A silk-based self-adaptive flexible opto-electro neural probe

Abstract

The combination of optogenetics and electrophysiological recording enables high-precision bidirectional interactions between neural interfaces and neural circuits, which provides a promising approach for the study of progressive neurophysiological phenomena. Opto-electrophysiological neural probes with sufficient flexibility and biocompatibility are desirable to match the low mechanical stiffness of brain tissue for chronic reliable performance. However, lack of rigidity poses challenges for the accurate implantation of flexible neural probes with less invasiveness. Herein, we report a hybrid probe (Silk-Optrode) consisting of a silk protein optical fiber and multiple flexible microelectrode arrays. The Silk-Optrode can be accurately inserted into the brain and perform synchronized optogenetic stimulation and multichannel recording in freely behaving animals. Silk plays an important role due to its high transparency, excellent biocompatibility, and mechanical controllability. Through the hydration of the silk optical fiber, the Silk-Optrode probe enables itself to actively adapt to the environment after implantation and reduce its own mechanical stiffness to implant into the brain with high fidelity while maintaining mechanical compliance with the surrounding tissue. The probes with 128 recording channels can detect high-yield well-isolated single units while performing intracranial light stimulation with low optical losses, surpassing previous work of a similar type. Two months of post-surgery results suggested that as-reported Silk-Optrode probes exhibit better implant-neural interfaces with less immunoreactive glial responses and tissue lesions.

Implantable Neural Microelectrodes: How to Reduce Immune Response

“…With the great transparency and biocompatibility of natural silk and its adjustable properties under different hydration conditions, Zhou et al created a cutting-edge probe called the Silk-Optrode, which was a hybrid device comprising a silk protein optical fiber and multiple flexible microelectrode arrays. 84 This innovative probe enabled optogenetic stimulation and multi-channel recording in freely moving animals in a synchronized manner. Each flexible electrode of this electrode device was composed of 100 nm thick gold microelectrodes with 128 channels, evenly distributed on 4 PI shafts with a thickness of 2.5 μm, an average width of 105 μm, and a length of 5 mm.…”

Wearable and implantable bioelectronics as eco‐friendly and patient‐friendly integrated nanoarchitectonics for next‐generation smart healthcare technology

“…Therefore, it is very difficult for bioelectronics to be in safe contact with the brain and spinal cord, which limits the treatment or regeneration of the nervous system. To address these issues of conventional electronics in the brain and spinal cord, several strategies have been suggested, such as direct drug release at the site of a tumor or lesion, 158 the use of biodegradable electronics to reduce surgical risk, 159 BCI 160 and electrical stimulation to muscles 161 Representatively, Neuralink (owned by Elon Musk) reported a brain‐machine interface platform, which links the brain to a thin film chip via thousands of microchannels 162 . Likewise, microscale electronics and biocompatible multifunctional materials are being utilized more in research.…”

“…To address these issues of conventional electronics in the brain and spinal cord, several strategies have been suggested, such as direct drug release at the site of a tumor or lesion, 158 the use of biodegradable electronics to reduce surgical risk, 159 BCI 160 and electrical stimulation to muscles 161 Representatively, Neuralink (owned by Elon Musk) reported a brain-machine interface platform, which links the brain to a thin film chip via thousands of microchannels. 162 Likewise, microscale electronics and biocompatible multifunctional materials are being utilized more in research. Furthermore, various eco-friendly approaches have been attempted to reduce the environmental costs, such as Mg corrision, 6 deesterification, 6 protein-based electronics, 163 and graphite-related materials.…”

Implantable neural electrodes: from preparation optimization to application

“…Light sources include optical fiber, m-LED array and other light sources, which can be divided into penetrating deep brain and placing in cerebral cortex according to stimulation location. 170,171 Among them, optical fibers, as a common photoconductive device, have been widely used in communication, biomedicine, and other fields, 172 and their surface area can be efficiently integrated into more functions. According to the recent report on the device prepared by combining multi-channel nerve electrode recording with optical fiber, we have drawn the structure diagram of the device, which is mainly divided into two types: the combination of flexible electrode array on the side of the optical fiber, and the combination of optical fiber and electrode self-assembly through elastic capillary (Fig.…”