insulated electrode

Voltage is applied to insulated electrodes with a millimetre-size gap through which the textile passes.

This planar light emitting structure is energized by an AC field from insulated electrodes.

In 1898, Sellier and Verger destroyed discrete areas in the caudate and anterior segment of internal capsule by passing current through double-needle insulated electrodes.

If you were to look at the object in that photograph under a microscope, my guess is you'd find it contains insulated electrodes that receive and process audiograms on particular frequencies.