Reference electrodes change their properties after they are implanted in the brain for a prolong time. This circumstance, leads to a shift the position of the reduction and oxidation peaks of dopamine on the subtracted voltammogram and can prevent proper identification of the neurotransmitter.
Replaceable Ag/AgCl reference electrodes manufactured by Invilog address this problem by offering always fresh, controllable and replaceable Ag/AgCl element incorporated into the polyimide body that is permanently attached to the skull.
A reference electrode for a rat consists of a solution filled* main implantable body (A) 2.0 mm in diameter, and 13-14 mm in length. A porous insert that forms a salt bridge is attached to the trepanation hole above the dura and fixed on the skull with dental cement.
Between the measurements, the main body is closed using a miniature plug (B). Before the measurements are taken, the plug is replaced with a threaded cup (C) with an Ag/AgCl element (16 sq. mm active area). Assembled electrode is shown on the panel D.
A reference electrode for a mouse is 11-13 mm in length.
The silver element of the cup (C) can be re-chloridized in seconds and re-tested in a beaker, the saline bridge/implantable body can also be re-filled as needed.
Invilog sells a set of these reference electrodes for 10 animals. This set includes one cup (C) and 10 implantable bodies (A) with threaded plugs (B).