Invilog offers two types of the carbon fiber working electrodes for in vivo voltammetry. The fist one is a glass insulated carbon fiber 7 or 32 micron in diameter suitable for recording in cells, tissues, brain slices and intact brain in anesthetized animals. The second type is 7 or 32 micron carbon fiber insulated with polyimide. Miniature size and special design of this electrode permit chronic implantation in mouse or rat brain and several months of recording of dopamine transients.