The thesis aims to develop an ISFET chip compatible miniaturized planar reference. Such planar reference electrode will be constructed by: silica / silica oxide / titanium / palladium / silver / silver chloride / saturated KCl agar / silica nitride / silica. For the size of the reference electrode is only 10mm (length), 5mm (width) and 1mm (height), which is diminished of hundred-fold to the traditional reference electrode. In addition to develop the fabrication techniques of the electrodes, this thesis will be devoted to systematic measuring and analyzing their stability, AC impedence, cyclic voltammery and electrochemical noise characteristics. The results show that the stability is inside 1mV, offset voltage is about -9 mV and the resistance of AC impedence is 400

Electroanalysis offers cheap and selective analysis of interesting solutions. However, one of the most common drawbacks is the accessibility for electrochemical sensing. By using high-pressure microfluidics with an integrated three-electrode system, new possibilities open for increased accessibility. Therefore, there is a need to fabricate sustainable reference surfaces into highly pressure tolerant microchannels. In this thesis, Ag/AgCl reference surfaces were in-situ fabricated in high-pressure microfluidic chips. This was performed by electroplating Ag on thin film Pt in microchannels and then chlorinating the silver into Ag/AgCl. Electroanalysis of ferrocyanide was carried out in a microfluidic chip using one of the in-situ fabricated Ag/AgCl references. The half-wave potential showed to be around +251 mV and the electrochemical water window was measured to 1400 mV with a range between -300 mV and +1100 mV. The obtained values show to be comparable to reference data of similar experiments performed elsewhere. For some applications of electrochemistry, a catalysis surface is beneficial. Nanoporous Pt black has proved to generate high catalytic performance in electrochemistry. Therefore, attempts have been carried out to fabricate Pt black onto Pt thin films, with the vision to succeed with such fabrication within microfluidic channels. To summarize, this project work has showed a possibility to in-situ fabricate Ag/AgCl reference surfaces. The project has also showed how to use such surfaces as reference electrodes for electroanalysis in high-pressure microfluidic chips. Lastly, new challenges and ideas to fabricate catalysis surfaces on thin film electrodes in flow channels have been presented. By this thesis, one more step has been taken to increase the accessibility for electroanalysis.

Molten salt reactors (MSRs) using chloride-based salt-matrixes as coolants or fuels are a promising option for advanced nuclear reactors, but the extreme temperatures and corrosivity of molten salts pose a challenge for implementation. Molten MgCl2-NaCl-KCl is a viable candidate for MSRs that is considered in this work. Thermochemical properties are derived from electrochemical tests that aid in characterizing the properties of salts. To study these properties, some work has proposed using a three-electrode system with a reference electrode housed in a ceramic membrane. This research aims to develop a stable high-temperature reference electrode using a ceramic membrane that is then applied to develop an on-line monitoring system of Ni-Cr alloy corrosion in chloride salt. A mullite tube used as the membrane of a Ni(II)/Ni reference electrode in molten MgCl2-NaCl-KCl is studied. The performance of two different membrane thicknesses (1.325mm and 0.255mm) was studied in temperature ranges from 635oC to 835oC and data collected on the calculated formal potential of the Ni(II)/Ni system. Tests indicated that the results were stable and repeatable, and the formal potential for both systems differed from the previous experimental data by 0.12V at most, indicating that the system can be applied as an effective reference electrode. Using the reference electrode, on-line monitoring the corrosion of Ni-15wt.%Cr, Ni-20wt.%Cr, and Ni-30wt.%Cr was studied for 120 hours in MgCl2-NaCl-KCl. The on-line measurements showed the concentration changes of dissolved Cr and Ni by corrosion in the bulk molten salt. This work confirms that Ni(II)/Ni reference electrodes with a mullite tube membrane are stable and effective in molten chloride salt systems, particularly MgCl2-NaCl-KCl. The mullite membrane prepared by the manufacturer may be used directly for electrochemical applications without polishing, simplifying the reference electrode manufacturing process, and making it easier to replicate. The use of a Ni(II)/Ni reference electrode provides an avenue to study a different range of salt systems than previous reference electrodes allowed, particularly alloys in chloride salts at high temperatures. This work also confirms that the mullite tube may be used to perform on-line analysis of alloy corrosion in high temperature molten chloride salts. The study of Ni-Cr alloys in chloride salts better prepares the nuclear industry to select coolant salts and alloy containers with the best set of thermochemical and corrosion resistant characteristics for MSRs. / Master of Science / The United States receives approximately 18% of its energy from nuclear technology. Many of the reactors supplying this energy are at the end of their lifecycle and the decommissioning of some of these plants has already begun. In order to replace this older generation of nuclear reactors, a safer and cheaper option has been suggested: Molten Salt Reactors. Molten salt reactors (MSRs) using high temperature salts as a fuel or coolant are a promising option, but the extreme conditions of molten salts pose a challenge for construction and use of MSRs. Molten MgCl2-NaCl-KCl is a salt being considered for MSR application, and is considered in this work. Properties of the salts considered for MSRs are being studied diligently before implementation of these reactors. Electrochemical tests are used to study and monitor these properties. These electrochemical tests use a three-electrode system with a reference electrode housed in a membrane. In this work, a mullite tube is used as a ceramic membrane for a reference electrode in molten MgCl2-NaCl-KCl. The performance of two different membrane thicknesses (1.325mm and 0.255mm) was studied in temperature ranges from 635oC to 835oC. Results indicate that the system is an effective reference electrode. Using this innovative reference electrode, a method of monitoring on-line corrosion of Ni-15wt.%Cr, Ni-20wt.%Cr, and Ni-30wt.%Cr alloys was studied for 120-hour time periods during exposure to MgCl2-NaCl-KCl. This work confirms that reference electrodes with a mullite membrane may be used for electrochemical applications when studying molten chloride salts. The use of a Ni(II)/Ni reference electrode with a mullite membrane provides an avenue to study a different range of salt systems than previous reference electrodes and ceramics allowed, particularly chloride salts. Additionally, this mullite membrane Ni(II)/Ni reference electrode system may be used for monitoring on-line corrosion of Ni-Cr alloys in chloride salt systems.

<p>  </p> <p>As our ability to make more sensitive measurements increases, we begin to reach for the ultimate measurement sensitivity: a single entity. Mass spectrometry and fluorescence-based methods exist for single entity studies, and through these the intriguing effects of confinement begin to be observed. These mass spectrometry and fluorescence-based techniques are however, often destructive, which precludes measurements over time. The advent of nanoelectrochemical methods, however, allows for the creation of tools that can make measurements inside of confined volumes—a droplet, a cell, <em>etc</em>.—over extended periods of time. While most nanoelectrochemical methods are based on amperometry or voltammetry, potentiometry allows for minimal perturbation of the system’s homeostasis by passing negligible current.</p> <p>To overcome many of the issues involved in these other methods, we design potentiometric tools that can be easily miniaturized to fit within single entities, particularly within single cells. These tools include enzymatic biosensors designed to be minimally influenced by the cell’s O2 or NAD+ levels, as well as a novel reference electrode that can be made to be very low leakage or completely leakless to avoid contamination of the cell by the reference electrode’s internal filling solution. Both of these tools are designed such that they are easily modified to suit a number of different applications, including for use inside non-aqueous solutions.</p>

This thesis devotes to develop a wafer-level packaging technique of the planar AgCl-based micro reference electrode and to investigate its various electrochemical characteristics (including the potential stability and offset voltage, AC impedance, cyclic-voltammetry analysis, electrochemical noise and reproducibility). The miniaturized all-solid-state reference electrode can integrated with many biomedical or biochemical sensors for substantially reduce the dimension of the whole sensing system and improve the commercial capability of portable detecting products. This study reports firstly a smallest module of the micro reference electrode with dimension only about 9 mm (L) ¡Ñ 6 mm (W) ¡Ñ 1 mm (H) in the worldwide using the silicon bulk-micromachining technology, thin film deposition and chloridation techniques. The packaged reference electrode module is constructed by two bonded wafers with different functions. One wafer of this module is defined as ¡§electrode chip¡¨ and it has a Ti/Pd/Ag/AgCl planar quasi-reference electrode deposited on its surface. Another wafer is called as ¡§packaging chip¡¨ and it has two bulk-micromachined silicon cavities for the filling/sealing of 1.33 ~ 6.40 £gL KCl-gel (as the salt-bridge of electrode) and electrical connection. Many electrochemical characteristics of the encapsulated solid-state micro reference electrode are tested and improved for the commercial applications. Including a very stable cell potential (<4 mV in 30000 sec.), an approximately zero offset-voltage, a low AC impedance (1~20 K£[), and high reproducibility (drift less than 3~8 mV in 30000 sec. and the range of offset voltage is -6 ~ 3 mV) of the packaged micro reference electrode are demonstrated. Furthermore, stable CV curve of the packaged Ti/Pd/Ag/AgCl/KCl-gel reference electrode were proved by cyclic-voltammetry analysis and its low electrochemical noise spectrum was investigated and discussed in this work. Compared with the commercial reference electrode, the planar miniaturized AgCl reference electrode module developed in this thesis has displayed its many excellent characteristics and with a dimension only 250 times smaller than the conventional reference electrode.

The first chapter of this thesis describes the motivation behind using room temperature ionic liquids (RTILs) in gas sensor research and reviews current applications of RTILs in various sensors. The second chapter describes electrochemical polymerization of aniline in room temperature 1-butyl-3-methylimmidazolium ionic liquids without addition of any acid. It is shown that the polymerization of aniline in BMI(BF4) does require small but controlled amounts of water whereas the polymerization in BMI(PF6) and in BMI(TF2N) does not require any water addition. The third chapter describes the construction of reference electrodes for RTIL applications that have a known and reproducible potential versus the ferrocene/ ferrocenium couple. They are based on reference electrodes of the first kind, Ag/Ag+ couple type, or of the second kind, based on Ag/AgCl in M+Cl-. The stability, reproducibility, and temperature behavior of the two reference systems have been characterized. The fourth chapter describes the electrochemical preparation and spectral analysis of gold clusters by adding gold atoms one-by-one through polyaniline s ability to form a strong complex with chloroaurate at the protonated imine sites. Our results confirm that both the amount and the size of gold clusters affects the properties of the composite material. The fifth chapter describes the development and characterization of a CHEMFET sensing layer based on a composite of CSA-doped polyaniline (PANI), and the room temperature ionic liquid BMI(TF2N) for the sensing of ammonia gas. The work function responses of the cast films with and without IL are analyzed by step-wise changes of ammonia gas concentration from 0.5 to 694 ppm in air as a function of the mole fraction of IL to PANI. The PANI CSA/BMI(TF2N) layers shows enhanced sensitivities, lower detection limit and shorter response times. The final chapter describes the preparation and characterization of field-effect transistors with mixed ionic-electronic conductors that have been created by varying the ratio of room temperature ionic liquid and emeraldine salt of polyaniline. Transistor with high electronic conductivity (32mol% ES-PANI) and Au gate contact exhibited theoretical behavior of an IGFET; whereas, the purely ionic gate behaved irreproducibly, indicating that a capacitive divider has been formed in the gate.

Afin d'approfondir la compréhension des mécanismes de vieillissement des batteries Li-ion, des analyses post-mortem ont été effectuées sur des cellules commerciales Li-ion C/NMC. Ces autopsies ont révélé des dégradations inattendues qui remettent en question les connaissances actuelles sur les mécanismes de vieillissement de ces cellules. Ainsi, il semble que la réaction parasite des dépôts de Li métallique sur l'électrode en graphite, actuellement associée dans la littérature à des charges à basses températures et / ou à courants élevés, aurait diverses origines selon la chimie et les conditions d'utilisation de la batterie. Dans ce travail de thèse, des dépôts locaux de Li métallique ont été observés sur des cellules vieillies en calendaire à haute température. Paradoxalement, dans des conditions de cyclage à basse température, ce dépôt de Li métallique a résulté de la perte de porosité au niveau de l’électrode négative. Par ailleurs, un modèle de vieillissement semi-empirique, prenant compte les pertes en cyclage ainsi que celles causées par la croissance de la SEI et la polymérisation du biphényl, est proposé. Pour finir, une méthode d'identification des modes de dégradation grâce à des mesures de capacité incrémentale a été entreprise, sur la base du décalage des potentiels de chacune des électrodes. / In order to deepen the understanding of the aging mechanisms of Li-ion batteries, post-mortem investigations were performed on C/NMC Li-ion commercial cells. These autopsies revealed unexpected degradations that question current knowledge about the aging mechanisms of these cells. Thus, it appears that the parasitic reaction of Li metal depositions on the graphite electrode, nowadays associated in the literature with charging at low temperature and / or high C-rates, would have various origins depending on the chemistry and conditions of use of the battery. In this thesis work, local Li deposits were observed on cells aged in calendar at high temperatures, due to the apparition of dry areas. Paradoxically, under low temperature cycling conditions, this Li resulted from anode porosity hindrance. Besides, a semi-empirical aging model, taking into account cycling losses as well as those caused by the SEI growth and the biphenyl polymerization, is proposed. Finally, a method of identifying degradation modes using incremental capacity measurements has been undertaken, based on the potential shifts of each of the electrodes.

The presented thesis investigates the transfer of drug molecules across interfaces that mimic biological membrane barriers. The permeability of drug molecules across biological membrane mimics has been investigated in a novel artificial membrane permeation assay configuration using an in situ time-dependent approach and reproducible rotation of the membrane. A method to determine the membrane permeability from the knowledge of measured permeability and the applied stirring rate is presented. The initial transient of the permeation response, previously not observed in situ, is investigated and its importance in data evaluation is discussed. The permeability coefficients of 31 drugs are optimised for the conditions found in vivo and a correlation with the fraction absorbed in humans is presented. The evidence for ionic and/or ion-pair flux across the artificial membrane obtained from measurement of permeability at different pH is supported by the investigation of the permeation assay with external membrane polarisation. The permeability coefficient of the solute's anionic form is determined. Liquid/liquid electrochemistry has been used to study the transfer of ionized species across the interface between water and 1,2-dichloroethane. An alternative method to study the transfer of partially ionised drug molecules employing a rotating liquid/liquid interface is presented. In addition, a bipolar electrochemical cell with a rotating-disc electrode is developed and its properties investigated in order to verify the hydrodynamics of the rotating artificial membrane configuration. Finally, in support of the electrochemical techniques used is this thesis, a detailed preparation and evaluation of the silver/silver sulphate reference electrode is presented.