1) The document discusses the potential of piezoelectric biopolymers for energy harvesting applications in wearable devices.
2) It specifically examines poly(L-lactic acid) (PLLA) nanofibers produced by electrospinning and how annealing affects their crystallinity, mechanical, and piezoelectric properties.
3) The research finds that annealing increases crystallinity and improves mechanical and piezoelectric properties compared to as-spun amorphous fibers. However, the piezoelectric response of PLLA fibers remains lower than poly(vinylidene fluoride-co-trifluoroethylene) thin films.
Carbon nanotubes are allotropes of carbon that exist as cylindrical structures with a high length-to-diameter ratio. They can be single-walled or multi-walled depending on the number of concentric cylinders. Carbon nanotubes have extraordinary properties including high strength, stiffness, thermal conductivity, and electrical conductivity. Due to these properties, carbon nanotubes show promise for applications in electronics, hydrogen storage, solar cells, biosensors, drug delivery, and more.
Mossbauer spectroscopy - Principles and applicationsSANTHANAM V
Mossbauer spectroscopy involves the absorption of gamma ray photons by atomic nuclei. It can provide information about chemical environments and oxidation states. The document discusses key principles such as recoil effect, Doppler tuning, conditions required for Mossbauer spectra, instrumentation, and information that can be obtained from isomer shift, quadruple splitting, and magnetic interactions. Iron-57 is the most commonly studied isotope due to its suitable nuclear properties and applications in chemistry, mineralogy, and biology.
This document provides information about a nanoelectronics and industrial applications program offered by the Nano Science & Technology Consortium. It defines nanoelectronics as using scientific methods at the atomic scale to develop nano machines and reduce their size, risk, and surface area. The program covers advantages of nanoelectronics like miniaturization and exploring molecular properties. It also discusses industrial applications in areas like computers, displays, and communications. Finally, it outlines the program delivery methodology and various career opportunities in related fields.
CARBON NANO TUBE -- PREPARATION – METHODSArjun K Gopi
The document discusses carbon nanotubes, including their structure and properties. It describes three common production methods: arc discharge, laser ablation, and chemical vapor deposition. Arc discharge was the initial discovery method and remains widely used, but it produces impurities. Laser ablation yields primarily single-walled nanotubes but is expensive. Chemical vapor deposition allows control over diameter and is suitable for scaling up. Purification techniques are needed to separate nanotubes from byproducts. Potential applications include electronics, energy storage, and reinforced composites.
The document summarizes research on understanding charge transport in low dimensional semiconductor nanostructures embedded in an insulating matrix. Specifically, it examines current-voltage characteristics of germanium nanowire arrays in an alumina matrix as a function of temperature. Key findings include:
1) At room temperature, conduction follows Ohm's law at low voltages and Mott-Gurney's space charge limited current law at higher voltages.
2) With decreasing temperature, conduction transitions from a trap-free regime to an exponentially distributed trap regime.
3) Mobility decreases with decreasing temperature, and activation energy is extracted from an Arrhenius plot, found to be 85 meV at low temperatures and 301 meV
Diamond and graphite are both allotropes of carbon that differ in their atomic structure and properties. Diamond is very hard with strong covalent bonds, while graphite is soft with layers of atoms that can slide over each other. Fullerenes are spherical structures made entirely of carbon, such as buckyballs composed of 60 carbon atoms. Nanotubes are made by joining fullerenes into tubes that are very strong and can conduct electricity. Nanoparticles, such as gold nanoparticles or quantum dots, also exhibit size-dependent properties useful for applications like drug delivery.
This document discusses nanotechnology and provides an overview of the topic in several paragraphs. It defines nanotechnology as manipulating matter at the nanoscale, or one billionth of a meter. It then outlines some of the potential applications of nanotechnology in electronics, energy, materials, and life sciences. Some advantages are described as stronger, lighter, cheaper and more durable materials. Disadvantages mentioned include potential job losses and health effects. The future of nanotechnology is presented as transforming almost every human-made object over the next century through developments like electronic paper and advanced contact lenses.
Carbon nanotubes are allotropes of carbon that exist as cylindrical structures with a high length-to-diameter ratio. They can be single-walled or multi-walled depending on the number of concentric cylinders. Carbon nanotubes have extraordinary properties including high strength, stiffness, thermal conductivity, and electrical conductivity. Due to these properties, carbon nanotubes show promise for applications in electronics, hydrogen storage, solar cells, biosensors, drug delivery, and more.
Mossbauer spectroscopy - Principles and applicationsSANTHANAM V
Mossbauer spectroscopy involves the absorption of gamma ray photons by atomic nuclei. It can provide information about chemical environments and oxidation states. The document discusses key principles such as recoil effect, Doppler tuning, conditions required for Mossbauer spectra, instrumentation, and information that can be obtained from isomer shift, quadruple splitting, and magnetic interactions. Iron-57 is the most commonly studied isotope due to its suitable nuclear properties and applications in chemistry, mineralogy, and biology.
This document provides information about a nanoelectronics and industrial applications program offered by the Nano Science & Technology Consortium. It defines nanoelectronics as using scientific methods at the atomic scale to develop nano machines and reduce their size, risk, and surface area. The program covers advantages of nanoelectronics like miniaturization and exploring molecular properties. It also discusses industrial applications in areas like computers, displays, and communications. Finally, it outlines the program delivery methodology and various career opportunities in related fields.
CARBON NANO TUBE -- PREPARATION – METHODSArjun K Gopi
The document discusses carbon nanotubes, including their structure and properties. It describes three common production methods: arc discharge, laser ablation, and chemical vapor deposition. Arc discharge was the initial discovery method and remains widely used, but it produces impurities. Laser ablation yields primarily single-walled nanotubes but is expensive. Chemical vapor deposition allows control over diameter and is suitable for scaling up. Purification techniques are needed to separate nanotubes from byproducts. Potential applications include electronics, energy storage, and reinforced composites.
The document summarizes research on understanding charge transport in low dimensional semiconductor nanostructures embedded in an insulating matrix. Specifically, it examines current-voltage characteristics of germanium nanowire arrays in an alumina matrix as a function of temperature. Key findings include:
1) At room temperature, conduction follows Ohm's law at low voltages and Mott-Gurney's space charge limited current law at higher voltages.
2) With decreasing temperature, conduction transitions from a trap-free regime to an exponentially distributed trap regime.
3) Mobility decreases with decreasing temperature, and activation energy is extracted from an Arrhenius plot, found to be 85 meV at low temperatures and 301 meV
Diamond and graphite are both allotropes of carbon that differ in their atomic structure and properties. Diamond is very hard with strong covalent bonds, while graphite is soft with layers of atoms that can slide over each other. Fullerenes are spherical structures made entirely of carbon, such as buckyballs composed of 60 carbon atoms. Nanotubes are made by joining fullerenes into tubes that are very strong and can conduct electricity. Nanoparticles, such as gold nanoparticles or quantum dots, also exhibit size-dependent properties useful for applications like drug delivery.
This document discusses nanotechnology and provides an overview of the topic in several paragraphs. It defines nanotechnology as manipulating matter at the nanoscale, or one billionth of a meter. It then outlines some of the potential applications of nanotechnology in electronics, energy, materials, and life sciences. Some advantages are described as stronger, lighter, cheaper and more durable materials. Disadvantages mentioned include potential job losses and health effects. The future of nanotechnology is presented as transforming almost every human-made object over the next century through developments like electronic paper and advanced contact lenses.
This document describes various types of chemical sensors (chemosensors) including intrinsic, conjugate, and self-assembled chemosensors. Intrinsic chemosensors have the analyte directly interact with the fluorophore, altering emission properties. Conjugate chemosensors separate the receptor and fluorophore with a spacer, requiring a transduction mechanism. Self-assembled chemosensors use coordination-driven assembly where the analyte binds a metal ion complex, potentially quenching the fluorophore. Examples are given of each using various fluorescent dyes to detect ions and biomolecules based on fluorescence intensity changes.
The document discusses how 2D materials can advance energy storage and discusses several research projects utilizing 2D materials for lithium and sodium-ion batteries. It summarizes that integrating selected 2D lithium host materials into 3D architectures can improve electrochemical performance through increased surface area and diffusion pathways. Composite 2D-3D microstructures incorporating graphene offer multiple functional enhancements for energy storage systems. There is a need to explore advanced manufacturing methods for nanostructured materials.
This presentation summarizes history and recent development of perovskite solar cells. If you have any questions or comments, you can reach me at agassifeng@gmail.com
This document provides an introduction to 2D materials, including a brief history and overview of types. It discusses graphene, the earliest known 2D material, which consists of a single layer of carbon atoms arranged in a honeycomb structure. Graphene is nearly transparent, yet over 100 times stronger than steel. It has the highest thermal and electrical conductivity of any known material. The document also mentions other 2D materials like germanene, silicene, phosphorene, and transition metal dichalcogenides.
Self-healing materials are smart materials that can intrinsically repair damage leading to longer lifetimes, reduction of inefficiency caused by degradation and material failure.
Applications include shock absorbing materials, paints and anti-corrosion coatings and more recently, conductive self-healing materials for circuits and electronics.
This document discusses carbon nanotubes, including their structure, properties, production methods, and applications. Carbon nanotubes have a cylindrical structure composed entirely of sp2 bonds. They have excellent mechanical and thermal properties and can be metallic or semiconducting depending on their structure. Common production methods include arc discharge, laser ablation, and chemical vapor deposition. Potential applications of carbon nanotubes include use in structural materials, electronics, energy storage, and biomedicine. However, health effects of carbon nanotube inhalation require further study.
Carbon foams will help to enhance capabilities and improve affordability, supporting today’s warfighter. Applications for coal-based carbon foams continue to be developed as the material is accepted as a mainstream structural building block for tomorrow’s technology. Current application examples include targeted advances in composite tooling, vehicle blast mitigation, radar absorption, and ablation panels.
biodegradable ceramics polymer matrix composite for bio medical applicationRanju M Ramachandran
The document discusses biodegradable ceramic-polymer composites for biomedical applications. It introduces biopolymers and biodegradable materials. Common issues with permanent implants like stress shielding and inflammation are described. The need for biodegradable implants that can degrade over time without issues is explained. Different types of biodegradable ceramic-polymer composites are summarized, including those based on silica, bioglass, wollastonite and calcium phosphates. These composites can provide controlled properties for tissue engineering by combining ceramics and polymers. In conclusion, biodegradable ceramic-polymer composites offer advantages over isolated ceramics or polymers for regenerative medicine applications.
This document discusses ferromagnetic nanomaterials. It introduces magnetic nanoparticles and their size requirements for various applications. It describes the magnetic properties of ferromagnetic materials and how temperature and magnetic fields affect them. Common ferromagnetic elements are iron, nickel and cobalt. Their magnetic domains can be aligned with external fields. Preparation methods like co-precipitation and thermal decomposition are discussed. Applications include nanomagnetism, targeted drug delivery, and using zero valent iron for groundwater remediation.
This document summarizes structural characterization techniques for amorphous materials. It discusses how amorphous materials have short-range order dominated by atomic bonding but no long-range translational order. Common characterization methods measure pair distribution functions to determine local structure. Structure varies between classes of amorphous materials like metallic glasses, molecular glasses, and covalent network glasses.
Quantum dots (QD) are semiconductors made via several possible routes. John Ashmead discusses how they are made, their properties and their applications in research.
Synthetic polymers have many applications in biomedical fields such as bone fracture repair, hip joint replacements, ligaments, tendons, contact lenses, sutures, and burn treatments. Polymers are used where biostability is needed for long-term implants, as biodegradable temporary implants, or as water soluble components of blood substitutes. Common polymers used include PMMA, PGA, PCL, silicone, PUs, nylon and polyacrylates which are chosen based on their mechanical properties, biocompatibility and degradation time frame needed for the application. The variety of polymers and their applications in biomedicine has grown tremendously and is expected to continue expanding to improve medical treatments.
The document discusses several applications of nanotechnology. It begins by summarizing some natural structures like spider silk and butterfly wings that demonstrate nanoscale properties like strength and iridescence. It then defines nanotechnology as the manipulation of matter between 1-100 nanometers. Some potential applications of nanotechnology mentioned include carbon nanotubes that are stronger than steel, graphene that is lighter than steel, and aerogels that are 98% air. The document also notes how nanotechnology can be developed using top-down or bottom-up approaches and lists some impacts like longer-lasting clothes, faster-healing bandages, and smoke-degrading lamps.
Carbon Nanotubes(CNTs) | Characterisation and Purification methodsNitesh Sharma
Carbon nanotubes are one of the emerging materials developed in recent two decades. This report summarises the information of carbon nanotubes with their various synthesis techniques to produce CNTs. Different structures have been discussed like single-shell tubes, multi-shell tubes, bundles and cones. Notable state of the art characterization techniques like SEM, TEM, Raman Spectroscopy, Fourier Transform Infrared Spectroscopy, EDS, EDX, HRTEM has been also briefly discussed to study their structure- property correlation in this candidate material. Properties such as low dimensability, high surface-to-volume ratio is observed in carbon nanotubes. Unique mechanical, optical, electrical and electrochemical properties for carbon nanotubes are elaborately discussed here. Carbon nanotubes are advanced materials having tubular structure with nanometre diameter and large length/diameter ratio. Other properties such as density, stability is important for CNTs. Finally, prospects for carbon nanotubes are considered for carbon nanotubes.
It's simple to understand the synthesis. Hydrothermal method is a chemical reaction in water in a sealed pressure vessel, which is in fact a type of reaction at both high temperature and pressure.
Interpreting the behavior of a quarter-wave transmission line resonator in a ...Dr. Gurusharan Singh Gogna
The behavior of a quarter-wave transmission line resonator immersed in a magnetized plasma was studied. Two possible resonances were observed, occurring either below or above the resonance frequency in vacuum. The lower resonance frequency yielded an electron density 25-30% smaller than that calculated using the upper resonance frequency. At a given magnetic field strength, the resonances shifted further from the vacuum resonance frequency as the background electron density increased. The lower resonance saturated when its value approached the electron cyclotron frequency. Dual resonances were interpreted using a model considering the perpendicular component of the plasma dielectric tensor.
The document describes a laser indirect exposure method for treating nanomaterials. The method involves dipping powder materials in a transparent plastic to allow laser beams to pass through without being absorbed by the plastic. This indirectly exposes the powder to laser irradiation, improving the powder's mechanical properties. After exposure, an organic solvent is used to separate the treated nanomaterials from the dissolved plastic. Testing found the method improved properties like hardness without causing economic losses or pollution. Raman spectroscopy analysis showed the laser treatment caused changes to material spectra indicating structural changes improved mechanical characteristics.
This document describes various types of chemical sensors (chemosensors) including intrinsic, conjugate, and self-assembled chemosensors. Intrinsic chemosensors have the analyte directly interact with the fluorophore, altering emission properties. Conjugate chemosensors separate the receptor and fluorophore with a spacer, requiring a transduction mechanism. Self-assembled chemosensors use coordination-driven assembly where the analyte binds a metal ion complex, potentially quenching the fluorophore. Examples are given of each using various fluorescent dyes to detect ions and biomolecules based on fluorescence intensity changes.
The document discusses how 2D materials can advance energy storage and discusses several research projects utilizing 2D materials for lithium and sodium-ion batteries. It summarizes that integrating selected 2D lithium host materials into 3D architectures can improve electrochemical performance through increased surface area and diffusion pathways. Composite 2D-3D microstructures incorporating graphene offer multiple functional enhancements for energy storage systems. There is a need to explore advanced manufacturing methods for nanostructured materials.
This presentation summarizes history and recent development of perovskite solar cells. If you have any questions or comments, you can reach me at agassifeng@gmail.com
This document provides an introduction to 2D materials, including a brief history and overview of types. It discusses graphene, the earliest known 2D material, which consists of a single layer of carbon atoms arranged in a honeycomb structure. Graphene is nearly transparent, yet over 100 times stronger than steel. It has the highest thermal and electrical conductivity of any known material. The document also mentions other 2D materials like germanene, silicene, phosphorene, and transition metal dichalcogenides.
Self-healing materials are smart materials that can intrinsically repair damage leading to longer lifetimes, reduction of inefficiency caused by degradation and material failure.
Applications include shock absorbing materials, paints and anti-corrosion coatings and more recently, conductive self-healing materials for circuits and electronics.
This document discusses carbon nanotubes, including their structure, properties, production methods, and applications. Carbon nanotubes have a cylindrical structure composed entirely of sp2 bonds. They have excellent mechanical and thermal properties and can be metallic or semiconducting depending on their structure. Common production methods include arc discharge, laser ablation, and chemical vapor deposition. Potential applications of carbon nanotubes include use in structural materials, electronics, energy storage, and biomedicine. However, health effects of carbon nanotube inhalation require further study.
Carbon foams will help to enhance capabilities and improve affordability, supporting today’s warfighter. Applications for coal-based carbon foams continue to be developed as the material is accepted as a mainstream structural building block for tomorrow’s technology. Current application examples include targeted advances in composite tooling, vehicle blast mitigation, radar absorption, and ablation panels.
biodegradable ceramics polymer matrix composite for bio medical applicationRanju M Ramachandran
The document discusses biodegradable ceramic-polymer composites for biomedical applications. It introduces biopolymers and biodegradable materials. Common issues with permanent implants like stress shielding and inflammation are described. The need for biodegradable implants that can degrade over time without issues is explained. Different types of biodegradable ceramic-polymer composites are summarized, including those based on silica, bioglass, wollastonite and calcium phosphates. These composites can provide controlled properties for tissue engineering by combining ceramics and polymers. In conclusion, biodegradable ceramic-polymer composites offer advantages over isolated ceramics or polymers for regenerative medicine applications.
This document discusses ferromagnetic nanomaterials. It introduces magnetic nanoparticles and their size requirements for various applications. It describes the magnetic properties of ferromagnetic materials and how temperature and magnetic fields affect them. Common ferromagnetic elements are iron, nickel and cobalt. Their magnetic domains can be aligned with external fields. Preparation methods like co-precipitation and thermal decomposition are discussed. Applications include nanomagnetism, targeted drug delivery, and using zero valent iron for groundwater remediation.
This document summarizes structural characterization techniques for amorphous materials. It discusses how amorphous materials have short-range order dominated by atomic bonding but no long-range translational order. Common characterization methods measure pair distribution functions to determine local structure. Structure varies between classes of amorphous materials like metallic glasses, molecular glasses, and covalent network glasses.
Quantum dots (QD) are semiconductors made via several possible routes. John Ashmead discusses how they are made, their properties and their applications in research.
Synthetic polymers have many applications in biomedical fields such as bone fracture repair, hip joint replacements, ligaments, tendons, contact lenses, sutures, and burn treatments. Polymers are used where biostability is needed for long-term implants, as biodegradable temporary implants, or as water soluble components of blood substitutes. Common polymers used include PMMA, PGA, PCL, silicone, PUs, nylon and polyacrylates which are chosen based on their mechanical properties, biocompatibility and degradation time frame needed for the application. The variety of polymers and their applications in biomedicine has grown tremendously and is expected to continue expanding to improve medical treatments.
The document discusses several applications of nanotechnology. It begins by summarizing some natural structures like spider silk and butterfly wings that demonstrate nanoscale properties like strength and iridescence. It then defines nanotechnology as the manipulation of matter between 1-100 nanometers. Some potential applications of nanotechnology mentioned include carbon nanotubes that are stronger than steel, graphene that is lighter than steel, and aerogels that are 98% air. The document also notes how nanotechnology can be developed using top-down or bottom-up approaches and lists some impacts like longer-lasting clothes, faster-healing bandages, and smoke-degrading lamps.
Carbon Nanotubes(CNTs) | Characterisation and Purification methodsNitesh Sharma
Carbon nanotubes are one of the emerging materials developed in recent two decades. This report summarises the information of carbon nanotubes with their various synthesis techniques to produce CNTs. Different structures have been discussed like single-shell tubes, multi-shell tubes, bundles and cones. Notable state of the art characterization techniques like SEM, TEM, Raman Spectroscopy, Fourier Transform Infrared Spectroscopy, EDS, EDX, HRTEM has been also briefly discussed to study their structure- property correlation in this candidate material. Properties such as low dimensability, high surface-to-volume ratio is observed in carbon nanotubes. Unique mechanical, optical, electrical and electrochemical properties for carbon nanotubes are elaborately discussed here. Carbon nanotubes are advanced materials having tubular structure with nanometre diameter and large length/diameter ratio. Other properties such as density, stability is important for CNTs. Finally, prospects for carbon nanotubes are considered for carbon nanotubes.
It's simple to understand the synthesis. Hydrothermal method is a chemical reaction in water in a sealed pressure vessel, which is in fact a type of reaction at both high temperature and pressure.
Interpreting the behavior of a quarter-wave transmission line resonator in a ...Dr. Gurusharan Singh Gogna
The behavior of a quarter-wave transmission line resonator immersed in a magnetized plasma was studied. Two possible resonances were observed, occurring either below or above the resonance frequency in vacuum. The lower resonance frequency yielded an electron density 25-30% smaller than that calculated using the upper resonance frequency. At a given magnetic field strength, the resonances shifted further from the vacuum resonance frequency as the background electron density increased. The lower resonance saturated when its value approached the electron cyclotron frequency. Dual resonances were interpreted using a model considering the perpendicular component of the plasma dielectric tensor.
The document describes a laser indirect exposure method for treating nanomaterials. The method involves dipping powder materials in a transparent plastic to allow laser beams to pass through without being absorbed by the plastic. This indirectly exposes the powder to laser irradiation, improving the powder's mechanical properties. After exposure, an organic solvent is used to separate the treated nanomaterials from the dissolved plastic. Testing found the method improved properties like hardness without causing economic losses or pollution. Raman spectroscopy analysis showed the laser treatment caused changes to material spectra indicating structural changes improved mechanical characteristics.
The document describes a laser indirect exposure method for treating nanomaterials. The method involves dipping powder materials in a transparent plastic to allow laser beams to pass through without being absorbed by the plastic. This indirectly exposes the powder to laser irradiation, which improves the mechanical properties of the materials. After exposure, an organic solvent is used to separate the treated nanomaterials from the dissolved plastic. Testing showed that laser treatment led to changes in Raman spectra and increased hardness of the treated materials. The method improves properties through laser energy absorption without causing economic losses or pollution.
The document describes a laser indirect exposure method for treating nanomaterials. The method involves dipping powder materials in a transparent plastic to allow laser beams to pass through without being absorbed. This indirectly exposes the powder to laser irradiation, improving its mechanical properties. After exposure, an organic solvent is used to remove the treated nanomaterials from the transparent plastic. The method physically improves properties without pollution and does not waste treated materials. It was found to improve hardness and modify Raman spectra of treated materials.
The document summarizes recent progress in piezoelectric materials for MEMS applications. It discusses advances in processing lead zirconate titanate (PZT) thin films with reduced composition gradients to improve piezoelectric properties. Applications explored include bulk acoustic wave devices, piezoelectric micro-machined structures in deflective mode like ultrasonic transducers, and future work on domain engineering of thin films.
The document discusses the concept of using laser trapped mirrors (LTM) in space. LTMs would involve using laser light to trap microscopic particles in patterns that act as reflective surfaces, allowing for the creation of very large, lightweight mirrors. The goals of the project discussed are to demonstrate a small LTM in water, model LTMs computationally including optical binding forces, and estimate mirror stability, quality and laser power needs for a vacuum environment. LTMs could enable very large aperture mirrors weighing only 100g that are resilient to damage and can self-heal.
Amorphous-nano-crystalline silicon composite thin films (a-nc-Si:H) samples were synthesized by
Plasma Enhanced Chemical Vapor Deposition technique. The measurement of DC conductivities was
accomplished using Dielectric spectroscopy (Impedance Spectroscopy) in wide frequency and temperature range.
In analysis of impedance data, two approaches were tested: the Debye type equivalent circuit with two parallel R
and CPEs (constant phase elements) and modified one, with tree parallel R and CPEs including crystal grain
boundary effects. It was found that the later better fits to experimental results properly describes crystal grains
dielectric effect and hydrogen concentration indicating presence of strain. The amorphous matrix showed larger
resistance and lower capacity than nano-crystal phase. Also it was found that composite silicon thin film cannot
be properly described by equivalent circuit only with resistors and constant phase elements in serial relation
This document provides a thesis abstract that summarizes a PhD thesis on light-triggered molecular electronics in the 100 nm size range. The abstract outlines three key sections of the thesis. The first section presents the methodology for creating electrodes, interconnects, and measurement environments, using light as a trigger for electrical measurements. The second section acts as a proof-of-concept, showing electrical transport can be observed through photochromic molecules trapped between electrodes. The third section investigates new molecular materials, including spin crossover nanoparticles and a self-assembling molecular system that unexpectedly forms highly conductive molecular wires between electrodes under light stimulation. The abstract emphasizes the importance of studying molecular electronics at an intermediate size scale of 10-100 nm.
This document discusses the integration of a layered ferromagnetic composite material into a microwave propagation structure to enable tunable microwave device applications. The material combines the large saturation magnetization of ferromagnetic material with the low loss of dielectrics. Electromagnetic analysis was carried out to understand how the material properties are affected by the microwave field pattern and dc magnetic fields. Experimental results demonstrated tunable band stop filter and switch devices using the material, with over 50% tunability achieved in the filter using a 250 Oe dc field.
This document describes an investigation of the LaAlO3-SrTiO3 (LAO-STO) heterointerface using transmission electron microscopy (TEM). The sample was prepared using pulsed laser deposition to grow a thin film of LAO on a STO substrate, followed by ion slicing to produce a wedge-shaped cross-section for TEM analysis. The TEM results revealed a high-density two-dimensional electron gas formed at the LAO-STO interface, which has potential applications in next-generation electronic devices and holds promise for novel electronic properties.
A review on_electrospinning_design_and_nanofibre_assembliesMahbubul Hassan
This document reviews different designs for electrospinning that produce various nanofibre assemblies. Electrospinning uses electric fields to draw polymer solutions into continuous nanofibre meshes. Researchers have developed new setups to control fibre flight and collection, producing nonwoven meshes, aligned fibres, patterns, and 3D structures. A dynamic collector like a rotating drum can align fibres for applications requiring orientation, while multiple spinnerets or electrodes can generate patterns. Understanding these assembly methods allows tailoring fibres for specific applications in areas like tissue engineering and filtration.
Seminário proferido pelo pesquisador Thiago Burgo (Unicamp) em 26 de agosto de 2015 para cerca de 20 estudantes e professores, na seção UCS (Caxias do Sul, RS) do Instituto Nacional de Engenharia de Superfícies.
The document summarizes a PhD thesis on numerically and experimentally studying melt flow under the influence of electromagnetic fields. It discusses motivations for improving directional solidification of silicon for solar cells. This includes increasing crucible size and using lower purity feedstock. Electromagnetic field stirring is proposed to tailor convection and address challenges from these trends. A model experiment is developed using a GaInSn melt, and ultrasound Doppler velocimetry is used to validate numerical simulations of melt flow patterns under symmetric and asymmetric electrode configurations. The flow structures are analyzed in terms of Lorentz forces and radial pressure gradients.
This document summarizes the results of a simulation study investigating light absorption in organic solar cells with smooth and pyramidal textured surfaces. The study first optimized a flat organic solar cell structure by simulating the effects of varying each layer's thickness on short-circuit current and quantum efficiency. The optimized flat cell achieved 13.65 mA/cm2 short-circuit current and 84% quantum efficiency at 640 nm. It then proposed a pyramid textured surface to enhance light trapping and absorption compared to a smooth surface. The effects of period and height of the pyramids were analyzed to validate the light trapping model.
Attenuation in optical fiber (incomplete)-1.pptxRohitKeole
This document discusses various types of signal attenuation that occur in optical fibers. It describes intrinsic absorption due to the material composition of the fiber and extrinsic absorption due to impurities. It also covers linear scattering mechanisms like Rayleigh and Mie scattering, as well as nonlinear effects such as stimulated Brillouin and Raman scattering. Additional attenuation factors discussed include fiber bending losses, dispersion effects, and the influence of fiber imperfections.
Field Effect Transistors Based on Composite Films of poly (4 vinyl phenol) wi...theijes
In order to adjust the characteristic of pentacene thin film transistor we modified the dielectric properties of the gate insulator: the poly(4-vinylphenol) (PVP). PVP is an organic polymer with a low dielectric constant, limiting the performance of organic thin film transistor. To increase the dielectric constant of PVP controlled amount of ZnO nanoparticles have been homogeneously dispersed in the dielectric layer. The effect of the concentration of ZnO on the relative permittivity of PVP is measured using impedance spectroscopy it has been demonstrated that the permittivity increase (from 3.6 to 5.5), with no percolation phenomenon even at concentration of 50 vol%. The performance of the OTFT in terms of charge carrier mobility, threshold voltage and linkage current is evaluated. It results in a dramatic increase in both the field effect mobility and the linkage current by a factor of 10. It has been demonstrated that the threshold voltage can be adjusted it shifts from 8 to 0 when the volume concentration of ZnO varied from 0 to 50 vol%.
Sputtering of Ga-doped ZnO nanocoatings on silicon for piezoelectric transducersMariya Aleksandrova
This talk was delivered on the 8TH INTERNATIONAL SCIENTIFIC CONFERENCE “TechSys 2019” – ENGINEERING, TECHNOLOGIES AND SYSTEMS, Technical University of Sofia, Plovdiv Branch, 16-18 May 2019. The research is funded by BNSF’s grant KП06-Н27/1.
Electrospinning, a broadly used technology for electrostatic fiber formation which utilizes electrical forces to produce polymer fiber with diameters ranging from 2 nm to several micrometers using polymer solutions of both natural and synthetic polymers.
Nunit vs XUnit vs MSTest Differences Between These Unit Testing Frameworks.pdfflufftailshop
When it comes to unit testing in the .NET ecosystem, developers have a wide range of options available. Among the most popular choices are NUnit, XUnit, and MSTest. These unit testing frameworks provide essential tools and features to help ensure the quality and reliability of code. However, understanding the differences between these frameworks is crucial for selecting the most suitable one for your projects.
Generating privacy-protected synthetic data using Secludy and MilvusZilliz
During this demo, the founders of Secludy will demonstrate how their system utilizes Milvus to store and manipulate embeddings for generating privacy-protected synthetic data. Their approach not only maintains the confidentiality of the original data but also enhances the utility and scalability of LLMs under privacy constraints. Attendees, including machine learning engineers, data scientists, and data managers, will witness first-hand how Secludy's integration with Milvus empowers organizations to harness the power of LLMs securely and efficiently.
Monitoring and Managing Anomaly Detection on OpenShift.pdfTosin Akinosho
Monitoring and Managing Anomaly Detection on OpenShift
Overview
Dive into the world of anomaly detection on edge devices with our comprehensive hands-on tutorial. This SlideShare presentation will guide you through the entire process, from data collection and model training to edge deployment and real-time monitoring. Perfect for those looking to implement robust anomaly detection systems on resource-constrained IoT/edge devices.
Key Topics Covered
1. Introduction to Anomaly Detection
- Understand the fundamentals of anomaly detection and its importance in identifying unusual behavior or failures in systems.
2. Understanding Edge (IoT)
- Learn about edge computing and IoT, and how they enable real-time data processing and decision-making at the source.
3. What is ArgoCD?
- Discover ArgoCD, a declarative, GitOps continuous delivery tool for Kubernetes, and its role in deploying applications on edge devices.
4. Deployment Using ArgoCD for Edge Devices
- Step-by-step guide on deploying anomaly detection models on edge devices using ArgoCD.
5. Introduction to Apache Kafka and S3
- Explore Apache Kafka for real-time data streaming and Amazon S3 for scalable storage solutions.
6. Viewing Kafka Messages in the Data Lake
- Learn how to view and analyze Kafka messages stored in a data lake for better insights.
7. What is Prometheus?
- Get to know Prometheus, an open-source monitoring and alerting toolkit, and its application in monitoring edge devices.
8. Monitoring Application Metrics with Prometheus
- Detailed instructions on setting up Prometheus to monitor the performance and health of your anomaly detection system.
9. What is Camel K?
- Introduction to Camel K, a lightweight integration framework built on Apache Camel, designed for Kubernetes.
10. Configuring Camel K Integrations for Data Pipelines
- Learn how to configure Camel K for seamless data pipeline integrations in your anomaly detection workflow.
11. What is a Jupyter Notebook?
- Overview of Jupyter Notebooks, an open-source web application for creating and sharing documents with live code, equations, visualizations, and narrative text.
12. Jupyter Notebooks with Code Examples
- Hands-on examples and code snippets in Jupyter Notebooks to help you implement and test anomaly detection models.
A Comprehensive Guide to DeFi Development Services in 2024Intelisync
DeFi represents a paradigm shift in the financial industry. Instead of relying on traditional, centralized institutions like banks, DeFi leverages blockchain technology to create a decentralized network of financial services. This means that financial transactions can occur directly between parties, without intermediaries, using smart contracts on platforms like Ethereum.
In 2024, we are witnessing an explosion of new DeFi projects and protocols, each pushing the boundaries of what’s possible in finance.
In summary, DeFi in 2024 is not just a trend; it’s a revolution that democratizes finance, enhances security and transparency, and fosters continuous innovation. As we proceed through this presentation, we'll explore the various components and services of DeFi in detail, shedding light on how they are transforming the financial landscape.
At Intelisync, we specialize in providing comprehensive DeFi development services tailored to meet the unique needs of our clients. From smart contract development to dApp creation and security audits, we ensure that your DeFi project is built with innovation, security, and scalability in mind. Trust Intelisync to guide you through the intricate landscape of decentralized finance and unlock the full potential of blockchain technology.
Ready to take your DeFi project to the next level? Partner with Intelisync for expert DeFi development services today!
Your One-Stop Shop for Python Success: Top 10 US Python Development Providersakankshawande
Simplify your search for a reliable Python development partner! This list presents the top 10 trusted US providers offering comprehensive Python development services, ensuring your project's success from conception to completion.
Building Production Ready Search Pipelines with Spark and MilvusZilliz
Spark is the widely used ETL tool for processing, indexing and ingesting data to serving stack for search. Milvus is the production-ready open-source vector database. In this talk we will show how to use Spark to process unstructured data to extract vector representations, and push the vectors to Milvus vector database for search serving.
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-und-domino-lizenzkostenreduzierung-in-der-welt-von-dlau/
DLAU und die Lizenzen nach dem CCB- und CCX-Modell sind für viele in der HCL-Community seit letztem Jahr ein heißes Thema. Als Notes- oder Domino-Kunde haben Sie vielleicht mit unerwartet hohen Benutzerzahlen und Lizenzgebühren zu kämpfen. Sie fragen sich vielleicht, wie diese neue Art der Lizenzierung funktioniert und welchen Nutzen sie Ihnen bringt. Vor allem wollen Sie sicherlich Ihr Budget einhalten und Kosten sparen, wo immer möglich. Das verstehen wir und wir möchten Ihnen dabei helfen!
Wir erklären Ihnen, wie Sie häufige Konfigurationsprobleme lösen können, die dazu führen können, dass mehr Benutzer gezählt werden als nötig, und wie Sie überflüssige oder ungenutzte Konten identifizieren und entfernen können, um Geld zu sparen. Es gibt auch einige Ansätze, die zu unnötigen Ausgaben führen können, z. B. wenn ein Personendokument anstelle eines Mail-Ins für geteilte Mailboxen verwendet wird. Wir zeigen Ihnen solche Fälle und deren Lösungen. Und natürlich erklären wir Ihnen das neue Lizenzmodell.
Nehmen Sie an diesem Webinar teil, bei dem HCL-Ambassador Marc Thomas und Gastredner Franz Walder Ihnen diese neue Welt näherbringen. Es vermittelt Ihnen die Tools und das Know-how, um den Überblick zu bewahren. Sie werden in der Lage sein, Ihre Kosten durch eine optimierte Domino-Konfiguration zu reduzieren und auch in Zukunft gering zu halten.
Diese Themen werden behandelt
- Reduzierung der Lizenzkosten durch Auffinden und Beheben von Fehlkonfigurationen und überflüssigen Konten
- Wie funktionieren CCB- und CCX-Lizenzen wirklich?
- Verstehen des DLAU-Tools und wie man es am besten nutzt
- Tipps für häufige Problembereiche, wie z. B. Team-Postfächer, Funktions-/Testbenutzer usw.
- Praxisbeispiele und Best Practices zum sofortigen Umsetzen
HCL Notes and Domino License Cost Reduction in the World of DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-and-domino-license-cost-reduction-in-the-world-of-dlau/
The introduction of DLAU and the CCB & CCX licensing model caused quite a stir in the HCL community. As a Notes and Domino customer, you may have faced challenges with unexpected user counts and license costs. You probably have questions on how this new licensing approach works and how to benefit from it. Most importantly, you likely have budget constraints and want to save money where possible. Don’t worry, we can help with all of this!
We’ll show you how to fix common misconfigurations that cause higher-than-expected user counts, and how to identify accounts which you can deactivate to save money. There are also frequent patterns that can cause unnecessary cost, like using a person document instead of a mail-in for shared mailboxes. We’ll provide examples and solutions for those as well. And naturally we’ll explain the new licensing model.
Join HCL Ambassador Marc Thomas in this webinar with a special guest appearance from Franz Walder. It will give you the tools and know-how to stay on top of what is going on with Domino licensing. You will be able lower your cost through an optimized configuration and keep it low going forward.
These topics will be covered
- Reducing license cost by finding and fixing misconfigurations and superfluous accounts
- How do CCB and CCX licenses really work?
- Understanding the DLAU tool and how to best utilize it
- Tips for common problem areas, like team mailboxes, functional/test users, etc
- Practical examples and best practices to implement right away
How to Interpret Trends in the Kalyan Rajdhani Mix Chart.pdfChart Kalyan
A Mix Chart displays historical data of numbers in a graphical or tabular form. The Kalyan Rajdhani Mix Chart specifically shows the results of a sequence of numbers over different periods.
Programming Foundation Models with DSPy - Meetup SlidesZilliz
Prompting language models is hard, while programming language models is easy. In this talk, I will discuss the state-of-the-art framework DSPy for programming foundation models with its powerful optimizers and runtime constraint system.
Ocean lotus Threat actors project by John Sitima 2024 (1).pptxSitimaJohn
Ocean Lotus cyber threat actors represent a sophisticated, persistent, and politically motivated group that poses a significant risk to organizations and individuals in the Southeast Asian region. Their continuous evolution and adaptability underscore the need for robust cybersecurity measures and international cooperation to identify and mitigate the threats posed by such advanced persistent threat groups.
Dive into the realm of operating systems (OS) with Pravash Chandra Das, a seasoned Digital Forensic Analyst, as your guide. 🚀 This comprehensive presentation illuminates the core concepts, types, and evolution of OS, essential for understanding modern computing landscapes.
Beginning with the foundational definition, Das clarifies the pivotal role of OS as system software orchestrating hardware resources, software applications, and user interactions. Through succinct descriptions, he delineates the diverse types of OS, from single-user, single-task environments like early MS-DOS iterations, to multi-user, multi-tasking systems exemplified by modern Linux distributions.
Crucial components like the kernel and shell are dissected, highlighting their indispensable functions in resource management and user interface interaction. Das elucidates how the kernel acts as the central nervous system, orchestrating process scheduling, memory allocation, and device management. Meanwhile, the shell serves as the gateway for user commands, bridging the gap between human input and machine execution. 💻
The narrative then shifts to a captivating exploration of prominent desktop OSs, Windows, macOS, and Linux. Windows, with its globally ubiquitous presence and user-friendly interface, emerges as a cornerstone in personal computing history. macOS, lauded for its sleek design and seamless integration with Apple's ecosystem, stands as a beacon of stability and creativity. Linux, an open-source marvel, offers unparalleled flexibility and security, revolutionizing the computing landscape. 🖥️
Moving to the realm of mobile devices, Das unravels the dominance of Android and iOS. Android's open-source ethos fosters a vibrant ecosystem of customization and innovation, while iOS boasts a seamless user experience and robust security infrastructure. Meanwhile, discontinued platforms like Symbian and Palm OS evoke nostalgia for their pioneering roles in the smartphone revolution.
The journey concludes with a reflection on the ever-evolving landscape of OS, underscored by the emergence of real-time operating systems (RTOS) and the persistent quest for innovation and efficiency. As technology continues to shape our world, understanding the foundations and evolution of operating systems remains paramount. Join Pravash Chandra Das on this illuminating journey through the heart of computing. 🌟
GraphRAG for Life Science to increase LLM accuracyTomaz Bratanic
GraphRAG for life science domain, where you retriever information from biomedical knowledge graphs using LLMs to increase the accuracy and performance of generated answers
TrustArc Webinar - 2024 Global Privacy SurveyTrustArc
How does your privacy program stack up against your peers? What challenges are privacy teams tackling and prioritizing in 2024?
In the fifth annual Global Privacy Benchmarks Survey, we asked over 1,800 global privacy professionals and business executives to share their perspectives on the current state of privacy inside and outside of their organizations. This year’s report focused on emerging areas of importance for privacy and compliance professionals, including considerations and implications of Artificial Intelligence (AI) technologies, building brand trust, and different approaches for achieving higher privacy competence scores.
See how organizational priorities and strategic approaches to data security and privacy are evolving around the globe.
This webinar will review:
- The top 10 privacy insights from the fifth annual Global Privacy Benchmarks Survey
- The top challenges for privacy leaders, practitioners, and organizations in 2024
- Key themes to consider in developing and maintaining your privacy program
1. NGUYEN THAI CUONG
Nanoscale characterization of piezoelectric bio-
based polymers for their energy harvesting
applications
Supervisors: Philippe Leclere, Sophie Barrau
Mons - July 2021
2. 12 May 2023 PhD Defense - Mons 2
Evolution of smart wearables promotes the use of self-powered systems
"We don't want humans to be aware of
what they are wearing. It has to be
self-contained piece that can charge
itself, store energy and perform useful
functions."
Maksim Skorobogatiy, physicist at
Ecole Polytechnique de Montreal.
H-index: 53 with more than 10000
citations.
Phase 4
Implantable
Phase 1
Accessory
Phase 3
Patchable
Phase 2
Portable
2016 2017 2020 2025
• Body implantable
• Low weight
• Self-sustain
• Safety to human body
Source: ID Tech, Smart Wearables: Reflection and Orientation paper,
European Commission, 2016.
• Flexible/Stretchable
• Ultrathin
• Conformal to skin
• Textile-Integrated
• Reduced in size
• Integrated to electronic
• Accessory-type devices
• Low-power
• Conformal to body
Issues
and
Shapes
3. A typical ceramic-based
piezoelectric harvester
12 May 2023 3
Piezoelectric materials - great candidates for wearable, self-powered devices
Piezoelectric effect
Force
Biochemical
sources
Radiant
sources
Thermal
sources
Mechanical
sources
µW/cm
2
or
µW/cm
3
100µW
100000
10000
1000
100
10
1
0,1
Inorganic piezoelectric materials
1µW 10µW 100µW 1mW 10mW 100mW 1W+
Smart Watch
~5µW
LCD clock
~500µW
Hearing aids
~2mW
Headphone
~60mW
Smartphone
~2W
Maurya, D., Yan, Y. & Priya, S. J.et al. Adv. Mater. Clean Energy 50–71 (2015).
The need for alternative piezoelectric material which is
biocompatible, flexible and cheap!
Brittle
Toxic to human body (e.g., PZT)
Expensive, not easy to process
High piezoelectric coefficients
PhD Defense - Mons
4. 12 May 2023 4
Poly(L-lactic acid) as a promising piezoelectric biopolymer
Shear piezoelectricity without poling
Low piezoelectric constant (compared to
PVDF and PVDF-TrFE)
Easy to process and cheap
Biocompatible
Highest piezoelectric constant for
piezoelectric biopolymer
Piezoelectricity of crystallized PLLA film originates from the re-alignment
of the C=O dipole under external stress!
Applying stress
PhD Defense - Mons
PLLA
Li, X. et al. Energy Technol. 8, 1901252 (2020)
Shear piezoelectricity response of PLLA
5. 12 May 2023 5
Electrospinning - an efficient approach to induce ferroelectricty in PLLA
What about crystallized PLLA nanofibers? Do they exhibit better ferroelectricity?
High voltage
power supply
Syringe bump
Plastic bump
Collector
Our relative questions are:
Non-polar
polar
What is the response of PLLA composite nanofibers? Do they exhibit better piezoelectricity as we expected?
Sultana, A. et al. J. Mater. Chem. B 5, 7352–7359 (2017).
Amorphous
PLA nanofibers!
Amorphous PLLA electrospun fiber displays not only piezoelectricity but also ferroelectricity!
PhD Defense - Mons
6. 6
Outline of my thesis
12 May 2023
Crystallinity
Mechanical
Properties
Piezoelectric
Properties
Crystallized
PLLA fibers
Part 1
BTO/PLLA
nanofibers
Mechanical
Properties
Piezoelectric
Properties
Crystallinity
Part 2
Part 3 Synthesis and characterization of bio-based Non-Isocyanate Polyurethane with
ferroelectric potential
PhD Defense - Mons
7. 12 May 2023 7
Advanced AFM technique - Peakforce QNM for nanomechanical properties
Approach
Withdrawal
Peakforce
Force
Time
Tip trajectory
Tip-sample separation
Force
Approach
Withdrawal
Fit for modulus
adhesion
disspation
deform
Peakforce
Laser
Quadrant
Photodiode
z-signal
Feedback
Electronics
Scanner
Cantilever
Sample
Contact mechanic
Models
Hertz
JKR
DMT
Surface
forces
Attraction Attraction
Up to 8 channels:
1. Topography
2. Peakforce Error
3. Elastic Modulus
4. Log DMT
5. Adhesion
6. Indentation
7. Deformation
8. Dissipation
Dimension Icon (Bruker)
PhD Defense - Mons
8. 12 May 2023 8
Piezoresponse Force Microscopy for piezoelectricity and ferroelectricity at nanoscale
Vertical PFM Lateral PFM
Vertical
Direction
Rotation
P P
• Vertical PFM: detect out-of-plane polarization
• Lateral PFM: detect in-plane polarization
Imaging method
Vorpahl, S. M. et al. ACS Appl. Energy Mater. 1, 1534–1539 (2018).
Topography VPFM Amplitude VPFM Phase
• For many years, the presence of PFM hysteresis loops is the
clear evidence of ferroelectricity at nanoscale!
MFP-3D (Asylum Research)
• Able to go up to ±220 V bias.
• Able to apply DFRT-PFM.
• Easy to carry out.
PhD Defense - Mons
Switching Spectroscopy method
Sample bias (V)
PFM
Amplitude
(pm)
Sample bias (V)
PFM
Phase
(degrees)
9. 12 May 2023 9
Fabrication and characterization methods
Sample Preparation:
Characterization methods:
Electrospinning
• V= 24 kV
• d= 19 cm
PLLA nanofibers
on different substrates
Post-annealing
6%wt PLLA (L130) in
DCM/Acetonitrile
DSC XRD FTIR Advanced AFM techniques
PhD Defense - Mons
10. 12 May 2023 10
Effect of annealing process on the overall crystallinity
• As-spun sample: amorphous
• Annealed samples: semi-crystalline.
• Highest crystallinity at 160°C.
• Annealing time had little effect.
exo up
PhD Defense - Mons
11. 12 May 2023 11
Effect of annealing process on crystalline phases
• As-spun and fibers annealed at 60°C remained as
amorphous.
• Two prominent peaks at 16.7° and 19.1° proves the
increased crystallinity.
• Samples annealed at 140°C and 160°C: α-phase.
Samples annealed at 80-120°C : α'-phase.
• 955 cm-1: amorphous fraction.
• 921 cm-1: crystalline fraction (α' and α).
• Multiple band-splitting in the spectral region of
750-650 cm-1 : α-phase is dominant. No band-
splitting in 750-650 cm-1 : α'-phase is dominant.
Samples annealed at 160°C were selected as the representatives for crystallized PLLA nanofibers!
PhD Defense - Mons
12. 12 May 2023 12
Morphologies of PLLA nanofibers by Tapping AFM
Amorphous
Crystallized
Mesophase
Crystalline
phase
PhD Defense - Mons
13. 12 May 2023 13
Effect of annealing process on fiber diameter
Amorphous Crystallized
• Estimation of fiber diameter by measuring the its width is
poorly accurate due to tip convolution effect.
• Fiber diameter = distance from the substrate to the
highest point of the cross-section profile.
• Number of fibers for the calculation: N = 100.
• The decrease of the fiber diameter upon annealing
originates from the collapse of the pores and the merging
of crystallite domains.
PhD Defense - Mons
14. 12 May 2023 14
Local mapping of mechanical properties by Peakforce QNM
Amorphous
Crystallized
• Crystallized PLLA nanofibers consist of spherical crystallite domains surrounded by armorphous domains.
PhD Defense - Mons
15. 12 May 2023 15
Elastic and plastic deformation as a function of applied force
Amorphous Crystallized
• The onset of plastic deformation is 50 nN for as-spun and 100 nN for annealed PLLA nanofiber.
• In the elastic region, the contact modulus remains constant as the force increases.
• The elastic contact modulus values were chosen from the region where elastic deformation is dominant.
PhD Defense - Mons
Elastic Plastic
Elastic Plastic
16. 12 May 2023 16
Mapping of adhesion force proves the onset of plastic deformation
50 nN 90 nN back to 50 nN 100 nN back to 50 nN
Amorphous
Crystallized
30 nN 50 nN back to 30 nN 60 nN back to 30 nN
PhD Defense - Mons
17. 12 May 2023 17
Comparison of contact modulus between as-spun and annealed PLLA nanofibers
Amorphous
Crystallized
crystallized
PLLA film
Amorphous PLLA film
• A common trend for both amorphous and crystallized PLLA
nanofibers: The smaller the diameter, the higher the contact
modulus.
• After 300 nm, the contact modulus reach the values of bulk
materials.
• All heat-treated nanofibers show enhanced contact modulus
compared to that of the pristine ones.
PhD Defense - Mons
18. 12 May 2023 18
P(VDF-co-TrFE) thin film as a reference sample for PFM measurement
P(VDF-co-TrFE) 70/30
-(VDF)- -(TrFE)-
• A well-studied ferroelectric polymer
• A popular material for flexible
piezoelectric harvesting application
P(VDF-co-TrFE)
in MEK
P(VDF-co-TrFE)
thin film
140°C
2h
1
2
3
4
Spin
Coating
ITO substrate
Before annealing After annealing
0 10 20 30 40
0
100
200
300
400
Height
(nm)
Distance (µm)
168
170 nm
PhD Defense - Mons
19. 12 May 2023 19
Ferroelectric analysis of P(VDF-co-TrFE) thin film by Piezoresponse Force Microscopy
Spectroscopy method
• Both methods indicate a PFM amplitude of ~ 500 pm, proving
that a consistent result can be achieved by both methods.
• Hysteresis PFM loops prove the ferroelectric nature of the
P(VDF-co-TrFE).
• Coercive voltage Vc = ±14 V.
+30V
-30V
+30V
-30V
Imaging method
PFM
Amplitude
PFM
Phase
0 2 4 6 8 10 12 14
-50
0
50
100
150
Phase
(°)
Distance (mm)
130°
-50°
PhD Defense - Mons
20. 12 May 2023 20
Local hysteresis loops of amorphous PLLA fibers by PFM
Fibre 175nm Fibre 228nm Fibre 305nm
Vc = ±44 V Vc = ±50 V Vc = ±60 V
PhD Defense - Mons
21. 12 May 2023 21
Local hysteresis loops of crystallized fibers by AFM
Fibre 168nm Fibre 235nm Fibre 352nm
Vc = ±33 V Vc = ±37 V Vc = ±46 V
PhD Defense - Mons
22. 12 May 2023 22
Comparison of local piezoelectricity between PLLA nanofiber and PVDF copolymer
• Mean and standard deviation values were calculated from 15 different nanofibers (n=15).
• Annealed nanofibers show increased piezoelectric response compared to as-spun samples.
• The piezoresponse of crystallized nanofibers are still low compared to PVDF-TrFE thin film.
PhD Defense - Mons
23. 12 May 2023 23
• Post-annealing process show a positive effect on crystallinity, mechanical and piezoelectric properties of electrospun PLLA nanofibers.
• Electrospun nanofibers show better mechanical properties than their film counterpart, but only in a certain range of diameter.
• The piezoelectric response of crystallized PLLA nanofibers are still much lower than that of PVDF-TrFE → room for improvement →
Part 2.
Conclusions for part 1
Amorphous
Crystallized
crystallized
PLLA film
Amorphous PLLA film
PhD Defense - Mons
24. 12 May 2023 24
Outline of my thesis
Crystallinity
Mechanical
Properties
Piezoelectric
Properties
Crystallized
PLLA fibers
Part 1
BTO/PLLA
nanofibers
Mechanical
Properties
Piezoelectric
Properties
Crystallinity
Part 2
Part 3 Synthesis and characterization of bio-based Non-Isocyanate Polyurethane with
ferroelectric potential
PhD Defense - Mons
25. 12 May 2023 25
Characterization of Barium Titanate nanoparticles
• Barium Titanate is a good piezoelectric ceramic (d33 =
350-460 pm/V) with non-toxic elements.
• Commercial BTO nanoparticles purchased from Inframat
(France).
• Average diameter (N= 200): 240 ± 62 nm.
• The presence of a doublet at 2θ = 45° confirms the
ferroelectric nature of the BTO powder.
Barium Titanate powder
(Inframat)
Cubic
(Paraelectric)
Tetragonal
(Ferroelectric)
PhD Defense - Mons
26. 12 May 2023 26
Fabrication and characterization methods of BTO/PLLA electrospun nanofibers
BTO/PLLA nanofibers
on different substrates
BTO/PLLA
Solution
PLLA in
DCM/Acetonitrile
5%wt BTO
DSC XRD SEM Advanced AFM methods
Post-annealing
160°C 2h
Sample Preparation:
Characterization methods:
Electrospinning
• V= 24 kV
• d= 15 cm
PhD Defense - Mons
27. 12 May 2023 27
Morphologies of BTO/PLLA nanofibers by SEM
6 wt% 10 wt% 15 wt% 20 wt%
PLLA
PLLA/BTO
• The addition of BTO significantly change the morphologies of the resulting fibers, compared to pure PLLA.
• The condition of 15 wt% of PLLA was selected as the optimum condition for electrospinning of BTO/PLLA composites.
PhD Defense - Mons
28. 12 May 2023 28
Effect of BTO addition and annealing process on the BTO/PLLA fiber diameter
As-spun
Annealed
PLLA 15%wt BTO 5%wt /PLLA 15%wt BTO 5%wt /PLLA 15%wt
• Size distribution is calculated from 100 individual nanofibers for each case.
• The addition of BTO nanoparticles lead to a decrease in the average diameter.
• Further heat-treatment at 160°C reduced the average diameter of the hybrid nanofibers, a similar trend as observed in the previous part.
PhD Defense - Mons
29. 12 May 2023 29
BSE and EDX results confirm the presence of BTO nanoparticles
As-spun
Annealed
• EDX spectra prove the existence of BTO
particles.
• BTO particles appear as brighter spots
compared to PLLA fiber due to higher Z
number.
• BSE images reveal that BTO particle are
embedded deeply inside the PLLA
nanofibers.
PhD Defense - Mons
30. 12 May 2023 30
Crystallinity and crystalline phase of BTO/PLLA nanofibers
• Pristine BTO/PLLA mostly amorphous with : χc = 4.7 %. Annealed BTO/PLLA highly crystallized: χc = 75.2 %
• Annealed BTO/PLLA sample mostly contains α-crystalline phase.
• The presence of a doublet at 2θ = 45° confirms the ferroelectric nature of the BTO nanoparticles after the fabrication
and post-treatment process.
• χc = 4.7 %
• χc = 75.2 %
PhD Defense - Mons
BTO
BTO
BTO
BTO
31. 12 May 2023 31
Local mechanical properties of BTO/PLLA fibers
Modulus Deformation Cross-section Profile
Amorphous
Crystallized
PhD Defense - Mons
32. 12 May 2023 32
Local mechanical properties as a function of applied force
50nN 70nN 90nN 100nN
120nN 150nN 170nN 200nN 220nN
50nN 70nN 90nN 100nN
120nN 150nN 170nN 200nN 220nN
Modulus
Deformation
• The influence of BTO nanoparticle become
more remarkable at high applied forces.
• A modulus value of ~ 90GPa is observed at
220 nN in the region embedded with BTO
nanoparticles.
• The results prove the increased impact
strength of the PLLA nanofibers by the
addition of BTO.
PhD Defense - Mons
33. 12 May 2023 33
Local piezoelectricity by PFM of BTO/PLLA nanofibers-Q factor and Resonant frequencies
4
3
1
2
• For the areas covered by pure PLLA nanofibers, there are no significant changes for Q factor and contact resonance frequencies.
• The increase in quality (Q) factor of the green region results from changes in the elastic and damping properties of BTO nanoparticles.
• The amplitude response of the cantilever increase signifcantly on the region embedded with BTO particles, which is an qualitative
indication of a better electroactive response.
Crystallized BTO/PLLA fiber
PhD Defense - Mons
34. 12 May 2023 34
Effect of BTO nanoparticles on the local piezoelectric response of PLLA fiber
3
1
2
Spot 3
Spot 2
Spot 1
• The piezoresponse of PLLA regions
embedded with BTO particle is much higher
than the pure PLLA regions.
• The PFM amplitude is improved by 7 times.
• The coercive bias Vc is about 24 V, much less
than pure PLLA fiber.
Crystallized BTO/PLLA fiber
PhD Defense - Mons
35. 12 May 2023 35
Comparison of local piezoelectricity between PLLA nanofiber and PVDF copolymer
PhD Defense - Mons
• BTO/PLLA nanofibers show enhanced piezoelectric and ferroelectric activities compared to P(VDF-co-TrFE) thin film!
36. 12 May 2023 36
• Post-annealing process at controlled temperature can improve the crystallinity and crystalline phase of the electrospun PLLA
nanofiber. Consequently, its mechanical and piezoelectric properties can also be improved.
• The addition of inorganic BTO nanoparticles has positive effects on the piezoelectric and ferroelectric properties of the PLLA
nanofibers.
• These results proves the potential of PLLA nanofibers and PLLA composites for self-sustained wearable applications.
Final conclusions
PhD Defense - Mons
37. 12 May 2023 37
Perspectives for future work
nano-PUND for direct piezoelectric
measurement
non-destructive PFM for soft,
piezoelectric materials
PhD Defense - Mons
38. 12 May 2023 38
People
• Prof. Philippe Leclère
• Prof. Valerie Gaucher
• Dr. Sophie Barrau
• Dr. Liam Collins
• Dr. Alexandre Fadel
• Dr. Malo Dufay
• Dr. Anthony Ferri
• Dr. Antonio Da Costa
• Dr. Nicolas Tabary
• Dr. Valentina Sessini
Institutions
o University of Lille
o University of Mons (UMONS)
o University of Artois
Laboratories
o UMET
o CMN
o SMPC
o Materia Nova
Acknowledgements
PhD Defense - Mons
39. 12 May 2023 PhD Defense - Lille 39
Thank you for
your attention!
40. 12 May 2023 PhD Defense - Lille 40
• Studies of mechanical and piezoelectric properties of electrospun
PLLA nanofibers with post-annealing process
• A correlation between crystallinity, crystalline phase, and the
resulting physical properties was studied.
Part 1
• Effects of piezoelectric inorganic nanoparticles incorporation on the
mechanical and piezoelectric properties of a single PLLA nanofibers
were studied.
Part 2
• Study the nanostructure and its effect on mechanical and
piezoelectric properties of Non-isocyanate polyurethane (NIPU)
films.
Part 3
41. 12 May 2023 PhD Defense - Lille 41
Synthesis routes for NIPUs
• Several NIPUs were synthesized from Resorcinol (RBC) and two diamines.
• Amino-telechelic oligoamide (bioATO) was used as a bio-based chain extender.
• Total of 3 samples: RBC-CAD, RBC-PUTR and RBC-CAD-bioATO.
42. 12 May 2023 PhD Defense - Lille 42
Morphologies of NIPU by Tapping AFM
RBC-CAD RBC-PUTR RBC-CAD-bioATO
43. 12 May 2023 PhD Defense - Lille 43
Morphological changes of NIPUs as a function of temperature
25 °C 30 °C 35 °C 40 °C
45 °C 50 °C 55 °C 60 °C
65 °C 70 °C 75 °C 25 °C
44. 12 May 2023 PhD Defense - Lille 44
Local mechanical mapping of NIPUs
RBC - CAD RBC - PUTR RBC – CAD - bioATO
Height
Modulus
Adhesion
45. 12 May 2023 PhD Defense - Lille 45
Quantitative contact modulus of NIPUs by AFM
RBC-CAD RBC-PUTR
RBC-CAD-bioATO
46. 12 May 2023 PhD Defense - Lille 46
Ferroelectric-like behaviour of RBC-CAD-bioATO
-20 -10 0 10 20
-0.2
-0.1
0.0
0.1
0.2
Polarization
(
m
C
cm
-2
)
Electric Field (kV mm
-1
)
-20 -10 0 10 20
-0.2
-0.1
0.0
0.1
0.2
Pr
= 0.05 mC cm
-2
Polarization
(
m
C
cm
-2
)
Electric Field (kV mm
-1
)
-20 -10 0 10 20
-0.01
0.00
0.01
Current
density
(
m
A
cm
-2
)
Electric Field (kV mm
-1
)
-20 -10 0 10 20
-0.02
-0.01
0.00
0.01
0.02
Current
density
(
m
A
cm
-2
)
Electric Field (kV mm
-1
)
a) b)
c) d)
-20 -10 0 10 20
-0.2
-0.1
0.0
0.1
0.2
Polarization
(
m
C
cm
-2
)
Electric Field (kV mm
-1
)
-20 -10 0 10 20
-0.2
-0.1
0.0
0.1
0.2
Pr
= 0.05 mC cm
-2
Polarization
(
m
C
cm
-2
)
Electric Field (kV mm
-1
)
-20 -10 0 10 20
-0.01
0.00
0.01
Current
density
(
m
A
cm
-2
)
Electric Field (kV mm
-1
)
-20 -10 0 10 20
-0.02
-0.01
0.00
0.01
0.02
Current
density
(
m
A
cm
-2
)
Electric Field (kV mm
-1
)
a) b)
c) d)
-20 -10 0 10 20
-0.2
-0.1
0.0
0.1
0.2
Pr
= 0.05 mC cm
-2
Polarization
(
m
C
cm
-2
)
Electric Field (kV mm
-1
)
-20 -10 0
-0.10
-0.05
0.00
0.05
0.10
Current
density
(
m
A
cm
-2
)
Electric Field (kV
a) b)
-20 -10 0 10 20
-0.2
-0.1
0.0
0.1
0.2
Pr
= 0.05 mC cm
-2
Polarization
(
m
C
cm
-2
)
Electric Field (kV mm
-1
)
-20 -10 0 10 20
-0.10
-0.05
0.00
0.05
0.10
Current
density
(
m
A
cm
-2
)
Electric Field (kV mm
-1
)
Ec
= 11 kV mm
-1
a) b)
RBC-CAD RBC-PUTR RBC-CAD-bioATO
A piezoelectric coefficient of 2 pC.N-1 was obtained for RBC-CAD-bioATO!
47. 12 May 2023 PhD Defense - Lille 47
A new trend in designing piezoelectric generators
Perovskite Materials
PVDF nanofiber
Copper
Aluminum foil
Old types of piezoelectric generator:
• Based on ceramic piezoelectric materials
• Toxic to human body
• Expensive
• Micro-sized
New types of piezoelectric generator:
• Biocompatible piezoelectric materials
• Eco-friendly and renewable
• Flexible and cheap
• Nano-sized
48. 12 May 2023 PhD Defense - Lille 48
Human motions- a great energy source for wearable, self-powered devices
Human is actually great source of energy.
Body Heat
Breathing
Finger
Motions
Footfalls
Arm
Motion
Sources
Harvesting energy from human motions is
more capable than from body heat.
6.9-19mW
2.4-4.8W
1.0W
60W
67W
Potential
Energy
Maurya, D., Yan, Y. & Priya, S. J.et al. Adv. Mater. Clean Energy 50–71 (2015).
Khalid, S., Raouf, I., Khan, A. et al. Int. J. of Precis. Eng. and Manuf.-Green Tech. 6,
821–851 (2019).
49. 12 May 2023 PhD Defense - Lille 49
Piezoelectric material-a key factor for self-powered, wearable devices
Basic building blocks of a self-powered, wearable devices:
Wearable Devices
Sensing unit
Data Processing unit
Communication unit
Human movements Energy Harvesting System
Piezoelectric
Harvester
Power
Management
Energy
Storage
Bottom Electrode
Flexible substrate
Top Electrode
Piezoelectric layer
Flexible substrate
Piezoelectric materials act as the core of all
piezoelectric harvesters!
Liu, Y., Khanbareh, H., Halim, M. A.. et al. Nano Sel. (2021) doi:10.1002/nano.202000242.
50. 12 May 2023 PhD Defense - Lille 50
Piezoelectricity and Piezoelectric coefficients
Piezoelectric
Force
Inverse Piezoelectric
Electric
stimuli
Mechanical
vibrations
32 crystallographic point group
20 non-centrosymmetric
piezoelectric
Less than 10 reversible polar
ferroelectric
(e.g., quartz)
(e.g., PZT,
PVDF, BTO)
51. 12 May 2023 51
Ferroelectricity: ferroelectric hysteresis and butterfly loop
Dielectric
Piezoelectric
Pyroelectric
Ferroelectricity
Electric
field
Ps
E
Ec
-Ec
-Pr
Pr
Ps
P
Polarization versus E
(Hysteresis loop)
Ps : Saturated polarization
Pr : Remanent polarization
Ec : Coercive field
P : Polarization
E : Electric field
S
E
-Ec Ec
Strain versus E
(Butterfly loop)
The presence of P-E and S-E loop
are often undeniable evidence for
piezoelectricity and ferroelectricity
at macro- and nanoscale!
PhD Defense - Mons
Editor's Notes
What is piezoelectric constant
Unit of piezoelectric constant
Reference for shear
a new bio-sourced piezoelectric polymer
Grade of PLLA
Voltage
Distance
it should be noted that when operating in Tapping mode, the AFM tip gently touches the sample surface and therefore minimize the damage to the fiber.
pm/v
pm/V unit
pm/V
P(VDF-co-TrFE)
Parameters for electrospinning
The mean value and standard deviation were calculated by fitting the distribution with a Gaussian function.
Pure PLLA had a wide distribution, ranging from 200 nm to 1800 nm, with an average diameter of... This value is significantly higher than the value obtained for 6%wt solution in the previous part.
The addition of BTO nanoparticles lead to a decrease in viscosity and conductivity of the polymer solution. Consequently, the resulting hybrid nanofibers are reduced in size.
Further heat-treatment at 160C reduced the average diameter to ...., a similar trend as indicated in previous part.