Implantable intracortical microelectrodes: reviewing the present with a focus on the future

Abstract

Implantable intracortical microelectrodes can record a neuron’s rapidly changing action potentials (spikes). In vivo neural activity recording methods often have either high temporal or spatial resolution, but not both. There is an increasing need to record more neurons over a longer duration in vivo. However, there remain many challenges to overcome before achieving long-term, stable, high-quality recordings and realizing comprehensive, accurate brain activity analysis. Based on the vision of an idealized implantable microelectrode device, the performance requirements for microelectrodes are divided into four aspects, including recording quality, recording stability, recording throughput, and multifunctionality, which are presented in order of importance. The challenges and current possible solutions for implantable microelectrodes are given from the perspective of each aspect. The current developments in microelectrode technology are analyzed and summarized.

Biohybrid neural interfaces: improving the biological integration of neural implants

“…24 Local tissue trauma may also be exacerbated due to mechanical mismatches and implant micromotion caused by normal respiratory and cardiovascular functions. 25,26 This is mainly because conventional NIs rely on electrode arrays made from stiff and inert materials such as platinum (Pt), platinum-iridium (Pt-Ir) or stainless steel, 27,28 which are mechanically distinct from the soft and viscoelastic neural tissues. The perpetuation of local tissue damage further aggravates neuronal depletion leading to a reduction of approximately 40% in the number of viable neurons at the device-tissue interface.…”

Use of 3D Printing Techniques to Fabricate Implantable Microelectrodes for Electrochemical Detection of Biomarkers in the Early Diagnosis of Cardiovascular and Neurodegenerative Diseases

“…Future research could focus on developing multifunctional implantable microelectrodes that detect biomarkers and deliver targeted therapies based on detected biomarker levels. Such devices would enable closed-loop, responsive treatment systems that adjust therapeutic interventions in real-time according to patient needs . This integration of diagnostic and therapeutic capabilities could significantly enhance the precision and effectiveness of treatment strategies for cardiovascular and neurodegenerative diseases.…”

Convergence of Implantable Bioelectronics and Brain–Computer Interfaces

“…(H) High-throughput and high-density 3D electrode array. Redrawn from ref , with permission. Mesh electrodes: (I) Mesh electrodes implanted in brain tissue and the interface between mesh electronics and the brain tissue.…”

“…Since the early stage of implantable BCI devices, rigid probe electrodes have been utilized . Some examples of flexible systems with probe electrodes are a flexible nanoelectronic thread (NET-e) probe (Figure A), a flexible electrode attached to a probe (Figure B), an electrode connected with the auxiliary tool through a probe–hole structure (Figure C), neurotassel electrodes with microelectrode filaments (Figure D), an electrode combined with the auxiliary tool by an electrostatic adsorption (Figure E), a parylene-C neural probe with six poly­(3,4-ethylenedioxythiophene) (PEDOT) nanostructured and gold electrodes (Figure F), high-throughput electrodes with more than 1000 channels (Figure G), and a high-throughput and high-density 3D electrode array (Figure H) …”

“…87 Some examples of flexible systems with probe electrodes are a flexible nanoelectronic thread (NET-e) probe (Figure 2A), 88 a flexible electrode attached to a probe (Figure 2B), 89 an electrode connected with the auxiliary tool through a probe−hole structure (Figure 2C), 90 neurotassel electrodes with microelectrode filaments (Figure 2D), 91 an electrode combined with the auxiliary tool by an electrostatic adsorption (Figure 2E), 92 a parylene-C neural probe with six poly(3,4-ethylenedioxythiophene) (PEDOT) nanostructured and gold electrodes (Figure 2F), 93 high-throughput electrodes with more than 1000 channels (Figure 2G), 7 and a high-throughput and high-density 3D electrode array (Figure 2H). 94 First, these electrodes can contact tissue in a 3D space that increases their efficacy. Second, the stiff construction of probe electrodes makes sensing and stimulating functions more stable than softer constructions.…”