Formation of electrically conductive surfaces based on carbon nanomaterials for neurostimulation devices

The paper proposes methods for forming laser-induced carbon nanomaterials for forming electrically conductive surfaces of neurostimulation devices. It was found that under the action of laser radiation with an energy density in the range of 0.001–2.2 J/cm$^2$, depending on the type of nanotubes, a carbon framework structure is formed with bound carbon nanotubes and their bundles in disordered arrays of single-wall carbon nanotubes (SWCNTs) and in vertically oriented arrays of multi-wall carbon nanotubes (MWCNTs) in a bovine serum albumin (BSA) matrix and without it. For a surface based on SWCNTs in a BSA matrix, the effect of vertical orientation of nanotubes perpendicular to the surface was obtained. The specific surface area of the samples with BSA significantly decreased compared to the original nanotube arrays, however, laser exposure provided an increase of 5 and 9 times for samples based on MWCNTs and SWCNTs. Also, the addition of BSA contributed to a significant decrease in electrical conductivity, however, as a result of laser treatment, the electrical conductivity of the MWCNT array increased by 2.2 times to 0.216 kS/m, and the electrical conductivity of the disordered SWCNT array increased by 2.4 times to 0.12 kS/m. The formed surface samples provided the highest value of proliferation of nerve tissue cells compared to the control sample. For a coating of disordered SWCNT arrays in a BSA matrix, an increase in the number of cells by 24% was obtained compared to the control value after 72 hours of incubation. Thus, the formed laser-induced samples based on carbon nanotubes can be used as electrode matrices of implantable neurointerfaces for selective interaction with nerve tissue.