Dissertations / Theses on the topic 'Dry electrodes'

Monitoring bio-electric events is a common procedure, which provides medical data required in clinical and research applications. Electrophysiological measurements are applied in diagnosis as well as evaluation of the performance of different body organs and systems, e. g. the heart, muscles and the nervous system. Furthermore, it is staple feature in operation rooms and extensive care units. The performance of the recording system is affected by the tools and instrumentation used and the bio-electrode is a key-player in electrophysiology, hence, the improvements in the electrode recording technique will be directly reflected in the system?s performance in terms of the signal quality, recording duration as well as patient comfort. In this thesis, a design methodology for micro-spike array dry bio-electrodes is introduced.

The purpose of this methodology is to meet the design specifications for portable long-term EEG recording and optimize the electrical performance of the electrodes by maximizing the electrode-skin contact surface area, while fulfilling design constraints including mechanical, physiological and economical limitations. This was followed by proposing a low cost fabrication technique to implement the electrodes. The proposed electrode design has a potential impact in enhancing the performance of the current recording systems, and also suits portable monitoring and long term recording devices. The design process was aided by using a software design and optimization tool, which was specifically created for this application.

The application conditions added challenges to the electrode design in order to meet the required performance requirements. On the other hand, the required design specifications are not fulfilled in the current electrode technologies which are designed and customized only for short term clinical recordings.

The electrode theory of application was verified using an experimental setup for an electrochemical cell, but the overall performance including measuring the electrode impedance is awaiting a clinical trial.

Lithium-ion batteries (LIBs) have been widely used as the most popular rechargeable energy storage and power sources in today’s portable electronics, electric vehicles, and plug-in hybrid electric vehicles. LIBs have gained much interest worldwide in the last three decades because of their high energy density, voltage, rate of charge and discharge, reliability, and design flexibility. I am exploring the possibility of developing battery manufacturing technologies that would lower the cost, reduce the environmental impact, and increase cell performance and durability. This dissertation is focused firstly on understanding the effect of mixing sequence (the order of introducing materials) and optimizing the electrode fabrication for the best electrochemical performance, durability, lower cost, and improve the existing manufacturing processes. The electrode system consists of active material, polymer binder, conductive agent, and solvent. I have investigated four different mixing sequences to prepare the slurries for making the positive electrode. The key sequence-related factor appears to be whether the active material and conductive agent are mixed in the presence of or prior to the introduction of the binder solution. The mixing sequences 1, 2, 3, and 4 were optimized, and the rheological behavior of the slurries, morphology, conductivity, and mechanical and electrochemical properties of electrodes were investigated. Slurries from sequences 1 and 4 show different rheological properties from 2 and 3. The amount of NMP required to achieve a comparable final slurry viscosity differed significantly for the sequences under study. The sequence 1 shows better long-term cycling behavior than sequences 2, 3 and 4. This study quantifies the link between electrode slurry mix parameters and electrode quality. Secondly, a new method of making lithium-ion battery electrodes by adapting an immersion precipitation (IP) technology commonly used in membrane manufacturing was developed and demonstrated. The composition, structure, and electrochemical performance of the electrode made by the IP method were compared favorably with that made by the conventional method. The toxic and expensive organic solvent (NMP) was captured in coagulation bath instead of being released to the atmosphere. The IP electrodes show an excellent performance and durability at potentially lower cost and less environmental impact. Thirdly, I have developed and demonstrated a solvent-free dry-powder coating process for making LiNi1/3Mn1/3Co1/3O2 (NMC) positive electrodes in lithium-ion batteries, and compared the performance and durability of electrodes made by the dry-powder coating processes with that by wet-slurry coating processes. The technology that has been used is the electrostatic spray deposition (ESD) process. This process eliminates volatile organic compound emission, reduces thermal curing time from hours to minutes, and offers high deposition rates onto large surfaces. The long-term cycling shows that the dry-powder coated electrodes have similar performance and durability as the conventional wet-slurry made electrodes.

Магістерська робота містить основну частину на 110 аркушах, 22 ілюстрацій, 22 таблиці кількість джерел за переліком посилань 53 джерела. Об’єктом дослідження є процес зняття електрокардіограми людини. Предметом дослідження є електроди для моніторингу біомедичних сигналів. Метою роботи є огляд роботи електродів в комплексі із датчиком ЕКГ для цифрової електронної лабораторії і запропонування оптимального варіанту електродів для подальшого застосування. Методом дослідження є теоретичний огляд існуючих різновидів біомедичних електродів та можливості їх технічного вдосконалення, а також практична перевірка роботи електродів у цифровій електронній лабораторії. Результатом роботи є отримані зображення ЕКГ при різних дослідженнях з використанням існуючих електродів та визначення оптимального варіанту електродів для застосування. Новизна результатів роботи полягає у застосуванні їх до цифрової електронної лабораторії, де будуть проводитися подальші дослідження та у визначенні вектору подальших досліджень у напрямку сухих ємнісних голчастих електродів. Результати даної роботи можуть бути використанні для подальшого їх застосування у лабораторних роботах та для проектування комбінованого типу електродів. Можливі напрямки продовження досліджень: проектування комбінованого типу сухих ємнісних голчастих електродів. Галузь застосування: навчальна цифрова електронна лабораторія, медицина.
Master's work contains the main part of 110 sheets, 22 illustrations, 22 tables and a number of sources by the list of references 53 source. The object of research is the process of taking human's electrocardiogram. The subject of the study is electrodes for monitoring biomedical signals. The aim of the work is to review the work of electrodes in conjunction with an ECG sensor for a digital electronic laboratory and to offer an optimal variant of electrodes for further application. The research method is a theoretical review of existing varieties of biomedical electrodes and the possibilities for their technical improvement, as well as practical verification of the work of electrodes in a digital electronic laboratory. The result of the work is the obtained ECG images in various studies using existing electrodes and the determination of the optimal variant of electrodes for use. The novelty of the results of the work is to apply them to a digital electronic laboratory, where further research will be carried out and in determining the vector of further research in the direction of dry capacitive needle electrodes. The results of this work can be used for their further application in laboratory work and for the design of a combined type of electrodes. Possible directions for the continuation of research: design of a combined type of dry capacitive needle electrodes. Field of application: educational Digital Electronic Laboratory, Medicine.

Il existe un réel besoin de développer des matériaux et des technologies avancés pour améliorer l’interface avec le cerveau humain. De tels enregistrements électrophysiologiques sont nécessaires pour des fins diagnostiques ou dans des domaines innovants tels que l’interface homme/machine. Les dispositifs issus de l’électronique organique représentent des alternatives prometteuses grâce à leurs propriétés mécaniques et leur biocompatibilité. L’utilisation de polymères conducteurs ouvre la voie vers une nouvelle interface avec le milieu biologique. Ce travail présente un procédé de fabrication innovant permettant d’intégrer le polymère conducteur PEDOT:PSS sur des électrodes sèches pour une application à l’électroencéphalographie (EEG). L’étape suivante consiste en l’utilisation d’un dispositif actif tel que le transistor organique électrochimique (OECT) afin de profiter de l’amplification locale qu’il permet. Cette dernière est extrêmement importante dans le cas de la neurophysiologie, domaine dans lequel l’amplitude des signaux enregistrés est très basse. En ce sens, l’intégration d’OECTs à des dispositifs d’enregistrement de signaux neuronaux a montré un bien supérieur rapport signal / bruit (SNR) en comparaison à des électrodes conventionnelles. La bioélectronique est un domaine innovant à applications variées. Cette thèse présente la conception et la validation par l’application de dispositifs organiques dans le domaine des neurosciences. D’autres progrès dans les domaines du diagnostic, des biocapteurs, ou de la distribution de médicaments pavent la voie pour de nouvelles applications dans l’agroalimentaire ou encore la qualité de l’eau ou de l’air
There is a tremendous need for developing advanced materials technologies for interfacing with brain and record neural activity. Such electrophysiological recordings are necessary for diagnostic purposes and brain/machine interfaces. Among the existing technologies, organic electronic devices constitute a promising candidate because of their mechanical flexibility and biocompatibility. The use of conducting polymers, which allow both ionic and electronic transport, allows new modes for interfacing with the biological milieu. This work presents an innovative process to incorporate the conducting polymer poly(3,4-Ethylenedioxythiophene: poly(styrene sulfonate) (PEDOT:PSS) onto electrodes for applications in electroencephalography (EEG). A step beyond conducting polymer electrodes is provided by the Organic Electrochemical Transistor (OECT). The primary advantage of using active devices is the local amplification they provide. This local amplification becomes extremely important in the case of electrophysiological signals, for which the amplitude is very low. The use of the OECT for various electrophysiological measurements is presented, done for clinical purposes like ECG or EEG, for new marketing studies like EOG, and for more fundamental neurological applications, like the recording in vitro of neuronal unitary activity. Bioelectronics is an inspiring field with broad scope. This thesis deals with applications of organic electronic devices in neuroscience. Other applications in diagnostics, biosensing, or drug delivery will offer huge opportunities for food safety, pollution control or even environmental applications

L’utilisation massive de batteries Li-ion au cours des deux dernières décennies a poussé les chercheurs de la communauté scientifique à s’intéresser à des systèmes alternatifs basés sur des éléments abondants et peu coûteux. Parmi ces nouveaux systèmes, les batteries Na-ion sont rapidement passées de simples prototypes de laboratoire à des systèmes sur le point d’être commercialisés. Plus récemment, l’intérêt de la communauté des batteries s’est porté sur l’utilisation du potassium. Cet élément présente des atouts non négligeables pour le développement de batteries à haute densité d’énergie et de puissance en raison du faible potentiel standard du couple K+/K (vs. ESH) et des faibles énergies de désolvatation des ions K+ dans les solvants organiques usuels. Les travaux de cette thèse ont été dédiés à l’étude des mécanismes réactionnels de potassiation/dépotassiation de matériaux d’électrodes négatives. La compréhension des mécanismes qui régissent le fonctionnement des batteries est essentielle pour le développement de ces dernières. Elle permet aussi de prévenir des défaillances et de guider les recherches sur l’optimisation des matériaux d’électrode et d’électrolyte. Pour cela, deux grandes familles de matériaux d’électrodes négatives ont été étudiées au cours de cette thèse : les matériaux carbonés et plus spécifiquement le graphite, et les matériaux d’alliages à base d’éléments du bloc p de la classification périodique comme l’antimoine, le bismuth, le plomb et l’étain. L’emploi de différentes techniques de caractérisation en conditions ex situ et operando a permis d’obtenir de nouvelles informations approfondies sur les mécanismes réactionnels de ces matériaux dans les batteries K-ion. Enfin, les formulations de l’électrode et de l’électrolyte ont été identifiées comme points clés batteries pour l’optimisation des performances du graphite et des matériaux d’alliages. Même si la recherche sur les batteries K-ion reste encore au stade fondamental, ces premiers résultats sont prometteurs et laissent entrevoir un possible avenir de ces batteries pour le stockage de l’énergie d’applications stationnaires
During the last two decades, the massive use of Li-ion batteries led the scientific research community to focus on alternatives systems based on low cost and abundant elements. Among these new systems, Na-ion batteries grew rapidly from the laboratory scale to reach a real commercial application. More recently, the research community focused on the interest of potassium. This element present significant assets for the development of high energy density and high power density batteries because of the low standard potential of K+/K redox couple (vs. SHE) and low desolvation energies of K+ ions in conventional organic solvents.This thesis was focused on the electrochemical reaction mechanism of negative electrode materials in K-ion batteries. The understanding of the reaction mechanisms occurring during cycling is essential for the battery development, it allows preventing the failure and optimise the electrode materials and electrolytes.In that way, two distinct materials for negative electrodes were studied during the thesis: carbonaceous materials, more specially graphite and alloy type materials from the p block of the periodic table such as antimony, bismuth, lead and tin. The use of different characterizations in operando and ex situ conditions allowed obtaining new insights on the reaction mechanism of these electrode materials in K-ion batteries. Finally, the electrode and electrolyte formulations were identified as a key point for the performance optimisation of graphite and alloy materials.Even if the research on K-ion batteries are still in its infancy, the first results are promising and suggest a possible future solution for the energy storage for stationary applications

The recent developments in Low Temperature Co-fired Ceramic (LTCC) as a substrate material enable it to be used in the micro and millimetre wave range providing low dissipation factors at high frequencies, good dielectric properties and a high degree of integration for further miniaturised devices. The most common metallisation method used in LTCC technology is screen printing with high cost noble metals such as silver and gold that are compatible with the high sintering temperatures (850°C). However, these techniques require high capital cost and maintenance cost. As the commercial world requires convenient and low cost process technologies for mass production, alternative metallisation methods should be considered. As a result, electroless copper plating of fired LTCC was mainly investigated in this research. The main goals of this project were to carry out electroless plating of fired LTCC with sufficient adhesion and to extend the process to metallise closed LTCC channel structures to manufacture Substrate Integrated Waveguide (SIW) components. The objectives were focused on electroless copper deposition on fired LTCC with improved adhesion. Electroless deposits on the Sn/Pd activated LTCC surface showed poor adhesion without any surface pre-treatments. Hence, chemical etching of fired LTCC was carried out using concentrated NaOH solution. NaOH pre-treatment of LTCC led to the formation of flake like structures on the LTCC surface. A number of surface and chemical analysis techniques and weight measurements were used to investigate the mechanism of the modification of the LTCC surface. The results showed that the flake like structures were dispersed in the LTCC material and a material model for the LTCC structure was proposed. SEM EDX elemental mapping showed that the flake like structure consisted of aluminium, calcium, boron and oxygen. Further experiments showed that both the concentration of NaOH and the immersion time affect the surface morphology and the roughness of fired LTCC. The measured Ra values were 0.6 μm for untreated LTCC and 1.1 μm for the LTCC sample treated with 4M NaOH for 270 minutes. Adhesion tests including peel test and scratch test were carried out to examine the adhesion strength of the deposited copper and both tests indicated that the NaOH pre-treatment led to an improvement, with the best results achieved for samples treated with 4M NaOH. A second aspect of the research focused on the selective metallisation of fired LTCC. Excimer laser machining was used to pattern a resist film laminated on the LTCC surface. This process also roughened the substrate and created channels that were characterised with respect to the laser operating parameters. After patterning the resist layer, samples were activated using Sn/Pd catalyst solution followed by the electroless copper deposition. Electroless copper was selectively deposited only on the patterned LTCC surface. Laser parameters clearly affected the copper plating rate. Even with a similar number of shots per area, the tracks machined with higher repetition rate showed relatively more machining depth as well as good plating conditions with low resistance values. The process was further implemented to realize a complete working circuit on fired LTCC. Passive components including a capacitor and an inductor were also fabricated on LTCC using the mask projection technique of the excimer laser system. This was successful for many designs, but when the separation between conductor lines dropped below 18 μm, electroless copper started to deposit on the areas between them. Finally, a method to deposit copper films on the internal walls of closed channel structures was developed. The method was first demonstrated by flowing electroless copper solutions through silane treated glass capillaries. A thin layer (approx. 60 nm) of electroless copper was deposited only on the internal walls of the glass capillaries. The flow rate of the electroless copper solution had to be maintained at a low level as the copper deposits tended to wash away with higher flow rates. The structures were tested for transmission losses and showed low (<10dB) transmission losses in the terahertz region of the electromagnetic spectrum. The process was further applied to deposit electroless copper on the internal walls of the LTCC closed channel structures to manufacture a LTCC Substrate Integrated Waveguide (SIW).

Le combustible nucléaire des Réacteurs à Eau sous Pression (REP), sous forme de pastilles d’oxyde d’uranium UO2 (ou MOx), est confiné dans un gainage en alliage de zirconium. Ce gainage est très important car il représente la première barrière de confinement contre la dissémination des produits de fission, générés par la réaction nucléaire, vers le milieu extérieur. La corrosion par le milieu primaire des alliages de zirconium, en particulier l’alliage Zircaloy-4, est un des facteurs limitant le temps de séjour en réacteur des crayons combustibles (pastilles UO2 + gainage). Afin de permettre aux exploitants de centrales d’optimiser la gestion des cœurs et de prolonger la durée de vie des crayons combustibles en réacteur, de nouveaux alliages à base de zirconium-niobium (M5®) ont été développés. Or, les mécanismes de corrosion de ces derniers ne sont, en l’état, pas complètement élucidés du fait notamment de la complexité de ces matériaux, de l’environnement de corrosion et de la présence de l'irradiation venant du combustible nucléaire. De ce fait, cette thèse porte spécifiquement sur l’effet de la radiolyse et des défauts induits par l’irradiation aux ions dans la matrice métallique et dans la couche d’oxyde sur la vitesse de corrosion de l’alliage Zircaloy-4 et M5®. L’objectif est de déconvoluer la part de l’influence des dommages d’irradiation subis par la matrice métallique, de celle relative aux défauts créés dans l’oxyde et de celle liée à la radiolyse du milieu primaire sur la vitesse d’oxydation des alliages de zirconium en réacteur.1) Concernant l’effet de l’irradiation de la matrice métallique sur la vitesse d’oxydation : des boucles de dislocation de type apparaissent et entrainent une augmentation de la vitesse d’oxydation des deux alliages. Pour le M5®, en plus de ce premier effet, une précipitation d’aiguilles fines de niobium diminue la concentration en niobium en solution solide dans la matrice métallique et in fine dans l’oxyde, ce qui réduit fortement la vitesse d’oxydation de l’alliage.2) Concernant l’effet de l’irradiation de la couche d’oxyde sur la vitesse d’oxydation : les défauts générés par les cascades de déplacement dans l’oxyde augmentent la vitesse d’oxydation des matériaux. Pour le M5®, la germination de zones enrichies en niobium par irradiation de l’oxyde entraine une également diminution de la concentration en niobium en solution solide dans l’oxyde, ce qui réduit une nouvelle fois, la vitesse d’oxydation de cet alliage.3) Concernant l’effet de la radiolyse de l’eau : nous n’avons pas relevé d’effet considérable de la radiolyse sur la corrosion de l’alliage Zy4 ou M5® dans nos conditions expérimentales
The nuclear fuel of pressurized water reactors (PWR) in the form of uranium oxide UO2 pellets (or MOX) is confined in a zirconium alloy cladding. This cladding is very important because it represents the first containment barrier against the release of fission products generated by the nuclear reaction to the external environment. Corrosion by the primary medium of zirconium alloys, particularly the Zircaloy-4, is one of the factors limiting the reactor residence time of the fuel rods (UO2 pellets + cladding). To optimize core management and to extend the lifetime of the fuel rods in reactor, new alloys based on zirconium-niobium (M5®) have been developed. However, the corrosion mechanisms of these are not completely understood because of the complexity of these materials, corrosion environment and the presence of radiation from the nuclear fuel. Therefore, this thesis specifically addresses the effects of radiolysis and defects induced by irradiation with ions in the matrix metal and the oxide layer on the corrosion rate of Zircaloy-4 and M5®. The goal is to separate the influence of radiation damage to the metal, that relating to defects created in the oxide and that linked to radiolysis of the primary medium on the oxidation rate of zirconium alloys in reactor.1) Regarding effect of irradiation of the metal on the oxidation rate: type dislocation loops appear and increase the oxidation rate of the two alloys. For M5®, in addition to the first effect, a precipitation of fines needles of niobium reduced the solid solution of niobium concentration in the metal and ultimately in the oxide, which strongly reduces the oxidation rate of the alloy.2) Regarding the effect of irradiation of the oxide layer on the oxidation rate: defects generated by the nuclear cascades in the oxide increase the oxidation rate of the two materials. For M5®, germination of niobium enriched zones in irradiated oxide also causes a decrease of the niobium concentration in solid solution in the oxide, which once again, reduced the oxidation rate of this alloy.3) Regarding the effect of water radiolysis: We did not identify any significant effect of radiolysis on corrosion of the alloys under our experimental conditions

The solar minimum of 2009 has been identified as an exceptional event with regard to cosmic ray (CR)modulation, since conditions in the heliosphere have reached unprecedented quiet levels. This unique minimum has been observed by the Earth–orbiting satellite, PAMELA, launched in June, 2006, from which vast sets of accurate proton and electron preliminary observations have been made available. These simultaneous measurements from PAMELA provide the ideal opportunity to conduct an in–depth study of CR modulation, in particular charge–sign dependent modulation. In utilizing this opportunity, a three–dimensional, steady–state modulation model was used to reproduce a selection of consecutive PAMELA proton and electron spectra from 2006 to 2009. Thiswas done by assuming full drifts and simplified diffusion coefficients, where the rigidity dependence and absolute value of themean free paths for protons and electrons were sequentially adjusted below 3 GV and 300 MV, respectively. Care has been taken in calculating yearly–averaged current–sheet tilt angle and magnetic field values that correspond to the PAMELA spectra. Following this study where the numerical model was used to investigate the individual effects resulting from changes in the tilt angle, diffusion coefficients, and global drifts, it was found that all these modulation processes played significant roles in contributing to the total increase in CR intensities from 2006 to 2009, as was observed by PAMELA. Furthermore, the effect that drifts has on oppositely charged particles was also evident from the difference between the peak–shaped time profiles of protons and the flatter time profiles of electrons, as is expected for an A < 0 polarity cycle. Since protons, which drift into the heliosphere along the heliospheric current–sheet, haven’t yet reached maximum intensity levels by 2008, their intensities increased notably more than electrons toward the end of 2009. The time and energy dependence of the electron to proton ratios were also studied in order to further illustrate and quantify the effect of drifts during this remarkable solar minimum period.
Thesis (M.Sc. (Physics))--North-West University, Potchefstroom Campus, 2012.

The transport of cosmic rays in the heliosphere is studied by making use of a newly developed modulation model. This model employes stochastic differential equations to numerically solve the relevant transport equation, making use of this approach’s numerical advantages as well as the opportunity to extract additional information regarding cosmic ray transport and the processes responsible for it. The propagation times and energy losses of galactic electrons and protons are calculated for different drift cycles. It is confirmed that protons and electrons lose the same amount of rigidity when they experience the same transport processes. These particles spend more time in the heliosphere, and also lose more energy, in the drift cycle where they drift towards Earth mainly along the heliospheric current sheet. The propagation times of galactic protons from the heliopause to Earth are calculated for increasing heliospheric tilt angles and it is found that current sheet drift becomes less effective with increasing solar activity. Comparing calculated propagation times of Jovian electrons with observations, the transport parameters are constrained to find that 50% of 6 MeV electrons measured at Earth are of Jovian origin. Charge-sign dependent modulation is modelled by simulating the proton to anti-proton ratio at Earth and comparing the results to recent PAMELA observations. A hybrid cosmic ray modulation model is constructed by coupling the numerical modulation model to the heliospheric environment as simulated by a magneto-hydrodynamic model. Using this model, it is shown that cosmic ray modulation persists beyond the heliopause. The level of modulation in this region is found to exhibit solar cycle related changes and, more importantly, is independent of the magnitude of the individual diffusion coefficients, but is rather determined by the ratio of parallel to perpendicular diffusion.
PhD (Space Physics), North-West University, Potchefstroom Campus, 2013

Dans ce travail de thèse, deux objectifs ont été fixés. Le premier a été de mieux comprendre le mécanisme très complexe qui est en jeu dans les accumulateurs Li/S. Pour cela, les modifications structurales du matériau actif ont été observées in operando et ont permis de valider un modèle clair concernant les réactions de transformations de phases qui contrôlent le lithium/soufre. La cristallisation d’une forme métastable du soufre (bêta-S8 monoclinique) en fin de recharge a ainsi été observée pour la première fois lors d’expériences au synchrotron de l’ESRF. La technique d’impédance électrochimique a également donné d’importantes informations sur les cinétiques deces réactions. Le deuxième objectif visait l’amélioration du système Li/S par l’optimisation des électrodes de soufre afin d’augmenter leurs performances mais également par la fabrication d’électrodes de Li2S efficaces permettant la transition vers le Li-ion/S, plus sécuritaire
In this work two main aspects has been conducted in parallel. The first one was focused on betterunderstanding the very complex working mechanism of Li/S cell. Structural changes evolution ofactive material upon real time battery operation was explored, giving a clear answer on thesolid/liquid reaction evolution, which govern the electrochemistry of Li/S technology. Formationof another allotropic form of sulfur (monoclinic beta-S8) during recharging the battery have beenreported for the first time ever in Li/S community. Impedance technique applied to such systemprovided additional information concerning the kinetics of these reactions. Apart from that,another aspect targeted rather on improvements of already existing solutions (making better sulfurelectrodes, with significantly improved specific capacities) as well as development the alternativesolutions, i.e. fabrication and test of new Li2S-based positive electrodes, which could be apromising transition from classical Li/S cells into safer Li-ion/S batteries

碩士
國立臺灣大學
機械工程學研究所
100
In this work, barbed dry electrodes are designed and fabricated by MEMS technology for biopotential measurement such as EEG.　Compared to the traditional wet electrodes, the dry electrodes do not need electrolytic gel to reduce the impedance between skin and electrodes, so dry electrodes are more suitable for long-term measurement. Our proposed dry electrodes consist of arrays of miniaturized spikes. These spikes are designed for penetrating human skin so that the high impedance problems associated with layers of the outer skin can be resolved. We design the electrodes 50-100μm in length to avoid the painful or uncomfortable feeling during the measurement. The fabrication of electrodes is based on wet etching, which is simple and low cost. The simulation software Etch3DTM is used to evaluate the fabrication parameters of the wet etching. The spikes are fabricated by KOH. Subsequently, the photoresist is patterned as the etching mask on the spikes, and then etched in the solution mixed with HNO3 and HF. The fabricated barbed electrodes are 81μm in length, and widest and narrowest width is 20μm and 12μm, respectively.

碩士
國立中央大學
電機工程學系
106
Electrocardiogram (ECG), electroencephalography (EEG), electromyogram (EMG), and etc. are important diagnosis instruments in clinics. Traditional instruments usually utilize wet type electrode for measuring biomedical signals. However, the use of wet type electrodes has to smear electrolyte gel on the measurement sites. The application of electrolyte gel is neither comfortable nor convenient. Especially, in EEG measurements, the electrolyte gel will inevitably make subject’s hairs dirty. This study aims to develop a high sensitive dry electrode for the measurement of electrophysiological signals. We have designed active electrode to increase the impedance in the frontal-end circuit. By providing active shield, external noise was decreased and common mode reject (CMRR) was increased to provide better impedance matching. The proposed dry electrode has proved its feasibility in the low-contact condition. Comparing the signal quality between our dry electrode and traditional wet-type electrode, the root-mean-square error (RMSE) is 0.28 mV which demonstrates the feasibility of our dry electrode for clinical applications.

碩士
中原大學
生物醫學工程研究所
100
Recently, the research direction of Brain–Computer Interface (BCI) changed from the neuroprosthetics into the mind control devices. The functional brain wave acquiring system of BCI should advance on more convenient and easier to capture biopotential at scalp. The electroencephalogram (EEG) acquiring system of this study based on wireless EEG modules that can fit the BCI requirements for an easy placement or removal of the electrodes at the cap, especially with “dry electrodes”. The dry electrode allows for acquisition of EEG without using of collodion or gels. It can not only reduce time of setting up the electrode but also allows a long-term recording. The system was integrated using a microprocessor (Ti MSP430-F149). It is to acquire six channels of EEG and one channel of ECG with a Bluetooth communication module that will send data to and receive command from a PC. The sample rate of this acquisition device was 200Hz. This battery-powered device overcomes the need of galvanic isolation. The validation of EEG & ECG signal in this study has been tested with 10 subjects in two different conditions. One is at resting or meditation condition and the other is at mentally athletic condition. The heart rate variability (HRV) is to confirm the subject was in the right condition. With two conditions we could find the subjects have a higher power of Alpha activity at resting condition than mentally athletic condition. The average power of Alpha at resting condition was 0.377±0.061. And, the average power of alpha at mentally athletic was 0.153±0.035. There is a statistical significantly different of the Alpha activity between the two different conditions. And, the subjects have a higher power of Beta activity at mentally athletic condition than at resting condition. The average power of Beta at resting condition was 0.211±0.026. And, the average power of alpha at mentally athletic was 0.430±0.045. There is also a statistical significantly different of the Beta activity between the two different conditions. This study has shown that the system has acquired the reliable EEG signal. The study has also presented a wireless EEG acquisition system using dry electrodes.

碩士
國立中央大學
認知與神經科學研究所
107
Motor imagery (MI) is one of the brain wave features used in the brain-computer interface(BCI). It is often discussed together with the motor execution (ME) and motor observation (MO), because these motor conditions all induce the event-related desychronization(ERD) of the mu rhythm in the motor-related cortex. The relationship between the source locations of where the mu-rhythm of the three motor conditions have been originated has been largely discussed in the literature. Therefore, the first purpose of this study was to identify and compare the sources of the three motor tasks. In addition, EEG acquisition equipment has developed toward more convenient dry electrodes in recent years. To facilitate the application and development of the BCI, the second purpose of this study was to compare the ability of the wet and dry electrodes to collect signals using the mu component characteristics. First experiment collected 13 participants with wet-electrode EEG. The within subjects experimental design included motor execution, motor imagery and motor observation. Source identification of different motor tasks was performed using two different sequences of independent component analysis. First, the ICA was applied to the preprocessed EEG data with the data from the three different motor condition altogether for the single ICA decomposition(thus, SD); second, the ICA was separately applied to the preprocessed EEG data of each motor condition to obtain ME, MI and MO with ICA being applied to the data of each motor condition separately. Then, the motor-related independent components, maximally projecting to surrounding the C4 channel location with the maximal mu-suppression feature, of each individual subject would be selected and subjected to source localization process using the DIPFIT2 extension under the EEGLAB. If the sources of the three motor conditions were co-located, there should not be any difference in the sources identified with different ICA steps. The results show that the SD ICA is more lateral than the MO ICA, and the MI ICA is more anterior than the ME ICA. Therefore, the mu ERD activity seemed to be originated from different brain regions for the motor execution, motor imagery, and motor observation conditions. In addition, to compare the mu rhythm characteristics obtained using the dry and wet electrodes, the dry electrode EEG of 16 participants were further collected with the performance of the three motor conditions combined. To compare the result of the dry EEG system to that of the wet EEG system, the number of wet EEG channels was reduced from the original 64 channels to 30 channels to match the setting of the dry EEG system. The results indicated that the number of channels had less influence on signal quality. However, the higher impedance inherently associated with the dry EEG electrodes might play more an important role in affecting the signal quality of the acquired EEG signals. Nonetheless, the dry EEG electrodes could still pick up some of the mu-suppression characteristics associated with the MI and other motor conditions.

碩士
國立交通大學
電機與控制工程系所
93
In this thesis, the fabrication and characterization of MEMS based silicon micro probe array, namely spiked dry electrodes, are explored for EEG measurement applications. A series of practical in-vivo tests have showed that the MEMS based spiked dry electrodes have more advantages and conveniences than the conventional standard electrodes. Compared with standard electrodes, the device area of the spiked dry electrodes is smaller. In addition, the spiked dry electrodes can be used without electrolytic gel, and they will not cause an uncomfortable feeling for the tested person. There is a 20×20 micro probe array fabricated using MEMS technology on the spiked dry electrode. When spiked dry electrode is applied to the skin, the probes can pierce the stratum corneum (SC) into the stratum germinativum (SG); thus, low skin-electrode-interface impedance effect can be obtained, stronger signal intensity can be collected. This makes the design of the amplifier circuit simpler and easier. Related experiments including qualitative/quantitative tests and practical EEG measurements are also introduced and discussed in this thesis.

碩士
國立臺灣師範大學
機電科技研究所
95
The research has developed a novel method of microneedle array through the combination of integrating silicon bulk micromachining, thick photoresist KMPR1050, electroforming and polymer material PDMS.The microneedle array was successful fabricated on a flexible PDMS substrate. This study complete establish experimental parameters of KMPR, and can produce thickness of 130 um KMPR by single spin. Combination of 130 um KMPR, KOH etching, electroforming, two-step removing KMPR, the length of the microneedle array is 170 um and width is 50 um (aspect ratio, 3.5) which is out of plane was successful fabricated on a flexible PDMS substrate.

碩士
國立臺灣大學
機械工程學研究所
101
In this work, barbed dry electrodes array for EEG measurement was designed and fabricated by using low-cost silicon wet etching techniques. Compared with traditional wet electrodes, the proposed dry electrodes can avoid skin preparation and electrolytic gel during measurement process. The preliminary pyramidal electrodes arrays were fabricated by KOH etching, and the barbed shapes were formed by HF/HNO3 etching. The radii of curvature of barbs decrease almost linearly as the etching time increases. Also, a through-silicon via (TSV), which improves the conductivity between the electrode lead and the tip array, was created on the substrate during the etching process. The average height of the dry electrodes is about 155 μm, and the average base width is 86 μm. By using conductive silver epoxy, the fabricated dry electrode was bonded with a traditional commercial ECG electrode, on which the electrolytic gel was removed. The detaching force measurement results showed that the barbed electrodes array was more adherent to soft materials than the pyramidal electrodes array. In the electrode-skin contact impedance measurement, the impedance of barbed dry electrodes is slightly higher than that of the wet electrodes. We also demonstrated that the proposed barbed dry electrodes can be used to measure the EEG signal effectively.

碩士
國立臺灣大學
機械工程學研究所
92
This research focuses on the study of electricity generation center of proton exchange membrane fuel cell — the development of low platinum content dry process for Membrane Electrode Assembly (MEA). The catalyst of this process is not prepared from any organic solvent; therefore the time of preparation can be drastically reduced. Only the suction method is used to produce the electrodes. Experimental analysis and observation is performed on the characteristics of attraction force to the micro-structure of catalyst layer.　 Pressure setting of the experiment is obtained by using the self-made lab equipment. To reduce the influence from other factors during the manufacturing process, the selection of material for the exchange membrane electrode assembly from pre-processing, including cleaning of exchange membrane, and carbon cloth filtering processing, to post-processing, including hot pressure temperature and pressure control, as well as the choices of other parameters are determined through repeated experiments. 　　This research uses Nafion 117 as the main body for producing membrane electrode assembly (MFA). The amount of platinum catalyst is controlled under 0.4 mg/ cm2. From the result of the experiment, it can be seen that the selection of suction force can affect the alignment of carbon platinum catalyst power and further lead to the difference in performance. 　　However, the establishment of more accurate attraction force and performance relationship, and the optimum alignment of the microstructure of each layer for the exchange membrane resistor array is depending on future experiments. It is also hoped that a faster preparation procedure and a low cost fuel battery can be obtained so that the fuel battery can be more commercialized and become popular.

碩士
國立交通大學
影像與生醫光電研究所
102
Electroencephalogram(EEG) comes from the neuron activity. Brain disease and human physical condition can be detected from EEG information. In general, EEG is measured by traditional adhesive Ag/AgCl electrodes as an effective way for well EEG signal quality. However, patients should have skin preparation and the conductive gels in traditional adhesive Ag/AgCl electrodes would harden which results signal attenuation after several hours. Therefore novel active comb-shaped dry electrode has been proposed for long time EEG monitoring in clinical usage. The active comb-shaped dry electrodes can measure EEG signal directly without conductive gel and skin scrub. The comb shape can easily penetrate hair on scalp for good contact. Besides, the active comb-shaped dry electrode could avoid the reduction of common mode rejection ratio (CMRR). The correlation of signal quality and motion artifact were also tested in this study. Finally, the experiments of alpha rhythm and steady state visual evoked potential (SSVEP) were applied. The results shows that the proposed active comb-shaped dry electrode could acquire EEG signal clearly.

碩士
國立臺灣大學
機械工程學研究所
92
As production cost will be one of the main challenges for commercialization of fuel cells, a new approach to MEA production for PEMFC has been considered. Electrodes are produced by a new dry layer preparation method in a suction procedure and co-operated with a particle diffusion design. All structures in MEA of this process were prepared without any organic solvent; therefore the time of preparation procedures can be drastically reduced. MEA’s sandwiched structures were constituted by many materials- diffusion substrate, carbon powder, PTFE, catalyst, ion conductor, Nafion membrane. A slight difference in the quantity and character of each material will cause a apparent influence on the performance of MEAs. In gas diffusion backing layer the content of PTFE is about 40wt% and with high surface-area Ketjen Black EC600 at an optimized thickness, show better performance compared with Acetylene black and Ketjen Black EC300 carbon in backing layer. In catalyst layer preparation the suction pressure and the flow rate of nitrogen affects directly in the performance of MEA. When the pressure at 12 cm water height and the nitrogen flow rate at 4L/min show an obvious higher power density 0.21 W/cm2. The Pt loading is controlled between 0.4~0.5mg/cm2. This new dry layer preparation method with suction and powder diffusion procedure offers a simple, rapid and reliable method for MEA’s production. A faster and a low cost objective can be achieved.