The triboelectric nanogenerator (TENG) has attracted global attention in the fields of power sources and self-powered sensors. By coupling the omnipresent triboelectrification effect and the electrical induction effect, the TENGs can transduce ambient mechanical energy into electrical energy. Such energy could be consumed instantaneously or stored for later use. In this way, they could be deployed distributedly to be compatible power sources in the era of the internet of things (IoTs), completing the powering structure that is currently relying on power plants. Also, the electrical signals can reflect the environment changes around the TENGs. Thus, the TENGs can serve as self-powered sensors in the IoTs. In this work, we adopted two approaches for TENG fabrication: the thermal drawing method (TDP) and 3D printing. With TDP, we have fabricated scalable fiber-based triboelectric nanogenerators (FTENG), which have been woven into textiles by an industrial loom for wearable use. This fabrication process can supply FTENG on a large scale and fast speed, bridging the gap between the TENG and weaving industry. With 3D printing, we have fabricated TENGs that are compatible with the shape of arbitrary substrates. They have been used as biocompatible sensors: human-skin-compatible TENG has been used to recognize silent speech in real-time by sensing the chin movement; the porcine-kidney-shaped fiber mesh has been used to monitor the perfusion rate of the organ. These works have extended the territory of TENGs and can be critical components in the IoTs. / Ph.D. / Portable electronic devices have become important components in our daily lives, and we are entering the era of the Internet of Things (IoTs), where everyday objects can be interconnected by the internet. While electricity is essential to all of these devices, the traditional power sources are commonly heavy and bulky and need to be recharged or directly connected to the immobile power plants. Researchers have been working to address this mismatch between the device and power systems. The triboelectric nanogenerators (TENG) are good candidates because they can harvest energy in the ambient environment. The users can use them to generate electricity by merely making the rubbing motion. In this work, we report two fabrication methods of the fiber-based triboelectric nanogenerators (FTENG). With the thermal drawing process, we have fabricated sub-kilometer-long FTENG and wove it with the regular cotton yarn into textiles. The wearable power source is human friendly as it does not induce any extra weight load for the user. Besides, we have demonstrated that such long fibers can work as self-powered distributed sensors, such as a Morse code generator. With 3D printing, we have fabricated FTENG-based devices that conform to the working substrates, which can be any shape. We have employed them as biofriendly sensors to translate the chin movement during speaking to language and to monitor the perfusion rate of a pig kidney. The FTENGs have offered excellent comfortability to the users and can play a vital role in reframing the power structure to be compatible with IoTs.

Målet med detta arbete var att konstruera en mycket känslig laddningsförstärkare som kan detektera och förstärka laddningar i storleksordningen femtocoulomb. Laddningsförstärkaren är tänkt att användas vid Habia Cables kabeltillverkning för att karaktärisera lågbruskabel med avseende på störning genererad av triboelektrisk uppladdning. Den bästa lågbruskabel Habia Cable tillverkar, så kallad super-lågbruskabel, uppvisar så låg triboelektrisk störning att vanliga laddningsförstärkare inte kan detektera den, därav behovet av en känsligare laddningsförstärkare. I en inledande litteraturstudie söktes information om triboelektrisk uppladdning och hur triboelektrisk uppladdning orsakar störning i kablar. Genom litteraturstudien inhämtades också teori kring hur laddningsförstärkare är uppbyggda och vilka speciella krav som ställs på dessa för att kunna detektera mycket små laddningar. Sedan vidtog arbete med att konstruera en laddningsförstärkare med kretsdesign, kretskortsdesign, lödning, inbyggnad och testning. Resultatet blev en laddningsförstärkaren som kan mäta laddningar från uppskattningsvis 0,1 femtocoulomb till 100 picocoulomb. Vid kvantifiering av triboelektrisk störning i super-lågbruskabel uppmättes så låga laddningar som 1,3 femtocoulomb. / The goal of this project was to construct a sensitive charge amplifier that could detect and amplify femtocoulomb charges. The charge amplifier is to be used at Habia Cable manufacturing sites to quantify the triboelectric noise performance of lownoise cables. Super-low-noise cables manufactured by Habia Cable perform so well regarding triboelectric noise that common charge amplifiers cannot detect the noise, thus the need for a more sensitive charge amplifier. Initially a literature study was performed in order to better understand triboelectric charging and triboelectric noise in cables. Thru the literature study knowledge of charge amplifiers and low charge measurements was also gained. After the literature study a charge amplifier was constructed. Work included circuit design, PCB design, soldering, construction of enclosure and testing. Tests shows that the constructed charge amplifier can detect charges as low as 1.3 femtocoulomb when quantifying triboelectric noise in super-low-noise cables. The charge amplifier can measure charges from approximately 0.1 femtocoulomb to 100 picocoulomb.

Wearable systems continue to gain new markets by addressing improved performance and lower size, weight and cost. Both civilian and military markets have incorporated wearable technologies to enhance and facilitate user's tasks and activities. A wearable system is a heterogeneous system composed of diverse electronic modules: data processing, input and output modules. The system is constructed to be body-borne and therefore, several constraints are put on wearable systems regarding wearability (size, weight, placement, etc.) and robustness rendering the task of designing wearable systems challenging. In this thesis, an overview of wearable systems was given by discussing definition, technology challenges, market analysis and design methodologies. Main research targeted at network architectures and robustness to environmental stresses and electromagnetic interference (EMI). The network architecture designated the data communication on the intermodule level - topology and infrastructure. A deeper analysis of wearable requirements on the network architecture was made and a new architecture is proposed based on DC power line communication network (DC-PLC). In addition, wired data communication was compared to wireless data communication by introducing statistical communication model and looking at multiple design attributes: power efficiency, scalability, and wearability. The included papers focused on wearable systems related issues including analysis of present situation, environmental and electrical robustness studies, theoretical and computer aided modelling, and experimental testing to demonstrate new wearable architectural concepts. A roadmap was given by examining the past and predicting the future of wearable systems in terms of technology, market, and architecture. However, the roadmap was updated within this thesis to include new market growth figures that proved to be far less than was predicted in 2004. User and application environmental requirements to be applied on future wearable systems were identified. A procedure is presented to address EMI and evaluated solutions in wearable application through modelling and simulation. Environmental robustness and wearability of wearable systems in general, and washability and conductive textile in particular are investigated. A measurement-based methodology to model electrical properties of conductive textile when subjected to washing was given. Employing a wired data communication network was found to be more appropriate for wearable systems than wireless networks when prioritizing power efficiency. The wearability and scalability of the wired networks was enhanced through conductive textile and DC-PLC, respectively. A basic wearable application was built to demonstrate the suitability of DC-PLC communication with conductive textile as infrastructure. The conductive textile based on metal filament showed better mechanical robustness than metal plated conductive textile. A more advanced wearable demonstrator, where DC-PLC network was implemented using transceivers, further strengthened the proposed wearable architecture. Based on the overview, the theoretical, modelling and experimental work, a possible approach of designing wearable systems that met several contradicting requirements was given.

Volcanogenic lightning has a long documented history in the scientific field, though its origins are still poorly understood. The interactions leading to electrification of ash plumes is essentially a function of the microphysics controlling and affecting ash particle collisions. This thesis presents measurements made on charged particle interactions in a fluidized bed, with large-scale applications to the phenomenon of volcanogenic lightning and charged particle dynamics in volcanic plumes. Using a fluidized bed of ash samples taken from Ecuador's Volcán Tungurahua, particles are introduced to a collisional environment, where they acquire an associated polarity. A charged copper plate is used to collect particles of a given polarity, and particle size distributions are obtained for different weight fractions of the ash. It is observed that relatively smaller particles acquire a net negative charge, while larger particles in the sample charge positively. This is a well-documented occurrence with perfectly spherical, chemically identical samples, but this work represents one of the first applications of the principle to volcanic ash. Image analysis is preformed to determine the size distribution associated with specific polarities, and the associated minimum charge on each particle is calculated based on the plate collection height and particle size. We also present results that demonstrate the relationship between particle collisions and the amount of charge exchanged. Using techniques developed to examine the collision rate within a flow, combined with the charging rates determined from this experiment, we determine a maximum charge exchange rate of 1.28±0.23 electrons transferred per collision.

Polymer-based piezoelectric and triboelectric generators form the basis of well-known energy harvesting methods that are capable of transforming ambient vibrational energy into electrical energy via electrical polarization changes in a material and contact electrification, respectively. However, the low energy conversion efficiency and limited thermal stability of polymeric materials hinder practical application. While nanostructured polymers and polymer-based nanocomposites have been widely studied to overcome these limitations, the performance improvement has not been satisfactory due to limitations pertaining to long-standing problems associated with polymeric materials; such as low crystallinity of nanostructured polymers, and in the case of nanocomposites, poor dispersion and distribution of nanoparticles in the polymer matrix. In this thesis, novel functional polymeric nanomaterials, for stable and physically robust energy harvesting applications, are proposed by developing advanced nanofabrication methods. The focus is on ferroelectric polymeric nanomaterials, as this class of materials is particularly well-suited for both piezoelectric and triboelectric energy harvesting. The thesis is broadly divided into two parts. The first part focuses on Nylon-11 nanowires grown by a template-wetting method. Nylon-11 was chosen due to its reasonably good ferroelectric properties and high thermal stability, relative to more commonly studied ferroelectric polymers such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE)). However, limitations in thin-film fabrication of Nylon-11 have led to poor control over crystallinity, and thus investigation of this material for practical applications had been mostly discontinued, and its energy harvesting potential never fully realised. The work in this thesis shows that these problems can be overcome by adopting nanoporous template-wetting as a versatile tool to grow Nylon-11 nanowires with controlled crystallinity. Since the template-grown Nylon-11 nanowires exhibit a polarisation without any additional electrical poling process by exploiting the nanoconfinement effect, they have been directly incorporated into nano-piezoelectric generators, exhibiting high temperature stability and excellent fatigue performance. To further enhance the energy harvesting capability of Nylon-11 nanowires, a gas -flow assisted nano-template (GANT) infiltration method has been developed, whereby rapid crystallisation induced by gas-flow leads to the formation of the ferroelectric δʹ-phase. The well-defined crystallisation conditions resulting from the GANT method not only lead to self-polarization but also increases average crystallinity from 29 % to 38 %. δʹ-phase Nylon-11 nanowires introduced into a prototype triboelectric generator are shown to give rise to a six-fold increase in output power density as observed relative to the δʹ-phase film-based device. Interestingly, based on the accumulated understanding of the template-wetting method, Nylon-11, and energy harvesting devices, it was found that thermodynamically stable α-phase Nylon-11 nanowires are most suitable for triboelectric energy generators, but not piezoelectric generators. Notably, definitive dipole alignment of α-phase nanowires is shown to have been achieved for the first time via a novel thermally assisted nano-template infiltration (TANI) method, resulting in exceptionally strong and thermally stable spontaneous polarization, as confirmed by molecular structure simulations. The output power density of a triboelectric generator based on α-phase nanowires is shown to be enhanced by 328 % compared to a δʹ-phase nanowire-based device under the same mechanical excitation. The second part of the thesis presents recent progress on polymer-based multi-layered nanocomposites for energy harvesting applications. To solve the existing issues related to poor dispersion and distribution of nanoparticles in the polymer matrix, a dual aerosol-jet printing method has been developed and applied. As a result, outstanding dispersion and distribution. Furthermore, this method allows precise control of the various physical properties of interest, including the dielectric permittivity. The resulting nanocomposite contributes to an overall enhancement of the device capacitance, which also leads to high-performance triboelectric generators. This thesis therefore presents advances in novel functional polymeric nanomaterials for energy harvesting applications, with improved performance and thermal stability. It further offers insight regarding the long-standing issues in the field of Nylon-11, template-wetting, and polymer-based nanocomposites.

La fonctionnalisation « intelligente » des vêtements et accessoires portés par la personne est un phénomène à croissance rapide. L’installation des smartphones dans le quotidien des personnes en une décennie à peine en témoigne. L’autonomie énergétique de ces systèmes est un enjeu important, tant en termes d’ergonomie que de ressources : l’usage de piles ou batteries électrochimiques à l’échelle de milliards d’objets connectés est difficilement envisageable. La récupération d’énergie se pose en alternative pour complémenter ou remplacer ces unités de stockages. Cette thèse explore plusieurs approches pour utiliser l’énergie mécanique de la personne afin d’alimenter un vêtement intelligent en énergie électrique.Après avoir identifié le besoin énergétique d’un vêtement connecté typique, et comparé les possibilités des récupérateurs d’énergie de la littérature, trois formats de récupérateurs d’énergie sont étudiés. Le premier est un générateur inertiel à induction résonant non linéaire, de la taille d’une pile AA et permettant l’exploitation des impacts des pas de la personne. L’étude porte essentiellement sur la modélisation et l’optimisation du système pour l’activité humaine. Le prototype associé présente une densité de puissance supérieure à 500µW/cm3 lors de la course à pied. Le second récupérateur étudié est aussi un générateur inertiel à induction. D’une forme « toroïdale », il exploite le balancier des membres de la personne, et est capable de produire des puissances supérieures au milliwatt lorsqu’il est fixé au niveau du pied ou du bras. Enfin, le troisième concept de récupérateur d’énergie proposé s’appuie sur la transduction électrostatique à capacité variable pour exploiter des déformations dans les vêtements. Le système associe la triboélectricité avec un circuit d’auto-polarisation passif, le doubleur de Bennet. Cette combinaison permet de polariser une capacité variable de façon importante, sans source de tension externe, et ainsi de maximiser l’énergie électrostatique générée. Le dispositif réalisé pour faire la preuve du concept produit ainsi plus de 150µJ par cycle. Cette architecture électrostatique ouvre d’intéressantes possibilités en matière d’ergonomie et d’intégration dans les vêtements. En effet, elle laisse entrevoir le développement de structures étirables et flexibles s’adaptant bien aux contraintes de cette application.La comparaison de ces trois approches est instructive quant aux perspectives de développement du domaine de la conversion de l’énergie mécanique de la personne. / The functionalization of common objects in the human’s environment with electronics is a fast-growing trend, as demonstrated by the emblematic example of smartphones which became almost essential in the everyday life in less than a decade. One important stake of these systems is their power supply, in terms of ergonomics as well as resources: the use of electromechanical batteries to fuel billions of connected “things” is not the most attractive prospect. Energy harvesting techniques may provide an alternative or a complement to the use of these storage units. This thesis explores different structures of generators to efficiently convert the user’s mechanical energy to ensure the electrical self-sufficiency of smart wearables.Based on power requirement considerations for a typical “smart shirt” and comparing human energy harvesters from the literature, different structures are investigated. The first one is an inertial electromagnetic generator, the size of an AA-battery, designed to convert footsteps impacts. A thoroughly modelled and optimized device is able to generate power densities over 500µW/cm3 while attached on the arm during a run. The second considered energy harvester format is a “looped” inertial structure which is adapted to exploit the swing-type motions of the user’s limbs. This system is able to produce milliwatts-level powers from the motion of a small magnetic ball inside the device. Finally, a third generator concept that relies on electrostatic induction was developed, which uses variable capacitance structures to turn clothes deformations into electricity. The architecture of this energy harvester combines the triboelectric effect with a circuit of built-up self-polarization, Bennet’s doubler. It enables high levels of bias voltages without the need of an external source, and thus to maximize the energy generated per electrostatic cycle. A simple test device is shown to produce over 150µJ per cycle. This approach is promising in terms of integration in smart clothing, because it enables the development of flexible and stretchable devices well complying with the comfort requirements of worn systems.The comparison of those three energy harvesters provides an interesting basis for the future developments of energy harvesters converting one’s mechanical energy.

This diploma thesis deals with the feasibility of using PVDF nanofibers as an active sensor layer generating electrical signal. PVDF and related electromechanical effects are described. A research study is conducted regarding existing PVDF nanofiber applications and based on it, an event sensor design utilizing triboelectric effect and electrostatic induction is proposed. The electrical response of the layers is experimentally investigated and a pulse detection algorithm is conceived and implemented. Finally, a way of integrating the sensor into a rail track is proposed.

<div>Recently, energy crisis and environment pollution has become global issues and there is a great demand for developing green and renewable energy system. At the same time, advancements in materials production, device fabrication, and flexible circuit has led to the huge prosperity of wearable devices, which also requires facile and efficient approaches to power these ubiquitous electronics. Piezoelectric nanogenerators and triboelectric nanogenerators have attracted enormous interest in recent years due to their capacity of transferring the ambient mechanical energy into desired electricity, and also the potential of working as self-powered sensors. However, there still exists some obstacles in the aspect of materials synthesis, device fabrication, and also the sensor performance optimization as well as their application exploration.</div><div>Here in this research, several different materials possessing the piezoelectric and triboelectric properties (selenium nanowires, tellurium nanowires, natural polymer hydrogel) have been successfully synthesized, and also a few novel manufacturing techniques (additive manufacturing) have been implemented for the fabrication of wearable sensors. The piezoelectric and triboelectric nanogenerators developed could effectively convert the mechanical energy into electricity for an energy conversion purpose, and also their application as self-powered human-integrated sensors have also been demonstrated, like achieving a real-time monitoring of radial artery pulses. Other applications of the developed sensors, such as serving as electric heaters and infrared cloaking devices are also presented here. This research is expected to have a positive impact and immediate relevance to many societally pervasive areas, e.g. energy and environment, biomedical electronics, and human-machine interface.</div><div><br></div>

This dissertation focuses on the development of and applications for Nano-Composite Piezoresponsive Foam (NCPF). This self-sensing foam sensor technology was discovered through research in a sister technology, High Deflection Strain Gauges (HDSG), and was subsequently developed with some of the same base materials. Both technologies use nano and micro conductive additives to provide electrically responsive properties to materials which otherwise are insulative. NCPF sensors differ from HDSGs in that they provide a dual electrical response to dynamic and static loading, which is measured through an internally generated charge, or a change in resistance. This dissertation focuses on the development of the dynamic or piezoresponsive aspect of the NCPF sensors which tends to have more consistent electrical response over a larger number of cycles. The primary development goal was to produce a sensor that was accurate, while providing a consistent, repeatable response over multiple impacts. The hypothesized electric generation is attributed to a triboelectric interaction between the conductive additives and the polyurethane foam matrix. This hypothesis was validated by examining different conductive additives with varying loading levels and specific surface areas while accounting for other design considerations such as the electrode used to harvest the response. The results of this analysis support the triboelectric model and point to carbon or nickel-based additives for optimal performance. The NCPF response measured by digital signal acquisition devices is directly dependent upon its input impedance. Increased input capacitance has a negative effect on the signal, however, higher input resistance has a positive linear correlation to voltage. Other considerations that affect the electrical response include the temperature and humidity in which the sensor is used and result in a scaled electrical response.NCPF sensors are ideally suited for use in systems which benefit from impact energy attenuation while measuring the same. This work demonstrates how the NCPF sensors can be used to detect severity and location of impacts in systems with multiple sensors (football helmets), and those with one continuous sensor (carpets). When NCPF sensors were used in a football helmet the impact severity and location of impact was accurately identified. NCPF sensors provide the benefit of simplified design by replacing existing foam while providing a direct measure of the forces. Additional research was conducted on the changes in material properties, specifically how it affects the foam structures ability to absorb energy in quasi static loading scenarios. NCPF sensors are demonstrated as viable tool to measure many different biomechanical systems.

Gegenstand dieser Arbeit ist die Entwicklung einer Methode zur Charakterisierung der komplexen Belastungssituation beim Tiefziehen mit unmittelbarer Kompression von Karton innerhalb geeigneter Ersatzversuche und deren Validierung mit Hilfe eines empirischen Models. Das Tiefziehen mit unmittelbarer Kompression stellt eine Möglichkeitzur Herstellung von dreidimensionalen Hohlkörpern mit hohem Umformgrad aus naturfaserbasierten, flächigen Halbzeugen mit geringem Vorfertigungsgrad dar.Aufbauend auf der Darstellung und Abgrenzung des Umformverfahrens werden relevante Prozessgrößen und deren Charakterisierung durch geeignete Ersatzversuche aus dem Stand der Wissenschaft recherchiert und bewertet. Zudem werden Möglichkeiten erörtert, die Ergebnisse der Ersatzversuche mit den Daten aus dem Umformverfahren zu vergleichen. Aus den technischen und wissenschaftlichen Defiziten ergibt sich die Zielsetzung und weitere Vorgehensweise dieser Arbeit.Zur Lösung der Problemstellung werden den identifizierten Prozessgrößen geeignete Ersatzversuche aus dem Stand der Technik zugeordnet bzw. neue Ersatzversuche entwickelt und im Rahmen eines modularen Versuchsstandes technisch umgesetzt. Zur Vorbereitung der experimentellen Analyse der ausgewählten Ersatzversuche werden Referenzversuche mit dem Umformverfahren innerhalb festgelegter Parametergrenzen durchgeführt. Bei der anschließenden Durchführung der Ersatzversuche wird vor allem die Verlässlichkeit der Ergebnisse berücksichtigt, indem die Anzahl der Versuche jeder Versuchsreihe an die Ergebnisauswertung angepasst wird.Durch die Modifikation des Umformverfahrens können die Ergebnisse der Ersatzversuche innerhalb eines stufenweise komplexer werdendes, empirischen Modelsmit denen des Referenzversuchs verglichen und bewertet werden. Die Charakterisierung der Prozesskraftkomponenten wird für vier faserbasierte Materialien durchgeführt,die teilweise mit einer polymeren Funktionsschicht ausgestattetsind.Abschließend werden die Ergebnisse dieser Arbeit zusammengefasst dargestellt und daraus folgende Forschungsansätze abgeleitet. / The purpose of this thesis is to present a newly developed method to investigate thecomplexload situation during the deep-drawing of paperboard within suitable substitute tests and its validation withinan empirical model.Deep drawing with direct compression represents analternativefor the production of three-dimensional traysfrom natural, fiber-based materials with a low degree of prefabrication.Based on the definition and description of the deep-drawing process within the literature, relevant process forces and associated substitute tests are identifiedand discussed. In addition, approachesare discussed to compare the results of the substitute tests with the data from the deep-drawingprocess. The objective and further procedure of this thesisresults from the technical and scientific deficits.The approach of this thesisis it to present a new, modular testing rig based on the substitute test which were chosen from the literature or were newly developed.In preparation ofthe experimental analysis of the selected substitutetests, reference tests are carried out with the forming process within specified parameter limits. In the subsequent implementation of the substitutetests, the reliability of the results is consideredabove all by adapting the number of tests in each test series parallel to the evaluation of the results. By modifying the forming process, the results of the substitute tests can be compared and evaluated with those of the reference test within an empirical model that becomes progressively more complex. The characterization of the process force components iscarried out for four fiber-based materials, some of which are equipped with a polymer functional layer.Finally, the results of this work are summarized,and the following research approaches are derived from them.