in the creation of phase-change composite fibers is centrifugal spinning. This process yields PVP/PEG fibers with outstanding thermal characteristics and stable fibrous morphology, showing great promise for real-world uses[ 26 ]. Centrifugal spinning, with spinning parameters optimized for fiber quality, was used to create hollow FeO₃ ultra-fine fibers, which were then calcined. SEM, XRD, TGA, FT-IR, and XPS analyses of the resultant fibers revealed tunable diameters and morphology that were impacted by spinneret size and rotational speed[ 27 ]. Using an ethanol–water binary solvent system, porous EC/PVP fibers were created by centrifugal spinning; rheological characteristics and solvent ratios had a significant impact on pore formation. Centrifugal spinning allowed for much larger surface area fibers than electrospinning, demonstrating the method's influence on fiber morphology[ 28 ]. Methods and materials In order to produce a homogenous PVDF solution by using DMF and acetone as the solvent the content temperature and stirring conditions must be accurately maintained, as shown in Fig. 1 . Although DMF is a high-boiling solvent that gives an efficient solution to PVDF, it retains the relatively low boiling acetone, which lowers the total viscosity of the solution and subsequently gives more fiber. The optimum solubility will generally use either DMF: Acetone 6:4 or 7:3 to get the highest solubility. After determining the correct solvent amount, the first step in the procedure is to accurately weigh 12–20 weight percent of PVDF according to the total volume of solvent. Once the weight has been calculated, the PVDF is then incrementally added to DMF-acetone with stirring at 50–60°C with a magnetic stirrer and speed adjustment (usually around 300–500 rpm). The unit is agitated for four hours to ensure that the polymer is completely dissolved, and a homogenous solution is achieved as shown in Fig. 2.2. The prolonged stirring time provides a stable solution because the stirring allows for the polymer chains to completely disperse, eliminating the phase separation. Temperature accuracy is important to maintain since too high temperatures could damage the PVDF or too little heat could slightly disintegrate the polymer. After stirring, the solution is settled and agitated for one to two hours to allow for any air bubbles to escape before the solution is eventually processed. In centrifugal spinning methods, it's important to use well-prepared homogeneous PVDF solutions, because it aids in fiber production, ensures better fiber shape consistency, and results in improved mechanical properties in the product. Preparation of homogeneous solutions is critical to delivering quality nanofibers that will be used in other applications. Always store a well-prepared solution in a sealed container to maintain solution stability, reduce evaporation and as a best practice to maintain the integrity of the solution, it will ensure consistent processing and performance of the nanofibers produced as shown in Fig. 2.4 Centrifugal spinning machine involves placing a polymer solution within a rapidly spinning head (7000 to 7500 rpm) and due to centrifugal forces, the solution will be dispensed through small nozzles and stretched into fibers. These fibers will solidify as the solvent evaporates and will be collected into either a stationary or spinning collector as shown in Fig. 2.3. This process allows for large-scale production of nanofibers in a relatively fast and efficient manner for a variety of different uses. Table 1 PVDF with filler percentage for various properties Sample Filler (%) Mechanical Strength (MPa) Thermal Stability (°C) Morphology / Structure PVDF (Pure) 0% 25–35 ~ 420 Smooth, uniform nanofibers or films PVDF / MWCNT 20% 45–60 ~ 460 Fibers with embedded nanotubes, increased roughness PVDF / Graphene 20% 40–55 ~ 470 Layered flakes, enhanced surface area PVDF / Polyaniline 20% 35–50 ~ 440 Rougher texture, some agglomeration if poorly mixed This approach successfully generates nanofibers with tailored diameter, allowing for further optimization through processing parameters such as temperature, solution viscosity, and rotational speed. PVDF nanofibers from centrifugal spinning have excellent piezoelectric properties, mainly attributed to their phase change from α-phase to β-phase polymer during the spinning process. Mechanical, thermal, and piezoelectric characteristics of the PVDF nanofibers can be improved by controlling polymer chain alignment during spinning and by adding additives such as carbon nanotubes (CNTs),polyaniline(PANI),graphene oxide(GO) as shown in Table 1. Centrifugal spinning can be used to produce PVDF nanofibers for much larger scale fabrication enabling their use as possible electronic and energy harvesting components in applications such as wearable electronics and sensors. Characterization Methods Scanning Electron Microscopy (SEM) Examining fibers via scanning electron microscopy (SEM) produces complete information regarding their shape characteristics/ morphology that aids in evaluating the performance and quality of fibers for different applications. With SEM images, we may examine very important characteristics consisting of fiber homogeneity, smoothness of the surface, and fiber defects including beads or irregularities. Furthermore, with image analysis, we can accurately compute the average fiber diameter as well as its distribution. This will generally include making several measures, enough to make those statistics statistically meaningful, so that we can adequately assess relevant fiber characteristics, information that is important for developing the manufacturing process and property characteristics of nanofibers for applications such as filtration, tissue engineering and energy harvesting. The appearance of beads in nanofibers suggests unstable spinning conditions or inappropriate solution characteristics, while well-formed nanofibers exhibit a uniform and smooth appearance. Scanning electron microscopy (SEM) examination also reveals fiber alignment, which is crucial for applications that require directional properties, such as sensors and actuators. If a sample also showed surface roughness and porosity, it could indicate the use of fillers and/or rapid solvent evaporation during the spinning process. These parameters could have a significant effect on the mechanical and functional properties of the nanofibers. Ensuring the variables in spinning conditions and solution formulation can help develop samples with the desired features for specific applications. Ultimately, scanning electronic microscopy (SEM) is an important method that allows a researcher to explore the integrity, consistency, and quality of their nanofibers. It can assist in the process of controlling conditions for advanced materials, as noted in the discussion above. SEM provides a wealth of data that allows a researcher to explore the morphology of their samples in way that assists with optimizing processing variables. Scanning electronic microscopy allows detailed studies into defects, measuring fiber diameter, and inspecting the surface features that allows detailed fiber characterization in numerous applications in areas of filtration, energy harvesting, and medical-based engineering. Illustrate the SEM micrographs of the morphological properties of PVDF nanofibers with and without powder created under controlled spinning conditions. The results include nanofibers of PVDF with graphene oxide (Fig. 3 a), multi-walled carbon nanotubes (MWCNT) (Fig. 3 b) and polyaniline (Fig. 3 e), alongside pristine PVDF effects of nanofibers (Fig. 3 d) and untreated PVDF powder (Fig. 3 c). All samples were made by centrifugal spinning at a speed of 7500 rpm, with a collecting distance of 15cm, using a spinneret diameter of 0.11 mm the spinning solvents were DMF and acetone, to ensure a homogenous solution and standard morphologies of fibers. The addition of conductive fillers, such as Graphene oxide, MWCNT, and polyaniline, greatly modifies the structure of the fiber, leading to a fiber with an improved fiber uniformity and may lead to improved piezoelectric and electrical properties of the PVDF nanofibers as well. The observed morphology of these nanofibers demonstrates that they also include nanofillers inside the PVDF matrix. It also indicated that the performance or aspects of the nanofibers are ideally suited to make advanced flexible devices for energy harvesting and sensing. Fourier Transform Infrared Spectroscopy (FTIR) Fourier Transform Infrared Spectroscopy (FTIR) is a widely utilized analytical process used for determining and validating the chemical structure and the functional groups present in objects. The tested FTIR uses an infrared light source in which its light beam is directed through a sample while recording the spectral absorption wavelengths to produce a spectrum based on molecular vibration. Each peak on this spectrum represents a functional group or persons or bond present in the spectrum. Examples of use FTIR is very effective in determining phase structures (i.e. β-phase in PVDF) or composition, and it enables determination of polymer architecture and the presence or interactions with various additives or fillers in nanofibers. Texture is moderately rapid, very accurate and non-destructive, FTIR plays a tremendous role in characterizing materials and ensuring quality and performance in applications in nanofibers. X-ray diffraction (XRD) X-ray diffraction (XRD) analysis was conducted to examine the crystalline structure of the prepared nanofibers. The peaks in the diffraction patterns indicated that the prepared materials had a semi-crystalline structure with intense and sharp peaks. The prepared nanofibers made from PVDF indicated the presence of the necessary electroactive crystalline structure corresponding to the β-phase with the sharp diffraction peak around 2θ = 20.3°. In addition, there were diffraction peaks at 18.4° and 26.6° respectively indicating the α-phase and γ-phase. The crystalline peaks intensity and sharpness indicated good crystalline quality which was required for the nanofiber performance as energy harvester materials. The absence of any impurities in the diffraction analysis indicated that the fillers had consistently been included and their structure had been maintained, thus meeting the basic structural qualifications required for energy harvesting applications. Thus, the structural integrity of the PVDF-based nanofibers is an important factor in maintaining the functional outcomes in diverse applications in advanced materials engineering. Result and Discussion 1. FTIR Spectroscopy Fourier Transform Infrared (FTIR) spectroscopy is a great tool for studying a wide variety of PVDF-based materials, particularly in discovery of functional groups and characterization of molecular interactions in polymer composites. On an FTIR spectrum, the y-axis is transmittance (%) or the percentage of infrared light that goes through the sample, while the x-axis is wavenumber in cm⁻¹ , or the relationship to the vibrational frequencies of molecular bonds. Each peak is attributed to specific functional groups or molecular vibrations and is an important piece of information pertaining to the chemical composition of the material and interactions within the material. This, in turn, is valuable when tuning the characteristics of the PVDF-based composites with the end goal is to create functional devices for energy in harvesting, sensor applications, etc. For this analysis five separate samples are looked at; PVDF/GO (graphene oxide), PVDF/MWCNT (multi-walled carbon nanotubes), pure PVDF, PVDF/polyaniline and PVDF powder. The FTIR spectrum reported for these samples show that there are indicative absorption peaks in the PVDF materials that are consistent with the polymer's crystalline phases. For example, the absorption peaks 840–880 cm⁻¹ are generally described by the β-phase of PVDF while absorption peaks 1170–1280 cm⁻¹, can generally be described by the α-phase of PVDF. The characteristic peaks that exist in all samples suggest that the intrinsic structural characteristics of PVDF have not been lost with the addition of various additives (i.e., graphene oxide, multi-walled carbon nanotubes, or polyaniline) as shown in Fig 11. This information can be useful for determining the relevant interactions and therefore the possible physical property enhancements related to PVDF based composites for a variety of applications. The FTIR spectrum of the pure PVDF powder sample (green) shows very pronounced, sharp peaks showing congruency with the high purity and crystalline nature of the material. In contrast, the nanofibrous PVDF samples including fillers, show peaks that are broadened and in some cases shifted. This implies that the centrifugal spinning process as well as the addition of various nanofillers has affected the crystallinity of the material and the nature of the molecular structure of PVDF rather than simply adding mass. The broadened and shifted behavior of the FTIR peak in the nanofibrous samples may indicate a loss of crystallinity or possibly new molecular interactions based off the starting materials that include filler materials. These changes can greatly affect the mechanical strength, thermal stability and electrical conductivity properties of the material, therefore it is important to understand in what consistent ways they can affect these properties which will enable us to gain greater effective performance from PVDF-based composites in a range of applications. The changes in the peak position and intensity for both PVDF/GO and PVDF/MWCNT samples can attributed to their interaction with the PVDF matrix. PVDF/GO exhibited relatively rounded broad peaks and low intensity while PVDF/MWCNT exhibit sharper and high intensity peaks suggesting enhanced compatibility and improved crystallinity from the MWCNTs. The successful insert of polyaniline into the matrix of PVDF as a physically entangled structure can be confirmed by the appearance of new absorption bands in the region 1500–1600 cm⁻¹. This indicated an aromatic C=C stretching vibration consistent with polyaniline this observation indicates a well-defined interaction between polyaniline and PVDF matrix. Overall, the Fig 4 indicates that the presence of a range of nanomaterials has a significant effect of the molecular structure and chemical environment of PVDF. Such changes are important for improving functional characteristics of PVDF based nanofibers for applications in flexible electronics, energy harvesting and sensor technologies. The ability to tailor the properties of these nanofibers through the incorporation of different nanofillers opens up new possibilities for advanced material design and application. 2.XRD Analysis The X-ray diffraction (XRD) patterns for the multiple samples of pure PVDF, PVDF powder and PVDF composites containing graphene (GR), polyaniline (PANI) and multi-walled carbon nanotubes (MWCNT) as fillers show the crystalline structure of the materials. XRD is an analytical technique that determines the crystalline structure using diffraction of X-rays incident on a sample. The XRD patterns are composed of a y-axis presenting relative intensity in arbitrary units (a.u.), which indicates the level of crystallinity, and an x-axis showing the angle of diffraction (2θ) in degrees. The peaks in the XRD patterns represent the crystalline phases of the pure PVDF, PVDF powder, and PVDF composites. The peaks can be examined for shape and intensity and correlated with crystallinity. The use of fillers such as GR, PANI and MWCNT could produce changes in peak locations and intensities, indicating changes in the crystalline structures and interactions in the PVDF matrix. This information is crucial for understanding how these modifications affect the overall properties and performance of PVDF-based composites in various applications. Different diffraction peaks demonstrating the existence of crystalline phases in each sample are visible on the graph. Known for its strong piezoelectric performance, the uppermost curve PVDF(1), has a broad peak centered at 20°. This corresponds to the typical (110)/(200) planes of the β-phase of PVDF. A peak at almost the same location is also seen in the sample designated GR(2) (graphene-reinforced PVDF), although it is somewhat broader and has changed intensity, indicating that graphene affects crystallite size and distribution. Similar peak positions but slightly different intensity and shape are shown in the third pattern, MWCNT(3), which suggests interaction between MWCNTs and the PVDF matrix, potentially changing crystallinity or facilitating β-phase development. Although the PVDF matrix continues to dominate the diffraction signal, the PANI(4) pattern displays a broad diffraction feature that is consistent with the semi-crystalline or amorphous nature of polyaniline. The final curve, PVDF Powder(5), which depicts raw PVDF powder has several distinct peaks that attest to the pure polymers were semi-crystalline structure. Overall, the Fig 5 indicates that PVDF crystallinity is changed and its functional qualities may be improved by adding various conductive fillers such as graphene, MWCNT and PANI. Successful composite production and potential improvement in electro active β-phase content are indicated by the broadening and shifting of peaks. This is important for applications such as energy harvesting in triboelectric or piezoelectric nanogenerators. 3. Conductivity test Table 2 indicates the Numerous conductive fillers include graphene, polyaniline and multi-walled carbon nanotubes (MWCNT) were included into the PVDF-based nanocomposites to extensively improve their electrical conductivity. As anticipated, pristine PVDF had a conductivity of 3.6 × 10⁻⁶ S/cm as the insulating polymer, but increasing it to 6.0 × 10⁻⁵ S/cm with MWCNT resulted in an almost 17-times increase because they were well dispersed in the material and are likely to have established conductive channels. The conductivity of graphene also approached enhanced that of 4.444 × 10⁻⁵ S/cm, about 12 times that of PVDF by itself. While all carbon-based fillers developmental dramatically increase conductivity, polyaniline had the most enhancement to 1.667 × 10⁻⁴ S/cm, which is more than 46 times more so than pristine PVDF as shown in table 2. This is due its intrinsic conductivity allowing for better charge transfer due to polyaniline's strong interaction with the PVDF matrix. These understandings demonstrate the ease at which integration of well conductive filler vastly increases the electrical properties of PVDF composites which could lead to numerous applications including energy harvesting devices, flexible electronics, and sensors. Finally, polyaniline appears to be the most viable filler in this study for achieving truly high conducting composites of PVDF. Table 2: Conductivity test on various samples Sample conductivity PVDF Only 3.6 × 10⁻⁶ PVDF / MWCNT 6.000 × 10⁻⁵ PVDF / Graphene 4.444 × 10⁻⁵ PVDF / Polyaniline 1.667 × 10⁻⁴ 4. Acoustic sensing analysis Fig 6 Explains the voltage response of PVDF and PVDF based composites with several conductive fillers such as MWCNTs (black), graphene (red), polyaniline (blue), and pristine PVDF (magenta) is illustrated over time.The voltage outputs clearly illustrate how conductive fillers have a notable effect on the electrical performance of the samples and will impact applications where voltage output under mechanical excitation is vital (i.e,energy harvesting or sensing).With the smooth sinusoidal waveform with the smallest amplitude and the smallest voltage output, Pristine PVDF with no conductive additives is demonstrating limited piezoelectric or triboelectric activities. To put it another way, Pristine PVDF essentially has no voltage output. There is a clear trend with the conductive fillers as there is an increase in voltage output as each conductive filler was added into the PVDF matrix.The PVDF/polyaniline composite (blue line) had an improved voltage response compared to pure PVDF indicating that polyaniline provided greater matrix dielectric constant and assisted with charge mobility.The PVDF/MWCNT exhibited the most significant voltage amplitude primarily because of the conductive properties of the multi-walled carbon nanotubes (MWCNTs) enhanced the piezoelectric properties. The arrangement and connectivity of MWCNTs in the polymeric PVDF matrix allow for improved charge transport and higher triboelectric charge density when compared to graphene and polyaniline composites. The increase in voltage amplitude seen in the PVDF/MWCNT composite can also be explained in part by the high aspect ratio of the multi-walled carbon nanotubes (MWCNT) that facilitated the formation of a well-established conductive network in the polymer matrix. A conductive network in the polymer matrix can facilitate efficient creation of percolation pathways for charge transport and separation. In general, the voltage-time response suggests that the presence of conductive fillers has a dramatic improvement in electrical performance of the PVDF-based materials as a whole, where MWCNT displays the greatest improvement, and graphene and polyaniline show successively less improvement. This supports the notion that careful selection of fillers is important for developing conductive PVDF-based composite materials for various applications, such as flexible electronics, energy harvesting and sensors. In terms of the total voltage developed, the outcomes are consistent with Nan Liu's electrical conductivity, Joan Solano's charge density and Marciel Rother's preliminary energy harvesting for the PVDF-based composites. This suggests filler selection has a major role with the output performance of PVDF-based nanogenerators and sensors, aligning well to previously reported conductivities of these composite materials. The improved electrical properties of the composites show that the filler material is vital in terms of performance. As the most promising filler for high-performance, self-powered electronic devices, MWCNTs possess excellent electric conductivity and mechanical properties. They also aid in charge transport, thus making PVDF composites more efficient. This makes MWCNTs an obvious candidate for future use in greater flexible electronics, energy harvesting and state-of-the-art sensors. This is why continued studies on potential filler material is important to better utilize PVDF systems. Conclusion This research clearly showcases the development and improvement of PVDF nanofibers for energy harvesting and sensing applications via centrifugal spinning with conductive fillers (multi-walled carbon nanotubes (MWCNTs), graphene oxide and polyaniline). Centrifugal spinning enables nanofibers to be produced at an industrial scale, and the morphology/ mechanical properties improved by using centrifugal spinning, as it is scalable, cheap, and offer substantial value over traditional electrospinning methods. The ability of centrifugal spinning to produce a uniform nanofibers increases the effectiveness of PVDF nanofibers for different applications related to energy harvesting and sensing technologies. By manipulating the processing conditions and using the correct combination of solvents (DMF and acetone), this research was able to produce smooth, uniform nanofibers with preferential β-phase crystallinity for enhanced piezoelectric performance.The incorporation of conductive fillers significantly increased the electrical conductivity of the PVDF nanofibers, further improving their suitability for energy harvesting and sensing applications.Polyaniline doped PVDF had the highest conductivity of all the materials examined (1.667 × 10⁻⁴ S/cm), followed by composites of PVDF and graphene and PVDF/MWCNT. Successful filler dispersion and structural change of the PVDF matrix were validated by SEM, FTIR, and XRD studies, which supported the development of the β-phase and structural integrity.The electromechanical response of these nanocomposites was further confirmed by acoustic sensing studies. Because of their high aspect ratio and effective conductive routes, MWCNT-based PVDF nanofibers demonstrated the highest voltage output during mechanical excitation. Although to a much lesser extent, graphene and polyaniline fillers also improved piezoelectric output. These results demonstrate the relationship between fiber shape, filler type and output performance, underscoring the potential of customized nanocomposites for flexible high-performance electronics. Ultimately, centrifugal spinning is a successful method for creating PVDF based nanofibers with adjustable characteristics by adding conductive fillers. These materials improved the conductivity and electromechanical output makes them ideal for energy-harvesting devices, self-powered systems and wearable sensors of the future. This study creates new opportunities for the development of multipurpose, scalable and reasonably priced materials for cutting-edge technological applications in the fields of electronics, biomedicine and the environment. Declarations Author Contribution Manikandan G K and Jeyanthi S both author contributed equally Data Availability The datasets used and/or analyzed during the current study available from the corresponding author on reasonable request. References Choi, S. S. et al. Electrospun PVDF nanofiber web as polymer electrolyte or separator. Electrochim. Acta . 50 (2–3), 339–343 (2004). Wang, X. et al. Tactile-sensing based on flexible PVDF nanofibers via electrospinning: a review. Sensors 18 (2), 330 (2018). Gee, S., Johnson, B. & Smith, A. L. Optimizing electrospinning parameters for piezoelectric PVDF nanofiber membranes. J. Membr. Sci. 563 , 804–812 (2018). Xin, Y. et al. A brief review on piezoelectric PVDF nanofibers prepared by electrospinning. 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Near-field electrospun piezoelectric fibers as sound-sensing elements. Polymers 10 (7), 692 (2018). Shehata, N. et al. Acoustic energy harvesting and sensing via electrospun PVDF nanofiber membrane. Sensors 20 (11), 3111 (2020). Li, J. et al. Flexible Self-Powered Low-Decibel Voice Recognition Mask. Sensors 24 (10), 3007 (2024). Ibtehaj, K., Jumali, M. H. H. & Al-Bati, S. A novel facile preparation method of self-polarized Poly (vinylidene fluorides) nanofiber for high-performance piezoelectric nanogenerator. Polymer 208 , 122956 (2020). McCann, J. T., Li, D. & Xia, Y. Electrospinning of nanofibers with core-sheath, hollow, or porous structures. J. Mater. Chem. 15 (7), 735–738 (2005). Atıcı, B., Ünlü, C. H. & Yanilmaz, M. A review on centrifugally spun fibers and their applications. Polym. Rev. 62 (1), 1–64 (2022). Ji, R. et al. Electrospinning fabricated novel poly (ethylene glycol)/graphene oxide composite phase-change nano-fibers with good shape stability for thermal regulation. J. Energy Storage . 40 , 102687 (2021). Zhang, X. et al. Preparation and performance of novel polyvinylpyrrolidone/polyethylene glycol phase change materials composite fibers by centrifugal spinning. Chem. Phys. Lett. 691 , 314–318 (2018). Xia, L., Ju, J. G., Xu, W., Ding, C. K. & Cheng, B. W. Preparation and characterization of hollow Fe2O3 ultra-fine fibers by centrifugal spinning. Mater. Design . 96 , 439–445 (2016). Hou, T., Li, X., Lu, Y. & Yang, B. Highly porous fibers prepared by centrifugal spinning. Mater. Design . 114 , 303–311 (2017). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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2","display":"","copyAsset":false,"role":"figure","size":453306,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e2.1: Centrifugal spinning machine \u0026nbsp;\u0026nbsp;setup\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2: Magnetic stir\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3: Collector collecting the nanofibers\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.4: Nanofiber\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7710086/v1/892e44539e9f66996d76685a.jpeg"},{"id":93749859,"identity":"a7be38d4-3ffe-4d1e-967a-8bbf242db690","added_by":"auto","created_at":"2025-10-17 07:30:18","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":4595946,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSEM images of(3a) PVDF Nanofibers with graphene oxide (3b) PVDF Nanofibers with MWCNT (3c) PVDF Powder (3d) PVDF Nanofiber (3e) PVDF Nanofiber with Polyaniline at rotational speed of 7500 rpm, collecting distance of 15 cm, spinneret diameter of 0.11 mm prepared with DMF and acetone as solvent.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7710086/v1/3b70e5e2c399acf80b29a8ab.png"},{"id":93749861,"identity":"3df97293-8f51-49b8-9abf-e6d38e12bf16","added_by":"auto","created_at":"2025-10-17 07:30:18","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":76000,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFTIR Analysis\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7710086/v1/d4da879ffc264789bddff349.png"},{"id":93750246,"identity":"d7df6555-4a4c-46ea-83c6-b3f834ec4817","added_by":"auto","created_at":"2025-10-17 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07:30:18","extension":"png","order_by":13,"title":"","display":"","copyAsset":false,"role":"graphical-abstract","size":44943,"visible":true,"origin":"","legend":"Centrifugal spinning is a very rapid and scalable method for generating PVDF nanofibers, especially if the nanofibers are doped with conductive fillers (like MWCNT, GO and PANI), that enhance the piezoelectric and electrical properties of PVDF, and that allow these composites to use in energy harvesting and sensing applications. In this study, a solvent combination of DMF and acetone was used to prepare a homogeneous PVDF solution which was spun at 7000\u0026ndash;7500 RPM; the increased β-phase content was desired to maximize piezoelectric activity in the polymer. Characterization techniques including SEM, FTIR and XRD showed that there was a uniform fiber formation and strong β-phase content in the fibers, which indicated good dispersion of the fillers. The pristine PVDF electrical conductivity was also tested, which was at 3.6 \u0026times; 10⁻⁶ S/cm, compared to the 1.667 \u0026times; 10⁻⁴ S/cm with fillers. Acoustic tests on the composites indicated that the PVDF/MWCNT composite produced the highest voltage output, confirming better sensing performance in this composite. Overall, results indicate that centrifugal spinning fabrication of flexible, self-powered sensing materials is a valid and promising option.","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7710086/v1/e31ed719d74fe17aacfcd9ee.png"},{"id":97249645,"identity":"6663f4f0-0eea-47fc-b911-b19e89941f43","added_by":"auto","created_at":"2025-12-02 13:13:09","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5828733,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7710086/v1/04ad7440-8c4c-465a-926f-5a45034cf1ce.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Centrifugal Spinning of Conductive Filler-Enhanced PVDF Nanofibers for Energy Harvesting and Sensing Applications","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThis study investigates PVDF nanofiber webs produced through electrospinning as polymer membranes, emphasizing their piezoelectric properties and use as energy harvesting and sensing devices. The research demonstrates the influence of fiber shape and crystallinity on the materials performance, and therefore the importance of fiber (shape and crystallinity) in maximizing the efficacy of these nanofiber membranes [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. PVDF nanofibers based flexible touch sensors are gaining popularity for wearable applications based on their piezoelectric characteristics and flexibility. Recent developments have even been dedicated to enhance sensitivity and overall performance through various new fabrication techniques like electro spinning and blow spinning; this allows these sensors to be integrated with more diverse health-wellness monitoring systems and interactive devices [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. This study optimizes the electrospinning conditions to enhance the piezoelectric properties of PVDF nanofibers. More specifically, the study investigates how voltage, flow rate and polymer concentration influence the β-phase formation within the fibers, and the morphology. Ultimately, the goal is to enhance the functional performance of the nanofibers for various applications, through tuning of the electro spinning conditions [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The article examines the advancements piezoelectric PVDF (polyvinylidene difluoride) nanofibers and their pivotal applications, structural characteristics, and production methods. It examined the advancements made previously to improve the piezoelectric performance of the PVDF nanofibers, which are typically used in sensing and energy harvesting applications. In addition, there was depth exploration into new processing technologies and novel material modifications which show promise for different areas of technology and usage of PVDF nanofibers [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. PVDF nanofibers can be used to make pliable and sensitive flow sensors because they have excellent piezoelectric properties, mechanical flexibility, and biocompatibility. These properties allow for responsive sensors, meaning they can accurately track the fluid dynamics in biomedical and industrial applications [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. In this study the development and characterization of electrospun PVDF nanofibers for piezoelectric applications. The study examines processing parameters that influence the morphology of the as-spun fibers and degree of β-phase as well as their use in energy harvesting and sensing applications. The goal of the study is to connect processing parameters with the resulting properties of the nanofibers and offer the potential to harness these nanofibers into engineered structures and applications [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Flexible capacitive sensors utilizing electrospun PVDF nanofibers exhibit varying performance based on nanofiber shape, which influences sensitivity and durability. Research highlights the importance of fiber morphology in optimizing sensor characteristics for applications in wearable technology and tactile sensing. [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. PVDF-MWCNT nanofibers produced through near-field electrospinning demonstrate enhanced piezoelectric properties due to their β-phase composition. These characteristics make them suitable for energy harvesting applications, as studies indicate improved electrical performance and potential for self-powered devices[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].This work investigates the impact of multi-walled carbon nanotubes (MWCNT) content on the mechanical and piezoelectric characteristics of PVDF nanofibers. It emphasizes how varying MWCNT concentrations influence tensile strength, β-phase development and overall piezoelectric performance. The findings aim to provide insights into optimizing the composite material for enhanced functionality in various applications[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. This research explores the mechanical and electrical characteristics of PVDF-based nanofibers to better understand their potential for energy harvesting and sensing applications. It addresses the effects of material composition and production conditions on the performance properties of the nanofibers, aiming to identify optimal parameters that enhance their functionality in various technological applications [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. This work examines the mechanical and dielectric characteristics of aligned PVDF nanofibers, focusing on their potential applications in energy storage and sensing. It evaluates the effects of fiber alignment on polarization, structural characteristics and overall performance highlighting how alignment can enhance the functional properties of the nanofibers for improved efficiency in energy-related applications[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. This dissertation discusses the exceptional qualities of PVDF-based nanofibers, with particular attention to their mechanical strength, piezoelectric response and potential applications. It emphasizes the impact of changes in fabrication methods and material modifications aimed at enhancing energy harvesting and sensing capabilities. The findings aim to provide a comprehensive understanding of how these factors contribute to the performance and applicability of PVDF nanofibers in advanced technologies[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The structural, mechanical and electrical features of carbon fibers are the main topics of this paper presentation of a wet-spinning method. It draws attention to the benefits of this process for producing high-performance carbon fibers for cutting-edge uses[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The current inquiry investigates how to optimize the structural and electrical characteristics of electrospun PVDF-MWCNT-based nanogenerators in order to increase power production. It draws attention to how MWCNT dispersion and processing parameters might increase the efficiency of piezoelectric energy harvesting[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Although there are many uses for nanofibers, the efficiency and scalability of conventional production techniques are problematic. One quick and affordable method for producing nanofibers on a big scale is centrifugal spinning [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. This study shows that SIBS fibers made by centrifugal spinning were smoother and produced much faster than those made by electrospinning. The fibers were highly water-repellent and could easily absorb oil, making them useful for separating oil from water[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Piezoelectric, electromagnetic, metamaterial, and resonator-based processes are used in acoustic energy harvesting to transform sound or noise into electrical energy that can be used. Acoustic metamaterials are a promising option for effective energy conversion and noise reduction in small-scale electronic applications, according to recent developments[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Applications in energy harvesting, sensing, and noise monitoring are made possible by nanogenerators' ability to capture acoustic energy from vibrations or sound waves. Their performance and versatility are greatly enhanced when combined with AI and ML, opening the door for intelligent, self-powered acoustic devices[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. An intelligent self-powered sound-sensing element (ISSE) with improved piezoelectric output can be developed thanks to three-dimensional near-field electrospun PVDF nano-microfiber architectures. With its ability to capture sound energy and identify throat vibrations, this incredibly thin and inexpensive gadget has potential uses in implantable technologies, wearable electronics, and voice control[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. In this study, electrospun PVDF nanofiber membranes are introduced as acoustic sensing devices that convert sound waves into frequency-and amplitude-dependent electrical outputs. Their piezoelectric performance is demonstrated in the study, which also emphasizes their potential as an inexpensive way to capture acoustic energy from various sound sources[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. For discrete speech sensing, a mask-integrated triboelectric nanogenerator (CS-TENG) is created, which transforms airflow vibrations into electrical signals for precise speech and identity recognition. The system's over 90% accuracy, which is attained through sophisticated signal processing and deep learning, allows for safe, discrete communication in peaceful settings[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Self-polarized PVDF nanofibers with a high β-phase content and improved piezoelectric response are produced using a simple centrifugal spinning technique. Centrifugal spinning is a promising path for scalable, high-efficiency energy harvesting devices, as demonstrated by the exceptional output performance of the resulting flexible nanogenerator[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The creation of one-dimensional nanostructures from polymers, ceramics, and composites with core-sheath, hollow, and porous architectures has been made possible by recent developments in electrospinning. The goal of these advancements is to improve fiber performance, functionality, and uniformity for a range of device applications[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Recent developments in centrifugal spinning are highlighted in this review, with particular attention paid to the structures, characteristics, and functionality of centrifugally spun fibers for uses in drug delivery, energy storage, and filtering. In order to improve this adaptable fiber fabrication method, it also addresses present issues and potential research avenues[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. This work describes the electrospinning process used to create PEG/GO composite phase-change fibers, which resulted in improved stability, phase-change performance, and thermal conductivity. Excellent thermal regulation, dependability, and shape stability are demonstrated by the optimized fibers containing 0.5 weight percent GO, which qualifies them for sophisticated thermo-regulated applications[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. A high-throughput, safer substitute for electrospinning in the creation of phase-change composite fibers is centrifugal spinning. This process yields PVP/PEG fibers with outstanding thermal characteristics and stable fibrous morphology, showing great promise for real-world uses[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Centrifugal spinning, with spinning parameters optimized for fiber quality, was used to create hollow FeO₃ ultra-fine fibers, which were then calcined. SEM, XRD, TGA, FT-IR, and XPS analyses of the resultant fibers revealed tunable diameters and morphology that were impacted by spinneret size and rotational speed[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Using an ethanol\u0026ndash;water binary solvent system, porous EC/PVP fibers were created by centrifugal spinning; rheological characteristics and solvent ratios had a significant impact on pore formation. Centrifugal spinning allowed for much larger surface area fibers than electrospinning, demonstrating the method's influence on fiber morphology[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e"},{"header":"Methods and materials","content":"\u003cp\u003eIn order to produce a homogenous PVDF solution by using DMF and acetone as the solvent the content temperature and stirring conditions must be accurately maintained, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. Although DMF is a high-boiling solvent that gives an efficient solution to PVDF, it retains the relatively low boiling acetone, which lowers the total viscosity of the solution and subsequently gives more fiber. The optimum solubility will generally use either DMF: Acetone 6:4 or 7:3 to get the highest solubility. After determining the correct solvent amount, the first step in the procedure is to accurately weigh 12\u0026ndash;20 weight percent of PVDF according to the total volume of solvent. Once the weight has been calculated, the PVDF is then incrementally added to DMF-acetone with stirring at 50\u0026ndash;60\u0026deg;C with a magnetic stirrer and speed adjustment (usually around 300\u0026ndash;500 rpm). The unit is agitated for four hours to ensure that the polymer is completely dissolved, and a homogenous solution is achieved as shown in Fig. 2.2. The prolonged stirring time provides a stable solution because the stirring allows for the polymer chains to completely disperse, eliminating the phase separation. Temperature accuracy is important to maintain since too high temperatures could damage the PVDF or too little heat could slightly disintegrate the polymer. After stirring, the solution is settled and agitated for one to two hours to allow for any air bubbles to escape before the solution is eventually processed. In centrifugal spinning methods, it\u0026apos;s important to use well-prepared homogeneous PVDF solutions, because it aids in fiber production, ensures better fiber shape consistency, and results in improved mechanical properties in the product. Preparation of homogeneous solutions is critical to delivering quality nanofibers that will be used in other applications. Always store a well-prepared solution in a sealed container to maintain solution stability, reduce evaporation and as a best practice to maintain the integrity of the solution, it will ensure consistent processing and performance of the nanofibers produced as shown in Fig. 2.4\u003c/p\u003e\n\u003cp\u003eCentrifugal spinning machine involves placing a polymer solution within a rapidly spinning head (7000 to 7500 rpm) and due to centrifugal forces, the solution will be dispensed through small nozzles and stretched into fibers. These fibers will solidify as the solvent evaporates and will be collected into either a stationary or spinning collector as shown in Fig. 2.3. This process allows for large-scale production of nanofibers in a relatively fast and efficient manner for a variety of different uses.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003e\u003cstrong\u003ePVDF with filler percentage for various properties\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFiller (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMechanical Strength (MPa)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eThermal Stability (\u0026deg;C)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMorphology / Structure\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePVDF (Pure)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25\u0026ndash;35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e~\u0026thinsp;420\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSmooth, uniform nanofibers or films\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePVDF / MWCNT\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e45\u0026ndash;60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e~\u0026thinsp;460\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFibers with embedded nanotubes, increased roughness\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePVDF / Graphene\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40\u0026ndash;55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e~\u0026thinsp;470\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLayered flakes, enhanced surface area\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePVDF / Polyaniline\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35\u0026ndash;50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e~\u0026thinsp;440\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRougher texture, some agglomeration if poorly mixed\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eThis approach successfully generates nanofibers with tailored diameter, allowing for further optimization through processing parameters such as temperature, solution viscosity, and rotational speed. PVDF nanofibers from centrifugal spinning have excellent piezoelectric properties, mainly attributed to their phase change from \u0026alpha;-phase to \u0026beta;-phase polymer during the spinning process. Mechanical, thermal, and piezoelectric characteristics of the PVDF nanofibers can be improved by controlling polymer chain alignment during spinning and by adding additives such as carbon nanotubes (CNTs),polyaniline(PANI),graphene oxide(GO) as shown in Table 1. Centrifugal spinning can be used to produce PVDF nanofibers for much larger scale fabrication enabling their use as possible electronic and energy harvesting components in applications such as wearable electronics and sensors.\u003c/p\u003e\n\u003ch2\u003eCharacterization Methods\u003c/h2\u003e\n\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003cdiv id=\"Sec4\" class=\"Section3\"\u003e\n \u003ch2\u003eScanning Electron Microscopy (SEM)\u003c/h2\u003e\n \u003cp\u003eExamining fibers via scanning electron microscopy (SEM) produces complete information regarding their shape characteristics/ morphology that aids in evaluating the performance and quality of fibers for different applications. With SEM images, we may examine very important characteristics consisting of fiber homogeneity, smoothness of the surface, and fiber defects including beads or irregularities. Furthermore, with image analysis, we can accurately compute the average fiber diameter as well as its distribution. This will generally include making several measures, enough to make those statistics statistically meaningful, so that we can adequately assess relevant fiber characteristics, information that is important for developing the manufacturing process and property characteristics of nanofibers for applications such as filtration, tissue engineering and energy harvesting. The appearance of beads in nanofibers suggests unstable spinning conditions or inappropriate solution characteristics, while well-formed nanofibers exhibit a uniform and smooth appearance. Scanning electron microscopy (SEM) examination also reveals fiber alignment, which is crucial for applications that require directional properties, such as sensors and actuators.\u003c/p\u003e\n \u003cp\u003eIf a sample also showed surface roughness and porosity, it could indicate the use of fillers and/or rapid solvent evaporation during the spinning process. These parameters could have a significant effect on the mechanical and functional properties of the nanofibers. Ensuring the variables in spinning conditions and solution formulation can help develop samples with the desired features for specific applications. Ultimately, scanning electronic microscopy (SEM) is an important method that allows a researcher to explore the integrity, consistency, and quality of their nanofibers. It can assist in the process of controlling conditions for advanced materials, as noted in the discussion above. SEM provides a wealth of data that allows a researcher to explore the morphology of their samples in way that assists with optimizing processing variables. Scanning electronic microscopy allows detailed studies into defects, measuring fiber diameter, and inspecting the surface features that allows detailed fiber characterization in numerous applications in areas of filtration, energy harvesting, and medical-based engineering.\u003c/p\u003e\n \u003cp\u003eIllustrate the SEM micrographs of the morphological properties of PVDF nanofibers with and without powder created under controlled spinning conditions. The results include nanofibers of PVDF with graphene oxide (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ea), multi-walled carbon nanotubes (MWCNT) (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eb) and polyaniline (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ee), alongside pristine PVDF effects of nanofibers (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ed) and untreated PVDF powder (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ec). All samples were made by centrifugal spinning at a speed of 7500 rpm, with a collecting distance of 15cm, using a spinneret diameter of 0.11 mm the spinning solvents were DMF and acetone, to ensure a homogenous solution and standard morphologies of fibers. The addition of conductive fillers, such as Graphene oxide, MWCNT, and polyaniline, greatly modifies the structure of the fiber, leading to a fiber with an improved fiber uniformity and may lead to improved piezoelectric and electrical properties of the PVDF nanofibers as well. The observed morphology of these nanofibers demonstrates that they also include nanofillers inside the PVDF matrix. It also indicated that the performance or aspects of the nanofibers are ideally suited to make advanced flexible devices for energy harvesting and sensing.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003ch3\u003eFourier Transform Infrared Spectroscopy (FTIR)\u003c/h3\u003e\n\u003cp\u003eFourier Transform Infrared Spectroscopy (FTIR) is a widely utilized analytical process used for determining and validating the chemical structure and the functional groups present in objects. The tested FTIR uses an infrared light source in which its light beam is directed through a sample while recording the spectral absorption wavelengths to produce a spectrum based on molecular vibration. Each peak on this spectrum represents a functional group or persons or bond present in the spectrum. Examples of use FTIR is very effective in determining phase structures (i.e. \u0026beta;-phase in PVDF) or composition, and it enables determination of polymer architecture and the presence or interactions with various additives or fillers in nanofibers. Texture is moderately rapid, very accurate and non-destructive, FTIR plays a tremendous role in characterizing materials and ensuring quality and performance in applications in nanofibers.\u003c/p\u003e\n\u003ch3\u003eX-ray diffraction (XRD)\u003c/h3\u003e\n\u003cp\u003eX-ray diffraction (XRD) analysis was conducted to examine the crystalline structure of the prepared nanofibers. The peaks in the diffraction patterns indicated that the prepared materials had a semi-crystalline structure with intense and sharp peaks. The prepared nanofibers made from PVDF indicated the presence of the necessary electroactive crystalline structure corresponding to the \u0026beta;-phase with the sharp diffraction peak around 2\u0026theta;\u0026thinsp;=\u0026thinsp;20.3\u0026deg;. In addition, there were diffraction peaks at 18.4\u0026deg; and 26.6\u0026deg; respectively indicating the \u0026alpha;-phase and \u0026gamma;-phase. The crystalline peaks intensity and sharpness indicated good crystalline quality which was required for the nanofiber performance as energy harvester materials. The absence of any impurities in the diffraction analysis indicated that the fillers had consistently been included and their structure had been maintained, thus meeting the basic structural qualifications required for energy harvesting applications. Thus, the structural integrity of the PVDF-based nanofibers is an important factor in maintaining the functional outcomes in diverse applications in advanced materials engineering.\u003c/p\u003e"},{"header":"Result and Discussion","content":"\u003cp\u003e\u003cstrong\u003e1. FTIR Spectroscopy\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFourier Transform Infrared (FTIR) spectroscopy is a great tool for studying a wide variety of PVDF-based materials, particularly in discovery of functional groups and characterization of molecular interactions in polymer composites. On an FTIR spectrum, the y-axis is transmittance (%) or the percentage of infrared light that goes through the sample, while the x-axis is wavenumber in cm⁻\u0026sup1; , or the relationship to the vibrational frequencies of molecular bonds. Each peak is attributed to specific functional groups or molecular vibrations and is an important piece of information pertaining to the chemical composition of the material and interactions within the material. This, in turn, is valuable when tuning the characteristics of the PVDF-based composites with the end goal is to create functional devices for energy in harvesting, sensor applications, etc. For this analysis five separate samples are looked at; PVDF/GO (graphene oxide), PVDF/MWCNT (multi-walled carbon nanotubes), pure PVDF, PVDF/polyaniline and PVDF powder. The FTIR spectrum reported for these samples show that there are indicative absorption peaks in the PVDF materials that are consistent with the polymer\u0026apos;s crystalline phases. For example, the absorption peaks 840\u0026ndash;880 cm⁻\u0026sup1; are generally described by the \u0026beta;-phase of PVDF while absorption peaks 1170\u0026ndash;1280 cm⁻\u0026sup1;, can generally be described by the \u0026alpha;-phase of PVDF. The characteristic peaks that exist in all samples suggest that the intrinsic structural characteristics of PVDF have not been lost with the addition of various additives (i.e., graphene oxide, multi-walled carbon nanotubes, or polyaniline) as shown in Fig 11. This information can be useful for determining the relevant interactions and therefore the possible physical property enhancements related to PVDF based composites for a variety of applications. The FTIR spectrum of the pure PVDF powder sample (green) shows very pronounced, sharp peaks showing congruency with the high purity and crystalline nature of the material. In contrast, the nanofibrous PVDF samples including fillers, show peaks that are broadened and in some cases shifted. This implies that the centrifugal spinning process as well as the addition of various nanofillers has affected the crystallinity of the material and the nature of the molecular structure of PVDF rather than simply adding mass. The broadened and shifted behavior of the FTIR peak in the nanofibrous samples may indicate a loss of crystallinity or possibly new molecular interactions based off the starting materials that include filler materials. These changes can greatly affect the mechanical strength, thermal stability and electrical conductivity properties of the material, therefore it is important to understand in what consistent ways they can affect these properties which will enable us to gain greater effective performance from PVDF-based composites in a range of applications. The changes in the peak position and intensity for both PVDF/GO and PVDF/MWCNT samples can attributed to their interaction with the PVDF matrix. PVDF/GO exhibited relatively rounded broad peaks and low intensity while PVDF/MWCNT exhibit sharper and high intensity peaks suggesting enhanced compatibility and improved crystallinity from the MWCNTs. The successful insert of polyaniline into the matrix of PVDF as a physically entangled structure can be confirmed by the appearance of new absorption bands in the region 1500\u0026ndash;1600 cm⁻\u0026sup1;. This indicated an aromatic C=C stretching vibration consistent with polyaniline this observation indicates a well-defined interaction between polyaniline and PVDF matrix. Overall, the Fig 4 indicates that the presence of a range of nanomaterials has a significant effect of the molecular structure and chemical environment of PVDF. Such changes are important for improving functional characteristics of PVDF based nanofibers for applications in flexible electronics, energy harvesting and sensor technologies. The ability to tailor the properties of these nanofibers through the incorporation of different nanofillers opens up new possibilities for advanced material design and application.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.XRD Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe X-ray diffraction (XRD) patterns for the multiple samples of pure PVDF, PVDF powder and PVDF composites containing graphene (GR), polyaniline (PANI) and multi-walled carbon nanotubes (MWCNT) as fillers show the crystalline structure of the materials. XRD is an analytical technique that determines the crystalline structure using diffraction of X-rays incident on a sample. The XRD patterns are composed of a y-axis presenting relative intensity in arbitrary units (a.u.), which indicates the level of crystallinity, and an x-axis showing the angle of diffraction (2\u0026theta;) in degrees. The peaks in the XRD patterns represent the crystalline phases of the pure PVDF, PVDF powder, and PVDF composites. The peaks can be examined for shape and intensity and correlated with crystallinity. The use of fillers such as GR, PANI and MWCNT could produce changes in peak locations and intensities, indicating changes in the crystalline structures and interactions in the PVDF matrix. This information is crucial for understanding how these modifications affect the overall properties and performance of PVDF-based composites in various applications. Different diffraction peaks demonstrating the existence of crystalline phases in each sample are visible on the graph. Known for its strong piezoelectric performance, the uppermost curve PVDF(1), has a broad peak centered at 20\u0026deg;. This corresponds to the typical (110)/(200) planes of the \u0026beta;-phase of PVDF. A peak at almost the same location is also seen in the sample designated GR(2) (graphene-reinforced PVDF), although it is somewhat broader and has changed intensity, indicating that graphene affects crystallite size and distribution. Similar peak positions but slightly different intensity and shape are shown in the third pattern, MWCNT(3), which suggests interaction between MWCNTs and the PVDF matrix, potentially changing crystallinity or facilitating \u0026beta;-phase development. Although the PVDF matrix continues to dominate the diffraction signal, the PANI(4) pattern displays a broad diffraction feature that is consistent with the semi-crystalline or amorphous nature of polyaniline. The final curve, PVDF Powder(5), which depicts raw PVDF powder has several distinct peaks that attest to the pure polymers were semi-crystalline structure. Overall, the Fig 5 indicates that PVDF crystallinity is changed and its functional qualities may be improved by adding various conductive fillers such as graphene, MWCNT and PANI. Successful composite production and potential improvement in electro active \u0026beta;-phase content are indicated by the broadening and shifting of peaks. This is important for applications such as energy harvesting in triboelectric or piezoelectric nanogenerators.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3. Conductivity test\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTable 2 indicates the Numerous conductive fillers include graphene, polyaniline and multi-walled carbon nanotubes (MWCNT) were included into the PVDF-based nanocomposites to extensively improve their electrical conductivity. As anticipated, pristine PVDF had a conductivity of 3.6 \u0026times; 10⁻⁶ S/cm as the insulating polymer, but increasing it to 6.0 \u0026times; 10⁻⁵ S/cm with MWCNT resulted in an almost 17-times increase because they were well dispersed in the material and are likely to have established conductive channels. The conductivity of graphene also approached enhanced that of 4.444 \u0026times; 10⁻⁵ S/cm, about 12 times that of PVDF by itself. While all carbon-based fillers developmental dramatically increase conductivity, polyaniline had the most enhancement to 1.667 \u0026times; 10⁻⁴ S/cm, which is more than 46 times more so than pristine PVDF as shown in table 2. This is due its intrinsic conductivity allowing for better charge transfer due to polyaniline\u0026apos;s strong interaction with the PVDF matrix. These understandings demonstrate the ease at which integration of well conductive filler vastly increases the electrical properties of PVDF composites which could lead to numerous applications including energy harvesting devices, flexible electronics, and sensors. Finally, polyaniline appears to be the most viable filler in this study for achieving truly high conducting composites of PVDF.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2: Conductivity test on various samples\u003c/strong\u003e\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 51.1673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSample\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48.8327%;\"\u003e\n \u003cp\u003e\u003cstrong\u003econductivity\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 51.1673%;\"\u003e\n \u003cp\u003ePVDF Only\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48.8327%;\"\u003e\n \u003cp\u003e3.6 \u0026times; 10⁻⁶\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 51.1673%;\"\u003e\n \u003cp\u003ePVDF / MWCNT\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48.8327%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e6.000 \u0026times; 10⁻⁵\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 51.1673%;\"\u003e\n \u003cp\u003ePVDF / Graphene\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48.8327%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e4.444 \u0026times; 10⁻⁵\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 51.1673%;\"\u003e\n \u003cp\u003ePVDF / Polyaniline\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 48.8327%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e1.667 \u0026times; 10⁻⁴\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4. Acoustic sensing analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Fig 6 Explains the voltage response of PVDF and PVDF based composites with several conductive fillers such as MWCNTs (black), graphene (red), polyaniline (blue), and pristine PVDF (magenta) is illustrated over time.The voltage outputs clearly illustrate how conductive fillers have a notable effect on the electrical performance of the samples and will impact applications where voltage output under mechanical excitation is vital (i.e,energy harvesting or sensing).With the smooth sinusoidal waveform with the smallest amplitude and the smallest voltage output, Pristine PVDF with no conductive additives is demonstrating limited piezoelectric or triboelectric activities. To put it another way, Pristine PVDF essentially has no voltage output. There is a clear trend with the conductive fillers as there is an increase in voltage output as each conductive filler was added into the PVDF matrix.The PVDF/polyaniline composite (blue line) had an improved voltage response compared to pure PVDF indicating that polyaniline provided greater matrix dielectric constant and assisted with charge mobility.The PVDF/MWCNT exhibited the most significant voltage amplitude primarily because of the conductive properties of the multi-walled carbon nanotubes (MWCNTs) enhanced the piezoelectric properties. The arrangement and connectivity of \u0026nbsp;MWCNTs in the polymeric PVDF matrix allow for improved charge transport and higher triboelectric charge density when compared to graphene and polyaniline composites. The increase in voltage amplitude seen in the PVDF/MWCNT composite can also be explained in part by the high aspect ratio of the multi-walled carbon nanotubes (MWCNT) that facilitated the formation of a well-established conductive network in the polymer matrix. A conductive network in the polymer matrix can facilitate efficient creation of percolation pathways for charge transport and separation. In general, the voltage-time response suggests that the presence of conductive fillers has a dramatic improvement in electrical performance of the PVDF-based materials as a whole, where MWCNT displays the greatest improvement, and graphene and polyaniline show successively less improvement. This supports the notion that careful selection of fillers is important for developing conductive PVDF-based composite materials for various applications, such as flexible electronics, energy harvesting and sensors. In terms of the total voltage developed, the outcomes are consistent with Nan Liu\u0026apos;s electrical conductivity, Joan Solano\u0026apos;s charge density \u0026nbsp;and Marciel Rother\u0026apos;s preliminary energy harvesting for the PVDF-based composites. This suggests filler selection has a major role with the output performance of PVDF-based nanogenerators and sensors, aligning well to previously reported conductivities of these composite materials. The improved electrical properties of the composites show that the filler material is vital in terms of performance. As the most promising filler for high-performance, self-powered electronic devices, MWCNTs possess excellent electric conductivity and mechanical properties. They also aid in charge transport, thus making PVDF composites more efficient. This makes MWCNTs an obvious candidate for future use in greater flexible electronics, energy harvesting and state-of-the-art sensors. This is why continued studies on potential filler material is important to better utilize PVDF systems.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis research clearly showcases the development and improvement of PVDF nanofibers for energy harvesting and sensing applications via centrifugal spinning with conductive fillers (multi-walled carbon nanotubes (MWCNTs), graphene oxide and polyaniline). Centrifugal spinning enables nanofibers to be produced at an industrial scale, and the morphology/ mechanical properties improved by using centrifugal spinning, as it is scalable, cheap, and offer substantial value over traditional electrospinning methods. The ability of centrifugal spinning to produce a uniform nanofibers increases the effectiveness of PVDF nanofibers for different applications related to energy harvesting and sensing technologies. By manipulating the processing conditions and using the correct combination of solvents (DMF and acetone), this research was able to produce smooth, uniform nanofibers with preferential β-phase crystallinity for enhanced piezoelectric performance.The incorporation of conductive fillers significantly increased the electrical conductivity of the PVDF nanofibers, further improving their suitability for energy harvesting and sensing applications.Polyaniline doped PVDF had the highest conductivity of all the materials examined (1.667 \u0026times; 10⁻⁴ S/cm), followed by composites of PVDF and graphene and PVDF/MWCNT. Successful filler dispersion and structural change of the PVDF matrix were validated by SEM, FTIR, and XRD studies, which supported the development of the β-phase and structural integrity.The electromechanical response of these nanocomposites was further confirmed by acoustic sensing studies. Because of their high aspect ratio and effective conductive routes, MWCNT-based PVDF nanofibers demonstrated the highest voltage output during mechanical excitation. Although to a much lesser extent, graphene and polyaniline fillers also improved piezoelectric output. These results demonstrate the relationship between fiber shape, filler type and output performance, underscoring the potential of customized nanocomposites for flexible high-performance electronics. Ultimately, centrifugal spinning is a successful method for creating PVDF based nanofibers with adjustable characteristics by adding conductive fillers. These materials improved the conductivity and electromechanical output makes them ideal for energy-harvesting devices, self-powered systems and wearable sensors of the future. This study creates new opportunities for the development of multipurpose, scalable and reasonably priced materials for cutting-edge technological applications in the fields of electronics, biomedicine and the environment.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eManikandan G K and Jeyanthi S both author contributed equally\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets used and/or analyzed during the current study available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eChoi, S. S. et al. Electrospun PVDF nanofiber web as polymer electrolyte or separator. \u003cem\u003eElectrochim. Acta\u003c/em\u003e. \u003cb\u003e50\u003c/b\u003e (2\u0026ndash;3), 339\u0026ndash;343 (2004).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWang, X. et al. 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Design\u003c/em\u003e. \u003cb\u003e114\u003c/b\u003e, 303\u0026ndash;311 (2017).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"PVDF Nanofibers, Centrifugal Spinning, Piezoelectric Nanogenerators, Energy Harvesting, Triboelectric Devices, Wearable Sensors, Biomedical Applications","lastPublishedDoi":"10.21203/rs.3.rs-7710086/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7710086/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Centrifugal spinning is a very rapid and scalable method for generating PVDF nanofibers, especially if the nanofibers are doped with conductive fillers (like MWCNT, GO and PANI), that enhance the piezoelectric and electrical properties of PVDF, and that allow these composites to use in energy harvesting and sensing applications. In this study, a solvent combination of DMF and acetone was used to prepare a homogeneous PVDF solution which was spun at 7000\u0026ndash;7500 RPM; the increased β-phase content was desired to maximize piezoelectric activity in the polymer. Characterization techniques including SEM, FTIR and XRD showed that there was a uniform fiber formation and strong β-phase content in the fibers, which indicated good dispersion of the fillers. The pristine PVDF electrical conductivity was also tested, which was at 3.6 \u0026times; 10⁻⁶ S/cm, compared to the 1.667 \u0026times; 10⁻⁴ S/cm with fillers. Acoustic tests on the composites indicated that the PVDF/MWCNT composite produced the highest voltage output, confirming better sensing performance in this composite. Overall, results indicate that centrifugal spinning fabrication of flexible, self-powered sensing materials is a valid and promising option.","manuscriptTitle":"Centrifugal Spinning of Conductive Filler-Enhanced PVDF Nanofibers for Energy Harvesting and Sensing Applications","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-17 07:30:13","doi":"10.21203/rs.3.rs-7710086/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b501155f-17d7-417a-9e0d-2dfa14935eff","owner":[],"postedDate":"October 17th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":56277898,"name":"Physical sciences/Energy science and technology"},{"id":56277899,"name":"Physical sciences/Engineering"},{"id":56277900,"name":"Physical sciences/Materials science"},{"id":56277901,"name":"Physical sciences/Nanoscience and technology"}],"tags":[],"updatedAt":"2025-12-02T02:23:49+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-17 07:30:13","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7710086","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7710086","identity":"rs-7710086","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}