Abstract This study was part of a project targeted at developing chemical sensors for organic cations and metal ions by exploiting the interactions between cations and anionic borate derivatives. As well, the chemical synthesis of thiophene monomers with charged or neutral ion-recognition sites was investigated. The primary task in the first part of the work was to prepare anionic receptor molecules based on synthesized borate derivatives and study their complexation with N-heteroaromatic and tropylium cations. The complexation was studied in solution by 1H NMR and ESIMS techniques and in solid state by X-ray crystallography. Crystal structures showed evidence of weak noncovalent interactions–hydrogen bonding, cation···π interactions, and π-stacking. In addition, the crystal structure of the alkali metal complex of tris[3-(2-pyridyl)pyrazolyl]hydroborate was determined. Stability constants of borate complexes were measured by 1H NMR titration in methanol/acetonitrile (1:1) solution at 30 °C. Various derivatives of aromatic borate anions synthesized within this project, some commercially available derivatives, and two neutral carriers containing aromatic anthryl groups were also studied as recognition sites for aromatic cations where N-methylpyridinium was used as primary ion in PVC membrane-based all-solid-state ion sensors. The results showed that borate derivatives offer new possibilities for molecular recognition by ion-selective electrodes (ISEs). The aim of the second part of the study was to develop chemical ion sensor materials where the ion-recognition unit and the charge-compensating ion are covalently coupled to the backbone of a conductive polymer. Sulfonated thiophenes were used as doping ions for the fabrication of Ag+-ISEs. More than 15 differently substituted monomers were synthesized. The materials differed with respect to the receptor unit, extent of oxidation, counteranion, and length of the chain.

Physicians’ understanding of bio-signals, measured using medical instruments, becomes the foundation of their decisions and diagnoses of patients, as they rely strongly on what the instruments show. Thus, it is critical and very important to ensure that the instruments’ readings exactly reflect what is happening in the patient’s body so that the detected signal is the real one or at least as close to the real in-body signal as possible and carries all of the appropriate information. This is such an important issue that sometimes physicians use invasive measurements in order to obtain the real bio-signal. Generating an in-body signal from what a measurement device shows is called “signal purification” or “reconstruction,” and can be done only when we have adequate information about the interface between the body and the monitoring device. In this research, first, we present a device that we developed for electrocardiogram (ECG) acquisition and transfer to PC. In order to evaluate the performance of the device, we use it to measure ECG and apply conductive textile as our ECG electrode. Then, we evaluate ECG signals captured by different electrodes, specifically traditional gel Ag/AgCl and dry golden plate electrodes, and compare the results. Next, we propose a method to reconstruct the ECG signal from the signal we detected with our device with respect to the interface characteristics and their relation to the detected ECG. The interface in this study is the skin-electrode interface for conductive textiles. In the last stage of this work, we explore the effects of pressure on skin-electrode interface impedance and its parametrical variation.

M. Ing. / The purpose of this study is to investigate the use of computer vision techniques to measure the electrode slip. The study investigates a potential location for camera placement in the furnace housing, as well as the use of computer vision algorithms that could be used to solve the problem. A slip measurement algorithm is then designed, implemented and tested. The implemented slip measurement algorithm is based on the manual slip measurement technique, by measuring relative electrode and slip arm displacement between the electrode and the slip arm. The algorithm uses SURF invariant features to extract the electrode features and slip arm features in one frame, and match these features to the next frame SURF. Scene calibration is then used to relate the pixel slip measurement to a metric distance measurement. The experimental results proved that there is scope for applying computer vision techniques to address the slip measurement problem, using a single HD camera. However, there is room for improvement and the recommendations and future work are also discussed.

In this paper, the electrochemical behaviors of a single gold nanoparticle attached on a nanometer sized electrode have been studied. The single nanoparticle was characterized by using electrochemical methods. Since there is only one nanoparticle on the electrode, unarguable information for that sized particle could be obtained. Our preliminary results show that it becomes more difficult to oxidize gold nanoparticle or reduce gold nanoparticle oxide as the radius of the particle becomes smaller. Also, the peak potential of the reduction of gold nanoparticle oxide is proportional to the reciprocal of the radius of the particle.

The sarcoplasmic reticulum (SR) of striated muscle plays a central role in control of contractile activity. It acts as an intracellular sink for calcium during relaxation and releases cav2 + during contraction. This highly differentiated endoplasmic reticulum is a self-contained network with a continuous hollow interior which surrounds each muscle fibril (Fig. 1) (Porter, 1961). The SR is fragmented at longitudinal intervals of one sarcomere in length by the transverse tubular or T-tubular system (Porter, 1961; Franzini-Armstrong, 1980). On each side of the T-tubules there are enlarged areas known as cisternae, with branched areas between the cisternae known as the longitudinal elements. The juncture of the three membranes (two terminal cisternae and one Ttubule) is referred to as the triad. The junction between the SR and • 0 the T-tubules is known as a junctional gap and has.a width of 100-200 A. Periodic densities, referred to as 'feet', cross the junctional gap to join the SR and T-tubular membranes (Franzini-Armstrong, 1980). Direct communication between the SR, the T-tubules and the feet have been postulated (Schneider· and Chandler, 1973; Mathias et al., 1979). The view has developed, starting with the experiments of Huxley and Taylor (1958) and Huxley and Straub (1958), that, under physiological conditions, contraction in skeletal muscle is triggered by depolarisation of the membranes of the T-tubules. This results in the release of ca 2 + into the myoplasm from its intracellular storage location, the SR, and thus activating the contractile proteins (Schneider and Chandler, 1973). (See Fuchs (1974) and Ebashi (1980) for a review on the possible mechanism involved in excitation-contraction coupling.)

Ultramicroelectrodes (UMEs) have gained considerable attention over the few past decades due to the important roles they play in electrochemical studies. Electrodes with dimension less than 25 mm can generally be classified as UMEs. These electrodes exhibit enhanced electrochemical properties as their dimensions get smaller hence making nanoelectrode (production of electrodes with limiting dimensions less than 100 nm) a continuing area of interest in research. Nanometer size electrodes have advantages of high sensitivity which enables them to be used in fields such as single particle characterization and single cell analysis, and fast electron and mass transport which permits use for studying short-lived and transient electrochemical reactions such as those involved in neurochemistry. Nanoelectrodes can be fabricated via a few different strategies which include but are not limited to electrochemically etching a thin metal wire down to a cone shape or flame-etching a carbon fiber, and chemical vapor deposition of carbon in nanopipette. This work seeks to employ the use of the laser-assisted pulling method to fabricate carbon fiber electrodes sealed in glass capillary tubes. Effects of various pre- and post- treatment techniques on electrode size and stability are explored. Key words: Electrodes, Electrochemical, carbon fiber.

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SERS (surface-enhanced Raman spectroscopy) has the potential to be used in a variety of commercial and basic applications, which often rely on molecules that are bound to a nanostructured metal surface. Thiols are usually used as the intermediate to modify the substrate surface for SERS. In recent years, N-heterocyclic carbene (NHC) has been introduced as an alternative approach for metal surface modification. Nanostructured gold surfaces suitable for SERS had been modified by NHC species. Those studies showed the promising of the NHC modification route for the fabrication of a robust platform for SERS. The objective of this work is to explore the SERS characteristics of NHC species on silver surfaces. The interactions between two different NHC molecules and a nanostructured silver surface, instead of a gold surface, were studied for the first time. The experiments were realized in electrochemical conditions, using a three-electrodes system, to fully test the stability of the NHC-modified surfaces. The SERS spectra were compared to theoretical calculations and normal Raman in order to identify the vibrational characteristics of the NHC molecules. The effects of different NHC molecule substituents on the electrochemical stability of the surface were also discussed. The results showed that NHC molecules can be decomposed on the silver surface easily under electrochemical conditions. This contrast with the observations in gold, where the NHC monolayers showed a high level of stability. This work also discusses potential side products which may be derived from the decomposition of the NHC molecules. Raman spectra of potential side products were collected and compared to the NHC SERS collected under electrochemical control at different potentials. This study provides insights into the influence of the substituents at the NHC on their stability under the electrochemical condition, which should guide the development of future applications. / Graduate