Carbon nanotubes for neuron–electrode interface with improved mechanical performance

The capacity of neuronal cells to elicit and propagate action potentials in response to electrical stimulation is harnessed in neuro-prosthetic devices to restore impaired neuronal activity. Recording and stimulating electrodes are accordingly one of the major building blocks of these systems, and extensive investigations were directed to build better performing electrodes. The electrochemical properties of the electrodes have clearly gained a lot of attention in securing an electrode technology suitable for high signal-to-noise recordings as well as low-power and high-efficacy stimulation. In addition to electrochemical considerations, the design of the electrodes has to take into account multitude of other concerns ranging from surface chemistry, electrode stability, biocompatibility, mechanical properties, to manufacturability. It is now widely accepted that the neuron-electrode interface is considerably impacted by physical cues and that the mechanical properties of the electrode have to be carefully addressed to achieve optimal performances. Mechanical properties affect the manner neurons proliferate, adhere, and possibly operate. In this chapter, we will focus on the mechanical properties of the neuron-electrode interface. We begin by reviewing neuronal mechanics and its relevance to electrode design and performance. In particular, we will address surface properties such as roughness and shape as important properties in the realm of neuronal electrodes. The ultimate aim and focus of this chapter will be to introduce carbon nanotube electrodes as a powerful system for improved mechanical performances and to discuss their unique properties.