Flexible Polymer Electrodes for Stable Prosthetic Visual Perception in Mice

Brain interfaces that can stimulate neurons, cause minimal damage and work for a long time will be central for future neuroprosthetics. Here we report on the long-term performance of highly flexible, thin polyimide shanks with several small (< 15 μm) electrodes during electrical microstimulation of the visual cortex. The electrodes exhibited a remarkable stability when we applied several billions of electrical pulses in vitro. When we implanted the devices in the primary visual cortex of mice and trained the animals to detect electrical microstimulation, we found that the perceptual thresholds were 2-20 microamperes which was far below the maximal currents that the electrodes could withstand. The long-term functionality of the devices in vivo was excellent, with stable performance for up to more than a year and little damage to the brain tissue. These results demonstrate the potential of thin floating electrodes for the long-term restoration of lost sensory functions. This article is protected by copyright. All rights reserved.