Advances in Soft Bioelectronics for Brain Research and Clinical Neuroengineering

Abstract

Recent advances in bioelectronics, such as skin-mounted electroencephalography sensors, multi-channel neural probes, and closed-loop deep brain stimulators, have enabled electrophysiological brain activities to be both monitored and modulated. Despite this remarkable progress, major challenges remain, which stem from the inherent mechanical, chemical, and electrical differences that exist between brain tissues and bioelectronics. New approaches are therefore required to address these mismatches between biotic and abiotic systems. Here, we review recent technological advances that minimize such mismatches by using unconventional soft materials, such as silicon/metal nanowires, functionalized hydrogels, and stretchable conductive nanocomposites, as well as customized fabrication processes and novel device designs. The resulting novel, soft bioelectronic devices provide new opportunities for brain research and clinical neuroengineering. Advances in bioelectronics for neuroscience and neuroengineering have enabled continuous monitoring of electrophysiological signals and feedback modulation of abnormal brain activities. Despite such progress, there remain issues in terms of long-term high-quality neural interfacing, mainly owing to inherent mechanical, chemical, and electrical mismatches between the device and the brain tissue. New approaches, therefore, are required to address these discrepancies between the biotic and abiotic system. This review introduces technological advances that potentially solve such issues by using soft materials and devices. Specifically, we summarize recent progress in soft materials, such as nanoscale materials, conductive polymers, functionalized hydrogels, and stretchable conductive nanocomposites. These unconventional materials, combined with customized processing techniques and device designs, provide novel soft device solutions for brain science and clinical neuroengineering. Techniques for recording and modulating neural activities are essential for brain science and clinical neuroengineering. This review introduces recent progress on unconventional soft materials and their processing techniques for the fabrication of soft bioelectronic devices. Such approaches could reduce the inherence discrepancies, including mechanical, chemical, and electrical mismatches, between the bioelectronic device and the brain tissue. As a result, the soft bioelectronic devices have successfully enabled high-quality neural interfacing in vivo over long-term periods.