Implantable neural probes represent one the most revolutionary technology of the last years, having experienced a large growth because of the wide range of applications in which they can be adopted, spacing from the treatment of neurological disease to the Internet of Things. They aim to record or stimulate the neurons activity using thin needles to be implanted into the brain cortex, with a depth and location depending on the particular device purposes. The biggest challenge for a more massive use of human machine interfaces for biomedical applications is related to the capability of developing small devices with a high density of recording/stimulation sites, able to last long in a biological medium.