Iontophoresis electrodes consist traditionally of a central fluid filled recording channel and various flanking channels for the drug delivery. These are used for the observation of local neuronal activity in the brain and its dependence on different brain chemicals/pharmaceuticals. The traditional design lacked mechanical stability and thus either required the use of guide tubes (which are inserted to variable depth into the brain tissue) or the opening of the dura. Both of these manipulations affect the integrity of the neural tissue and are therefore best avoided.
The new capillary profiles of Hilgenberg have a central glass capillary, in which a tungsten-electrode is sealed and two (or four) flanking capillaries, which are used as channels for the delivery of the drugs/pharmaceuticals of interest to the neuronal tissue. The design is so small that the surrounding tissue is not damaged, but it is sturdy enough to pass through the duramater (the connective tissue surrounding the brain) without needing a guide tube. The capillaries have a filament structure, which enables a blister-free filling of the channels with an appropriate conductive liquid.
The new profiles allow the group, headed by Prof. Thiele, the manufacturing of very thin tungsten-in –glass electrodes with flanking pipettes. In comparison with classic iontophoresis pipettes, the end product, based on the new Hilgenberg pipettes, has a much better mechanical stability, excellent electrical recording properties and allow for the highly accurate application of the pharmaceuticals of interest.