Carbon powder-filled microelectrode: An easy-to-fabricate probe for cellular electrochemistry.

Carbon fiber and carbon fiber disc microelectrodes are widely used for electrochemical detection of biochemicals released from cells. However, fabricating these types of microelectrodes is difficult and time-consuming. Here, we report an easy-to-fabricate, carbon powder-filled microelectrode consisting of a pulled glass capillary backfilled with carbon powder. Carbon tip size and responsiveness can be controlled by adjusting the settings of the puller. Carbon powder-filled microelectrodes with tip opening diameters of 7-24 µm detected sub-micromolar to sub-millimolar levels of dopamine and catecholamines released from PC-12 cells. This simple microelectrode should promote further work on cellular and tissue electrochemistry.