Fabrication of nanoelectrodes for neurophysiology: cathodic electrophoretic paint insulationand focused ion beam milling

Abstract

The fabrication and characterization of tungsten nanoelectrodes insulated with cathodic electrophoreticpaint is described together with their application within the field of neurophysiology. The tip of a127 µm diameter tungsten wire was etched down to less than 100 nm and then insulated withcathodic electrophoretic paint. Focused ion beam (FIB) polishing was employed to removethe insulation at the electrode’s apex, leaving a nanoscale sized conductive tip of100–1000 nm. The nanoelectrodes were examined by scanning electron microscopy (SEM)and their electrochemical properties characterized by steady state linear sweepvoltammetry. Electrode impedance at 1 kHz was measured too. The ability of a 700 nmtipped electrode to record well-isolated action potentials extracellularly from single visualneurons in vivo was demonstrated. Such electrodes have the potential to open newpopulations of neurons to study.