A first study on nanoporous tungsten recording electrodes for deep brain stimulation

The present study compares aspects of the performance of new tungsten (W) nanoporous implantable electrodes to their smooth (non-porous) counterparts. In vivo studies in healthy rats indicated that after four months of implantation the change in the power spectral density function in the low frequency range (which is where the electroencephalogram data reside/EEG) was smaller for the nanoporous recording electrodes, indicating that the porosity allowed to maintain a more consistent reading of the EEG. Molecular dynamics simulations illustrated that during compression, protrusions form on the surface of smooth W microwires, which can produce severe stress concentrations in the brain tissue that damage cells and affect the electrical conductivity. This problem may become critical for thinner electrodes or under abnormal circumstances. Our simulations showed that inducing a porous structure, allowed to dispense such mechanical instabilities. These results indicate that inducing a porosity on the electrode surface increases, both, the in vivo electrical signal and mechanical stability. This is a first study that illustrates possible advantages with respect to signal degradation.