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Devon Martin, Borosilicate and Fused-Silica Capillary Microelectrode Electrochemical Comparison and Micromanipulator Adaptor for Fused-Silica Capillary Microelectrodes
September 10, 2018 | 4:00 pm - 5:00 pm EDT
Borosilicate glass is the material predominately used for encasing carbon fiber (CF) microelectrodes for fast-scan cyclic voltammetry (FSCV) experiments. These capillaries insulate unexposed CF from the surrounding environment, while leaving a 150-200 um exposed CF tip in vivo that allows for electrochemical measurements of neurotransmitters. However, borosilicate glass commonly breaks during implantation; this can leave debris in the rat brain and prevent lowering of subsequent electrodes, reducing experimental yield. Additionally, borosilicate glass electrodes often contain cracks at the seal, resulting in undesirable electrochemical characteristics. This can be alleviated with the use of epoxy resin to fill cracks and solidify the seal. Recently, a new design of CF microelectrodes using fused-silica (FS) was announced, which was more flexible and resilient to strain1 . This study compares non-epoxied borosilicate, epoxied borosilicate capillary microelectrodes, and FS microelectrodes. The electrochemical characteristics (RMS noise, background amplitude, and background peak locations) between these three designs were compared. Additionally, the larger diameter of the glass electrodes (600 um compared to 90 um FS) allow them to be used in micromanipulators, which allow for precise control of electrode depth along the dorsal-ventral axis and new electrodes to be used for each experiment. The FS electrodes lack any such device, so an adaptor prototype was developed to match the smaller diameter; the FS electrode construction process was also adjusted to fit the design. These two experiments make FS a more acceptable and useful electrode for in vivo testing.