Focused Ion Beam technology as a fabrication and inspection tool in neuron interfacing

Abstract

Recent trends in the development of devices for electrophysiology involve the fabrication of electrodes with three-dimensional micro- and nanoprotrusions. These devices take advantage of the natural capacity of cells to actively interact with nanostructured substrates in order to realize a more intimate cell-to-electrode coupling. In this chapter, we review the use of focused ion beam (FIB) technology as a versatile tool for fabricating nanostructures of different shape and size on top of freely chosen substrates. This approach allows custom design and fabrication of nanoprotrusions to optimize cell-to-electrode electrical coupling, while at the same time allowing leeway to optimize the microelectronic substrate. Examples of enhanced interaction of cells with nanostructures are reviewed, with respect to nanoprotrusion geometry and surface functionalization, to illustrate the potential of FIB-based deposition as a tool for realizing new types of nanostructures for neurophysiological measurements. Finally, the combined focused ion beam/scanning electron microscope is presented as a tool for investigating the physical basis for interactions between neuronal cell membranes and nanostructured surfaces.