On the basis of our exceptionally sensitive 32 micron carbon fiber working electrodes* we developed the first easily manageable system for chronic implantation and registration of dopamine transients during several months of experiments. The photograph above shows mouse in an experiment on registration of dopamine transients in dorsal striatum 1.5 months after implantation.
The chronic recording is based on two core principles pioneered by Paul Phillips and his laboratory**:
– a very small in diameter shaft of the electrode covered by biologically indifferent polyimide, and
– waiting time which is required to let inflammation around the shaft and sensing element to disappear.
The most critical part of the shaft near the sensing element is 40 micron in diameter including polyimide cover. It is twice smaller than the originally described electrodes. At this tiny diameter the shaft is 2.5-3 mm in length. The shaft of such a length is long enough to prevent inflammation at the sensing tip and still solid enough to be implanted in the brain. The rest of the shaft (partly implantable and partly used for handling, 210-250 micron polyimide tubing) does not impede functionality.
The sensitivity of these electrodes is 30-60 nA/μM when measured by means of fast cyclic voltammetry. The background current which they produce is 3-4 μA. These electrodes require a suitable head-stage (current to voltage converter). The head-stage is a part of the In Vivo Voltammetry Setup.
We also manufacture 7 micron carbon fiber electrodes for chronic implantation. Sensitivity of these electrodes is 10-20 nA/μM.
The working electrodes are packed in a robust plastic box, 10 electrodes per box and sent by registered airmail or FEDEX. Minimal order is one box of 10 electrodes.
* Chadchankar H and Yavich L, Journal of Neuroscience Methods 211 (2012) 218.
** Clark JJ et al., Nature Methods 7 (2010) 126.