fabrication of micrometer- and nanometer-sized electrodes
Several procedures of electrode fabrication are established in the group. For active electrode radii of 250 µm down to 10 µm the standard process consists of sealing a platinum wire of defined diameter in a borosilicate glass capillary and subsequent polishing to reveal a regular electrode surface. Alternatively, the electrode tip is melted and pulled out before polishing to obtain electrodes with a lower aspect of insulating sheath to active electrode area. Routine fabrication of nanometer-sized electrodes is much more complicated and the procedure used in the group is quite unique. A small platinum wire of 25 µm diameter is sealed into a quartz glass capillary and pulled out by means of a Sutter P-2000 laser puller. The laser puller allows to fabricate nano-electrodes with electrode diameters between 5 nm and 1 µm. A custom designed polishing unit is used to homogenize the active electrode area and obtain regular disk shaped electrodes.