If i remember well, WPI and Harvard Apparatus propose platinum/iridium electrode but perhaps not for in vitro electrophysiology.

https://www.wpiinc.com/electrophysiology/electrodes/single-bipolar-concentric

@yanis inglebert, thanks for your reply, yes indeed they do, but only monopolar electrodes, not the twisted wire ones I am looking for :)

We've constructed our own stimulating electrodes for many years using formvar-insulated nichrome wire (see attached photo). What you need to do is form a loop of wire (e.g. take a length and fold in half so the two ends are lined up) and pass it through a cannula (we use a cut off 26G spinal needle). Put some glue on either end where the wire enters/exits the cannula. Once the glue has dried, twist the ends together by grasping them together and spinning with a hemostat. The looped end at the opposite end of the cannula is then cut, insulation is removed from the ends of the wire with a razor blade, and connectors attached.

Dear Alexander F Hoffman

Thank you very much for your input! That was very helpful! And might I add: what a beautiful picture!

Best

Nikolaj