New manufacturing technology of carbon fibre microelectrodes

Kurzfassung

A Hungarian SME offers carbon fibre microelectrodes used for electrophysiological and/or electrochemical purposes and their manufacturing technology. Elementary carbon fibres (7µm in diameter) are built in borosilicate glass capillary tubing of various diameters for support and electrical insulation. Resulting from a dry manufacturing technology, the carbon fibre microelectrodes can be sold over long distances by mail delivery. Partners for commercial or financial agreements are awaited.

Details

A Hungarian company manufactures and sells carbon fibre microelectrodes and related instruments including micropipette pullers and constant current sources for micro-iontophoresis.
Nerve cells (neurons) of animals and humans produce electrical signals (spikes) when activated by natural or artificial stimuli. In extra-cellular mode of recording, the frequency and pattern of these spikes are the primary data of interest. The offered carbon fibre microelectrodes are well suited for extra-cellular recordings of neural spikes. On the top of this, they are suitable for electrochemical measurements (voltammetry or amperometry) of certain agents produced in the nervous tissue.
The diameter of the cell body of an average neuron is about 40µm so that the recording electrode must be similar or smaller in size. These microelectrodes are manufactured from 7µm in diameter elementary carbon fibres and are insulated with a less than 1µm-thick borosilicate glass layer. The carbon fibre protrudes from the glass insulation by about 20µm and shaped into a conical tip for easy tissue penetration. This non-insulated carbon tip provides a very low-noise spike recording and suitable for electrochemical measurements.
Recordings of neural spikes are often combined with drug application on a miniature scale. To do so, the described carbon fibre electrodes are equipped with micro capillaries through those drugs (e.g. compounds of medicinal interests), which can be delivered in minute amounts into the close vicinity of the recorded neuron. Drug delivery is usually made by iontophoresis or sometimes by pressure. The orifices of the drug delivery capillaries at the tip of this multi-barrel assembly are less than 1µm in diameter.
The offered technology can be used in the field of extra-cellular physiology, by which compounds of medicinal interest can be tested in vivo on single neurons of an anesthetised experimental animal. As the electrode is located outside the neuron, functions of cell surface receptors can be manipulated and studied using this technique.

- Extra-cellular electrophysiology: branch of the electrophysiology where the recording electrode is placed outside of (but close to) the studied neuron.
- Receptor: protein molecules integrated into the surface membrane of a neuron and specialised in initiating or regulating various functions of that neuron.

Innovative Aspects:
This dry manufacturing technology of making glass-insulated carbon fibre microelectrodes has the advantages over previous wet methods of providing high-quality extra-cellular recording, exhibiting long shelf life, ability to be combined with drug delivering micro capillaries, and being suitable for mail delivery over long distances. Usage and handling of these electrodes are learnt quickly and easily.