Dr. Kevin Otto and collaborators’ article, “Histological evaluation of flexible neural implants; flexibility limit for reducing the tissue response?” was one of the most impactful and highly cited articles in Journal of Neural Engineering over the last 2 years.

The overall impact of this research is to advance the lifetime of neural implants.

One primary objective of the neuroprosthetic field has been to engineer devices that are capable of interfacing with tissue for dozens of years in order for neural implants to be considered a viable treatment option for individuals with neurological disorders or injuries.

The functionality of implanted microelectrodes typically degrades over time and is reported to be associated with a foreign body response that persists as the implant stays in the brain. A number of strategies have been proposed to improve the brain’s foreign body response to neural implants via modulating mechanical and/or biochemical aspects of the device-tissue interface. In order to integrate multiple approaches to devise a complex, multimodal solution, identifying individual factors that critically impact the FBR has been of particular importance.

Resolving the biological tissue response to neural implants requires a multi-dimensional approach. This includes flexibility, dimension, architecture, tethering to the skull, tissue integration, insertion profile, bioactive coatings, and drug release. One or more of these may be limiting factors that dictate the eventual tissue response regardless of improvements in other aspects. This study evaluated the performance limits from softer devices and suggests that softer is better, but may have limited improvement if all other factors remain unchanged.