Piezoelectric Polyvinylidene Difluoride Research Articles

PVDF-Based Piezo-Catalytic Membranes-A Net-Zero Emission Approach towards Textile Wastewater Purification.

Among the various water purification techniques, advancements in membrane technology, with better fabrication and analysis, are receiving the most research attention. The piezo-catalytic degradation of water pollutants is an emerging area of research in water purification technology. This review article focuses on piezoelectric polyvinylidene difluoride (PVDF) polymer-based membranes and their nanocomposites for textile wastewater remediation. At the beginning of this article, the classification of piezoelectric materials is discussed. Among the various membrane-forming polymers, PVDF is a piezoelectric polymer discussed in detail due to its exceptional piezoelectric properties. Polyvinylidene difluoride can show excellent piezoelectric properties in the beta phase. Therefore, various methods of β-phase enhancement within the PVDF polymer and various factors that have a critical impact on its piezo-catalytic activity are briefly explained. This review article also highlights the major aspects of piezoelectric membranes in the context of dye degradation and a net-zero approach. The β-phase of the PVDF piezoelectric material generates an electron-hole pair through external vibrations. The possibility of piezo-catalytic dye degradation via mechanical vibrations and the subsequent capture of the resulting CO2 and H2 gases open up the possibility of achieving the net-zero goal.

Performance Enhancement of Flexible and Self-Powered PVDF-ZnO Based Tactile Sensors

Flexible, self-powered, and intelligent tactile sensors are essential for accurate sensing in prosthetic devices. This paper explores piezoelectric polyvinylidene difluoride - zinc oxide (PVDF-ZnO) nanocomposite layer-based sandwich assembly as tactile sensor. ZnO nanoparticle addition as filler can overcome the challenges associated with PVDF-based tactile sensors. The effect of filler particle size on the enhancement of sensing performance of PVDF-ZnO-based tactile sensors is investigated. Structural, morphological, piezoelectric and thermal studies were performed on the PVDF-ZnO composite layers using SEM, EDS, DC-EFM and Raman Spectroscopy. A comparative investigation of the potential developed across the sensor samples with different filler particle sizes was performed for touch and bending actions. The obtained results showed a remarkable improvement in performance due to particle size reduction of the ZnO fillers. The nanocomposite sensor with less filler particle size generated more voltage on the same applied force. The experimental analysis demonstrates that the filler size reduction can improve the piezo-voltage response up to 123 mV/N for dynamic touch events. The self-powered sensor also has excellent potential in detecting finger bending action with a response of 29 mv/°. The results demonstrate the promising application of the polymer nanocomposite-based sensor in the prosthetic application.

Solution processed high performance piezoelectric eggshell membrane – PVDF layer composite nanogenerator via tuning the interfacial polarization

Bio-compatible and eco-friendly flexible piezoelectric nanogenerators with transparency are emerging energy devices for next-generation energy application. A novel high performance natural, biodegradable and flexible eggshell membrane – polyvinylidene difluoride (PVDF) based piezoelectric nanogenerator has been developed using a low-temperature solution and spin coating route. X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and Raman patterns exhibited all characteristic signature peaks of the eggshell membrane and PVDF film. Piezoelectric pristine PVDF, eggshell membrane and eggshell membrane-PVDF layered structure based nanogenerators are fabricated using the flexible ITO coated PET substrate and spin coating technique. The fabricated device of eggshell membrane-PVDF layer exhibited better performance with very high output voltage and current of 15 V and 150 nA as compared to 2 V and 20 nA electric output generation from pristine PVDF film based device under same compressive strain, without electric poling. Dielectric properties of piezoelectric PVDF film and eggshell membrane-PVDF were also measured to analyze the working mechanism of the nanogenerator. Hybrid eggshell membrane-PVDF structure shows very high dielectric constant (260) as compared to pristine PVDF (22). A very high output voltage with an average value of 65 V was also obtained from electrical poled hybrid nanogenerator under force of about 10 kgf. Such high piezoelectric output voltage and current from biodegradable eggshell membrane-PVDF based flexible piezoelectric nanogenerator was attributed to dramatic increase in interfacial polarization, capacitance and improved piezoelectric properties of PVDF and triple helical structure created polarization induced electrical dipole moment in the eggshell membrane lattice. The results not only provide a new way to utilize the solid waste for generating green energy from mechanical vibration but also an agent to increase the performance of the PVDF based nanogenerator for powering next generation self-powered implantable medical devices with reduced e-waste elements.

Effect of Electrospun PVDF-Fibers Orientation for Vibration Sensing

Advanced Structural Health Monitoring (SHM) systems require the use of high performing, ultra-thin and light weight flexible sensing devices to reduce impact in a hosting material or structure. In this paper piezoelectric polyvinylidene difluoride (PVDF) electrospun fibers were investigated to realize advanced vibration sensors. The microscale structure of the fabricated sensors is of a porous nature and consists of an aggregation of microfibers that are either randomly distributed or oriented. Being piezoelectric these fibers are capable to detect mechanical stress or strain over time in terms of a voltage signal. To investigate the reliability of piezoelectric fibers as vibration sensors, tests of a dynamic nature were conducted. It is found that the developed sensors are capable to detect a cantilever vibration over time with great accuracy and that the microfibers orientation is an important factor to maximize the sensor performance.

Multifunctional Glass-Fiber Composite with Self-Monitoring Capability

Composites that are capable to provide multiple functionalities represent a fundamental step toward the realization of light weight, high performing and autonomous materials. In this paper a piezoelectric polyvinylidene difluoride (PVDF) electrospun fabric is investigated as sensing layer for making a self-monitoring composite material. The micro-scale structure of the fabric consists of an aggregation of micro-fibers that are randomly distributed forming a porous film that allows a full absorption of the epoxy matrix as required for multi-layered composites. The application of a force on the composite induces a charge separation within the atomic structure of the embedded PVDF fabric generating an electrostatic output voltage. These unique features allowed to continuously monitor vibrations under dynamic conditions.

Magnetoelectric nanocomposite scaffold for high yield differentiation of mesenchymal stem cells to neural‐like cells

While the differentiation factors have been widely used to differentiate mesenchymal stem cells (MSCs) into various cell types, they can cause harm at the same time. Therefore, it is beneficial to propose methods to differentiate MSCs without factors. Herein, magnetoelectric (ME) nanofibers were synthesized as the scaffold for the growth of MSCs and their differentiation into neural cells without factors. This nanocomposite takes the advantage of the synergies of the magnetostrictive filler, CoFe2 O 4 nanoparticles (CFO), and piezoelectric polymer, polyvinylidene difluoride (PVDF). Graphene oxide nanosheets were decorated with CFO nanoparticles for a proper dispersion in the polymer through a hydrothermal process. After that, the piezoelectric PVDF polymer, which contained the magnetic nanoparticles, underwent the electrospun process to form ME nanofibers, the ME property of which has the potential to be used in areas such as tissue engineering, biosensors, and actuators.

Thermo-Magneto-Electric Generator Arrays for Active Heat Recovery System

Continued emphasis on development of thermal cooling systems is being placed that can cycle low grade heat. Examples include solar powered unmanned aerial vehicles (UAVs) and data storage servers. The power efficiency of solar module degrades at elevated temperature, thereby, necessitating the need for heat extraction system. Similarly, data centres in wireless computing system are facing increasing efficiency challenges due to high power consumption associated with managing the waste heat. We provide breakthrough in addressing these problems by developing thermo-magneto-electric generator (TMEG) arrays, composed of soft magnet and piezoelectric polyvinylidene difluoride (PVDF) cantilever. TMEG can serve dual role of extracting the waste heat and converting it into useable electricity. Near room temperature second-order magnetic phase transition in soft magnetic material, gadolinium, was employed to obtain mechanical vibrations on the PVDF cantilever under small thermal gradient. TMEGs were shown to achieve high vibration frequency at small temperature gradients, thereby, demonstrating effective heat transfer.

Fast and Reproducible Wettability Switching on Functionalized PVDF/PMMA Surface Controlled by External Electric Field

In this paper, the novel material with controllable wettability switching triggered by external electric field is developed. The material is based on the piezopolymer blend of poly(methyl methacrylate) (PMMA) and polyvinylidene difluoride (PVDF), grafted with various hydrophobic and hydrophilic molecules to alter the initial wettability of polymer films. Organic functional groups are grafted on the blend surface via formation of covalent bonds between PMMA and arenediazonium tosylates. The surface chemical structure and morphology of prepared samples are studied by X‐ray photoelectron spectroscopy, UV–vis, and attenuated total reflection infra red (ATR‐IR) spectroscopies, atomic force microscopy (AFM), and confocal microscopy. Attachment of gold nanoparticles to grafted thiol chemical groups is additionally used to confirm the modification procedure. Application of external stimuli in the form of the electric field leads to dramatic changes in water contact angle. Wettability switching is found to be extremely fast and completely repeatable without the destructions of the polymer film. Mechanism of switching is attributed to the morphological smoothening of piezoelectric responsible composite PVDF–PMMA under the application of external stimuli.

Periodic metamaterial plates with smart tunable local resonators

Vibration band gaps and elastic wave propagation are examined in the metamaterial plates manufactured with periodic locally resonant membranes arranged in a square array. Periodic metamaterials exhibit unique dynamic characteristics stemming from their ability to act as mechanical filters for wave propagation. As a result, waves propagate along the periodic cells only within specific frequency bands called the pass bands, while being blocked within other frequency bands called the stop bands. The proposed metamaterial plates are equipped with sources of local resonances which act as local absorbers of mechanical vibrations. The macroscopic dynamical properties of the resulting periodic structures depend on the resonant properties of substructures which contribute to the rise of interesting effects such as broad stop band characteristics that extend to lower frequencies. Externally excited piezoelectric polyvinylidene difluoride membranes are used to support the local resonators. The stiffness of the piezo-membranes is tunable by means of an external voltage allowing us to control the location and bandwidth of the local resonance frequencies. The predicted band structures are validated by investigating the frequency response of the plate to external mechanical excitations using a comprehensive finite element model of the entire structure. By examining the proposed metamaterial plate, it is shown that it would be possible to actively control the wave propagation both in the spectral and spatial domains in an attempt to steer, stop, and/or confine the propagation of undesirable external disturbances.

Fabrication of a biomimetic piezoelectric polyvinylidene difluoride (PVDF) fibre with a metal core and its application in vibration sensors

The fabrication is described of a vibration sensor based on the structure of the sensitive hair of some insects. The biomimetic hair has a metal core wrapped with a polyvinylidene difluoride (PVDF) layer. Two surface electrodes were coated on the PVDF surface of the fibre. A single SMPF (symmetric electrodes of metal core piezoelectric fibre) pasted on a matrix can be used as a vibration sensor. We propose a theoretical model describing the cantilever beam structure of the vibration sensor. The SMPF can detect both vibration amplitude and direction of the matrix. It can also detect the matrix harmonic excitation frequency and amplitude. We prepared PVDF fibres with metal cores (diameter: 230 µm) with the mould drawing method and used the surface electrodes and the metal core to polarize the PVDF layer. When the SMPF is used as a sensor, we only use the output signal of the two surface electrodes. Our experiments indicate that the SMPF can detect both vibration amplitude and direction of the matrix as well as the harmonic excitation frequency and the vibration direction. Our experimental results are consistent with the theoretical considerations.

Impact force of low velocity liquid droplets measured using piezoelectric PVDF film

When a liquid droplet impacts on a solid surface, a transient impact force is developed at the interface between the liquid and the solid surface. Impact velocity, surface tension and density of the liquid are the important parameters that influence the impact force. In the present study, impact forces of two different oils’ droplet (hydraulic oil ISO VG 68 and lubrication oil SAE 30) are compared with the impact force of water droplet. The impact velocity is varied from about 1.38 to 2.96 m/s. The impact force is determined experimentally using polyvinylidene difluoride (PVDF) piezoelectric film attached on the solid surface. The dynamic response of the PVDF piezoelectric film is acquired using data acquisition system with personal computer. The film is dynamically calibrated using bead drop impact method. A linear relationship between voltage output of the PVDF piezoelectric film and impact force is established. The droplet impact force is determined by measuring the voltage output delivered by the PVDF piezoelectric film and converted it into the impact force. Impact forces developed by both the oils’ droplets are lesser than the impact force of water droplet. The impact duration observed is about 600 μs.

Modelling of a Piezoelectric Polymer Film System for Biosensing Applications

Most piezoelectric gravimetric biosensors are based on quartz crystal microbalances or surface acoustic wave devices. In this paper we describe a polymer film system, made of piezoelectric polyvinylidene difluoride (PVDF) and the Immobilon-P membrane (porous PVDF), for biosensing applications. In operation a film is accommodated in a flow cell and connected to an electronic circuit, constituting an oscillatory resonant device; the output signal is its resonance frequency. This device successfully detected the binding between bovine IgG and bovine anti-IgG. Work on the modelling of this film system is presented. Two different approaches are being considered: the finite element method (FEM) and the ABCD matrices. Results comparing theoretical and experimental data are presented.

P‐102: Audible OLED Device on Flexible PVDF Substrate with Laser Patterned ITO Electrode

AbstractFor the new combination of audio and display devices on flexible polymer substrate, we present the audible OLED device on piezoelectric polyvinylidene difluoride (PVDF) with ITO electrode prepared by roll to roll sputter coating and laser ablation pattern technique. Our flexible audible display (FAD) device showed the luminescence as well as the sound generating functions under the structural schematics with two device characteristics sharing the one flexible polymer substrate for the next generation “superposed” electronic devices.