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

Abstract

The fabrication and characterization of tungsten nanoelectrodes insulated with cathodic electrophoretic paint is described together with their application within the field of neurophysiology. The tip of a 127 μm diameter tungsten wire was etched down to less than 100 nm and then insulated with cathodic electrophoretic paint. Focused ion beam (FIB) polishing was employed to remove the insulation at the electrode's apex, leaving a nanoscale sized conductive tip of 100-1000 nm. The nanoelectrodes were examined by scanning electron microscopy (SEM) and their electrochemical properties characterized by steady state linear sweep voltammetry. Electrode impedance at 1 kHz was measured too. The ability of a 700 nm tipped electrode to record well-isolated action potentials extracellularly from single visual neurons in vivo was demonstrated. Such electrodes have the potential to open new populations of neurons to study.

Ultrasmall and customizable multichannel electrodes for extracellular recordings

“…Furthermore, recording contacts are always opened at the tips of the carbon fibers, and it is not possible to make them along the shank of the fibers with this method. To increase control over geometry of the recording sites, we applied focused ion beam (FIB) milling (Qiao et al 2005) (Helios NanoLab; FEI) to selectively remove the insulation. FIB is a nanomanufacturing technique that utilizes a high-energy ion beam that is focused on the surface of the specimen to produce extremely fine details (working resolution below 10 nm).…”

Recent Advances in Nanotechnology: Potential Prospects in Neuromedicine and Neurosurgery

“…al. [103] demonstrated that 700 nm tipped electrode recorded wellisolated action potentials extracellularly from single visual neurons in vivo. Further experimental studies using sub-100 nm silicon nanowires revealed its integration into live cells without causing detrimental effects.…”

Perisynaptic astroglial processes: dynamic processors of neuronal information

“…Finally one also needs to design electrodes with tip size below 1 lm. Although this can be presently achieved using filamented glass with micropipette puller, nanotechniques such as focused ion beam microscopy (Qiao et al 2005) or carbon nanotubes (Krapf et al 2006) are very promising approaches to produce finer electrodes with a better control. Remarkably, such electrodes will not only enable to patch tiny processes, but shall also contribute to a better signal to noise ratio due their high resistance, as well as minimize deformation of tissue (Scanziani and Häusser 2009).…”