Novel 3D microelectrodes and pipettes by wet and dry etching

The purpose of this work is to develop novel 3D micro- and nanoelectrodes and pipettes by use of carefully optimised standard microfabrication techniques such as wet (by KOH) and dry silicon etching. Two types of electrodes have been fabricated and characterized: small nanoelectrodes to be used for localised measurements on cell cultures and high aspect ratio scalloped microelectrodes for measurements in brain slices. This paper presents improved fabrication processes for both types of electrodes and the pipettes, as well as the electrical and electrochemical characterization of the small electrodes in order to confirm their functionality. Although functional, an increase in the electrode surface area is needed if they are to be used for electrophysiological measurements. Finally, the pipettes fabricated have openings of the order of 500 nm, which makes them ideal candidates for localised stimulation of cell or brain slice cultures.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We show the reproducible and uniform fabrication of 3D electrodes with tip sizes down to 100 nm. ► The fabrication is based on standard microfabrication processes only. ► Hollow needles to be used as pipettes have been fabricated with openings of 500 nm. ► The electrical characterization of these structures is presented.