Sonde

摘要

A probe unit (1) includes a disk-like substrate (2) made of transparent material, a transparent electrode (3) coated on all over the substrate (2), and a metal wire (4) whose sharp tip is projected vertically and upwardly from the center of the substrate (2) through the transparent electrode (3). The meal wire (4) is made of Pt-Ir, which incudes a sharp tip projected from the upper surface of the substrate and a stem embedded in a hole of the electrode and fixed to the electrode and substrate by conductive adhesive.