EDM is widely accepted in tool and die industries for its versatility in machining hardened steels. Its ability to machine heat treated hardened steels eliminates the conventional method of heat treatment after machining which results in distortions. However one draw back of the EDM process, which makes its uses limited, is the high cost and time for the electrode manufacture. The die sinking EDM process employs complex shaped electrodes which require specialized machining operation and often results in high lead times. Solid free form fabrication is found to be an excellent alternative for the conventional all metal electrodes for EDM. Rapid prototyping of the electrode models and electroforming with copper is a fervently studied method of producing cost effective electrodes. However most of the studies have reported premature failure of the electroformed electrodes, limiting its commercial use on a large scale. This study attempts to analyze the failure mechanism of electroformed stereo-lithography electrodes by conducting a finite element analysis of the electrode model using LSDYNA- 970. It has been shown that high temperatures and coefficient of thermal expansion mismatch are the primary reasons for the premature failures experienced in these types of electrodes. The study also proposes some design modifications to improve the electrode performance during repeated thermal loading. The modified electrodes showed significantly improved performance in analysis studies. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Industrial and Manufacturing Engineering / "December 2005." / Includes bibliographic references (leaves 109--111)

Stress constitutes a more and more common cause for many health disorders inmodern society. Salivary -amylase (AA), the most abundant enzyme in humanwhole saliva, has in recent years been found to be a good surrogate biomarker formonitoring stress levels in individuals. This work aims to form the foundation ofa novel approach for measuring the activity of the enzyme in saliva samples bymeans of electrochemistry. The idea is to implement several enzymes along witha starch substrate and an electron mediator in a single system. This system isthen to be coated onto a screen-printed electrode (SPE), which is used along withan electrical component, designed to give rise to a quantifiable, electrical signalwhen the starch is broken down by the AA contained in an added saliva sample.Several such enzyme systems are here qualitatively evaluated. As electron mediator,ferro-/ferricyanide is used. Two different enzymes, glucose oxidase (GOx) andpyrroloquinoline quinone dependent glucose dehydrogenase (PQQ-GDH), are testedfor making up the saccharide oxidising part of the system. Both prove themselvescapable in terms of qualitatively giving rise to an electrical signal. But, in terms ofinternal quantitative comparisons between the two, no practical experiments areperformed in this work. In some runs, the enzyme -glucosidase (AG) is used asan intermediate for breaking down the AA/starch oligosaccharide products intomonosaccharides. This to increase the system’s electrical signal output when usingGOx as oxidising agent. Regrettably, due to lack of AG enzyme, these runs do notprovide any conclusive data, and so further investigations of systems including thisenzyme are needed. Otherwise, all systems tested seem to work, and neither ofthem appear better than the others. Therefore, all of them will require furtherquantitative testing to determine which one is best to implement in the final designof the enzyme system to be applied onto the SPE.

Abstract In this study, a static electric contact tester with a vacuum system and gas supply system is used to investigate the effects of experimental parameters, such as inert gas kind, supply voltage, and the gap between the contacts, on the electric-arc characteristics and the erosion type for the electric contacts of silver. The experimental results show that chargeable threshold voltage in helium is higher than that in argon or air. In addition, the erosion surface of anode is observed, and the erosion area and volume are calculated and analyzed. Results show that the erosion area and volume in helium are smaller than that in argon or air. According to the observation of SEM photomicrographs, metal sputtering of the erosion hole in helium is smaller than that in argon or air. It is expected to provide the domestic electrical contact manufacturer in improving the research and development technique of the electrical contacts, and the design reference related to ultra-precision machining using a clean room.

Many electrophysiological experiments require the recording, stimulating, or both in the peripheral nervous system. There are many electrodes currently on the market, but they are either not designed for implantation or are not robust enough to be used multiple times in situ. The cost of buying these electrodes from a manufacturer can be prohibitive and many labs prefer to make their own. This introduces variability between studies, as different techniques and configurations in the design and fabrication of electrodes can create variance in electrical impedance, spatial arrangement, or other factors. This paper presents a detailed methodology for the construction of electrodes that are robust, have uniform impedance values of Z = 2.38 ± 0.906 kΩ. at 1 kHz alternating current (AC), and can be used in multiple in vitro or in situ experiments, or for chronic implantation in vivo. This method will reduce the amount of time and material needed to construct electrodes for experimental studies in animals.

This work focused on the study of self-discharge mechanisms of carbon electrochemical capacitor electrodes in 1.0 M H2SO4 electrolyte. Electrochemical capacitors have an increasingly important role in the future of energy storage for specific applications due to their high cycle lives, high power capabilities and the ability to use environmentally friendly materials. Remediation of the occurrence of self-discharge – the loss of charge over time when left in open-circuit configuration – must take place before electrochemical capacitors can be used more widely as this diminished potential results in a reduction of stored energy. By examining the now poorly understood causes and mechanisms of self-discharge, beneficial modifications to the electrochemical capacitors systems can be made, improving device performance. Three-electrode electrochemical set-ups were used to separate self-discharge mechanisms on the negative and positive electrodes. Various electrode and electrolyte reactions were investigated in relation to self-discharge, including Fe-contamination reaction, electrolyte decomposition, oxygen-reduction, carbon oxidation, and carbon surface group development. All experiments were conducted on porous carbon electrodes. It was determined that Fe-contamination increased self-discharge on both carbon electrodes at concentrations >10-3 M, and that previously developed planar kinetic models applied to these porous systems. Electrolyte decomposition did not result in increased self-discharge on either electrode. Electrolyte oxygen content must be minimized as oxygen is believed to undergo reduction to hydrogen peroxide on the negative-electrode, resulting in an increase in self-discharge. The carbon electrodes used in this work must be cycled prior to energy storage as the capacitance varies greatly with continued cycling, and the lack of cycling results in increased self-discharge. Additionally, interest in the carbon electrode’s surface functionalities resulted in the standardization of the Boehm titration.

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Thesis (Ph.D.)--Boston University / The most common polagraphic electrode in use at the present time is the dropping mercury electrode (DME). There are, however, certain well-recognized disadvantages attendant on the use of the DME: (1) oxidation analysis is limited to 0.4 v.; (2) there are rather large charging currents associated with the growing drop; (3) the area of the drops, and hence the sensitivity can not be appreciably increased; (4) because of drop growth, a a spiky sort of current is obtained which introduces a reading error into the results obtained, especially at low concentrations. It can be seen that these disadvantages are largely a function either of the electrode shape and size, or of the method of electrode propagation. [TRUNCATED]

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MEMS based mechanical switches are seen to be the likely replacements for CMOS based switches due to the several advantages that these mechanical switches have over CMOS switches. Mechanical switches can be used in systems under extreme conditions and also provide more reliability and cause less power loss. A major problem with mechanical switches is bouncing. Bouncing is an undesirable characteristic which increases the switching time and causes damage to the switch structure affecting the overall switch life. This thesis proposes a new switch design that may be used to mitigate bouncing by using two voltage sources using a double electrode configuration. The effect of many switch’s tunable parameters is also discussed and an effective tuning technique is also provided. The results are compared to the current control schemes in literature and show that the double electrode scheme is a viable control option.