The carbon fiber electrode is closely surrounded by 6 fused-together micropipettes allowing combined microiontophoresis and extracellular recording.
Microiontophoresis injection is most often used in conjunction with extracellular recording of neuronal firing. Since extracellular ‘spikes’ generated by action potentials across the membranes of neurons are typically only a few hundred microvolts in amplitude. They require a low noise recording electrode. Traditional electrolyte-filled glass micropipettes in a multibarrel assembly are electrically very noisy. Solid conductor micro-electrodes such as carbon fiber electrodes show significantly less noise in extracellular recordings. Carbon fibers are 5-8 micrometer in diameter are perfect for recording with an excellent signal-to-noise ratio recordings. The Microiontophoresis electrode-pipette assemblies are manufactured from our high quality Harvard-Clark borosilicate capillary tubing. Two standard types of tapers are available: 15 to 25 mm and with a tip length of ~25 mm.