Novel electrode technologies for neural recordings

Abstract

Neural recording electrode technologies have contributed considerably to neuroscience by enabling the extracellular detection of low-frequency local field potential oscillations and high-frequency action potentials of single units. Nevertheless, several long-standing limitations exist, including low multiplexity, deleterious chronic immune responses and long-term recording instability. Driven by initiatives encouraging the generation of novel neurotechnologies and the maturation of technologies to fabricate high-density electronics, novel electrode technologies are emerging. Here, we provide an overview of recently developed neural recording electrode technologies with high spatial integration, long-term stability and multiple functionalities. We describe how these emergent neurotechnologies can approach the ultimate goal of illuminating chronic brain activity with minimal disruption of the neural environment, thereby providing unprecedented opportunities for neuroscience research in the future.

An integrated brain-machine interface platform with thousands of channels

“…Microelectrodes are the gold-standard technology for recording action potentials, but there has not been a clinicallytranslatable microelectrode technology for large-scale recordings [11]. This would require a system with material properties that provide high biocompatibility, safety, and longevity.…”

“…Most devices for long-term neural recording are arrays of electrodes made from rigid metals or semiconductors [12,13,14,15,16,17,18]. While rigid metal arrays facilitate penetrating the brain, the size, Young's modulus and bending stiffness mismatches between stiff probes and brain tissue can drive immune responses that limit the function and longevity of these devices [19,11]. Furthermore, the fixed geometry of these arrays constrains the populations of neurons that can be accessed, especially due to the presence of vasculature.…”

Bioinspired Prosthetic Interfaces

“…[203] Some of these strategies are by optimizing the device geometry or using flexible materials that match the mechanical stiffness and strength of surrounding tissue/brain. [204] The overall implantable component should be small in size in airtight packaging (Hermetic package), perform their intended function (biofunctional), and be compatible with modern imaging techniques such as computed tomography and magnetic resonance imaging. [205] Biocompatibility, hemocompatibility, and integration with surrounding tissue is key to reliable signal transmission and minimization of any adverse foreign body response [206] and breach in the blood-brain barrier [207] while the implanted device is in the body.…”

“…[239,240] Further details on the electrical requirements of recording electrodes can be found in a recent review by Hong and Lieber. [204] Other factors such as biocompatibility, hemocompatibility, mechanical integrity, and integration with surrounding tissue mentioned in Section 4.1 also apply to the recording devices.…”

“…In recent years, other forms of neural stimulation have emerged to complement the conventional recording electrodes in probes. [183,204] Two promising methods that complement current techniques will be highlighted here-optogenetics and biochemical drug delivery. Optogenetics uses visible light of defined wavelength to directly stimulate neurons which were genetically modified to express light-sensitive membrane proteins.…”