As part of the Center effort to develop and broaden the application of polarographic electrodes to the self-referencing modality we are beginning the production of our own electrodes. Although theoretically straight forward the mechanics of production are difficult. In brief a glass micro-electrode is filled with Woods Metal and etched to form a recess. The surface of the metal is coated with gold by electroplating and the remaining space filled or not with an 'oxygen-selective' membrane. Whether the membrane is used remains a matter of debate for our applications. In both the case of a large recess and a membrane, a main function is to reduce the oxygen depletion gradient at the tip of the electrode. This summer saw the first attempts at building our own electrodes. This work was done in collaboration with Paul Malchow with technical advice from Kim Mitchell (Center for Neurobiology and Immunology Research, University of Kansas), and Robert Linsenmeier and Lissa Padnick (both of Northwestern University, Chicago). In the latter case these investigators gifted the gold-plating solution. Electrodes have been successfully manufactured and applied to the study of oxygen consumption by Skate rod cells (see sub-project 21). Previous studies with commercially manufactured electrodes (Diamond General) produced similar results giving us a degree of confidence that our procedures are correct. The need to manufacture our own polarographic electrodes is driven largely by cost. Each electrode is priced at approximately $150 and our experience has demonstrated that only about one in five are quiet enough for our application. Presently, Diamond General are replacing all electrodes found to be below our needed standard. The additional advantage in producing our own electrodes is the ability to diversify the design as needed for the manufacture of nitric oxide detectors. This will be our next R&D step in this area where we hope to gain immensely from our consultative arrangement with Kim Mitchell and the recruitment to our advisory group of Thomas Goldstick.
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