A simple way to build a grinder for carbon-fibre electrodes for amperometry or voltammetry

Carbon-fibre electrodes are used widely for studying exocytosis by amperometry. Currently, there are two major methods for insulating fibres so as to leave the tip as the only conductive surface: encapsulation with plastic or glass. The latter offers advantages such as better insulation and a known electro-active surface. In addition, such electrodes are suitable for in vivo electrochemistry because they can penetrate brain tissues. However, the construction of glass-encapsulated electrodes requires a grinder to polish the electrode surface with precision. This apparatus is expensive because it needs a very stable motor, a diamond surface and a micromanipulator. We describe the construction of a cheap precision grinder using a computer drive and an old microscope.