An ultramicroelectrode (UME) is a working electrode with a low surface area primarily used in voltammetry experiments. The small size of UMEs limits mass transfer, which give them large diffusion layers and small overall currents at typical electrochemical potentials. These features allow UMEs to achieve useful cyclic steady-state conditions at fast scan rates (V/s) with limited current distortion. UMEs were developed independently by Wightman[1] and Fleischmann around 1980.[2] UMEs enable electrochemical measurements in electrolytes with high solution resistance, such as organic solvents. The low current at an UME limits the Ohmic (or iR) drop, which conventional electrodes do not limit.[3] Furthermore, the low Ohmic drop at UMEs lead to low voltage distortions at the electrode-electrolyte interface, allowing for the use of two electrodes in a voltammetric experiment instead of the conventional three electrodes.