Materials Chemistry of Neural Interface Technologies and Recent Advances in Three-Dimensional Systems

Abstract

Advances in materials chemistry and engineering serve as the basis for multifunctional neural interfaces that span length scales from individual neurons to neural networks, neural tissues, and complete neural systems. Such technologies exploit electrical, electrochemical, optical, and/or pharmacological modalities in sensing and neuromodulation for fundamental studies in neuroscience research, with additional potential to serve as routes for monitoring and treating neurodegenerative diseases and for rehabilitating patients. This review summarizes the essential role of chemistry in this field of research, with an emphasis on recently published results and developing trends. The focus is on enabling materials in diverse device constructs, including their latest utilization in 3D bioelectronic frameworks formed by 3D printing, self-folding, and mechanically guided assembly. A concluding section highlights key challenges and future directions.

Graphdiyne-Based Nanofilms for Compliant On-Skin Sensing

“…Ultrathin, compliant, and conformal on-skin sensors with high imperceptibility have received widespread attention for potential uses in healthcare monitoring, − sensory prosthetics, , and human-machine interfaces. − In this regard, extensive work has been conducted to develop imperceptible electronics , that can mechanically bend and conform to nonplanar and dynamic surfaces to measure subtle deformations and physiological signals. ,, For instance, serpentine and buckled metal interconnections (typically with a thickness of tens of microns) have metallic conductivity and an improved degree of deformability. , Still, they show limited resistance changes (sensitivity) and fabrication complexity . Hybrid structural engineering combined with various nanomaterials such as transitional metal dichalcogenides (TMD), metal–organic frameworks (MOF), and MXenes on a separate substrate have also been developed with improved sensitivity.…”

“…3,11,12 For instance, serpentine and buckled metal interconnections (typically with a thickness of tens of microns) have metallic conductivity and an improved degree of deformability. 13,14 Still, they show limited resistance changes (sensitivity) and fabrication complexity. 15 Hybrid structural engineering 16 combined with various nanomaterials such as transitional metal dichalcogenides (TMD), 17 metal− organic frameworks (MOF), 18 and MXenes 19 on a separate substrate have also been developed with improved sensitivity.…”

Challenges of Emerging Wearable Sensors for Remote Monitoring toward Telemedicine Healthcare

“…Even though some of them have some low piezoelectric coefficients, their flexibility and lightweight properties are fitting for wearable applications . In some extreme circumstances, such as after mechanical damage, stretchability combined with the self-healing ability of the piezo materials’ recovery capability presents a major impact in improving the life span of wearable devices for uninterrupted continuous monitoring. , Given the piezoelectric effect relied on the phenomenon that charge accumulation is induced oppositely on both sides of the dielectric materials, the sensors were limited mostly for physical sensing, pressure sensing, and movement disorders. − To overcome a drawback as piezoelectric inorganics aimed for physical sensing, for instance, the advance of modified piezoelectric polymers was used for neural interface technologies with deeper level sensing of neurotransmitters in the brain . While a large scale of piezoelectric sensors is important for wearable sensor development, movement sensors for health monitoring based on piezoresistive and capacitive responses still have signal crosstalk, which leads for inaccurate measurement.…”

Assembly of complex 3D structures and electronics on curved surfaces

“…Biological systems, including both plants (e.g., stems, flowers, and seeds) and animals (e.g., hearts, alveolus pulmonis, brains, blood vessels, and tracheas), mostly have complex three-dimensional (3D) curved surfaces, some with dynamic, time-varying features. Developments of manufacturing approaches/technologies to allow conformal integration of electronic systems with these 3D surfaces are of utmost importance for high-fidelity information interactions with these biological systems (1,2). The resulting 3D conformal electronic systems have widespread applications in health monitoring (3)(4)(5)(6), human-machine interfaces (7,8), curved displays (9,10), therapeutic devices (11)(12)(13)(14)(15)(16), artificial tissues/organs (17)(18)(19)(20)(21)(22)(23), and fundamental biomedical research (24)(25)(26)(27)(28)(29).…”