The rise of flexible electronics in neuroscience, from materials selection to in vitro and in vivo applications

Abstract

Neuroscience deals with one of the most complicate system we can study: the brain. The huge amount of connections among the cells and the different phenomena occurring at different scale give rise to a continuous flow of data that have to be collected, analyzed and interpreted. Neuroscientists try to interrogate this complexity to find basic principles underlying brain electrochemical signalling and human/animal behaviour to disclose the mechanisms that trigger neurodegenerative diseases and to understand how restoring damaged brain circuits. The main tool to perform these tasks is a neural interface, a system able to interact with brain tissue at different levels to provide a uni/bidirectional communication path. Recently, breakthroughs coming from various disciplines have been combined to enforce features and potentialities of neural interfaces. Among the different findings, flexible electronics is playing a pivotal role in revolutionizing neural interfaces. In this work, we review the most recent advances in the fabrication of neural interfaces based on flexible electronics. We define challenges and issues to be solved for the application of such platforms and we discuss the different parts of the system regarding improvements in materials selection and breakthrough in applications both for in vitro and in vivo tests.

A Review: Electrode and Packaging Materials for Neurophysiology Recording Implants

“…with desired properties (e.g., signal transduction, amplification, multiplexing, etc.) to achieve a complex, integrated biointerface system (Maiolo et al, 2019 ; Zhang et al, 2020 ). Organic semiconductors provide unique advantages of mechanical compliance, biodegradability, and stretchability.…”

Discussion on the Rehabilitation of Stroke Hemiplegia Based on Interdisciplinary Combination of Medicine and Engineering

“…BCI-based forehead EEGs have also been developed to assess sleep quality and can also be used as a depression treatment screening system, providing new possibilities for the treatment and evaluation of stroke patient sleep and depression risk [ 54 ]. Future efforts to improve BCI for neurorehabilitation include the development of “flexible electronics” [ 55 ] that can provide a flexible hardware platform for signal amplification to achieve closed-loop interaction, in addition to precise sensing functions. The advantages and disadvantages of BCI are summarized in Table 4 .…”

Glial Interfaces: Advanced Materials and Devices to Uncover the Role of Astroglial Cells in Brain Function and Dysfunction

“…Usually, devices with a total thickness in the range of few microns can guarantee a certain degree of stretchability and higher level of conformability, even for implants composed of hybrid materials, like polyimide, and active inorganic films, like metals or silicon semiconductors. [138][139][140][141] Indeed, thin devices may be a suitable strategy to minimize the impact of the implant on brain tissue. In line with this evidence, in a recent work, Luan et al [142] demonstrated that ultraflexible nanoelectronic thread electrodes enable glial scar-free implant integration with impedances, noise levels, single-unit recording yields, and signal amplitudes that are stable up to 3.5 months implantation.…”