Multifunctional soft implants to monitor and control neural activity in the central and peripheral nervous system: A review

The development of neural implants is seeking minimally invasive approaches by utilizing novel polymer substrates and integration concepts to interface the living tissue. In the recentyears, versatile, soft, flexible interfaces have been proposed due to the emerging results in micro- and nanoengineering as well as material chemistry. New devices are able to record neural potentials, modulate neuronal populations or peripheral nerves with optogenetic or chemical stimuli controlled in both space and time. Additionally, combination of ECoG recording with other imaging techniques like fMRI or two-photon microscopy may offer new insights into brain function, which requires careful design in terms of material composition and device configuration. The aim of this paper is to give a concise review on the progress in this rapidly developing field focusing on substrate materials, microfabrication techniques and integration concepts. Multiple device functionality and compatibility with other neuroimaging methods will be discussed. Recent findings of in vivo biocompatibility studies on polymer based neural implants will be also summarized. (C) 2016 Elsevier B.V. All rights reserved.